FJ40 V8 SBC TBI still overheating after cooling system upgrade

[1lukeduke]

Hello to all. I have searched here and online, and have only found corrections that I have already done. This is a 1990 Chevy 5.7 TBI with a 700r4 trans. I have a 8274 Warn winch that does block some of the opening. I have put in an aluminum radiator. It sits just between the headlight buckets (wide), almost hitting the plugs. it is as tall as stock. It has a fan clutch (the short one) and a Duramax diesel 11 blade fan. It also has a custom made fan shroud that the fan is half way out and is spaced perfectly on the sides. It also is spaced away from the radiator, per spec. The motor is well away from the firewall and the thermostat was 195 and then I switched it to 180 with better results. Timing is stock. The only upgrades are headers and a 110amp alternator. It runs like a champ around town, but going up hills it just keeps heating up. I have been stopping around 230 degrees and then stopping to let it cool down. This was the same problem with the small radiator and electric fan. Only difference is, that it wasn't great around town before. I have only been able to test this during 95-100 degree days in California, but I want it to work during hot days also. I was thinking of cut the inner fenders by the headers to see if this is causing the heat soak. Hoping it would release the heat causing the buildup. I will then screen them in once this may fix the problem. I was thinking of taking the hood off to test the theory first. What do you think. Any theories or opinions would be appreciated.

Lucas

 

[sadam_husain]

Is it running the correct reverse rotation water pump if its a serpentine belt TBI engine

 

[charliemeyer007]

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[pb4ugo]

Do you hear the fan clutch lock up. On my GMC pickup when hauling big load up a long hill I watch my mechanical temp gauge rise and around 215 to 220 I hear the fan make a big worling sound when the fan clutch locks up and my temps quickly drop below 200, then unlocks. Is the fan clutch adjustable? For full disclosure, my truck is a 92 6.5td with 1997 GM upgraded cooling system. It has a higher gpm water pump, and a similar fan as yours. Idk if they offer something similar for your sbc.

How are you cooling your trans? Does the shroud cover the whole radiator? When you stop to cool things down are you leaving it running? Turning it off will make temps spike.

 

[B y r o n]

This is the water pump I installed on my SBC 350. It's produced by a company called Flow Kooler. Click on the link and it will take you to the page that explains how they work. They make unit for either rotation you need, V-belt or serpentine belt. You could also try dropping the thermostat to 160 or 170 degrees.

 

[Dudleyfj40]

I had this same problem with the same engine and trans. I ended up adding a temp gauge to the trans to see the issue.
Does your 700r4 lock up the torque converter?
My 700r4 was not locking up the torque converter in OD. This was creating heat .
I had since added a auto and manual push button lockup and a led to tell me when it locks.

No more heat issues.

 

[DangerNoodle]

They symptoms still sound like a lack of radiator. How many cores and passes? A mechanical fan should be more than enough to keep up with that, unless the fan clutch is going bad. You might also look into a severe duty clutch with more lockup.

 

[rlong]

1) re: pb4ugo valid comment. it is pretty easy to test and ensure at what temp your fan clutch is locking up (put it in a pan of water on the stove “feel resistance” as temps rise measured with infrared temp gun)
2) DudleyFJ40 should be considered. I did not see where your doing trans cooling, but if integrated with current radiator in particular this can be an issue. This is all over more hot rod forums (more auto tranny’s). Adding a temp gauge to transmission is always a good idea, another good data point!

Both of these are good ideas regardless if they end up being the problem!

 

[centerlineseal]

Is it running the correct reverse rotation water pump if its a serpentine belt TBI engine

We screwed up way back when we put in our Ramjet by using our old SBC fan, which was NOT correct ( basically backwards flow) for the reverse rotation water pump. Homer Simpson move easily rectified with correct fan!

 

[1lukeduke]

Is it running the correct reverse rotation water pump if its a serpentine belt TBI engine

I believe it is. But it is brand new. Would it be cooling well around town if it was spinning the wrong way?

 

[1lukeduke]

Do you hear the fan clutch lock up. On my GMC pickup when hauling big load up a long hill I watch my mechanical temp gauge rise and around 215 to 220 I hear the fan make a big worling sound when the fan clutch locks up and my temps quickly drop below 200, then unlocks. Is the fan clutch adjustable? For full disclosure, my truck is a 92 6.5td with 1997 GM upgraded cooling system. It has a higher gpm water pump, and a similar fan as yours. Idk if they offer something similar for your sbc.

How are you cooling your trans? Does the shroud cover the whole radiator? When you stop to cool things down are you leaving it running? Turning it off will make temps spike.

I kind of hear the fan clutch lock up. I put the fan off of a Duramax because how quiet they are and how much air they pull. My transmission is being cooled by the radiator. The fan shroud is the entire radiator. When I let it cool down I leave it running and give it a little throttle.

 

[1lukeduke]

I had this same problem with the same engine and trans. I ended up adding a temp gauge to the trans to see the issue.
Does your 700r4 lock up the torque converter?
My 700r4 was not locking up the torque converter in OD. This was creating heat .
I had since added a auto and manual push button lockup and a led to tell me when it locks.

No more heat issues.

This is a great question. I have no idea. The person I bought it from put this engine in this vehicle 25 years ago. It was his daily driver. When I bought it, it had been sitting for five years. I would imagine it didn’t overheat that whole time. Could the converter be worn out and not lockup anymore?

 

[whitey45]

I have always run a 70’s chevy truck 4 blade steel fan, they are quiet and pull a ton of air! Cooled my bbc for 10 years!!( also did you buy a generic china rad? ) they are not as effective as higher dollar double pass or tripple pass cross flow radiators

 

[1lukeduke]

They symptoms still sound like a lack of radiator. How many cores and passes? A mechanical fan should be more than enough to keep up with that, unless the fan clutch is going bad. You might also look into a severe duty clutch with more lockup.

I agree, but I can not get much more radiator in there. Also my understanding is that after 30mph the fan no longer pulls as much air as the wind being forced through the radiator. The fan can become a block even. Just a regular 2 core single pass I believe.

 

[1lukeduke]

We screwed up way back when we put in our Ramjet by using our old SBC fan, which was NOT correct ( basically backwards flow) for the reverse rotation water pump. Homer Simpson move easily rectified with correct fan!

The fan is pulling fantastic. It sucks a towel out of your hand right into the grill.

 

[charliemeyer007]

2 core isn't enough, 3 or 4 offers way more surface area to pass heat IMHO. Cheap to try coolant enhancer and a lower thermostat.

Go to the car wash and power wash the radiator cooling fins from the engine side to make sure air passage is free.

Maybe the aluminum has crud build up on the inside - looking into chemical flush for aluminum

 

[1lukeduke]

I have always run a 70’s chevy truck 4 blade steel fan, they are quiet and pull a ton of air! Cooled my bbc for 10 years!!( also did you buy a generic china rad? ) they are not as effective as higher dollar double pass or tripple pass cross flow radiators

I’m sure it is Chinese. Summit. Although the reviews said it fixed their cooling problems. All were very happy with its cooling capabilities.

 

[Chamba]

I ran a 350 Vortec with an H55 in my Troopy for years using the stock copper rad. Even with the air con on in Phoenix heat she never got above 210°. I had the 8274 and a bull bar and still she never gave me problems.

My son's Camaro had some cooing issues and that water wetter made no real difference. The solution was better electric fans with a higher CFM. You've likely got good air flow from your description, so my money would be that the fault lies with the radiator. Buying a factory copper radiator from someone like @cruisermatt would likely solve all your issue and last another 20 years.

 

[cruisermatt]

Bigger picture question, Is the cooling system not keeping up with heat management or masking an actual problem?

Many reasons that an engine could generate more heat then normal, including:
Lean fuel mixture
Restrictive exhaust
Physical problem with the engine itself

Are you SURE that everything else is right?
How about some pictures of your engine bay and the vehicle?

 

[DangerNoodle]

I agree, but I can not get much more radiator in there. Also my understanding is that after 30mph the fan no longer pulls as much air as the wind being forced through the radiator. The fan can become a block even. Just a regular 2 core single pass I believe.

Core count and flow style will drastically change a radiator with the same size.

Let's see some pics of the engine bay.