Fist major trip since rebuild

1976GMC

1976GMC

Active member
Dec 16, 2017
260
39
28
Washington State
Hello Fellow GMCers,
While many of you were at Tuscon rally, I had finally had a chance to take my GMC on a major "maiden" voyage after replacing transmission last year.
The round trip was almost 900 miles and the unit ran beautifully. I stayed at 55-60 MPH most of the trip. It seems like that was best speed for
smooth steering and happy sound coming form the engine. Did my best to shift to "S" when heading up long steep grades. That worked well and I'm
finally getting used to it. I have a couple of questions that I hope someone might be able to answer:

1. Once in awhile (especially in heavy stop-and-go city traffic or on long uphills) I could smell the odor of the transmission fluid. Since this was
my unit's first major run since rebuild, first couple times when that happened, I stopped and examined the underside of the coach and all trans cooler
line connectors. All is dry and there is no leaks anywhere. I also checked the transmission vent outlet and there is no fluid coming from there
ether (all dry). Where would this odor be coming from? Is is just venting fumes from transmission?

2. Engine oil pressure was running at 35-40PSI at all times, even at idle. Does it need to be higher/lower, or am I good with this?

3. On my way back (after about 700 miles) I lost an AC compressor belt. I wasn't running AC, so it didn't really matter. This was a new belt. My
question is - what would cause it to fail? Did I install it too tight? Other reasons?

4. Engine temp stayed at 175F most of the time while we were moving. However, I noticed that my GMC REALLY does not like the stop and go traffic in
the big cities. As soon as we slowed down to a crawl or were stuck in standing traffic the temps would slowly creep up to 220F. It was on first
yellow light of the Digi-Pannel and never went above that. Again, as soon as we'd start moving the temp will slowly drop until the next stop... I did
not like that part of the drive :(. Is this normal for the GMC? Suggestions for possible fix?

5. GMC consumes about a quart of oil per fill up (after burning 40+ gallons of fuel). Is this excessive or can I live with it as long as I keep my
eye on it?

Thank you in advance.
Vadim
--
Vadim Jitkov
'76 Glenbrook 26'
Pullman, WA
 
1 not normal. Calibrate stick and try again
2 sounds like a bad oil sender or dirty connection. Lower at idle higher at speed is typical
3 Probably wrong width belt. There is a writeup in the parts interchange
4 sounds like a weak fan clutch not moving air like it should
5 not normal. Your stick may be out of cal which causes you to overfill and sling off excess level by whipping it up and ingesting.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
Note on one. Be sure to use S going down grades as well. Use brakes only to limit engine overspeed not to hold back coach.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
On your question 5 about oil consumption. It has been noted by many on here (myself included) that the top quart of engine oil seems to burn off, then
it will stay at that level for the next 1,000 or 1,500 miles. I believe the consensus is that the extra oil is being flung up onto the cylinder walls
by the crankshaft from the front sump. Once this extra oil is gone the crank does not hit the oil sitting in the front sump.

Someone else may have more details on this.

--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
 
So have much oil should we put in with a new filter to calibrate a new
dipstick?

> On your question 5 about oil consumption. It has been noted by many on
> here (myself included) that the top quart of engine oil seems to burn off,
> then
> it will stay at that level for the next 1,000 or 1,500 miles. I believe
> the consensus is that the extra oil is being flung up onto the cylinder
> walls
> by the crankshaft from the front sump. Once this extra oil is gone the
> crank does not hit the oil sitting in the front sump.
>
> Someone else may have more details on this.
>
> --
> Bruce Hislop
> ON Canada
> 77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
> My Staff says I never listen to them, or something like that
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--

*John Phillips*
 
Coach level, new dry oil filter installed, previously run engine, well
drained of oil.. Pour 5 qts oil into engine. Wait a few minutes to insure
that it has all run down. Check oil with dipstick. It should show one quart
low on the stick. If it does not, mark the stick where the oil level shows
on the stick with a narrow file. This is the add oil mark. Add one quart to
the engine, recheck the dipstick. This is the full level. If it does not
match the factory marks, re mark the stick. This will be low by the amount
the filter holds. After running the engine, and the engine sits for a few
minutes, add oil to the new full mark. Drive it and see if it burns a
similar amount of oil as previously. If not, you could have been
overfilling the engine. If it still burns oil, take an oil sample and send
it to Blackstone lab for analysis. That's what I got.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

On Sat, Apr 14, 2018, 2:07 PM John Phillips
wrote:

> So have much oil should we put in with a new filter to calibrate a new
> dipstick?
>

>
> > On your question 5 about oil consumption. It has been noted by many on
> > here (myself included) that the top quart of engine oil seems to burn
> off,
> > then
> > it will stay at that level for the next 1,000 or 1,500 miles. I believe
> > the consensus is that the extra oil is being flung up onto the cylinder
> > walls
> > by the crankshaft from the front sump. Once this extra oil is gone the
> > crank does not hit the oil sitting in the front sump.
> >
> > Someone else may have more details on this.
> >
> > --
> > Bruce Hislop
> > ON Canada
> > 77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
> > http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
> > My Staff says I never listen to them, or something like that
> >
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
>
>
>
> --
>
> *John Phillips*
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
I did use "S" gear for some of the downhills.

Oil consumption and dipstick calibration: While transmission was out, I took off the oil pan and replaced the oil pan gaskets. I also had to replace
the engine oil cooler lines. This means all the oil was drained out of the engine and engine oil cooler. When getting it back together, I've added 6
quarts of oil (or very close to that). From the owners manual it seem to be exactly what is need to fill when changing the oil and oil filter. The
oil level was exactly at the top of "FULL" line on the dipstick. It does seem like the oil consumption is reduced once it drops down to "ADD ONE
QUART" level mark. Does everyone run their coaches with the oil at that level to prevent crankshaft splashing extra oil around? Would it be a good
idea to try that? Should I run a compression test to make sure rings are good? I will try the calibration method Jim has posted.

Fan clutch: I noticed that the fan starts rotating and blowing air right from the first engine start. With engine off and cold, the blades do spin
freely. If I have engine warmed up to operating temps and try to spin the fan blades (with engine off of course), should the clutch be fully engaged
and have strong resistance to rotation? I never tried that. Will this be an indication of a bad fan clutch? Does anyone have a part number and
recommendation for the brand of the fan clutch to get?

Transmission fluid dip stick is original. I would have thought that its calibrated correctly. I think I've seen the calibration write up somewhere
here for homemade dip sticks. I'll try to check it. The question is still - where does the smell coming form if there is no leaks anywhere and I'm
not loosing trans fluid?

Oil sender: pressure was fluctuating and it does not read the same number all the time. When engine is off and immediately at start it shows 0. Once
engine starts to turn over, you can see the lights on Digi-Pannel go up and up, till about 35 PSI mark (pressure building up). That is where they
stay. Only when revving up above 3,000 RPM (uphills) the pressure would go up to 37-40. How much fluctuation form idle to higher RPM is "normal"?
Are you sure the sender is bad? If so, what part number to use?

--
Vadim Jitkov
'76 Glenbrook 26'
Pullman, WA
 
On engine oil level reading procedure. On Olds the oil fill tube dumps into the front pan section, then tops over into the main pan where the stick
is. The crank slings most oil from the front and into main. So--- when you afd oil, start and run engine, shut off, wait a minuite for drain down.
Check oil level. This is the true level. Otherwise you will be chronically overfilling and ingesting oil.
On trans -- are you checking level hot and running engine in park? Are you sure the smell is not engine oil and is Dexron that different of a
burning smell?
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
Quick and easy fan clutch diag --- after sitting over night you should hear "fan roar" on normal high idle for about 2 mins until the fluid
redistributes after gravity settling over night. Roar should then deminish. Cold if you fling the fan by hand it should not free wheel more than 1/4
turn. See if these tests pass or fail before the next tests and get back to us. There are different fail modes .
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
> Quick and easy fan clutch diag --- after sitting over night you should hear "fan roar" on normal high idle for about 2 mins until the fluid
> redistributes after gravity settling over night. Roar should then deminish. Cold if you fling the fan by hand it should not free wheel more than
> 1/4 turn. See if these tests pass or fail before the next tests and get back to us. There are different fail modes .

Just ran the tests JohnL455 indicated. Flinging the cold fan by hand only rotates it to less than 1/4 turn. Starting the engine (after sitting for
almost 5 days) did not produce any roar at all. Looking at the fan, it does rotate, but it seems like it is definitely not as fast rotation as the
shaft and fan pulley.

I'm pretty sure I've smelled transmission fluid odor on my trip. I'm using Mobil 1 Synthetic ATF and it has very specific odor. Just in case, I've
smelled engine oil dipstick today and it has very different smell. Transmission fluid level is checked with engine running transmission in Park.
Level is just below the top mark (Full Hot). Checked the vent tube on transmission again today - there is absolutely no wetness on the back of
transmission nor any signs of transmission fluid coming from the vent earlier. The trans pan is clean and dry too.
--
Vadim Jitkov
'76 Glenbrook 26'
Pullman, WA
 
As far as using S on down grades,the'man' Manny does NOT recommend down shifting for more than a couple of miles. The trans isn't making enough
pressure on back loading and will be damaged on extended hills. Hal
--
1977 Royale 101348,

1977 Royale 101586, Diesel powered,

1975 Eleganza II, 101230,

1974 Eagle Bus 45',w/slideout,

Rio Rancho, NM
 
Lots of great points made here by previous posters and all were on target.

I have one small suggestion. Because you have worked on it there will always be residual oil hanging around on the outside inside of the engine and
trans and inside the bell housing and on the torque converter. As you drive it and get it hot eventually that oil will not burn but heat up and
evaporate off. If some of it is still there you will only smell it when the engine / trans gets hotter. Do not be surprised if the smell goes away
on it's own as that stiff goes away. Also consider the possibility of an small oil leak onto the exhaust manifold or exhaust system. Also look for a
coolant leak somewhere. It smells too. It might just be stiff left on the outside of the engine and trans or inside the trans bell housing and on
the torque converter. .

As others have said try running 1 quart low. A normal oil change does not drain the front part of the pan so 5 quarts is what it should take on a
change with filter. In your case since you had the pan off and it was empty, it should have taken six.

You can also calibrate the trans stick by running the engine to fill up the torque converted, then shut it off. Pull the modulator immediately
(remove one bolt and pull). Let any excess oil drain out down to the bottom of the modulator hole. Re-inset the modulator and check the level on the
stick ASAP. Mark the stick at that point as that is the full level. Use that point for all future level checks.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
As far as your fan clutch-- sounds like it still has some of it's silicone fluid intact, but perhaps the front bimetalic spring is not turning the
valve with temp changes. They normally weep a tiny bit of fluid up there, and this collects road grunge due to the high air flow it is exposed to.
Before replacing the clutch with a new one of questionable quality, try flushing the spring and rotating valve stem with WD-40 and some air. The space
between the turns of the spring can get totally packed and prevent it from contracting and expanding to turn the valve. Cheap easy fix if it works.
If not you will have to search the archives for the current best choice or upgrade to the MB electro-viscous kit.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
As far as S for ascending, I know Manny prefers that to electrical kick down as higher clutch apply pressure, but not sure I understand the S engine
braking scenario as going down a hill in S the engine will be running about 4000 RPM which should be spinning the pump just fine.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
> Lots of great points made here by previous posters and all were on target.
>
> I have one small suggestion. Because you have worked on it there will always be residual oil hanging around on the outside inside of the engine
> and trans and inside the bell housing and on the torque converter. As you drive it and get it hot eventually that oil will not burn but heat up and
> evaporate off. If some of it is still there you will only smell it when the engine / trans gets hotter. Do not be surprised if the smell goes away
> on it's own as that stiff goes away. Also consider the possibility of an small oil leak onto the exhaust manifold or exhaust system. Also look for
> a coolant leak somewhere. It smells too. It might just be stiff left on the outside of the engine and trans or inside the trans bell housing and
> on the torque converter. .
>
> As others have said try running 1 quart low. A normal oil change does not drain the front part of the pan so 5 quarts is what it should take on a
> change with filter. In your case since you had the pan off and it was empty, it should have taken six.
>
> You can also calibrate the trans stick by running the engine to fill up the torque converted, then shut it off. Pull the modulator immediately
> (remove one bolt and pull). Let any excess oil drain out down to the bottom of the modulator hole. Re-inset the modulator and check the level on
> the stick ASAP. Mark the stick at that point as that is the full level. Use that point for all future level checks.

Good point on the residuals fluids on the housing. It did not occur to me originally, but makes perfect sense. Good plan for both engine oil level
and transmission dipstick check/calibration.

One question related to tansmission dipstick calibration procedure above: do I need to get transmission fluid to operating temperature for this or
having it cold is OK, as long as engine ran for a little bit to fill up the torque converter?

--
Vadim Jitkov
'76 Glenbrook 26'
Pullman, WA
 
> As far as your fan clutch-- sounds like it still has some of it's silicone fluid intact, but perhaps the front bimetalic spring is not turning the
> valve with temp changes. They normally weep a tiny bit of fluid up there, and this collects road grunge due to the high air flow it is exposed to.
> Before replacing the clutch with a new one of questionable quality, try flushing the spring and rotating valve stem with WD-40 and some air. The
> space between the turns of the spring can get totally packed and prevent it from contracting and expanding to turn the valve. Cheap easy fix if it
> works. If not you will have to search the archives for the current best choice or upgrade to the MB electro-viscous kit.

Definitely will try the cleaning procedure.
--
Vadim Jitkov
'76 Glenbrook 26'
Pullman, WA
 
Manny says use trans for going and brakes for stopping.

Sully
77 eleganza 2
Bellevue

On Sat, Apr 14, 2018 at 4:20 PM John R. Lebetski
wrote:

> Note on one. Be sure to use S going down grades as well. Use brakes only
> to limit engine overspeed not to hold back coach.
> --
> John Lebetski
> Woodstock, IL
> 77 Eleganza II
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Problem wth that is that you won't have any brakes left long before you
get to the bottom of that really twisty 7 miles of 6% downgrade. BTDT,
used the S position after the first time it hapened. Believe me, going
into a 50 mph curve at 65 mph with no brakes is not for sissies. Didn't
even consider the 5 miles of 9% grade with the 15 mph speed posted. Even
without the Tee at the bottom, I wouldna.

Ronc

> Sully
> 77 eleganza 2
> Bellevue
>
> On Sat, Apr 14, 2018 at 4:20 PM John R. Lebetski
>

>
> > Note on one. Be sure to use S going down grades as well. Use
> brakes only
> > to limit engine overspeed not to hold back coach.
> > --
> > John Lebetski
> > Woodstock, IL
> > 77 Eleganza II
> >
> >
> > _______________________________________________
> > 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
>
 
> Problem wth that is that you won't have any brakes left long before you
> get to the bottom of that really twisty 7 miles of 6% downgrade. BTDT,
> used the S position after the first time it hapened. Believe me, going
> into a 50 mph curve at 65 mph with no brakes is not for sissies. Didn't
> even consider the 5 miles of 9% grade with the 15 mph speed posted. Even
> without the Tee at the bottom, I wouldna.
>
> Ronc
> Got to do what you've got to do to be safe but your trans won't like it. The pumps only making pressure when driven by the engine, not when
> reverse loading it. Manny went over this in great detail at his Tucson seminar. Uphill, manually pulling it into S applies full pressure vs the old
> kick down switch which only applies partial pressure.
> Hal
> > Sully
> > 77 eleganza 2
> > Bellevue
> >
> > On Sat, Apr 14, 2018 at 4:20 PM John R. Lebetski
> >

> >
> >> Note on one. Be sure to use S going down grades as well. Use
> > brakes only
> >> to limit engine overspeed not to hold back coach.
> >> --
> >> John Lebetski
> >> Woodstock, IL
> >> 77 Eleganza II
> >>
> >>
> >> _______________________________________________
> >> 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
> >
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

--
1977 Royale 101348,

1977 Royale 101586, Diesel powered,

1975 Eleganza II, 101230,

1974 Eagle Bus 45',w/slideout,

Rio Rancho, NM
 
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