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Cooling System Overhaul - Stumped and Frustrated

Based on the fact that I figured out my non HD clutch was in there yesterday, I didn't pull the tstat.

Curious to pull with it as is, to see what temps I'm actually reaching. I only have to pull one short grade, so i should be good as-is, anyways.

Will update you guys on sunday.
 
Temp fluctuations have been verified with another gauge.

HD clutch has been installed, no real changes.

Going to look into one of the custom AL radiators i guess. Need to tow next weekend, hope its not hot out.....


Also, never pulled my tstat. Going to try running without it.
 
Do you have an Oil Cooler installed?

This should not be a capacity issue as long as you have not downsized your system. I am running a very similar powertrain to you - 1991 3/4 ton, 3.73:1 rear end, 33" tires, 383 cid motor, 4l80e trans, Stock-ish radiator (rebuild from local radiator shop), Stock oil cooler, mid-size tranny cooler, 50/50 anti-freeze - water.
My temp will climb a bit under big hills in >90* temps, but does not spike too much. Occasionally the fan clutch will engage. I drive up highway 395 from OC to Mammoth often in the summer - just not towing.
 
Stock oil cooler in front of the radiator, aftermarket trans fluid cooler (Matches oil cooler) in front of the radiaor on the passenger side.
 
Pull the thermostat first. I don't really think it's your issue, but just try it. Really need to verify it's a radiator/capacity issue before you spend the money on a radiator.

But you are having this problem even NOT towing, correct? Still going far above 208* (or so) with a 195* thermostat?

*IF* I determined I needed another radiator, and I was in your situation, I would buy the 34" wide (and that must be core width, not OAW) radiator that was as thick as GM ever used. Anything short of that leaves too much on the table IMO, and GM must have thought them necessary in some applications for some reason. I still think there is some guesswork involved here, and I don't like guessing with your money.
 
dyeager535 said:
Pull the thermostat first. I don't really think it's your issue, but just try it. Really need to verify it's a radiator/capacity issue before you spend the money on a radiator.

But you are having this problem even NOT towing, correct? Still going far above 208* (or so) with a 195* thermostat?

*IF* I determined I needed another radiator, and I was in your situation, I would buy the 34" wide (and that must be core width, not OAW) radiator that was as thick as GM ever used. Anything short of that leaves too much on the table IMO, and GM must have thought them necessary in some applications for some reason. I still think there is some guesswork involved here, and I don't like guessing with your money.
Click to expand...


Agreed. Tough part of goign to teh larger radiator is getting the wider shroud. Wish i had grabbed more parts last time i was at the salvage yard....


Hm, they aren't ungodly expensive at LMC.

http://www.lmctruck.com/icatalog/csb/full.aspx?Page=60

We'll see how it does w/o the tstat.
 
Really, if this full brass vistapro isn't doing the trick, i'm considering having a conversation with them about it.

Maybe they'll make me a deal on a bigger one.
 
dhcomp said:
Really, if this full brass vistapro isn't doing the trick, i'm considering having a conversation with them about it.

Maybe they'll make me a deal on a bigger one.
Click to expand...

I have the 454 4 core and shroud in my blazer for years and have never come close to the center mark, that's towing a 19' boat to Whiskey town in the Redding summer heat.
 
I am not certain what LMC lists is the large shroud.

Not saying the 34" radiators weren't used in the old trucks, but their interchange shows back to 1973, and I have never seen the huge radiators in '73-80.

There are at least two big block shrouds, and I don't see two listed there. I suspect the one they list is just for the 28" core radiator.

Anyone tow with the Windstar fans? Might be easier than trying to find all the 34" radiator parts if you go that way. As Frankin5 says, and I think others have mentioned, they aren't having similar problems under similar conditions, and that makes me leery of saying for certain it's the radiator. But I simply can't think of any way to test to narrow it down beyond what you've done so far.
 
I had a custom made brass rad made by a local radiator shop. It is the stock width but he used early BBC truck side tanks and a 4 row hi-efficient core. I had to modify the mounts and trim the shroud. I also use a Meziere belt driven water pump. It runs 5 degrees hotter then any thermostat I put in it. To be honest I have not towed anything heavy with it, but I drive thru the hills in 100+ weather and it never gets hot.

I recommend a high flow waterpump from a reputable manufacture. Meziere, Edelbrock, Stewart. Whatever you do never use underdrive pulleys on a truck engine. More flow plus more pump pressure will help to keep the hot spots from developing. More flow = more cycle thru the radiator.

Are you sure the fan is not backward, not sure if it's possible on these cluchfans but i now someone who did this once on a cluchless fan. I still don't understand how he did it, but he will never live it down...
 
can't beat a big 2 row alum for cooling... summit has BIG universal ones for under $200... custom mounting required..
 
Was it already discussed the difference between a serpentine and v-belt water pump?
 
1leg said:
Was it already discussed the difference between a serpentine and v-belt water pump?
Click to expand...

Its routed just like the picture on my core support :waytogo:

I've had the belt off numerous times....and have had a few different pumps on there. Don't think it would cool as well as it is with a reverse pump, would it?
 
1leg said:
Was it already discussed the difference between a serpentine and v-belt water pump?
Click to expand...

Based on others results with the wrong rotation water pump, you normally can't get out of the driveway without overheating. I don't see that as the issue here at all.

I suppose wrong fan could be, but without going back and checking, I'm guessing the fan blades are original for the truck...or original WITH the truck, not necessarily the right one?

The fan clutches aren't different based on rotation are they? I wouldn't think so, but haven't dealt with the "reverse rotation" stuff either.
 
Fan has been on there forever. I can check the rotation, but pretty sure its right.

I've also had numerous fan clutches on there, so i doubt they have all been wrong.
 
No idea how you'd compare the fan blades for which is which, but when the vehicle is hot you could simply check if the fan is "pulling" air into the engine bay, or pushing it out the radiator. Really know nothing about them, they physically may not even bolt up if the wrong one.

I would *think* the fan would work fine pushing or pulling under most idle conditions honestly, but under heavier use/moving, would be very counterproductive. :)

More about eliminating any possibility of a problem before going the radiator route.
 
I know its a new radiator, but I seem to remember an IR heat gun being invoked earlier in the novel.
If you still have it, let the truck come up to temp, then shoot different places all over the radiator to see if its got some cool spots.

There might have been some crud that broke loose from other places and have stopped up a few passages.
 
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