Overheating issues with 85 GT - Need radiator advice.

[cnoll76]

I have had the water pump, fan/clutch (with shroud), and t-stat replaced. Temp only starts to rise when I'm sitting still in traffic. I'm moving on to just replacing the radiator. I looked at LMR and found two: The Fluidyne and the SVE. Can someone provide some recommendations please? FYI...the engine is moderately modified but it is the original 302 rebuilt. Thank you!

[wraithracing]

Fluidyne makes excellent radiators, but they are on the expensive side. Again great radiators, but you may not need/want to spend that much.

The SVE radiator from LMR I believe is made by Mishimoto and private labeled as SVE. If that is the case, the Mishimoto brand of radiators are good quality and I have used them in several Mustangs with no issues.

Griffin is another option that is often less expensive than Fluidyne, but more expensive than say a Mishimoto. I have used their radiators in the past too with good luck.

I have also heard good things about Champion brand of radiators and have considered buying one of their 3 or 4 row aluminum radiators for my 5.4DOHC swapped 82 GT when I get closer to completion on that project. Here is a 3 row option on Ebay. https://www.ebay.com/itm/3-Row-Perfo...UAAOSw9NZa5z5P

[cnoll76]

Thank you. Much appreciated. If this doesn't work, my mechanic said we may have to check to see if person who rebuilt the motor put the head gasket on backward. But, before I do all that, I keep reading on the forum about various sensors that related to the coolant system. Maybe I have some back sensors. Do you know anything about that?

[cnoll76]

Sorry, "bad" sensors...

[emerygt350]

Get yourself a laser temperature reader. They are cheap and useful. Timing matters too. Is it fuel injected? I assume it is a four barrel. Is your fan clutch good? If it is serpentine, did you get the right reverse direction water pump?

Unless you have reason to believe your radiator is bad I would make sure your engine is running correctly first and that the fan/water pump are correct. Finding that out is free.

[cnoll76]

My mech put a manual temp gauge on it and it was running hot, as suspected. It is not fuel injected. The fan clutch is good. The water pump direction has been checked. After this radiator replacement, I don't know what to do. I have to think outside the box. Maybe ignition timing, check if the head gaskets are on backward, maybe replace the coolant sensor. I don't know. It's so frustrating.

[wraithracing]

If you mechanic has verified that all the current parts are correct and working properly, then I would definitely recommend double checking the timing. Not only initial advance, but total advance too. That can definitely cause an issue in regards to overheating.

The coolant sensor is not going to cause the problem you have. Besides if the temp gauge in the car shows overheating and the mechanical gauge by your mechanic showed the same, then the sensor is working properly.

Head gaskets installed incorrectly could be the issue, but hopefully that is not it. Other than overheating in traffic , does the car run fine? Is your carburetor adjusted properly and not running lean, especially at idle as that could be part of the overheating issue due to a lean condition. Check all the simple stuff first.

Also since you state its modified, are you running underdrive pulleys on the engine. That can cause overheating or running hot conditions at low speeds. If you do have underdrive pulleys you might consider swapping back to standard pulleys. You might also consider the 93 Cobra WP pulley as that helps speed up the WP which can improve cooling, especially at lower speeds and idle. Good luck!

[emerygt350]

Modern thermostats come bad out of the box most of the time these days. If the radiator doesn't help (no harm in a new radiator), I know it is a bitch to pull but if it comes to it, you could remove the thermostat and see how it does at idle.

Does it also rise during a long climb or only when you are not moving?

[liv2roc]

I bought this 3 row one https://lmr.com/item/SVE-8005A-BL/mu...or-black-79-93 back in june. I got it for $162 shipped back during the 4th of july sale. My engine is a stock with roller cam .040 over with a 281 comp cam and the temp would start climbing with the ac on if I sit and a stop light. my old radiator was and advanced auto parts 1 row with plastic side tanks. so far mine is fixed gauge never moves now. I did put a 180 thermostat in mine last year because I did not like it running around 200 degrees it sits right at 185 now all the time.

[cb84capri]

Modern thermostats come bad out of the box most of the time these days.

^what he said. What brand is you t-stat?

Cale

[cb84capri]

Also, it is extremely common in these cars for them to have air in the cooling system if the coolant was drained and measures were not taken to get the air out when refilled. The upper radiator hose sits a lot higher up than the radiator cap.

Cale

[Jerry peachuer]

Headgasket orientation can be checked visually looking at the head itself when you open hood
Stare at where the head gasket is and you will see a tab sticking out

This is genius by gasket manufacture (Fel pro)

You can absolutely get head gasket on backwards on the 302/351 easily
This will block off coolant ports

Again this is easily checked with visual 20 seconds visual and you will know
No tools required

[erratic50]

No one has mentioned this so I will......

make absolutely certain you have a good seal at the radiator cap and no coolant leaks anywhere. I’ve battle overheating issues and had it turn out to be a radiator cap multiple times now

As far as thermostats, I don’t run anything other than the correct OE part number or a Mr Gasket high flow

We had a 460 that constantly ran hot no matter what we did. I had to make a 100 mile trip after the correct factory 190 degree HD high flow thermostat and it cured it. She’ll idle in traffic all day and stay cool with the AC running full blast. Also in the summer heat with 10K lbs hooked on behind

I did also put in a new radiator and cap on the 460 so even a broken clock is right twice per day

As for radiators in a foxbody — FB-169 (frostbite) is a great product. It’s rated to be able to keep a 750 HP combo cool in the summer heat

I had underdrive crank pulley and a stock water pump pulley on my 86GT. It was marginal sitting and idling but fine going down the road. My solution was a 93 Cobra style water pump pulley from Summit which brought the water pump back to 1:1 with the motor. Factory they are slightly overdriven so it was still a reduction vs stock, but water flow was adequate

I run a 192 Motorcraft thermostat in my 86 and 13.5 degrees of base advance