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Car Runs Too Hot

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PhoenixRPR

20+ Year Contributor
450
0
Oct 9, 2002
San Diego, California
My 92 Eclipse GSX (stock) runs too hot and I want ideas why. The stock temperature gauge is always jumping around between the halfway mark and the full hot mark. As I accelerate the needle tends to slowly move hotter, then as I come to a stop it will move back to halfway. How can I fix this? Thanks.
 
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Sounds to me like your cooling system is not getting full circulation. If you were getting no circulation then I'd say you have a bad water pump and you would be overheating. But by this time you'd be posting a thread saying I have a blown head gasket and coolant is coming out my tailpipe! Therefore ask yourself 1 question. Is my car getting heat? If the answer is NO then your heater core is restricted reducing the cooling systems circulation.
This is an easy but accurate answer. I am afraid the fix however, is a lot harder and very time consuming. Good Luck.
 
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ditto on waterpump, hell maybe your tstat is being stuck closed sometimes? Replace tstat with 180 or even 160 and if that doesnt solve it, check if you're leaking coolant cause it maybe your radiator or your waterpump.
 
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/\ I would also have to agree with the above, but one thing no one mentioned is that you may also have a exhaust gasket blown somewhere. My 99GSX was going through the same porblem last year it got so hot in the engine bay that it melted my cooling fan blades. Make sure that you exhaust mani gasket, 02 gasket, and dp have not blow out the gaskets or that you may have a crack in your exhaust mani, or 02 dp. Both of these problems would create very high engine bay temps while driving and show signs of cooling when stoping or comming to a stop light.
 
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I receive a fair amount of heat from my car's heater. It's not scorching hot, but its moderately warm. Does anyone else agree that a partially blocked heater core could result in my car's symtoms?

My car's radiator has been completely flushed twice in the last 4 months, so it's not that. I'm not leaking any coolant, thank god.

The T-stat is an interesting idea. The T-stat I have in there is OEM aftermarket (Not Mitsubishi). I have heard that it's best to use the stock Mitsubishi t-stat. What do you guys think?

I have not ruled out the possibility of an exhaust gasket leak somewhere. Where exactly should I check for these leaks/cracks and how should I check for them? Thanks!
 
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check for gasket leaks between your exhaust mani and turbo, ehxaust housing and 02 housing, 02housing and down pipe ... could also be loose boolts around those areas. as far as cracks most are on the exhaust mani so look at your runners ... unless you have a oem mani they usually dont crack but you never know.
 
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ITSME4G63 said:
Replace tstat with 180 or even 160 and if that doesnt solve it, check if you're leaking coolant cause it maybe your radiator or your waterpump.
Click to expand...


The stock t-stat is 195. Dont change the t-stat more than 15 degrees. Changing the t-stat more the 15 degrees isnt good for the computer. Will cause bad side affects with the car. Poor idle, drivablility and so forth. I recommend no more than a 180 :talon:
 
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A thermostat restricts the flow allowing the car to reach temp. faster. You have replaced the thermostat twice. When they open full circulation is supposed to be achieved. The aftermarket theoy is bunk. Technically you could run without a thermostat. You problem is restricted flow in the cooling system. Your lukewarm heat proves just that.
 
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Does anyone else agree with Judacoth that the heater core could be causing my problem? If so, suggestions?
 
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Remember, when heat is shut off, coolant does not flow through the heater core anyway, since there is usually a valve that restricts the flow.

But...............

Quick way to ck the heater core.

Get some heater hose, whatever the diameter is, maybe 5/8".

Drain coolant.

Disconnect both heater lines, at the engine inlet and outlet points.

Install heater hose from one to the other inlet/outlet points on the engine.

Tie up the existing coolant lines so they are secure and out of the way.

Refill and check coolant levels, and then go for a test ride and watch your gauge!

If temp is OK, try flushing the heater core.

;) :laser:
 
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Judacoth said:
Theres no bypass. Its a straight shot to the core. If there was one it would have been replaced long ago.
Click to expand...

but, there are two heater hoses, one in, one out, otherwise, you would never have heat, cause the water would go there, and sit, and cool. All cars have that set up!

Ck your shop manual...........I doubt it be the core anyway, since when you shut off your heater, your shutting off the flow to the core.
 
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of course there are two hoses. Of course not turning on the heater means no heat. But what does that have to do with a bad heater core resticting flow?
 
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I believe what he is trying to say is to see if it is the heater core eliminate it from the system completely.

Remove the return line from the core at the TB, and loop the "to core" line into the return on the TB. Then the heater core is eliminated and therefore cannot restrict flow, the coolant will just loop through the line and back into the motor.
 
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I fully understand the method to bypass the heater core altogether. Phoenixrpr's 1g shows the temp. gauge indicator just slightly over half. Prior to his heater core getting plugged up it was slightly under half. If changing the heater core was a simple fix then it would not be an issue. However, core replacement take many hours.
 
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Judacoth said:
of course there are two hoses. Of course not turning on the heater means no heat. But what does that have to do with a bad heater core resticting flow?
Click to expand...

Well first.......it does not make sense to flow 200+ deg coolant through the heater core, which is located inside the car, when no heat is required!! So there must be a shut off valve somewhere, but it is not on the hoses themselves, as I have normally seen. Trust me, I think you would definately feel the heat if it was flowing all the time, even if the air ducts were not blowing air through it.

Second, probably the heater core is not the issue, and yes, all I was referring to was a quick check to deteremine this, by bypassing the core all together!!!

Check for flow: With the car running, and warmed up to normal temp, at idle, check for flow in the upper radiator hose by carefully grasping it, with gloves or a rag to prevent you burning your hands. Squeeze it and Rev the motor, if it flowing you will feel it. Just for kicks, with the heat off, feel both the heater hoses, one should be hot, one will be colder, IF there is no flow through the core. With heat one, both will be hot.

If your core is clogged, try this first. Disconnect the hoses, and reverses flush it with a garden hose. Might just clear it enough to prevent replacement.

I would suspect, radiator cap or themostat (even if new, could be bad, remove it just to see if anything changes, thermostat that is, not the cap!!). Or, water pump weak, belt slipping??. Even flushing a radiator, might not mean the radiator is good, could be partially clogged, to cause what is happening, hope not.

Bottom line is, unles you systemically eliminate other items which may be causing the problem, it is just a guessing game!!

Just trying to help and Good luck! :thumb:
 
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