Home » Public Forums » GMCnet » Radiators (has anyone found a real solution to keep the engine at a constant temp?)
| Radiators [message #225165] |
Thu, 10 October 2013 23:42  |
cameron
Messages: 10
Registered: December 2011
Karma: 0
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Has any one out there found a solution to keeping the engine at a constant temp now mater what you are doing?
I have read a bunch of things but it all seems to be about the same where the temps are still going up and down.
Has anyone tired running two radiators?
It seems that with the size of the rig and if you put in an High HP engine that there just is not enough cooling for the system.
I was thinking that you could easily run a second radiator off of the water heater plumbing. Has anyone tried that with any results?
Please let me know
Cameron
76 Palm Beach with Mondello engine
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| Re: Radiators [message #225167 is a reply to message #225165] |
Thu, 10 October 2013 23:48  |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Use the Griffin aluminum radiator from Gene Dotson or Jim K. and you will take care of your problem.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Radiators [message #225174 is a reply to message #225165] |
Fri, 11 October 2013 02:14 |
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fitzmorrispr
Messages: 137
Registered: February 2013
Location: Los Angeles
Karma: 0
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It sounds like you want the engine temperature to be constant, once the
engine warms up. Unfortunately, I don't believe this is possible. Remember
that the heat source is literally explosions. The surface area for the
radiator is very large, perhaps even larger than the effective surface area
of the water jacket, but it is still not going to be able to dissipate heat
rapidly enough to maintain constant temperature, and double the radiator
won't make much difference to this essential fact
When I talk about rapidity of heat dissipation, I mean how long it takes
for a given amount of heat energy to get from the combustion chamber to the
outside air. There will always be a delay, because the water can only flow
so rapidly, and heat transfer isn't ever instantaneous, anyway. This delay
also effects the regulating features, like the fan clutch and the
thermostat, because they can only respond to a change when they find out
about it. This means that a spike in load on the engine will heat the water
up a bit before the fan and thermostat notice, and the water will get a
little on the cool side before they realize their job is done.
Electronic sensors and controls can reduce this lag time by detecting
changes earlier and responding more immediately, but never eliminate it.
More radiators would only reduce the amount of time the thermostat would be
open, so that a temp graph would have slow rises and fast drops. The system
would still average about the same temperature, and would still hit the
same highs and lows, with about the same frequency.
Many modern cars have temperature guages that never seem to move. This
isn't because they keep their temperature more constant so much as it's
because the guage is scaled poorly, and a nealy invisible movement
indicates several degrees difference in temperature.
So to sum up, don't bother, it won't make a worthwhile difference. Besides,
those heater lines are too small for use as a significant source of engine
cooling except maybe in an emergency.
On Oct 10, 2013 9:42 PM, "cameron" <cameron.hong@comcast.net> wrote:
>
>
> Has any one out there found a solution to keeping the engine at a constant
> temp now mater what you are doing?
> I have read a bunch of things but it all seems to be about the same where
> the temps are still going up and down.
> Has anyone tired running two radiators?
> It seems that with the size of the rig and if you put in an High HP engine
> that there just is not enough cooling for the system.
>
> I was thinking that you could easily run a second radiator off of the
> water heater plumbing. Has anyone tried that with any results?
>
> Please let me know
> Cameron
> 76 Palm Beach with Mondello engine
> _______________________________________________
> GMCnet mailing list
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The Greatfruit: 1973, 26', Canyon Lands or Painted Desert, in Pineapple Yellow
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| Re: Radiators [message #225205 is a reply to message #225165] |
Fri, 11 October 2013 09:53 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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The biggest improvement for getting the engine to sit at the Tstat temp was the chin spoiler under the core support purchased from Jim K. Seems every other GM vehicle has a deflector of some sort there except us with the TZE. I know if this is lost or missing on GM cars there will be overheat issues. Really helps. When the fan does come on it helps minimize recirculating the waste heat. Temp drops rapidly. Also you do have 2 radiators (of sorts) in terms of 6 gallons of water in the factory water heater if still connected. More of a heat storage/ stabilizing device slowing temp rise and fall rates. My radiator is just a brass recore of stock tanks.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Radiators [message #225244 is a reply to message #225165] |
Fri, 11 October 2013 13:35 |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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I had problems with cooling in temps above 90* or so. I seemed that the fan clutch was coming on every 15 minutes or so. What I noticed is that the temp would climb from 195 (thermostat) to 210 or so, the fan would come on and fairly quickly it would drag the temp down to 195 and the fan clutch would turn off. What that told me is that the radiator is more than adequate to do the job...we just got to get the air running through it. So, on Bob Drews suggestion, using conveyer belt material that I bought at a farm supply, I built a kind of funnel all around the inside forward of the radiator and behind the grill. Now, once air enters the grill, it has nowhere to go accept through the radiator. Now my temp rarely exceeds 200*, accept after a hot run and stopped in traffic, and correspondingly the fan clutch almost never comes on. If I get a chance, I'll post some pics of the "funnel" tonight. Sure has worked for me....JWID
Larry 
78 Royale w/500 Caddy
Menomonie, WI.
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| Re: Radiators [message #225251 is a reply to message #225165] |
Fri, 11 October 2013 14:51 |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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Senior Member |
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Larry,
Looking forward to your pictures. It is on my list to do that sort of thing soon.
reading this forum daily, I can see there are people out there not experiencing any sort of overheating issues in pretty hot temperatures, or just not noticing. and there are some that constantly struggle. I thought I read the other day someone did not think that baffling the radiator changed the cooling. yet the next person might claim that it did.
just seems that nothing engine cooling related is 100% consistent across all of our coaches.
I know my own coach, I have done some things, and it has changed the way my coach has cooled. I am still not 100% happy. I am just happy it I am not trying to drive mine across a desert pulling a trailer. Most vehicles I really do not watch the temp gauge, they just do not move. but I see lots of fluctuation on my GMC when it comes to outside temps, towing, hills, stop and go traffic ect...so I am always watching, and wondering sometimes if it is going to stop creeping up in those circumstance(so far always has stopped).
obviously there are coaches are running all over stock for 30-40 years. and not leaving antifreeze everywhere they park.
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
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| Re: [GMCnet] Radiators [message #225253 is a reply to message #225251] |
Fri, 11 October 2013 14:56 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Senior Member |
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Jon
Do you have the original radiator? If so then it is probably partially clogged.
The tubes in the GMC radiator run from side to side. The lower tubes often get clogged with rust or corrossion and they don 't let coolant flow throught them.
The radiator can be removed and a radiator shop can rod the tubes and get them working again. If it really bad then you may have to replace the radiator.
You can buy the aluminum one about as cheap as recoring the old one.
Emery Stora
On Oct 11, 2013, at 1:51 PM, Jon Roche wrote:
>
>
> Larry,
>
> Looking forward to your pictures. It is on my list to do that sort of thing soon.
>
> reading this forum daily, I can see there are people out there not experiencing any sort of overheating issues in pretty hot temperatures, or just not noticing. and there are some that constantly struggle. I thought I read the other day someone did not think that baffling the radiator changed the cooling. yet the next person might claim that it did.
>
> just seems that nothing engine cooling related is 100% consistent across all of our coaches.
>
>
> I know my own coach, I have done some things, and it has changed the way my coach has cooled. I am still not 100% happy. I am just happy it I am not trying to drive mine across a desert pulling a trailer. Most vehicles I really do not watch the temp gauge, they just do not move. but I see lots of fluctuation on my GMC when it comes to outside temps, towing, hills, stop and go traffic ect...so I am always watching, and wondering sometimes if it is going to stop creeping up in those circumstance(so far always has stopped).
>
>
> obviously there are coaches are running all over stock for 30-40 years. and not leaving antifreeze everywhere they park.
>
>
>
> --
> 75 palm beach
> St. Cloud, MN
> http://lqqkatjon.blogspot.com/
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| Re: [GMCnet] Radiators [message #225257 is a reply to message #225244] |
Fri, 11 October 2013 15:17 |
Gary Worobec
Messages: 867
Registered: May 2005
Karma: -1
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Senior Member |
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I installed the aluminum radiator with one of the Curtis's fan shrouds and a
heavy duty fan clutch about 15,000 miles ago. Even pulling the Tracker on
100F + days the temp rarely gets above 195-200F (mechanical gauge). The
aluminum rad does a great job of cooling the water but also the oil and
transmission fluids as well. I truly think it is one of the best and most
important mods you can make to sustain engine life.
Thanks,
Gary and Joanne Worobec
1973 GMC Glacier
Anza, CA
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Larry
Sent: Friday, October 11, 2013 11:36 AM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Radiators
I had problems with cooling in temps above 90* or so. I seemed that the fan
clutch was coming on every 15 minutes or so. What I noticed is that the
temp would climb from 195 (thermostat) to 210 or so, the fan would come on
and fairly quickly it would drag the temp down to 195 and the fan clutch
would turn off. What that told me is that the radiator is more than
adequate to do the job...we just got to get the air running through it. So,
on Bob Drews suggestion, using conveyer belt material that I bought at a
farm supply, I built a kind of funnel all around the inside forward of the
radiator and behind the grill. Now, once air enters the grill, it has
nowhere to go accept through the radiator. Now my temp rarely exceeds 200*,
accept after a hot run and stopped in traffic, and correspondingly the fan
clutch almost never comes on. If I get a chance, I'll post some pics of the
"funnel" tonight. Sure has worked for me....JWID
--
Larry :)
78 Royale w/500 Caddy
Menomonie, WI.
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| Re: Radiators [message #225334 is a reply to message #225165] |
Sat, 12 October 2013 10:50 |
gbarrow2
Messages: 765
Registered: February 2004
Location: Lake Almanor, Ca./ Red Bl...
Karma: 3
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Senior Member |
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Cameron,
Is your engine overheating? You didn't say.
If it is not overheating what is the problem with temp variations?
I have driven my 76 Palm Beach with a Bob Laney 455 for 11 years and over 100,000 miles. It has OEM radiator, OEM fan shroud and 180* thermostat. I drive in the mountains a lot and in the high temps of Cal's Central Valley. I also often tow a trailer or my Jeep. The after market engine temp gauge remains constant except when under heavy load. As temp rises the fan clutch engages and temp drops back right away. No problems that I know of caused by the temp variations
Works the same in my 1989 Suburban, my wife's 2004 Jeep Grand Cherokee, my 1993 Cherokee.
I guess I don't understand the problem. If it ain't broke, ect.,ect.
Gene Barrow
Lake Almanor, Ca.
1976 Palm Beach
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| Re: [GMCnet] Radiators [message #225335 is a reply to message #225290] |
Sat, 12 October 2013 10:50 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Cameron,
There is nothing wrong with the design of the GMC cooling system if all the components are working properly. Think about it for a
moment there were 12,941 of these units built and if the cooling system was not designed properly owners would have been all over
GMC!
I've inserted some comments below in CAPS for clarity (not shouting), hope you don't get upset.
Regards,
Rob M.
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of cameron
Interesting results
I actually asked a engine building friend of mine and what he told me was that cooling systems are designed to cool the engine at
100% of its heating capacity running normally.
THE COOLING SYSTEM IS DESIGNED TO HANDLE THE HEAT GENERATED BY THE ENGINE WHETHER IT IS IN NOME, ALASKA IN THE MIDDLE OF WINTER TO
DEATH VALLEY IN THE MIDDLE OF SUMMER.
So it would make sense that since the engines that we have in our rigs are not running normally but under a extra amount of load it
would make scene that the cooling capacity of the existing cooling system would be insufficient to cool the engine.
THE DRIVE DRAIN IN A GMC WAS LIFTED OUT OF THE TORONADO AND INSTALLED IN THE GMC - BUT THE RADIATOR SIZE WAS INCREASED TO HANDLE THE
EXTRA HEAT LOAD THE ENGINE DEVELOPED MOVING A 12,500 VEHICLE.
Also since I have rebuilt the engine to produce more HP etc then there will be more heat produced beyond that.
LETS SAY IT TAKES 100 HP TO MOVE A GMC DOWN THE ROAD AT 60 MILES PER HOUR IF YOU HAVE AN ENGINE THAT PRODUCES TWICE AS MUCH HP AS
THE STOCK ENGINE IT IS STILL ONLY GOING TO TAKE 100 HP TO MOVE YOUR GMC DOWN THE ROAD AT 60 MPH.
This is actually proven since the aluminum radiators have a greater cooling capacity then the stock brass.
YOU ARE CORRECT ALUMINUM TRANSFERS HEAT FASTER THAN BRASS.
When I rebuilt my engine I had the radiator rodded and cleaned so I know it is cooling as best as it can.
GET AN INFARED THERMOMETER FROM HARBOR FREIGHT AND WITH YOUR GMC AT OPERATING TEMP SHOOT THE RADIATOR IN AS MANY PLACES AS POSSIBLE
TO SEE WHAT THE TEMP IS. IT IS QUITE POSSIBLE THAT WHEN YOU HAD YOUR RADIATOR REPAIRED THEY MAY HAVE BLOCKED PASSAGES THAT WERE
LEAKING.
So my conclusion would be that there are three significant defects in the cooling design.
First there is too much of a high pressure air zone in the engine compartment, thus keeping the hot air swirling around the
compartment. Even with the additional vents the air pressure is still too high in the engine compartment.
AT SPEED THE AIR GOES IN THROUGHT THE GRILL PAST THE RADIATOR AROUND THE ENGINE, HITS THE REAR FIREWALL AND EXITS UNDER THE COACH. I
DON'T UNDERSTAND WHAT WOULD MAKE IT "swirling around the compartment."
Second the radiator does have a poor design for air flow as an intake. If you look at all of the newer designs for any radiator
there is a high pressure zone in front of the radiator and low in the back. This is accomplished by the fan in the GMC but when the
fan is free wheeling then there is little to no pressure that is created. The ducting work that some others have done look like
they would solve this problem.
THERE IS A HIGH PRESSURE ZONE IN FRONT OF THE RADIATOR, IT FACES FORWARD. IT IS HIGH PRESSURE BECAUSE IT FACES THE AIR STREAM THAT
IS COMING THROUGH THE GRILL AND LOW PRESSURE BEHIND IT BECAUSE THE RADIATOR RESTRICTS THE AMOUNT OF AIR THAT WILL FLOW THROUGH IT.
GMC DID ADDRESS THE AIRFLOW AND ISSUED A SERVICE BULLETIN THAT INSTALLS "FLAPS" ON THE SIDES AND BOTTOM OF THE RADIATOR TO GUIDE
AIRFLOW FROM THE GRILL INTO THE RADIATOR. I CAN'T REMEMBER IF THERE IS ONE ON THE TOP OR NOT.
Third the cooling capacity is just not enough for the engine and the transmission.
I BEG TO DISAGREE. IF THAT WERE THE CASE WHY ARE THERE SO MANY STOCK GMC'S OUT THERE THAT DON'T HAVE ANY COOLING PROBLEMS. ONE GMC
NET CONTRIBUTOR NOTED THAT HE HAD OVER 300,000 MILES ON HIS BOX STOCK GMC AND HAD NEVER HAD A PROBLEM. BTW WHEN HE PUBLISHED THAT
INFORMATION THE PERSON THAT RAISED THE SUBJECT FLAMED HIM BIG TIME.
I look forward to your input.
Cameron
1976 Palm Beach
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: Radiators [message #225341 is a reply to message #225165] |
Sat, 12 October 2013 11:47 |
habbyguy
Messages: 896
Registered: May 2012
Location: Mesa, AZ
Karma: 3
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Senior Member |
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My '78 403-equipped Royale stays plenty cool, even in the ridiculous Arizona summer temperatures. The PO did install baffles beside the radiator, behind the grill - this keeps the air coming in the grill from flowing around the radiator so much. My temperature gauge seems to be pegged to the first mark (with the stock sender unit, so that's where it should be), no matter what the actual temperature. I do hear my fan clutch kick in fairly often when it's hot out, but can't really say it's doing it more than it should (or not). Yesterday on the way back from Mexico (with air temps around 80) I'd hear the fan clutch slowly kick in, and it seemed like feathering the throttle slightly would cause it to disengage.
But at any rate, I've got no complaints about my cooling system, though I also can't swear how stock it is or isn't (the PO was pretty thorough).
Mark Hickey
Mesa, AZ
1978 Royale Center Kitchen
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| Re: [GMCnet] Radiators [message #225373 is a reply to message #225371] |
Sat, 12 October 2013 19:55 |
sgltrac
Messages: 2797
Registered: April 2011
Karma: 1
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Senior Member |
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If 210 is as high as it gets fugettabout it
Todd Sullivan
Sully
77 royale
Seattle
> On Oct 12, 2013, at 5:22 PM, cameron <cameron.hong@comcast.net> wrote:
>
>
>
> No it has not overheated but it runs hotter than I think it should
> At times going up to Tahoe the temp will get as high as 210 but it does start to come back down. I am just concerned as I have a lot of time and money invested in the engine.
> Also I am planning a trip to Arizona and don't want to have any troubles.
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Sully
77 Royale basket case.
Future motorhome land speed record holder(bucket list)
Seattle, Wa.
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| Re: Radiators [message #225387 is a reply to message #225380] |
Sat, 12 October 2013 22:34 |
jim kanomata
Messages: 257
Registered: March 2007
Location: fremont,ca
Karma: 12
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Senior Member |
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If your pulling a long grade to Taho,
Most system will gain heat.
TheFan clutch should be functioning at that point to control the temp.
In engineering we learned that larger the temperature differane , the heat disapation is improved,
If the airtemp is 90, and the radiater is 180, the difference(DeltaT) would be 90.
Should the air be 90, and the radiator is 195, the difference(DeltaT) would be105.
So the air going through the radiator has a better chance of disapating more heat.
On the other side, some feel if you start up a hill at 180,then it will not reach 210 as quickly.
If starting at 195 at the base of the hill, it will reach 210 quicker.
I say it is a toss up as to if you want to fart in church or belch.
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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