The Top DSM Community on the Web

For 1990-1999 Mitsubishi Eclipse, Eagle Talon, Plymouth Laser, and Galant VR-4 Owners. Log in to remove most ads.

Please Support Rix Racing
Please Support STM Tuned

Turning my heat on, stops car from overheating?!?!

This site may earn a commission from merchant
affiliate links, including eBay, Amazon, and others.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Jeff D Desantis

Proven Member
54
4
Nov 5, 2018
Rochester, New_York
Been having times where my car over heats when I turn off the heat in my car. I'm assuming its head gasket issues? Car runs perfect with heat is turned on in car, when the heat is turned off car will overheat and bubble the coolant and cause pressure.
 
This is an old school trick to prevent overheating way back in the olden days. The heater core is part of the engine's coolant circuit and acts as a second radiator. So in an emergency if you see you are starting to overheat, turn the temp controls to full heat and turn the fans on full blast. Then just slow down and find some place safe to pull over and let the car cool down.

And as you mentioned, you are overheating because of the blown head gasket. Get that taken care of before you warp the head even worse than it probably already is.
 
Ahh thanks for the info! I'd love to have it looked at and repaired but my patience is running low for this beauty! I'm putting her up for sale, and if I can't get any decent offers i'll just have her repaired down the road. These cars are cursed! LOL jk
 
I posted in your other thread you should check STM Tuned. And IIRC you recently did the paint job on your car and your car pics looks like it's in good condition. I hate seeing new people give up on DSMs. Besides the blown head gasket, what other problems are you having?
 
Yes the car is MINT! I had the body, interior done, looks everything! I don't want to get rid of the car. I'm too scared getting ripped off at a mechanic to take it anywhere near one around here! Only issue is the head gasket, car runs drives amazing.

I'll pay for a DSM Tuner to come out and fix it LOL. How much? I'll pay travel expenses plus time fixing + parts obviously.
 
Last edited:
This is an old school trick to prevent overheating way back in the olden days. The heater core is part of the engine's coolant circuit and acts as a second radiator. So in an emergency if you see you are starting to overheat, turn the temp controls to full heat and turn the fans on full blast. Then just slow down and find some place safe to pull over and let the car cool down.

And as you mentioned, you are overheating because of the blown head gasket. Get that taken care of before you warp the head even worse than it probably already is.

He never said he had a blown head gasket he said he was assuming he has a bad head gasket.

Been having times where my car over heats when I turn off the heat in my car. I'm assuming its head gasket issues? Car runs perfect with heat is turned on in car, when the heat is turned off car will overheat and bubble the coolant and cause pressure.

Before you jump to conclusions I would first make sure you radiator fan is working properly and it turns on when your car starts to heat up. You mentioned when your " Car runs perfect with heat is turned on in the car ". Check the fan and see if its working properly and then report your findings.
 
Can you hear bubbling at the front of the car when you park it?

Had this issue on my car when I was just starting out, your coolant isn't properly bled. Try a coolant flush and follow proper bleed procedure, which you can do on your own in 15 minutes.

Could be a number of other things as well but this is my guess.

EDIT: Is there white smoke coming out of your tailpipe? Are you losing coolant over time?
 
Yes so the coolant bubbled and got super hot. Causing steam/almost smoke coming from the engine at one point. When the car over heated white smoke came out. This happened when I turned off the heater. Car instantly over heated within 5 minutes. But with heat on I can drive it for hours with no issues. I'm so confused.
 
That's not good.

Fans are definitely worth checking/fixing.

Start with a flush and a proper bleed, see where it gets you. If you can afford for someone to travel over to fix it, you can buy some coolant and risk it being wasted.
An improper coolant bleed can trick the thermostat and not let it open, you might be running into this issue.

When you drive for hours, do you notice if you are losing a bit of coolant?
 
I've done that. When the car over heated the first time I put coolant in because there was none left. The guy who sold it to me probably knew of this issue and kind of took off after selling it to me, which is fine or whatever I know it needed TLC and had potential. I am just getting pretty tired with the car for right now LOL.
 
Yeah so it probably has a small headgasket leak. The major bubbling and whatever stems from you not bleeding the coolant system. The thermostat is reading incorrectly and, in your case, is just staying closed most/all of the time.
Bleed it correctly and you should be fine for a bit until you get that HG fixed.
 
Thank you, sounds good. So bleed the coolant system and get a radiator fan that works to start. I'll probably have the mechanic do that in one shot. Is there a link for an affordable one? Mine is not side mounted its behind the intercooler.
 
Kind of, but not major. Technically you're getting heat soak but so is everyone else who is driving their cars more than 5 minutes at a time. If you're overheating a bit, you're just getting a bit more than everyone else, but the horsepower losses are likely incredibly minimal in your case.

I wouldn't beat on it too hard before getting the stuff fixed anyways. Running a car with problems will only lead to more problems.
 
So Basically the current list is:
1) Bleed Coolant (is this what they call a coolant flush?
2) New Radiator Fan (can you guys provide any links to ordering a decent one for the money)
3) Head Gasket Issue (geez where do I begin with this, this is where I can get destroyed at the shop by not being savvy with automobiles)
 
1. Technically it's called purging or "burping" the coolant system. You jack the front of the car up some, fill the coolant to the top, run the car (with heat on high) and as it's running you squeeze the rad hoses repeatedly, which "burps" the air out. As the car warms up, the t-stat opens, as well as the FIAV, which helps release any trapped air pockets and ensures the system is completely topped up. One of THESE will help to keep from spilling coolant everywhere during the process.

2. I would recommend Performance Part Out or Miller Import Please for a good priced, stock unit. Spal or Fal fans are a good, yet spendy aftermarket option. Make sure you can get a shroud of some kind to direct the air properly, as this aides greatly in cooling efficiency. If you have to mount the fans between the rad and intercooler, just make sure you have plenty of fans of decent quality. FWIW, stock fans work excellently as long as you can fit them.

3. You will want to be 100% sure it's a HG before diving in, so do a leak down test to see if you get bubbles in the cooling system when the combustion chamber is pressurized. You can also do a gas test (true name escapes me rn) where you test for exhaust/emissions gas in the cooling system with a 5 gas analyzer. Most shops can do this, but it's reserved for the hard to find issues generally.
A leak down should give you a pretty good idea if it's truly leaking.

Is the car blowing white smoke from the tail pipe when running? What do the spark plugs look like after running for a few min? Usually if you have compression going into the cooling system, you will end up with coolant pushing back into the CC after you shut off the car. This will then burn when you start it again and will cause white smoke, as well as discolored spark plugs, depending on how long you run it.

You could always just shotgun the HG and do a timing job at the same time to cover bases, but that can get expensive, though if you're paying a shop for the other procedures it might be the best route to go anyway.
 
Waaay to hard to guess. Depending on parts used and shop rates. If you get your own quality parts you might save money and have better pieces than some shops may offer you.
Call around and see what different ones may offer, ask questions, see who seems the most knowledgeable, honest and fair priced.
 
Support Vendors who Support the DSM Community
Boosted Fabrication ECM Tuning ExtremePSI Fuel Injector Clinic Innovation Products Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications MyMitsubishiStore.com RixRacing RockAuto RTM Racing STM Tuned

Latest posts

Build Thread Updates

Vendor Updates

Latest Classifieds

Back
Top