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Resolved 2G Overheating

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Mike s 95 gst

Probationary Member
28
4
Feb 20, 2016
Pembroke Pines, Florida
Ok so over a grand in parts later and 3 months of researching this specific problem I've tried everything. Only thing left I can think of is the block or head got damaged.

So just randomly one day my car starts from never going over 185deg to a slow constant rise till near overheating then I shut it down. This just randomly started one day as I noticed my aem gauge was over norm temps along with the oem sensor reading hot as well. Once the car reaches past normal operating temp the afr's start to spike into the 20's and the car feels like it wants to fall on its face.

Here's what I've done so far trying to fix the issue:
1. new oem water pump from mitsu direct.
2. brand new radiator exact same as the one that was working flawlessly previously mishimoto.
3. checked for and repaired 2 minor common spot leaks.
4. flushed system.
5. new hks MLS head gasket, cleaned/checked head for straightness, with a thin film of copper spray for any imperfections which I have done over 10x with no issues.
6. at least 7 new thermostats
7. 40/60 cool/water mixture
8. compression test all cyl's within 10% did an at home leak down pressurized the cylinder and no bubbles in the coolant.
9. no leaks what so ever rad cap is topped off and system burped.

Wthhhh please someone give me something else to try. Wow I've had this car so long and never have I had a temp issue like this. Any help is much appreciated as all this work was not easy being handicapped LOL thanks in advance guys.

BTW the valves were super dirty almost not seating dirty could that be an issue I know it can effect the afr's like I'm seeing?
 
Solution
FIXED!!! alright guys so I finally after about 3k dropped in the motor I found the problem hopefully this helps someone in the future but the overheating was a clog in the banjo bolt leading to the water pump could've taken me all of 10mins to fix 3 head gaskets later new bearings new rods new rings to find this bolt clogged leading to the water pump might be worth a look if u feel your system isn't cycling correctly how silicone got in there to clog it is beyond me I'm guessing a gasket somehow got stuck in it thanks for all the replys guys problem solved!!!
Block was not decked but it's never had an issue before and I straight edged it with a feeler gauge criss crossed and both ways parallel couldn't even get the first tooth on the feeler gauge under the straight edge...

Give numbers. What is the car showing temp wise while "overheating".
Once the Temps get to over 213 I shut it down my car like I've said has never seen past 185 at first I thought thermostat tried about 5 of them then noticed my water pump wasn't squeezing like it usually had so I replaced that with a gates new. Thought that may not be good enough so I went oem pump as well...

Once the Temps get to over 213 I shut it down my car like I've said has never seen past 185 at first I thought thermostat tried about 5 of them then noticed my water pump wasn't squeezing like it usually had so I replaced that with a gates new. Thought that may not be good enough so I went oem pump as well...
Squeeling*

Was the blocked decked also ? Are you using arp studs or oem head bolts ?
Arp studs
 
213 is nowhere near "overheating". 2G fans don't come on "high" until 210-212 degrees.

A 50/50 mix of anti-freeze won't boil in these cars (stock pressure cap) until around 260 degrees (I don't suggest trying this--this is just based on ethylene glycol/water 50/50 mix in a 13 psi pressurized system, and it's being read by a sensor that isn't monitoring the coolant EVERYWHERE in your engine).

You're in Florida, in the summer, and I bet you still have A/C and a FMIC..

Keep an eye on it and start to worry when your 220+

The AFRs on the other hand....

Here's some info:

You must be logged in to view this image or video.
 
213 is nowhere near "overheating". 2G fans don't come on "high" until 210-212 degrees.

A 50/50 mix of anti-freeze won't boil in these cars (stock pressure cap) until around 260 degrees (I don't suggest trying this--this is just based on ethylene glycol/water 50/50 mix in a 13 psi pressurized system, and it's being read by a sensor that isn't monitoring the coolant EVERYWHERE in your engine).

You're in Florida, in the summer, and I bet you still have A/C and a FMIC..

Keep an eye on it and start to worry when your 220+

The AFRs on the other hand....
The fans are always on and they are flex a lite fans as well..

The fans are always on and they are flex a lite fans as well..
& like I said before my car never went over 185 temp ever. This just started happening a few months ago

The fans are always on and they are flex a lite fans as well..
213 is nowhere near "overheating". 2G fans don't come on "high" until 210-212 degrees.

A 50/50 mix of anti-freeze won't boil in these cars (stock pressure cap) until around 260 degrees (I don't suggest trying this--this is just based on ethylene glycol/water 50/50 mix in a 13 psi pressurized system, and it's being read by a sensor that isn't monitoring the coolant EVERYWHERE in your engine).

You're in Florida, in the summer, and I bet you still have A/C and a FMIC..

Keep an eye on it and start to worry when your 220+

The AFRs on the other hand....

Here's some info:

You must be logged in to view this image or video.
Sry I'm bad at this I replied somewhere else somehow LOL I have my fans on at all times & like I said previously my Temps never went above 185 & now I'm pretty sure if I don't shut it down it's going to keep creeping up. My vacuum is reading around -8 when warm as well not sure if that's the valves not sealing properly being they have alot of carbon built up or maybe something with the head/block but compression tested out good even warm and I pressurized the system with compressed air and no bubbles in the coolant..
 
& like I said before my car never went over 185 temp ever. This just started happening a few months ago
Do you mean---before the ambient temperature has been blistering hot?

You've missed/ignored several aspects of my post.

***213 in Florida heat, in a car with an intercooler and A/C is NOT abnormal****

I also told you what boiling (which is what creates actual issues) is WAYYYY hotter than what you're seeing.

I also told you that the AFRs *are* an issue (depending on when they are occurring)

Have the fans rewired to work correctly. That's neither of the above issues (if they even are issues--I'm not seeing them as such at this point without more information), but it's one thing that is wrong that you CAN fix at this point.

More data is needed by far, and that doesn't mean "213 degrees in Florida heat with my (unknown) setup (FMIC? AC? Etc...) worries me"--because that's an expected situation.
 
Do you mean---before the ambient temperature has been blistering hot?

You've missed/ignored several aspects of my post.

***213 in Florida heat, in a car with an intercooler and A/C is NOT abnormal****

I also told you what boiling (which is what creates actual issues) is WAYYYY hotter than what you're seeing.

I also told you that the AFRs *are* an issue (depending on when they are occurring)

Have the fans rewired to work correctly. That's neither of the above issues (if they even are issues--I'm not seeing them as such at this point without more information), but it's one thing that is wrong that you CAN fix at this point.

More data is needed by far, and that doesn't mean "213 degrees in Florida heat with my (unknown) setup (FMIC? AC? Etc...) worries me"--because that's an expected situation.
Yes but why all of a sudden the temp is not under control I had a 185 degree thermostat in there and I could literally see when it opened with the temp sensor from 185 it would drop a few points when the thermostat opens then slowly creep back to 185 and hold steady now it just keeps raising and I'm about 95% sure if I left it running it would definitely keep raising plus the car runs like crap when it does warm up yes I have front mount and a/c which in florida mid summer weather has never been an issue and I've had the car over 20yrs just got a solid block had it decked when I got it head resurfaced never 1 leak rad cap is also new oem mitsu my question is why now all of a sudden is my afr's all over the place way too high and vacuum low and only when getting "hotter than norm" Temps is this occurring my fans constantly on have never been an issue as well as they have a control module attached to the radiator when they reach 180 they turn on and stay on unless it drops back below 180 I am literally stumped at this point.
 
Yes but why all of a sudden the temp is not under control I had a 185 degree thermostat in there and I could literally see when it opened with the temp sensor from 185 it would drop a few points when the thermostat opens then slowly creep back to 185 and hold steady now it just keeps raising and I'm about 95% sure if I left it running it would definitely keep raising plus the car runs like crap when it does warm up yes I have front mount and a/c which in florida mid summer weather has never been an issue and I've had the car over 20yrs just got a solid block had it decked when I got it head resurfaced never 1 leak rad cap is also new oem mitsu my question is why now all of a sudden is my afr's all over the place way too high and vacuum low and only when getting "hotter than norm" Temps is this occurring my fans constantly on have never been an issue as well as they have a control module attached to the radiator when they reach 180 they turn on and stay on unless it drops back below 180 I am literally stumped at this point.

I dunno. Why are you stumped about a car that (with the data you've given) is acting like a normal car (other than the fans running "constantly"--whatever that means).

Because it's now 27 years old? Because it's a hot summer? Because we've told you what you're seeing now is "normal" and you're obsessing about why your car ran cooler than normal at one point? Because Venus is in the "X" position?

Come back with data showing that with the restrictions (harder running, more blockages (FMIC)) you've added are NOT making it run inside of normal parameters.

You've refused to add any data on your part--and continue to just throw up "Well! At one point it ran cooler!".

Show data that's actually indicating an issue.

Until then, I can tell you that at minimum, *I* am not wasting more time appeasing you.
 
Random question, have you verified the temperatures with a temp gun? Have you seen how many degrees of cooling you're getting across the radiator? Possible faulty temperature sensor?
 
Random question, have you verified the temperatures with a temp gun? Have you seen how many degrees of cooling you're getting across the radiator? Possible faulty temperature sensor?
Few months ago I did some testing and found out that if you're using anything OTHER than a genuine OEM mitsubishi temp sensor for those model years (1995-2000) it will read almost 10C HIGHER in any logger or Link, which will throw the entire tune and performaance/cooling out the window. It took me so long and a few coolant temp sensors to come to this conclusion. My car never overheated, it simply had a higher-reading aftermarket sensor. I went to the junkyard and pulled a CTS off an 8th gen Galant and everything was back to order.

So if OP had needlessly changed his CTS with something non-OEM, I suggest he revert back to it and test again.
 
I dunno. Why are you stumped about a car that (with the data you've given) is acting like a normal car (other than the fans running "constantly"--whatever that means).

Because it's now 27 years old? Because it's a hot summer? Because we've told you what you're seeing now is "normal" and you're obsessing about why your car ran cooler than normal at one point? Because Venus is in the "X" position?

Come back with data showing that with the restrictions (harder running, more blockages (FMIC)) you've added are NOT making it run inside of normal parameters.

You've refused to add any data on your part--and continue to just throw up "Well! At one point it ran cooler!".

Show data that's actually indicating an issue.

Until then, I can tell you that at minimum, *I* am not wasting more time appeasing you.
I'm sorry what other data is needed I'm not a mechanic man? I've just been doing all the work since I've got the car and that's what I'm saying I haven't changed a thing I've always had the front mount and a/c should I let my car over heat and post a video LOL I'm not willing to try that man my car last yr at this same time was running at 185 degrees never a degree above now it will NOT stop climbing is my point. I'm not trying to damage the heqd or block just to prove to myself it won't get to overheating temps cause I'm about 90% sure it will especially with the low vacuum and afr's going crqzy yes there is a problem. I have 0 boost leaks so something is not right at all the car drives like it wants to die when warm what other information can I provide to help solve the issue...?

Random question, have you verified the temperatures with a temp gun? Have you seen how many degrees of cooling you're getting across the radiator? Possible faulty temperature sensor?
My rad cap is a temp sensor & it matches my aem sensor installed in the water neck perfectly so I've already tried that route LOL that's what I thought too maybe faulty temp sens but nope...& how would I test that with the radiator I would guess a thermometer on the inlet and one on the outlet to get that#?

Few months ago I did some testing and found out that if you're using anything OTHER than a genuine OEM mitsubishi temp sensor for those model years (1995-2000) it will read almost 10C HIGHER in any logger or Link, which will throw the entire tune and performaance/cooling out the window. It took me so long and a few coolant temp sensors to come to this conclusion. My car never overheated, it simply had a higher-reading aftermarket sensor. I went to the junkyard and pulled a CTS off an 8th gen Galant and everything was back to order.

So if OP had needlessly changed his CTS with something non-OEM, I suggest he revert back to it and test again.
Been there too brother LOL 😆 I guess thats common I've had just about every problem with this car u could possibly have. Just never a cooling issue at all...

My rad cap is a temp sensor & it matches my aem sensor installed in the water neck perfectly so I've already tried that route LOL that's what I thought too maybe faulty temp sens but nope...& how would I test that with the radiator I would guess a thermometer on the inlet and one on the outlet to get that#?
Plus the car starts driving like crap when it gets warmed up I think I'm going to rip the heqd off again this weekend and get it tested... this issues really turning to a nightmare LOL

The front mount/AC condenser is blocking airflow to your radiator, but until you post a log of it running over 230 degrees I’d say your fine:idontknow:
Ok let me get a log this weekend maybe that will show something that I'm unaware of thanks man!
 
FIXED!!! alright guys so I finally after about 3k dropped in the motor I found the problem hopefully this helps someone in the future but the overheating was a clog in the banjo bolt leading to the water pump could've taken me all of 10mins to fix 3 head gaskets later new bearings new rods new rings to find this bolt clogged leading to the water pump might be worth a look if u feel your system isn't cycling correctly how silicone got in there to clog it is beyond me I'm guessing a gasket somehow got stuck in it thanks for all the replys guys problem solved!!!
 
Solution
FIXED!!! alright guys so I finally after about 3k dropped in the motor I found the problem hopefully this helps someone in the future but the overheating was a clog in the banjo bolt leading to the water pump could've taken me all of 10mins to fix 3 head gaskets later new bearings new rods new rings to find this bolt clogged leading to the water pump might be worth a look if u feel your system isn't cycling correctly how silicone got in there to clog it is beyond me I'm guessing a gasket somehow got stuck in it thanks for all the replys guys problem solved!!!

The banjo bolt on the block in front of the turbo?
 
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