Complete new radiator experiment for $225

T

tyler

Active member
Jun 22, 2013
515
96
28
Putting this out for feedback - cost effective, all new, and minimal fabrication work is my goal. What capacity, thermal efficiency, air flow, or
other pros/cons do you anticipate?

I bought this radiator from Advance Auto, part 433730, to check fit, it is about as wide as OEM, and about five inches short. It has a tranny cooler
in tank on pass side. $150 w coupons. It is listed/findable under a 1980 Chevy K30 with a 454 engine:

https://shop.advanceautoparts.com/p/carquest-radiator-433730/5891175-P?searchTerm=radiators

I bought this oil cooler. It is searchable as a 1985 RX7 engine oil cooler.
https://www.amazon.com/ALUMINUM-OIL-COOLER-MAZDA-OILCOOLER/dp/B07GRPTCG9/ref=sr_1_5?keywords=rx7+engine+oil+cooler&qid=1580822346&sr=8-5

I have a 455 with the early version 80% fan shroud. Radiator core is exact same width as TZE OEM, tanks are inch narrower each.

My situation was such that I have to do new transmission cooler and lines, new oil cooler and lines, and engine coolant radiator anyway. I wanted to
cut the support frame for easier removal if ever needed again. Most of what I am having to do would occur even if I went back with an original/size
shape. And there is the cost - If you went with a more standard, square, external oil cooler this could come in under $200. I wanted the oil cooler in
the gap left by the smaller coolant radiator

The coolant radiator will be flush to original frame top, the tranny cooler is internal on passenger side, and the oil cooler will occupy passenger
side 2/3 of bottom gap, with an air dam built for driver side bottom gap (about 16x5 inches). Plan is to make oil cooler removable separate from main
engine radiator when I do the frame split.

http://www.gmcmhphotos.com/photos/data/7272/medium/S6300674.JPG

http://www.gmcmhphotos.com/photos/data/7272/medium/S6300675.JPG

Thoughts?

--
1975 Glenbrook, 1978 Royale rear bath
Raleigh, NC
 
The only question would be thermal capacity. i.e. with the trans and oil coolers outboard will that radiator remove enough heat from the coolant to
preclude overheating when you're pulling a long grade. Given the cost savings, how's to try it out and report back? Unlike the all metal originals,
that one's a throwaway when it leaks isn't it?

--johnny
--
Foolish Carriage, 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
 
Yes Johnny...from some reading the key term i looked for is "heat rejection rating" and I have not been able to find that kind of info on much of
anything. So I'm left with logic deduced from other GM engineering (if flawed interpretation, i'm open to other considerations). The radiator I chose
is from a GVWR vehicle rated at 10000 pounds, rated to tow another 10000. The million factors of gears, and fins, and materials and whatever seems ad
infinitum. But a nearly identical engine with a carburetor moving 20000 pounds down the road seems comparable.

And for more armchair engineering, the Griffin aluminum (better in every way, and four times the cost) - claims 30% better cooling. If that is similar
construction to my K30 experiment, I have reduced surface area by 25%, so I should not be losing total. (I'm posting all this to exhange ideas, if
this is wacky in real world, y'all speak up). Plus, I have moved a better oil cooler into its own clean air flow, which in my head gives some margin
back.

--
1975 Glenbrook, 1978 Royale rear bath
Raleigh, NC
 
This scenario reminds me of something my Mother told me. Does the old
saying "Penny Wise and Pound Foolish" apply here?
Kinda like, "Hey! Hey! Watch this. Here, hold my beer."
Installing a smaller radiator, and doing a lot of modifications to
"make it fit" just because it is cheaper than OEM, is not likely to ease
your overheating problem.
Do the math. New engine vs cheap radiator?? Hmmmm.
Jim Hupy
Salem, Oregon

On Tue, Feb 4, 2020, 7:48 AM Tyler via Gmclist
wrote:

> Yes Johnny...from some reading the key term i looked for is "heat
> rejection rating" and I have not been able to find that kind of info on
> much of
> anything. So I'm left with logic deduced from other GM engineering (if
> flawed interpretation, i'm open to other considerations). The radiator I
> chose
> is from a GVWR vehicle rated at 10000 pounds, rated to tow another 10000.
> The million factors of gears, and fins, and materials and whatever seems ad
> infinitum. But a nearly identical engine with a carburetor moving 20000
> pounds down the road seems comparable.
>
> And for more armchair engineering, the Griffin aluminum (better in every
> way, and four times the cost) - claims 30% better cooling. If that is
> similar
> construction to my K30 experiment, I have reduced surface area by 25%, so
> I should not be losing total. (I'm posting all this to exhange ideas, if
> this is wacky in real world, y'all speak up). Plus, I have moved a better
> oil cooler into its own clean air flow, which in my head gives some margin
> back.
>
>
> --
> 1975 Glenbrook, 1978 Royale rear bath
> Raleigh, NC
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
I would be concerned of the cooling capacity considering the overall size
reduction, square area, thickness, coolant flow and air flow. You will
need to make sure that all of the air flow goes thru the radiator and
provide ducting to close off the radiator housing. I would suspect that
the internal cooler ( connection sizes??) has the necessary area to cool
and size the external coolers as big as you can get in there. Your also
going to need to know the oil and transmission temps in and out. You live
in GA and should have a number of grades to test on a hot summer day under
a load. When you test the unit, don't expect equal results. JMHPO

As for cutting the cage this is what I have done on our coaches and by
several others.
http://www.gmcmhphotos.com/photos/g3850-radiator-support-bracket-modification.html
That way you can install a rebuilt stock or the newer aluminum unit if you
need to.
<
https://www.ebay.com/itm/1973-1978-GMC-Motor-home-radiator-23-26-ft-model/164031077720?hash=item2631039d58:g:GMAAAOSwOXJaj1rk
>
or
<
https://www.ebay.com/itm/Chevy-GMC-Motor-home-RV-Radiator-with-Engine-oil-cooler-all-aluminum-all-welded/153692816266?hash=item23c8ce438a:g:ciEAAOSwZQRYY7Qs
>
The second unit does not have the same layout for trans and oil cooler taps
as the first or stock radiators and is missing the low water sensor fitting.

As for coolers I use one similar to this for both trans and oil.
https://www.ebay.com/itm/Tru-Cool-4588-19-000-GVW-Cooler-Fluid-Oil-Tow-Towing-RV-HD-Truck-Transmission/382882520473
Pictures of cooler showing only the part of it. Yes, I have fans on the AC
condenser that run when the AC unit is in operation.
<
http://www.gmcmhphotos.com/photos/general-pictures/p58204-hw-shutoff-valves.html
>
Second picture shows the tranny cooler, AC Fans and the power steering
cooler and filter. I have a modified Bob Stone system without the power
booster plus a Lenzi sensitized booster. For picture orientation you
should turn the picture 90 degs CW!
<
http://www.gmcmhphotos.com/photos/member-galleries/p63883-power-steering-upgrade.html
>

J.R. Wright
GMC Great Laker
GMCGL Tech Editor
GMC Eastern States
GMCMHI
TZE Zone Restorations
78 Buskirk Custom 29.5' Stretch
75 Avion (Under going Frame up Restoration)
On location in Tucson (I don't do winter)

On Tue, Feb 4, 2020 at 7:01 AM Johnny Bridges via Gmclist <

> The only question would be thermal capacity. i.e. with the trans and oil
> coolers outboard will that radiator remove enough heat from the coolant to
> preclude overheating when you're pulling a long grade. Given the cost
> savings, how's to try it out and report back? Unlike the all metal
> originals,
> that one's a throwaway when it leaks isn't it?
>
> --johnny
> --
> Foolish Carriage, 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
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
I'd give it a try. If it overheats, bite the bullet for an original replacement and put it on craigslist. Given the removal of the transmission and
oil heat load it sounds close. A watch over the engine temp will keep you from hurting it should it overheat. I'd test locally to the degree
possible before embarking cross country. If it gets hot, you can go home in spurts without hurting anything.

--johnny
--
Foolish Carriage, 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
 
I can look back and probably come up with about 4-5 others who have fitted a "P30 General motors 454 radiatior" in their coach. I do believe they
were entire aluminum and in my notes I show:
1973 75 87 CHEVY GMC C/K 10/20/1500/2500/3500 Radiator off ebay.


I never got photos on the modification to get it to fit, and I was concerned about originality and what it would take to do the modification to make
sure the fillers and such ended up original. I understand it was shorter on one side and it took a quick tig welded piece of aluminum to make it fit
nice. But I have no photos or proof. from what I remember- they actually seemed to overcool. similar to my superior. but no one complains of that
problem, I know I don't.

I think one of our local GMC guys did this as well, but I have not seen his coach since he installed the radiator.



I ended up spending huge $$ on the superior aluminum that was almost an exact fit.(oil cooler lines need to be adjusted or replaced with longer).

good luck and post photos.

--
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
 
larification - I'm in Ga, he's in North Carolina..

--johnny
--
Foolish Carriage, 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
 
If that RX7 oil cooler has the same capacity as the Mazda factory cooler, it's going to be way overkill... RX7s are actually 1/3 oil cooled, and
rotaries throw out a ton of heat so they need a massive oil cooler. I own 4 rotary powered vehicles, and track a couple down here in Texas, so I know
from experience.

I also own a 90 RX7 that I swapped in an LS6 out of a 2002 vette... It's not uncommon for guys doing an LS swap into an RX7 to use the factory Mazda
cooler as it is already there, mounted etc... Those that do so without installing an oil thermostat quickly find that their oil will not get up to
temp. I remember a guy who said even on the track, he could not get his oil temps over 150 in his LS swapped RX7 using a factory RX7 oil cooler.

Bottom line is I would monitor your oil temps and install a thermostatic bypass on the oil cooler feed, or go with a smaller cooler. Bad things
happen to oil that does not get up to temp. Among other things the oil can form acidic compounds that will eat up your motor from the inside.
--
Mark S. '73 Painted Desert,
Manny 1 Ton Front End,
Howell Injection,
Leigh Harrison 4bag and Rear Brakes,
Fort Worth, TX
 
If it works in Winter Springs, it will probably work in Rahliegh.

--johnny
--
Foolish Carriage, 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
 
The New Aluminum radiator are available.
Seen where people posted that they were not available.
We can supply them and the prices are lower than previous.

On Wed, Feb 5, 2020 at 8:34 AM Johnny Bridges via Gmclist <

> If it works in Winter Springs, it will probably work in Rahliegh.
>
> --johnny
> --
> Foolish Carriage, 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
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmcrvparts.com
1-800-752-7502
 
While at the CoOp in Orlando today I was shown a new radiator “kit” that is under development. Looked pretty complete with a 4 core aluminum radiator and separate oil and transmission coolers. Also has a pair of electric fans, and sheet metal fairing. Might want to check this out if you need a replacement .Don't know the exact cost but it seemed reasonable.

Sent from my iPad

>
> The New Aluminum radiator are available.
> Seen where people posted that they were not available.
> We can supply them and the prices are lower than previous.
>
>> On Wed, Feb 5, 2020 at 8:34 AM Johnny Bridges via Gmclist <

>> If it works in Winter Springs, it will probably work in Rahliegh.
>> --johnny
>> --
>> Foolish Carriage, 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
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
>
> --
> Jim Kanomata
> Applied/GMC, Newark,CA
> jimk
> http://www.appliedgmcrvparts.com
> 1-800-752-7502
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
i have always gone by the addage that smarter men than you or I have designed this in the first place if you believe you are smarter than go for it
--
Trevor
Brisbane Australia
Siesta Koala 76 Edgemont (old Bobby Moores)
71 Cadillac Eldo Convert
58 Cadillac Eldorado Brougham Project
 
> i have always gone by the addage that smarter men than you or I have designed this in the first place if you believe you are smarter than go for
> it

Trevor,

The adage has merit, (having been on design teams) but it does not account for manufacturing process redesigns and cost accountants. The places that
these show up are in the knuckles (That Dave L. fixes), the wipers (That KenH. Fixes), a few missing Zerks and a few others. Fortunately for us, the
bean counters were pretty much held at bay for the original program.
You ask,"What about the Brakes?"
In the day, these coaches were celebrated for the terrific brakes. That was with bias ply tires.....
Then came radial tires. New Ball Game. We still aren't real bad and with reaction arms, they are pretty good.

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
 
> If that RX7 oil cooler has the same capacity as the Mazda factory cooler, it's going to be way overkill... RX7s are actually 1/3 oil cooled, and
> rotaries throw out a ton of heat so they need a massive oil cooler. I own 4 rotary powered vehicles, and track a couple down here in Texas, so I
> know from experience.
>
> I also own a 90 RX7 that I swapped in an LS6 out of a 2002 vette... It's not uncommon for guys doing an LS swap into an RX7 to use the factory
> Mazda cooler as it is already there, mounted etc... Those that do so without installing an oil thermostat quickly find that their oil will not get
> up to temp. I remember a guy who said even on the track, he could not get his oil temps over 150 in his LS swapped RX7 using a factory RX7 oil
> cooler.
>
> Bottom line is I would monitor your oil temps and install a thermostatic bypass on the oil cooler feed, or go with a smaller cooler. Bad things
> happen to oil that does not get up to temp. Among other things the oil can form acidic compounds that will eat up your motor from the inside.

I have a RX7 cooler that came off of a Mazda RX7. It has a built-in thermostat. I used that cooler for many years until engine troubles forced me to
scrap it. Rather than replace the Aluminum radiator, for a oil cooler, I used a oil cooler out front like this one (
https://www.summitracing.com/parts/bmm-70266 ) and a Hayden 225 Thermostatic Sandwich Oil Filter Adapter, that I got from Summit. Here is what they
say about it:

These Hayden Automotive oil filter adapters are designed to fit between the filter and the engine block. When the oil temperature reaches 160 degrees,
the Hayden oil filter adapters start to release oil to the engine oil cooler, and they release all oil to the cooler when the temperature reaches 180
degrees or higher.

This really worked for me. With this adapter, oil circulates in the engine until it reaches thermostat temp, then brings in cooler oil from the
cooler. While it did not change oil pressure at road speeds,(45-48lbs), at a hot idle, after a long hot run, pressure was up from 25-30psi to about
38psi. Seems to be doing the job. JWID
--
Larry
78 Royale w/500 Caddy
Menomonie, WI.
 
> i have always gone by the addage that smarter men than you or I have designed this in the first place if you believe you are smarter than go for
> it

If we all live by that addage, then no one would ever try anything...

I'd say OPs logic is good - vehicle from which you are sourcing the radiator is designed for heavy duty towing. Engine is nearly the same size. With
precautions and monitoring the gauges it is a good and reasonable try. The problem is the original shroud that does not fully cover the radiator.
There has been many posts here as to what's better - new modified shroud or electric fans on radiator to pull air through. Not going to get into it.
All I can say - I'm rooting for you.
--
Vadim Jitkov
'76 Glenbrook 26'
Pullman, WA
 
The 2 electric fans might create more Amp draw than the max 80A we have available. Turn on for sure would exceed that, that's ok, but our 80A do not
put out 80A at idle.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
Where is 80A figure coming from? The two fan combinations I've seen for large radiators are rated at 17-20A. That should be plenty to run at idle.
--
Vadim Jitkov
'76 Glenbrook 26'
Pullman, WA
 
Put six photos of progress and part numbers on gmcmhphoto site. Here is one link and you can browse the album if interested.

http://www.gmcmhphotos.com/photos/data/7272/medium/S6300715.JPG

Does anyone have a better part number for the rubber mounts? I have Dorman 926-276 and they fit the radiator perfect, but are not as round as our
original frame slots.

I am making the frame split while I am at it, so what you see is a newly fabricated middle shelf to hold the smaller new radiator that attaches inside
frame. "L" brackets outside the frame for bolting up the bottom. RX-7 cooler in place, leaves a 5x12 spot to simply block off. Should this whole
experiment fail, I can remove the center shelf (it's bolt in) and have a nice split frame to easily put in an OEM size radiator.

Had to cut a little edge of top frame to allow different overflow nipple. Had to cut a little edge of bottom frame to allow oil cooler connections.

I bought the Hayden 225 thermostatic coupler, but not convinced it will work as it states by simple observational physics. The thermostatic bypass
hole is barely 3/8, and the always open holes to cooler are 1/2. So it is always easier to flow to cooler even when cold. I may go with the inline
type that is more restrictive when cold, and same open when hot. Like this Derale 25719
https://www.summitracing.com/parts/der-25719?seid=srese1&gclid=EAIaIQobChMI2eKNqrDv5wIVSrzACh1VjQtjEAQYASABEgLvyfD_BwE

And for clarity - gmcmotorhomeenhancements a.k.a Jim Buchanan was selling Griffin made aluminum radiators. The Buchanan's are not continuing that
venture, but told me someone else "may take it over in the future". Jim K, and maybe others, still sell an aluminum radiator that should work and fit
like OEM. My goal here is information for a combo that is cheap and available at a local store...even if there are tradeoffs from OEM. And yes, just
to see if I can do it.
--
1975 Glenbrook, 1978 Royale rear bath
Raleigh, NC
 
We quit selling the Griffen as it was not fitting well at the pads and we
were not getting discount and lost on every sale.
&Now we have a unit that fits and prices lower!

On Wed, Feb 26, 2020 at 6:21 AM Tyler via Gmclist
wrote:

> Put six photos of progress and part numbers on gmcmhphoto site. Here is
> one link and you can browse the album if interested.
>
> http://www.gmcmhphotos.com/photos/data/7272/medium/S6300715.JPG
>
> Does anyone have a better part number for the rubber mounts? I have Dorman
> 926-276 and they fit the radiator perfect, but are not as round as our
> original frame slots.
>
> I am making the frame split while I am at it, so what you see is a newly
> fabricated middle shelf to hold the smaller new radiator that attaches
> inside
> frame. "L" brackets outside the frame for bolting up the bottom. RX-7
> cooler in place, leaves a 5x12 spot to simply block off. Should this whole
> experiment fail, I can remove the center shelf (it's bolt in) and have a
> nice split frame to easily put in an OEM size radiator.
>
> Had to cut a little edge of top frame to allow different overflow nipple.
> Had to cut a little edge of bottom frame to allow oil cooler connections.
>
> I bought the Hayden 225 thermostatic coupler, but not convinced it will
> work as it states by simple observational physics. The thermostatic bypass
> hole is barely 3/8, and the always open holes to cooler are 1/2. So it is
> always easier to flow to cooler even when cold. I may go with the inline
> type that is more restrictive when cold, and same open when hot. Like this
> Derale 25719
>
> https://www.summitracing.com/parts/der-25719?seid=srese1&gclid=EAIaIQobChMI2eKNqrDv5wIVSrzACh1VjQtjEAQYASABEgLvyfD_BwE
>
> And for clarity - gmcmotorhomeenhancements a.k.a Jim Buchanan was selling
> Griffin made aluminum radiators. The Buchanan's are not continuing that
> venture, but told me someone else "may take it over in the future". Jim K,
> and maybe others, still sell an aluminum radiator that should work and fit
> like OEM. My goal here is information for a combo that is cheap and
> available at a local store...even if there are tradeoffs from OEM. And yes,
> just
> to see if I can do it.
> --
> 1975 Glenbrook, 1978 Royale rear bath
> Raleigh, NC
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.gmcrvparts.com
1-800-752-7502
 
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