Engine is running hot. Any ideas?

[deabionni]

Background: Last summer I swapped the GE engine in my'86.5 for a GTE engine. I left the stock auto transmission in the car. I got the car running at sometime in the fall, and noticed that the car would run hotter then normal after a cruise down the road; and would start to overheat once I drove slower through a town.

My dad (ASE certified mechanic) and I quickly determined that the fan clutch wasn't engaging once the engine was warm, and we rigged the fan clutch to be engaged to run constantly. That worked pretty good, and the engine temps stayed normal after that. (It was fall, and the weather was cooler then it is now).

Over the course of winter, I changed the fan clutch for a nearly new clutch from a Toyota Tacoma; and the fan clutch engages as it should.

This summer, with a new working fan clutch, I'm having the same overheating problems that I had last fall. I can drive where I need to go, and the engine temp will VERY SLOWLY rise going down the road. Once in town, the temp quickly rises to the point of overheating.

My cooling system is as follows:

-Stock radiator ~ Tested to be free flowing with a lazer thermometer, and shows a 50* temperature drop from the top (hot) hose, to the lower (cold) hose.

-Stock fan with fan shroud using a good working Toyota Tacoma fan clutch. ~ I can verify that the fan engages, and runs constantly once the engine is warm.

-Stock intercooler.

-Stock oil cooler.

-Stock A/C condenser ~ A/C is not being used.

-Big transmission cooler sandwiched between the A/C condenser and the radiator. The tranny cooler in the radiator is not being used, and the tranny is being cooled only by the added tranny cooler. (The tranny cooler came off from a Dodge diesel 2500 or 3500, and is at least 1/3 of the size of the A/C condenser).

My dad is under the impression that with all of the coolers in front of the radiator, that the air entering the radiator is too warm to adequately cool the radiator and the engine. Everything on the cooling system is stock, with the exception of my large tranny cooler and the working Tacoma fan clutch.

Would the tranny cooler add so much heat that the radiator can't keep cool? If so, what would be some alternatives that I could do to get my engine temps back where they should be? If not, what should I check that I haven't checked already?

 

[tissimo]

::bhg::

 

[deabionni]

^^^ Speaking of BHG, the head gasket was supposedly changed by the person I bought the engine from less then 10,000 miles ago. He used a composite gasket with ARP studs. That said, I'm not ruling out a BHG, and plan on doing a test on the cooling system to see if there's exhaust gasses present when I have some time later this week.

It just seems strange that it didn't overheat last fall when it was about 20* cooler, and everything is basically the same; but it's overheating now.

 

[gtsfirefighter]

How hot will it get? Has it ever boiled over or just run above the half way point of the temp gauge?

Do you have the GE 6 blade fan or the GTE 10 blade fan?

Might try relocating the tranny cooler in front of the condenser.

Quite possible you still might have some blocked passages in the radiator.

Thermostat??

Rule out BHG as soon as you can. If the test is negative, it'll stop people from jumping on that wagon.

 

[Canuckrz]

I'd take out the fog lights and put the tranny cooler in one of those. Also I'd get a coolant system flush kit, the bottle of the additive is like 6-8 bucks, it will get out any bottlenecks caused by the crap that may have built up.

Also I run redline water wetter, helps the fluid do its job better. Its about $10 iirc.http://www.redlineoil.com/products_coolant.asp

 

[JDMMA70]

the sensors on the T-Stat Housing been checked or changed? Might want to look into that

 

[Rennat]

checked the cap lately?

 

[deabionni]

How hot will it get? Has it ever boiled over or just run above the half way point of the temp gauge?

Do you have the GE 6 blade fan or the GTE 10 blade fan?

Might try relocating the tranny cooler in front of the condenser.

Quite possible you still might have some blocked passages in the radiator.

Thermostat??

The coolant gets to the point of boiling a little bit above 3/4 of the way up the gauge.

I have the 10 blade turbo fan on the Tacoma clutch.

The tranny cooler is so big, the only place for it was between the condenser and the radiator. I have it mounted to the back side of the condenser, and there's about 1/2" of clearance between it and the radiator.

The thermostat seems to open/close as it should. It's just once it's open, the coolant in the radiator heats up and the radiator can't dissipate the heat. It's almost like there's no excess cooling capacity in the radiator, and the radiator can't cool down the coolant with the warmer air flowing through it from the tranny cooler.

My dad is suggesting putting in a bigger radiator, but that seems like a band aid fix to me; as with the exception of the tranny cooler (and fan clutch), the cooling system is stock. The engine is stock with no mods. A relatively stock cooling system should be able to cool off the stock engine. ~ Unless, that is, the tranny cooler really is putting the cooling system over budget.

the sensors on the T-Stat Housing been checked or changed? Might want to look into that

Checked. All check out per the TSRM.

checked the cap lately?

We suspected that, and are looking at it when we work on it this weekend.

 

[tissimo]

The tranny wont add more heat then the a/c system. My car (stock) with a near dead fan clutch would still cool fine. Occasionally the a/c would turn off (usually after sitting for 10 minutes+ with it 90* outside..... I assume A/c temp switch was switched and turned off the a/c) but still wouldn't over heat. My car is an auto and uses the stock radiator cooler as well. Do the block test.

 

[jdub]

Did you check the radiator with the IR thermometer to see if there were any hot/cold spots...that would indicate a partial blockage.

 

[sogi99]

Did you check the radiator with the IR thermometer to see if there were any hot/cold spots...that would indicate a partial blockage.

I'm with jdub and also if the radiator looks original you need to replace it. Mine acted like what your car is doing. I changed the headgasket myself so I know that's not the problem and also the thermostat. There's only one thing I need to replace and it was my radiator that fixed it. My car is a 5 speed

 

[deabionni]

Did you check the radiator with the IR thermometer to see if there were any hot/cold spots...that would indicate a partial blockage.

I never even thought of that. All we did was measure the coolant temp difference from the entrance/exit of the radiator.