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my name is derek and i drive a 1991 mitsubishi 3000 gt vr4 with 59000 miles on it… im having an issue with the heat only blowing warm air at or above 2000 rpm… anything less is cold air…any ideas??? also when engine is cold if i open rad cap and start engine… coolant immediately foams out of rad…. i dont have coolant in oil or oil in coolant… car doesnt use oil or ever loses coolant…any ideas? thanks…
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A few things come to mind…
Air pocket in cooling system (Bleed the system)… Eric has a good video for this
Head gasket is going… When the engine is running the exhaust is pushing into the coolant jacket… Check using a block tester (Vacuum bulb with special chemicals to check for exhaust hydrocarbons in the coolant).
I would try to bleed the system first…
o wow definately not the news i was hoping to hear… car is not even at 60,000 miles yet… im assuming the coolant is the original stuff from 1991 as id did have the original plugs still in it when i bought the car… some one told me that dirty coolant or restrictions would cause the foam that im experiencing so i am really unsure…. the car runs great just doesnt produce heat unless at or above 2000 rpm…. car never comes close to over heating… wouldnt exhaust in the coolant raise the coolant temp significantly?
[quote=”bumpn6″ post=86946]o wow definately not the news i was hoping to hear… car is not even at 60,000 miles yet… im assuming the coolant is the original stuff from 1991 as id did have the original plugs still in it when i bought the car… some one told me that dirty coolant or restrictions would cause the foam that im experiencing so i am really unsure…. the car runs great just doesnt produce heat unless at or above 2000 rpm…. car never comes close to over heating… wouldnt exhaust in the coolant raise the coolant temp significantly?[/quote]
If your coolant is from 1991, you probably want to flush out and change the coolant… No telling what the radiator looks like after it has been in there that long..
Concerning your question about exhaust in the coolant, it very well could raise the temperature, but since it is cold out now (or I am assuming it is cold where you are), this might not be the case… the bubbling of your coolant in the radiator when running cold is what made me think of a head gasket leak… It very well may not be a head gasket leak, this is just a possibility..
-Karl
yes it is definately cold here in ohio lol…. car runs in the normal band… usually a little less then mid way… if i recall, it was the same as far as last summer goes as well… i dont recall it running much warmer to be honest
I would first start by removing the air as ToyotaKarl suggested. After that if you still have an issue with the fluid getting low then perhaps do a pressure test. Also, if your coolant is that old I agree that you should flush it out. You might even start with flushing the coolant and then bleeding the air out. More information in these articles.
http://www.ericthecarguy.com/faq/solving-automotive-hvac-problems
http://www.ericthecarguy.com/faq/what-to-do-when-your-engine-overheats
Keep us posted.
I wanted one of those badly back when they were new. Economics dictated a DSM.
Standard advice for a Mitsubishi of this era is pop in a new thermostat anytime the heat is anything but normal. This fixed a friends 3000 after it had been diagnosed as head gasket by the dealer. Anyway, if the thermostat is original it is long past needing replacement.
While at the store buy a block check too.
Thanks guys and thanks eric… I will swap out the thermostat next.,. I just cant believe they cost over 20 dollars tho.., quite expensive in my opinion… I have added more coolant since then tho and the heat is working better…. Its nice and toasty with rpm at 1100 or higher and slightly warm at idle… 700 rpm
If you still are having problems try flushing the heater core and hoses to heater core. Sounds like it is a little pluged up and when engine is at higher rpms you get more flow through the heater core. My car was doing the same and it seemed to help. good luck.
I would strongly suggest bleeding the air out of the system before you do anything else. You just might save yourself $20.
wish this car had a little bleeder screw because it is being a little stinker to bleed…. just when i think i got it done it seems that the heat works good for a few days and slowly the performance downgraded… i decided to rent a block tester that uses a test fluid to check for combustion gas in the coolant… my result came back good as far as that goes… had to re do it a few times do to the fact of accidently sucking up a little coolant but all in all i cood not get the fluid to turn yellow… should i try a pressure test next? i also find it very strange that my coolant foams out of the thermostat housing with cap off on an ice cold engine immediately after start up and lasts for a couple mins then stops… i have even tried smelling the fluid when it foams out and dont detect any wierd smells that would suggest combustion leaks aka head gasket failure so this is becoming a nightmare lol
Do pressure test first. It may also be that there’s wrong types of coolants mixed. Or leak stopping cement.
For mixed coolants flush cooling system and fill it with correct stuff. For leak stopping cement flush cooling and back flush heater core system and fill it with correct stuff.
I did work on Audi a4 did flush coolant it and back flush heater core then filled it back with coolant and bled it. It worked for some time but then heater core clocked up again. Ended up replacing it.
You do NOT need a bleeder valve to bleed the air out of the cooling system. It’s only there to make filling the system easier. Please follow all the other steps in the video that was posted to bleed the air from the system, just ignore the part about the bleeder valve. If you follow that procedure it should purge the air from the system. If you’re not able to purge the air, all other testing is moot. You MUST start with purging the air from the cooling system pressure test or not.
Keep us posted.
welp just wanted to check back in here as i followed everyones advice and tips… everything is good to go now….case closed lol
what i did to solve the problem was take off radiator cap on a cold engine…. then start the car and bring up to normal op temp….. next i turned heat to max temp and fan speed to off and filled radiator while holding throttle to around 2000 rpm….ran car for about 10 mins this way and kept adding coolant when needed….. heat is working nice last i checked and coolant level is staying consistent
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