Running hot

[Nightrage]

I just got my car back from the service station. I had the coolant flushed and it's still running hot. I think the guy said my fan wasn't coming on. If this is the case, what's the solution? Should I go with an aftermarket fan?

Also, any recommendations on a new clutch? Apparently it's not supposed to release right at the top. At least that's what the mechanic told me. I guess that would explain the sluggishness I experience off the line. What about an aluminum flywheel? Good idea or bad idea?

[esoteric]

does it stay cool going down the road at say 45/60 MPH but then on the highway at say 70+ it gets too hot. Or is it the other way around. If it gets hot on the highway it might be your radiator, if its the other way around I would check to see if the thermostat is working.

If the fan is not coming on you might have a bad fan motor.

My older TA was getting hot and I found the radiator was just rotten on the bottom. New radiator and happiness!

[Injuneer]

As you can see "running hot" is too vague a description for people to understand the problem and offer help. What are the specific temperatures you see on the dash gauge, at idle, driving slow in heavy traffic, and at high speeds on the freeway. Have you verified the gauge by using a scanner to check the coolant temp in the PCM? Has anyone checked the coolant temp sensor in the water pump for accuracy?

Do the fans come on when you turn on the A/C?

Are you sure the "service station" mechanics know the correct air bleed procedure for an LT1 reverse flow cooling system? Most of them don't even know what that is, and that it has been used only on this one engine.

The stock cooling system should keep the car cool under virtually all operating conditions. There is no need for aftermarket fans.

[Nightrage]

Sorry guys. I was in a rush so I just typed it.

Around town it tends to run at 210*, sometimes it heats up to 215* or so. On the parkway it usually rides between 225* and 235*.

I haven't really checked anything and I don't know how great the mechanics were. The one guy told me that he'd worked on his ex girlfriend's Formula, so I figured he'd have an idea as to what he was doing.

[Iceslim0]

I have a similar problem with mine. Both my fans turn on and the water begins circulating immediatly when the engine turns on. Turns out the guy before me took out the thermostat, and a gasket blew, so instead of a 13lb cap, he just put an 18lb cap on. Now it just runs around the temp that yours does and I don't have the money to fix it right now.

[Injuneer]

With stock programming, 210degF in slow traffic is normal. That's exactly the way GM intended for it to run. The odd part is that the temperature goes up when you go faster. Usually, it will drop down closer to 200degF with stock programming. Is the air dam still in place under the bumper?

[TraceZ]

Regarding your clutch....

Mine has aleays released up close to the top of the pedal. Even after installing my new SLP clutch, it still released up towards the top.

My black 95 Z also released up towards the top, and I bought that car brand new back in 94.

I think it's normal for our hydraulic clutches to behave that way. Does yours slip? Does it make noise?

[Joe K. 99 Zeee!!]

The system can be upgraded to allow you to adjust the clutch engagement, but what you have now seems fine. Mine also engages near the top, I believe that's normal.

[Nightrage]

Today it was running at around 215* on the parkway whiich is what it was running at when I first got the car. I guess it was just built up crap in the coolant that was raising the temperature. I'm planning on getting some exhaust work done, plus a PCM For Less tune in the near future now that I've finally got some money coming in. Could a mail order tune help my car run cooler, or would I need a 160* thermostat or what? Also, how long does it take to install headers? My stepdad's friend is a mechanic that's willing to do it, but I think he charges a pretty penny. I don't want the installation to cost as much as the headers do and I really have no means of doing it myself. I thought I'd have some means of doing it myself but I don't. I pretty PO'd because I was looking forward to the experience and being able to say, "I did that on my own". Since it's a friend of my stepdad's, maybe he'll let me help.

Regarding my clutch issue, I guess the guys I took it to were bad mechanics or maybe they just don't much about F-bodies. I've always liked where my clutch releases because it allows me to shift faster under spirited driving. I'm at 92,000 miles now, but probably 95% of that is highway mileage. I guess my clutch should still have quite a bit of life left in it. That still doesn't explain the lag I experience off the line, though.

[Injuneer]

To get the full benefits, you need BOTH the 160* t'stat and the fan on/off temps reprogrammed, with maybe a couple extra degrees of timing advance thrown in.

[Nightrage]

If I were to get ceramic coated headers and wrap them in thermal tape, that would keep the heat down, right? What about a hood with heat extractors? Do they work well or are they even worth the money?

[Injuneer]

You do NOT want to wrap your headers, even if they are cera-metallic coated. The coating by itself reflects heat off the internal coating, and keeps the actual tube metal temperatures lower, reducing the tendancy of plain carbon steel, or even stainless steel to embrittle and crack. The lower tube metal temperature helps reduce under hood tempratures.

Add a wrap, (with or without the coating) and the insulating value of the wrap will significantly reduce heat loss to the engine compartment, but it will cause the tube metal temperatures to come very close to the exhaust temperatures. Plain carbon steel will lose its strength and embrittle, and the iron in the steel will start to oxidize, causing a very rapid rusting of the tubes. Its not really happy operating at 1,100+degF. Even stainless, while not oxidizing quite as quickly, will see accelerated cracking of the tubes and the welds due to the excessive temperatures.

Wrapped headers are often used on pure racing applications, because it will maximize the heat retention in the tubes. But in those applications, the headers are viewed as "consumables", requiring frequent replacement.

I've tried running without the gasket that seals the hood to the cowl, and it helped reduce underhood temperatures appreciabley. Unfortunately, it also allows rain to enter the engine compartment, and drip on the engine and on the PCM. OK for a track car, but not real good for a street driven car.

[Nightrage]

Sorry to bump this thread back to life, but the problem is apparently fixed. I got my car back from the shop yesterday. He fixed my window (part of the track needed to be welded) and he fixed the intake manifold leak. Now my car plants me in the seat real well, and it runs at about 185* all the time. I've fallen madly in love with my car now. Thanks for the help guys!!!