The stock temp gauge doesn't really tell you your operating temps. Why that's a problem

B

Bob Dunahugh

New member
Sep 17, 2012
2,784
4
3
Our first 78 Royale came with a Digi panel. I knew my engine temps under al=
l conditions. Then the fire. Bought another 78 Royale. But the Digi panel w=
asn't being made at that time. Both GMC stock temp gauges read the same. B=
ut it didn't take long before I had a feeling that this second Royale was r=
unning hotter. No boil overs. Just did't feel right. So on our next trip. I=
raise the engine cover several times to check the engine temp sender with=
an inferred temp reader. Found that this Royale was generally operating a=
bout 10 degrees hotter with the stock gauge reading in the normal range as=
compared to our first GMC. Jim at Applied GMC had started producing the Di=
gi panel. And had them at the GMCMI rally that we were going too. Installed=
the Digi panel at the rally. On the way home the panel also confirmed wha=
t I thought. So why the running hotter? Checked the thermostat. It was a go=
od operating 180. But I changed to a proper 195. Fan clutch? Maybe. Well =
Jim K at Applied started selling a fan clutch that is controlled by engine =
block sensors. I liked the idea that this system is more proactive in contr=
olling engine heat buildup. Plus I can turn the clutch on for the fan by a =
dash mounted switch when I want. So I bought that fan clutch at the GMCMI r=
ally. I had recently put on an aluminum 307 Olds intake manifold. So I kne=
w the engine was clean inside. Did the engine have a car water pump? Don't =
know. But even if there's a car pump. That's not the real big problem. Next=
I drained the radiator. Put my inspection camera in the radiator. Radiato=
r's my problem. Looked heavily corroded at the crossover tubes. Going to pu=
t the radiator from the burned GMC in soon. Probably check/change water pum=
p anyway while I'm doing other work in that area. Installing more gauges to=
look at isn't the best idea in my opinion. One. I want to be looking at t=
he road for safe driving. Two.The Digi panel has gages. But it's audible a=
larm is your best engine/trans protection. Bob Dunahugh 78 Royale
 
Bob D.: I like your thought process and how you put things in simple term=
s, so we non mechanics can follow along. Thanks for being you and Happy N=
ew Beginnings to you and Linda - have a Gr8 2018. Mike/The Corvair a holi=
c Sent from my iPhone > On Jan 2, 2018, at 11:24 AM, Bob Dunahugh=
wrote: > > Our first 78 Royale came with a Dig=
i panel. I knew my engine temps under all conditions. Then the fire. Bought=
another 78 Royale. But the Digi panel wasn't being made at that time. Both=
GMC stock temp gauges read the same. But it didn't take long before I had=
a feeling that this second Royale was running hotter. No boil overs. Just =
did't feel right. So on our next trip. I raise the engine cover several tim=
es to check the engine temp sender with an inferred temp reader. Found th=
at this Royale was generally operating about 10 degrees hotter with the sto=
ck gauge reading in the normal range as compared to our first GMC. Jim at =
Applied GMC had started producing the Digi panel. And had them at the GMCMI=
rally that we were going too. Installed the Digi panel at the rally. On th=
e way home the panel also confirmed what I thought. So why the running hot=
ter? Checked the thermostat. It was a good operating 180. But I changed to =
a proper 195. Fan clutch? Maybe. Well Jim K at Applied started selling a =
fan clutch that is controlled by engine block sensors. I liked the idea tha=
t this system is more proactive in controlling engine heat buildup. Plus I =
can turn the clutch on for the fan by a dash mounted switch when I want. So=
I bought that fan clutch at the GMCMI rally. I had recently put on an alu=
minum 307 Olds intake manifold. So I knew the engine was clean inside. Did =
the engine have a car water pump? Don't know. But even if there's a car pum=
p. That's not the real big problem. Next I drained the radiator. Put my ins=
pection camera in the radiator. Radiator's my problem. Looked heavily corr=
oded at the crossover tubes. Going to put the radiator from the burned GMC =
in soon. Probably check/change water pump anyway while I'm doing other work=
in that area. Installing more gauges to look at isn't the best idea in my=
opinion. One. I want to be looking at the road for safe driving. Two.The =
Digi panel has gages. But it's audible alarm is your best engine/trans pro=
tection. > > Bob Dunahugh 78 Royale > _____________________________=
__________________ > GMCnet mailing list > Unsubscribe or Change List O=
ptions: > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org=
 
Mike K. Thanks. I think this is more of a problem then is generally though=
t. I pull higher GVW's more then most. And never had any add on items insta=
lled on our 403 GMC. Radiator inspections on attendees GMC's. Might make f=
or a good tech session at the GMCMI rally in Tucson. Line them up, and star=
t checking with my inspection camera. Drain pan, funnel, and the camera. A=
t a cost of FREE. Good idea, or not. Any input out there? Bob Dunahugh =
Our first 78 Royale came with a Digi panel. I knew my eng=
ine temps under all conditions. Then the fire. Bought another 78 Royale. Bu=
t the Digi panel wasn't being made at that time. Both GMC stock temp gauge=
s read the same. But it didn't take long before I had a feeling that this s=
econd Royale was running hotter. No boil overs. Just didn't feel right. So =
on our next trip. I raise the engine cover several times to check the engin=
e temp sender with an inferred temp reader. Found that this Royale was ge=
nerally operating about 10 degrees hotter with the stock gauge reading in t=
he normal range as compared to our first GMC. Jim at Applied GMC had start=
ed producing the Digi panel. And had them at the GMCMI rally that we were g=
oing too. Installed the Digi panel at the rally. On the way home the panel =
also confirmed what I thought. So why the running hotter? Checked the ther=
mostat. It was a good operating 180. But I changed to a proper 195. Fan c=
lutch? Maybe. Well Jim K at Applied started selling a fan clutch that is co=
ntrolled by engine block sensors. I liked the idea that this system is more=
proactive in controlling engine heat buildup. Plus I can turn the clutch o=
n for the fan by a dash mounted switch when I want. So I bought that fan cl=
utch at the GMCMI rally. I had recently put on an aluminum 307 Olds intake=
manifold. So I knew the engine was clean inside. Did the engine have a car=
water pump? Don't know. But even if there's a car pump. That's not the rea=
l big problem. Next I drained the radiator. Put my inspection camera in th=
e radiator. Radiator's my problem. Looked heavily corroded at the crossover=
tubes. Going to put the radiator from the burned GMC in soon. Probably che=
ck/change water pump anyway while I'm doing other work in that area. Instal=
ling more gauges to look at isn't the best idea in my opinion. One. I want=
to be looking at the road for safe driving. Two. The Digi panel has gages=
. But it's audible alarm is your best engine/trans protection. Bob Du=
nahugh 78 Royale
 
Bob: I really like your idea for the tech session. Another way to help =
fellow GMCers! Assuming we get there (we are planning on it), I would like=
my Dream Machine checked in this way - I also would be interested in assis=
ting you in this endeavor if you could use an amateur!!! Mike/The Corvair=
a holic Sent from my iPhone > On Jan 2, 2018, at 5:08 PM, Bob Du=
nahugh wrote: > > Mike K. Thanks. I think this=
is more of a problem then is generally thought. I pull higher GVW's more t=
hen most. And never had any add on items installed on our 403 GMC. Radiator=
inspections on attendees GMC's. Might make for a good tech session at the=
GMCMI rally in Tucson. Line them up, and start checking with my inspection=
camera. Drain pan, funnel, and the camera. At a cost of FREE. Good idea, =
or not. Any input out there? Bob Dunahugh > > > > > > =
> Our first 78 Royale came with a Digi panel. I knew my engine temps und=
er all conditions. Then the fire. Bought another 78 Royale. But the Digi pa=
nel wasn't being made at that time. Both GMC stock temp gauges read the sa=
me. But it didn't take long before I had a feeling that this second Royale =
was running hotter. No boil overs. Just didn't feel right. So on our next t=
rip. I raise the engine cover several times to check the engine temp sende=
r with an inferred temp reader. Found that this Royale was generally opera=
ting about 10 degrees hotter with the stock gauge reading in the normal ra=
nge as compared to our first GMC. Jim at Applied GMC had started producing =
the Digi panel. And had them at the GMCMI rally that we were going too. Ins=
talled the Digi panel at the rally. On the way home the panel also confirm=
ed what I thought. So why the running hotter? Checked the thermostat. It wa=
s a good operating 180. But I changed to a proper 195. Fan clutch? Maybe.=
Well Jim K at Applied started selling a fan clutch that is controlled by e=
ngine block sensors. I liked the idea that this system is more proactive in=
controlling engine heat buildup. Plus I can turn the clutch on for the fan=
by a dash mounted switch when I want. So I bought that fan clutch at the G=
MCMI rally. I had recently put on an aluminum 307 Olds intake manifold. So=
I knew the engine was clean inside. Did the engine have a car water pump? =
Don't know. But even if there's a car pump. That's not the real big problem=
. Next I drained the radiator. Put my inspection camera in the radiator. R=
adiator's my problem. Looked heavily corroded at the crossover tubes. Going=
to put the radiator from the burned GMC in soon. Probably check/change wat=
er pump anyway while I'm doing other work in that area. Installing more gau=
ges to look at isn't the best idea in my opinion. One. I want to be lookin=
g at the road for safe driving. Two. The Digi panel has gages. But it's au=
dible alarm is your best engine/trans protection. > > Bob Dunahugh 7=
8 Royale > _______________________________________________ > GMCnet mai=
ling list > Unsubscribe or Change List Options: > http://list.gmcnet.or=
g/mailman/listinfo/gmclist_list.gmcnet.org
 
Good, idea, and as a bonus the coolant gets changed, which is likely long overdue :)
--
Cary, NC

1978 Center Kitchen Royale.
 
Pete,
The factory temp gauge sender has caused a number of issues. The range indicated is really not useful or a good indication of actual engine temp and you can damage an engine thinking that you have been a safe zone. Go to the following information:

http://bdub.net/gmcmotorhome.info/engine.html

If you are running the stock radiator you should be running a 9# cap and they are still available and never more than a 10# cap. You can damage the radiator by using any higher pressure rated cap. The aluminum radiators typically use a 14-16# rated cap because they are built differently and do not expand and contract like the stock one would with a higher rated cap.

http://bdub.net/gmcmotorhome.info/engine.html

Regards,

J.R. Wright
GMC GreatLakerTech Editor
78 Buskirk 30' Stretch
75 Avion Under Reconstruction
Michigan (On Location in Tucson)

>
> Good, idea, and as a bonus the coolant gets changed, which is likely long overdue :)
> --
> Cary, NC
>
> 1978 Center Kitchen Royale.
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
I replaced the OEM temp sender. That thing is terrible.

Go to NAPA and get a TS-6469 sender and it will show:
1/4= 180 degrees,
1/2 = 215 degrees,
3/4 = 240 degrees, and
H = 255 degrees.

http://bdub.net/gmcmotorhome.info/engine.html
[http://bdub.net/gmcmotorhome.info/figs/dists.jpg]http://bdub.net/gmcmotorhome.info/engine.html

ENGINE - GMC MOTORHOME INFORMATIONhttp://bdub.net/gmcmotorhome.info/engine.html
gmcmotorhome.info
Supplementing the September 2007 issue of GMC Motorhome News, Sam Carson of Indian Harbour Beach, Florida, has advised that new American Petroleum Institute (API) SM ...

________________________________
From: Gmclist on behalf of John Wright
Sent: Wednesday, January 3, 2018 9:36:18 AM
To: gmclist
Subject: Re: [GMCnet] The stock temp gauge doesn't really tell you your operating temps. Why that's a problem

Pete,
The factory temp gauge sender has caused a number of issues. The range indicated is really not useful or a good indication of actual engine temp and you can damage an engine thinking that you have been a safe zone. Go to the following information:

http://bdub.net/gmcmotorhome.info/engine.html

If you are running the stock radiator you should be running a 9# cap and they are still available and never more than a 10# cap. You can damage the radiator by using any higher pressure rated cap. The aluminum radiators typically use a 14-16# rated cap because they are built differently and do not expand and contract like the stock one would with a higher rated cap.

http://bdub.net/gmcmotorhome.info/engine.html

Regards,

J.R. Wright
GMC GreatLakerTech Editor
78 Buskirk 30' Stretch
75 Avion Under Reconstruction
Michigan (On Location in Tucson)

>
> Good, idea, and as a bonus the coolant gets changed, which is likely long overdue :)
> --
> Cary, NC
>
> 1978 Center Kitchen Royale.
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Thanks John W.:
Good info and well stated.
I love it when you knowledgeable guys share good info so directly that a non mechanic like myself can learn from it.
Have Gr8 2018

Sent from my iPhone

>
> Pete,
> The factory temp gauge sender has caused a number of issues. The range indicated is really not useful or a good indication of actual engine temp and you can damage an engine thinking that you have been a safe zone. Go to the following information:
>
> http://bdub.net/gmcmotorhome.info/engine.html
>
> If you are running the stock radiator you should be running a 9# cap and they are still available and never more than a 10# cap. You can damage the radiator by using any higher pressure rated cap. The aluminum radiators typically use a 14-16# rated cap because they are built differently and do not expand and contract like the stock one would with a higher rated cap.
>
> http://bdub.net/gmcmotorhome.info/engine.html
>
> Regards,
>
> J.R. Wright
> GMC GreatLakerTech Editor
> 78 Buskirk 30' Stretch
> 75 Avion Under Reconstruction
> Michigan (On Location in Tucson)
>
>

>>
>> Good, idea, and as a bonus the coolant gets changed, which is likely long overdue :)
>> --
>> Cary, NC
>>
>> 1978 Center Kitchen Royale.
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
To John W.:
Oops - hit send button B 4 I identified myself.
Have a Gr8 2018.
Mike/The Corvair a holic (also a GMC 6 Wheeler)

Sent from my iPhone

>
> Pete,
> The factory temp gauge sender has caused a number of issues. The range indicated is really not useful or a good indication of actual engine temp and you can damage an engine thinking that you have been a safe zone. Go to the following information:
>
> http://bdub.net/gmcmotorhome.info/engine.html
>
> If you are running the stock radiator you should be running a 9# cap and they are still available and never more than a 10# cap. You can damage the radiator by using any higher pressure rated cap. The aluminum radiators typically use a 14-16# rated cap because they are built differently and do not expand and contract like the stock one would with a higher rated cap.
>
> http://bdub.net/gmcmotorhome.info/engine.html
>
> Regards,
>
> J.R. Wright
> GMC GreatLakerTech Editor
> 78 Buskirk 30' Stretch
> 75 Avion Under Reconstruction
> Michigan (On Location in Tucson)
>
>

>>
>> Good, idea, and as a bonus the coolant gets changed, which is likely long overdue :)
>> --
>> Cary, NC
>>
>> 1978 Center Kitchen Royale.
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Pete. That's a good idea. The owner could just bring new antifreeze. Flush=
, and then put the new antifreeze in. Have to find out what's the best way =
to dispose the old antifreeze there. We'd also have to have a pre event reg=
istration list to know what to be prepared for. Bob Dunahugh M=
ike K. Thanks. I think this is more of a problem then is generally thought=
. I pull higher GVW's more then most. And never had any add on items instal=
led on our 403 GMC. Radiator inspections on attendees GMC's. Might make fo=
r a good tech session at the GMCMI rally in Tucson. Line them up, and start=
checking with my inspection camera. Drain pan, funnel, and the camera. At=
a cost of FREE. Good idea, or not. Any input out there? Bob Dunahugh =
Our first 78 Royale came with a Digi panel. I knew my eng=
ine temps under all conditions. Then the fire. Bought another 78 Royale. Bu=
t the Digi panel wasn't being made at that time. Both GMC stock temp gauge=
s read the same. But it didn't take long before I had a feeling that this s=
econd Royale was running hotter. No boil overs. Just didn't feel right. So =
on our next trip. I raise the engine cover several times to check the engin=
e temp sender with an inferred temp reader. Found that this Royale was ge=
nerally operating about 10 degrees hotter with the stock gauge reading in t=
he normal range as compared to our first GMC. Jim at Applied GMC had start=
ed producing the Digi panel. And had them at the GMCMI rally that we were g=
oing too. Installed the Digi panel at the rally. On the way home the panel =
also confirmed what I thought. So why the running hotter? Checked the ther=
mostat. It was a good operating 180. But I changed to a proper 195. Fan c=
lutch? Maybe. Well Jim K at Applied started selling a fan clutch that is co=
ntrolled by engine block sensors. I liked the idea that this system is more=
proactive in controlling engine heat buildup. Plus I can turn the clutch o=
n for the fan by a dash mounted switch when I want. So I bought that fan cl=
utch at the GMCMI rally. I had recently put on an aluminum 307 Olds intake=
manifold. So I knew the engine was clean inside. Did the engine have a car=
water pump? Don't know. But even if there's a car pump. That's not the rea=
l big problem. Next I drained the radiator. Put my inspection camera in th=
e radiator. Radiator's my problem. Looked heavily corroded at the crossover=
tubes. Going to put the radiator from the burned GMC in soon. Probably che=
ck/change water pump anyway while I'm doing other work in that area. Instal=
ling more gauges to look at isn't the best idea in my opinion. One. I want=
to be looking at the road for safe driving. Two. The Digi panel has gages=
. But it's audible alarm is your best engine/trans protection. Bob Du=
nahugh 78 Royale
 
The radiator cap should also be tested. Most only last about 2 years. The spring weakens as it opens and closes thousands of times on a trip. And the rubber seals deteriotate over time.

I have a Stant pressure gauge that I use. It can also pressurize the radiator cold so it can be checked for leaks, bad hose connections, etc. I can bring that tester to the rally

I once made a bet at a GMC Classics rally that at least half of the motorhome there would have bad radiator caps. Of the 24 tested 17 had bad caps!

Emery Stora

>
> Pete. That's a good idea. The owner could just bring new antifreeze. Flush, and then put the new antifreeze in. Have to find out what's the best way to dispose the old antifreeze there. We'd also have to have a pre event registration list to know what to be prepared for. Bob Dunahugh
>
>
>
> Mike K. Thanks. I think this is more of a problem then is generally thought. I pull higher GVW's more then most. And never had any add on items installed on our 403 GMC. Radiator inspections on attendees GMC's. Might make for a good tech session at the GMCMI rally in Tucson. Line them up, and start checking with my inspection camera. Drain pan, funnel, and the camera. At a cost of FREE. Good idea, or not. Any input out there? Bob Dunahugh
>
>
>
>
>
>
> Our first 78 Royale came with a Digi panel. I knew my engine temps under all conditions. Then the fire. Bought another 78 Royale. But the Digi panel wasn't being made at that time. Both GMC stock temp gauges read the same. But it didn't take long before I had a feeling that this second Royale was running hotter. No boil overs. Just didn't feel right. So on our next trip. I raise the engine cover several times to check the engine temp sender with an inferred temp reader. Found that this Royale was generally operating about 10 degrees hotter with the stock gauge reading in the normal range as compared to our first GMC. Jim at Applied GMC had started producing the Digi panel. And had them at the GMCMI rally that we were going too. Installed the Digi panel at the rally. On the way home the panel also confirmed what I thought. So why the running hotter? Checked the thermostat. It was a good operating 180. But I changed to a proper 195. Fan clutch? Maybe. Well Jim K at Applied
> started selling a fan clutch that is controlled by engine block sensors. I liked the idea that this system is more proactive in controlling engine heat buildup. Plus I can turn the clutch on for the fan by a dash mounted switch when I want. So I bought that fan clutch at the GMCMI rally. I had recently put on an aluminum 307 Olds intake manifold. So I knew the engine was clean inside. Did the engine have a car water pump? Don't know. But even if there's a car pump. That's not the real big problem. Next I drained the radiator. Put my inspection camera in the radiator. Radiator's my problem. Looked heavily corroded at the crossover tubes. Going to put the radiator from the burned GMC in soon. Probably check/change water pump anyway while I'm doing other work in that area. Installing more gauges to look at isn't the best idea in my opinion. One. I want to be looking at the road for safe driving. Two. The Digi panel has gages. But it's audible alarm is your best engine/trans
> protection.
>
> Bob Dunahugh 78 Royale
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Hi Bob D.: Would there be a source of distilled water there or should we =
each bring our own water also? I am sure we could buy 2 or 3 Gallons from =
the local Walmart or such! I am really liking this idea for a tech sessio=
n. Mike/The Corvair a holic Sent from my iPhone > On Jan 3, 201=
8, at 10:43 AM, Bob Dunahugh wrote: > > Pete. T=
hat's a good idea. The owner could just bring new antifreeze. Flush, and t=
hen put the new antifreeze in. Have to find out what's the best way to disp=
ose the old antifreeze there. We'd also have to have a pre event registrati=
on list to know what to be prepared for. Bob Dunahugh > > > > =
Mike K. Thanks. I think this is more of a problem then is generally though=
t. I pull higher GVW's more then most. And never had any add on items insta=
lled on our 403 GMC. Radiator inspections on attendees GMC's. Might make f=
or a good tech session at the GMCMI rally in Tucson. Line them up, and star=
t checking with my inspection camera. Drain pan, funnel, and the camera. A=
t a cost of FREE. Good idea, or not. Any input out there? Bob Dunahugh =
> > > > > > > Our first 78 Royale came with a Digi panel.=
I knew my engine temps under all conditions. Then the fire. Bought another=
78 Royale. But the Digi panel wasn't being made at that time. Both GMC sto=
ck temp gauges read the same. But it didn't take long before I had a feeli=
ng that this second Royale was running hotter. No boil overs. Just didn't f=
eel right. So on our next trip. I raise the engine cover several times to c=
heck the engine temp sender with an inferred temp reader. Found that this=
Royale was generally operating about 10 degrees hotter with the stock gaug=
e reading in the normal range as compared to our first GMC. Jim at Applied=
GMC had started producing the Digi panel. And had them at the GMCMI rally =
that we were going too. Installed the Digi panel at the rally. On the way h=
ome the panel also confirmed what I thought. So why the running hotter? Ch=
ecked the thermostat. It was a good operating 180. But I changed to a prop=
er 195. Fan clutch? Maybe. Well Jim K at Applied started selling a fan clu=
tch that is controlled by engine block sensors. I liked the idea that this =
system is more proactive in controlling engine heat buildup. Plus I can tur=
n the clutch on for the fan by a dash mounted switch when I want. So I boug=
ht that fan clutch at the GMCMI rally. I had recently put on an aluminum 3=
07 Olds intake manifold. So I knew the engine was clean inside. Did the eng=
ine have a car water pump? Don't know. But even if there's a car pump. That=
's not the real big problem. Next I drained the radiator. Put my inspection=
camera in the radiator. Radiator's my problem. Looked heavily corroded at=
the crossover tubes. Going to put the radiator from the burned GMC in soon=
. Probably check/change water pump anyway while I'm doing other work in tha=
t area. Installing more gauges to look at isn't the best idea in my opinio=
n. One. I want to be looking at the road for safe driving. Two. The Digi p=
anel has gages. But it's audible alarm is your best engine/trans protectio=
n. > > Bob Dunahugh 78 Royale > ___________________________________=
____________ > GMCnet mailing list > Unsubscribe or Change List Options=
: > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Emery S.:
More good GMC info and distinctly stated for us non mechanics - Well done and thanks!!!
I love this site and you guys who share good info (in a direct and easy to follow method).
Mike/The Corvair a holic
And a GMC 6 Wheeler in IL.

Sent from my iPhone

>
> The radiator cap should also be tested. Most only last about 2 years. The spring weakens as it opens and closes thousands of times on a trip. And the rubber seals deteriotate over time.
>
> I have a Stant pressure gauge that I use. It can also pressurize the radiator cold so it can be checked for leaks, bad hose connections, etc. I can bring that tester to the rally
>
> I once made a bet at a GMC Classics rally that at least half of the motorhome there would have bad radiator caps. Of the 24 tested 17 had bad caps!
>
> Emery Stora
>

>>
>> Pete. That's a good idea. The owner could just bring new antifreeze. Flush, and then put the new antifreeze in. Have to find out what's the best way to dispose the old antifreeze there. We'd also have to have a pre event registration list to know what to be prepared for. Bob Dunahugh
>>
>>
>>
>> Mike K. Thanks. I think this is more of a problem then is generally thought. I pull higher GVW's more then most. And never had any add on items installed on our 403 GMC. Radiator inspections on attendees GMC's. Might make for a good tech session at the GMCMI rally in Tucson. Line them up, and start checking with my inspection camera. Drain pan, funnel, and the camera. At a cost of FREE. Good idea, or not. Any input out there? Bob Dunahugh
>>
>>
>>
>>
>>
>>
>> Our first 78 Royale came with a Digi panel. I knew my engine temps under all conditions. Then the fire. Bought another 78 Royale. But the Digi panel wasn't being made at that time. Both GMC stock temp gauges read the same. But it didn't take long before I had a feeling that this second Royale was running hotter. No boil overs. Just didn't feel right. So on our next trip. I raise the engine cover several times to check the engine temp sender with an inferred temp reader. Found that this Royale was generally operating about 10 degrees hotter with the stock gauge reading in the normal range as compared to our first GMC. Jim at Applied GMC had started producing the Digi panel. And had them at the GMCMI rally that we were going too. Installed the Digi panel at the rally. On the way home the panel also confirmed what I thought. So why the running hotter? Checked the thermostat. It was a good operating 180. But I changed to a proper 195. Fan clutch? Maybe. Well Jim K at Applied
>> started selling a fan clutch that is controlled by engine block sensors. I liked the idea that this system is more proactive in controlling engine heat buildup. Plus I can turn the clutch on for the fan by a dash mounted switch when I want. So I bought that fan clutch at the GMCMI rally. I had recently put on an aluminum 307 Olds intake manifold. So I knew the engine was clean inside. Did the engine have a car water pump? Don't know. But even if there's a car pump. That's not the real big problem. Next I drained the radiator. Put my inspection camera in the radiator. Radiator's my problem. Looked heavily corroded at the crossover tubes. Going to put the radiator from the burned GMC in soon. Probably check/change water pump anyway while I'm doing other work in that area. Installing more gauges to look at isn't the best idea in my opinion. One. I want to be looking at the road for safe driving. Two. The Digi panel has gages. But it's audible alarm is your best engine/trans
>> protection.
>>
>> Bob Dunahugh 78 Royale
>> _______________________________________________
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>
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> GMCnet mailing list
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G'day,

I hate to rain on your parade but I would suggest someone check with Kim Weeks before this party gets going as the KOA in Tucson
might not allow work like this to be done or having gallons anti-freeze dumped in their sewers, rain water drains, or on the ground.

Google "how to dispose of anti-freeze" and see what comes up.

Regards,
Rob M.
The Pedantic Mechanic
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808
 
I take old coolant to Advacnce since they're closest. All cooling system work around here is done outside the fence... we got dogs.

--johnny
--
76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
"I forgive them all, save those who hurt the dogs. They must answer to me in hell" - ol Andy, paraphrased
 
Rob
Just about any auto parts store in the US will take used antifreeze just as they will take used motor oil and transmission fluid.
There are services that come around to auto parts stores and pump out their tanks of use material. Some even pay the store for it.

Bob has already checked that out.

Emery Stora
77 Kingsley
Frederick, CO

>
> G'day,
>
> I hate to rain on your parade but I would suggest someone check with Kim Weeks before this party gets going as the KOA in Tucson
> might not allow work like this to be done or having gallons anti-freeze dumped in their sewers, rain water drains, or on the ground.
>
> Google "how to dispose of anti-freeze" and see what comes up.
>
> Regards,
> Rob M.
> The Pedantic Mechanic
> Sydney, Australia
> AUS '75 Avion - The Blue Streak TZE365V100428
> USA '75 Avion - Double Trouble TZE365V100426
> USA '77 Kingsley - TZE 267V100808
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Bob -

Would it be possible to pass the camera in with the coolant still in on at least the first few coaches? You migh find you don't need to drain the
system. You ought to be able to quickly tell if that's a viable alternative.

--johnny
--
76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
"I forgive them all, save those who hurt the dogs. They must answer to me in hell" - ol Andy, paraphrased
 
Johonny. The problem s there are that the radiator should be full if the o=
verflow tank is at it's correct level. Next. The corrosion at the top could=
be drastically different farther down. The radiators have drains at the bo=
ttom that is simple to open. Good thought though. Bob Dunahugh __=
______________________________ From: Bob Dunahugh =
Sent: Tuesday, January 2, 2018 5:08 PM To: gmclist S=
ubject: RE: The stock temp gauge doesn't really tell you your operating tem=
ps. Why that's a problem Mike K. Thanks. I think this is more of a=
problem then is generally thought. I pull higher GVW's more then most. And=
never had any add on items installed on our 403 GMC. Radiator inspections =
on attendees GMC's. Might make for a good tech session at the GMCMI rally =
in Tucson. Line them up, and start checking with my inspection camera. Drai=
n pan, funnel, and the camera. At a cost of FREE. Good idea, or not. Any =
input out there? Bob Dunahugh Our first 78 Royale came=
with a Digi panel. I knew my engine temps under all conditions. Then the f=
ire. Bought another 78 Royale. But the Digi panel wasn't being made at that=
time. Both GMC stock temp gauges read the same. But it didn't take long b=
efore I had a feeling that this second Royale was running hotter. No boil o=
vers. Just didn't feel right. So on our next trip. I raise the engine cover=
several times to check the engine temp sender with an inferred temp reade=
r. Found that this Royale was generally operating about 10 degrees hotter =
with the stock gauge reading in the normal range as compared to our first =
GMC. Jim at Applied GMC had started producing the Digi panel. And had them =
at the GMCMI rally that we were going too. Installed the Digi panel at the =
rally. On the way home the panel also confirmed what I thought. So why the=
running hotter? Checked the thermostat. It was a good operating 180. But I=
changed to a proper 195. Fan clutch? Maybe. Well Jim K at Applied starte=
d selling a fan clutch that is controlled by engine block sensors. I liked =
the idea that this system is more proactive in controlling engine heat buil=
dup. Plus I can turn the clutch on for the fan by a dash mounted switch whe=
n I want. So I bought that fan clutch at the GMCMI rally. I had recently p=
ut on an aluminum 307 Olds intake manifold. So I knew the engine was clean =
inside. Did the engine have a car water pump? Don't know. But even if there=
's a car pump. That's not the real big problem. Next I drained the radiator=
. Put my inspection camera in the radiator. Radiator's my problem. Looked =
heavily corroded at the crossover tubes. Going to put the radiator from the=
burned GMC in soon. Probably check/change water pump anyway while I'm doin=
g other work in that area. Installing more gauges to look at isn't the bes=
t idea in my opinion. One. I want to be looking at the road for safe drivin=
g. Two. The Digi panel has gages. But it's audible alarm is your best eng=
ine/trans protection. Bob Dunahugh 78 Royale
 
> Bob -
>
> Would it be possible to pass the camera in with the coolant still in on at least the first few coaches? You migh find you don't need to drain the
> system. You ought to be able to quickly tell if that's a viable alternative.
>
> --johnny

Johnny,

While the coolant should be clear, it seldom truly is. Even if it were, where you need to see is inside the tubes most places and between the fins in
Michigan. Our radiators get attacked from the outside by the copious amount of fender solvent spread on the roads in winter so that the bozos that
insist on driving faster than the conditions should allow don't hurt innocent people.

For a state that gets some snow every year, an amazing number of drivers show up at the first fall that seem to have never ever seen it before.

Matt

--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
 
looking at the fins isn't going to matter whether there's coolant in the radiator or not since they're outside the tubes. A quick look inside might
well show clear coolant and smooth tubes, negating the need to drain the thing. It might not. The salient point is, neither I nor you nor Bob knows
whether this is a worthwhile action or not until it's tried. Given the ease and simplicity, it ought to be worth a try, which would tell us quickly a
usable technique or not.

--johnny
--
76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
"I forgive them all, save those who hurt the dogs. They must answer to me in hell" - ol Andy, paraphrased
 
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