major overheating problem

[onephatz]

I've got a 75 with a '82 turbo motor and fuel system in it.

 

I'm running the stock ecu with 10psi and a fmic.

 

problem:

 

idling she sits right at 180 all day no problems

crusing at 70mph she wants to run around 210

one hard pull and she's running around 230+

 

I took the thermostat out to see if that was my problem and it still acts the same way. checked the timing, and it's set at 20deg. did a road test where I ran a jumper wire from the o2 sensor(while still hooked up to the computer) inside the car to a multimeter, it was running between .5-.6 volts. everything seems to run right but it just over heats like a monster.

 

I had the same radiator in the car with my high compression l28 and no overheating problems. it also has a new water pump.

 

any ideas?

 

jesse

[Guest bastaad525]

I have the exact same problem. My car runs nice and cool on the streets, and even in traffic on warm days on the street, temp rarely reads higher than 190* on my gauge... just a tad bit over the middle line. However, at speed on the freeway it will run warmer, maybe by 10-15*, or stuck in really bad traffic on the freeway on a hot day, temps climb considerably. Getting on boost for more than a few seconds will cause a jump in temps as well. Any boosting or hill climbing on a hot day will push the needle up to about 3/4 of the way to the red, or about 210-220*.... Adding the FMIC agitated this problem further... it's obviously hurting airflow a bit. I'm running the stock ZXT radiator, fan, fan shroud... I've replaced the water pump, fan clutch, belt, thermostat (running a 180*), hoses and coolant. When I used to run my N/A, high compression, 2.9L motor with stock ZX radiator it NEVER got this hot... at the most during hard driving it'd get maybe to 195*... I guess the turbo just runs a lot hotter. Some guys here are of the oppinion that temps in the 200* range on the turbo motor are fine, while others say this means something IS wrong and needs to be addressed. I know I dont like my gauge sitting at 3/4 of the way up.

 

The first thing I strongly suggest you do is get a good accurate thermometer to verify what your actual temps are running at. I followed some suggestions on here and ran to Vons to pick up a long needle shaped meat thermometer. I tried sticking it in the radiator filler neck at different points during warmup and after driving, and found that the temp on the thermometer ran a consistent 15-20* cooler than what the stock gauge was indicating. I also verified that the meat thermometer itself was accurate by checking it against a few other thermometers. So that gave me a little peace of mind, though now with the FMIC and accounting for the gauge being off, it still gets too hot for my tastes on hot days on the freeway. Another reason I am reluctant to trust the gauge though... it's very easy to affect. For instance, if I make a left turn the gauge goes up. A long sweeping left turn on the freeway, will cause the gauge to go up 10 or 20*, but it takes a while for it to settle back down. Right turns cause it to drop down. Hey.. these cars are old it's no wonder the gauges maybe arent as accurate as they should be. One thing you may want to do is get a good temp gauge like an autometer, and possibly replace the coolant temp sensor as well.

 

A few other things were suggested to me as possible causes and solutions, none of which I've really been able to verify. One is that air is not flowing properly thru the radiator at speed, which explains why it runs hotter at speed, the opposite of any other car I've had with cooling problems. Possible solutions are to create some kind of ducting or a chin pan/spoiler to help concentrate airflow thru the radiator. Another caused suggested is that the lower radiator hose may possible be collapsing when the engine cruises at freeway speeds. I'm running a new, stock lower hose from Napa. Unfortunately I have no way to check if it's doing this, and no idea how to fix it if it were. Other possible reasons are a clogged radiator... I've been lazy but will get around to removing mine and taking it someplace to have it flushed at some point. But I will say that what little I can see from the top, it looks clean and not much corrosion at all, and the radiator was in like new condition inside and out when I pulled it out of the ZXT. Another thing I've been meaning to try is replacing my auto zone t-stat with a nissan tstat... some guys have suggested the nissans flow better, though I've NEVER had problems with off brands before.

 

One last thing I can suggest to you is to get your hands on some Neo Keep Cool. I just dumped some of this in my coolant the other day (4 oz.) and noticed an immediate improvement in the temps on my way to and from work... about 10-15* cooler running. I have yet to test it during a hot day... I work at night and head home in the morning... but either way it definately ran cooler overall. Another similiarm product you may find easier to locate would be Redline Water Wetter... I've heard of people getting similiar results with that stuff as well.