Mitsubishi 3000 gt vr4 heat issues

[Derek Olding]

Hello all, I have a 1991 mitsubishi 3000 gt vr4 twin turbo with 56,000 original miles on it and i would like to figure out my heating problem out…. essentially what is happening is that when im idling my heater blows out ice cold air… When keeping rpm up to around 1300 or more the heat gets toasty hot… Not sure what the problem is…The car does not over heat and is full with coolant and i dont notice any leaks or ever have to add coolant…. your thoughts please and thank yu

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[rick]

sound like your heater core is dieing. when was the last time you had the cooling system flushed? can you smell a burnt sugar smell coming from the vents? if not i would suggest a “backflush” but there are alot of people that wouldnt recommend it as it can cause more damage. if you feel confident though you can try it.

you need a drain pan, pliers, and a garden hose hooked up to the house.

let the car cool down (obviously)
take your heater core hoses off making sure you know which goes where.
drain your heater core until its a small trickle.
put the hose on one of the nipples to the heatercore.
using LOW pressure let the water run through the heater core until no more sediment is coming out.
dont crank the water on, you can rupture the heater core. replace hoses afterward and check fluid levels after a run.

now this could fix it or if the heater core is too far gone, it can make it worse.

[Derek Olding]

actually i just bought the car last month so i have not did any kind of flushing yet myself but it does sound like a possability…… seeing as the car still had the original factory spark plugs from 1991, it wouldnt be a surprise to me as if the coolant wasnt the same….. if the heater core was too far gone wouldnt it leak or something? i have no leaks and no sweet smells coming from the vents what so ever…… heat is really hot when rpm is at or above 1300 rpm…anything less than 1300 is basically ice cold air…… is it possable for air to be in the system and it just needs a good old bleed job? if so how do i properly do that on this car?

[rick]

if it was leaking you would smell a really funky sweet smell when the heaters on or even see a “fog” come out of the vents. does the coolant look good? (no chunkies, rust, floaties). if its gross i would flush it. i dont know for sure if the 3000gt has a bleeder on it. if it does it would probably be on or around the thermostat housing.

[Derek Olding]

the coolant from what i can tell looks really good….the nice pretty green color and doesnt look dirty….. i dont smell anything unusual when operating the heater…. dont see any fog or any water droplets or film on windshield when operating the defroster……

[rick]

as to the proper way to bleed it, watch erics video on how to bleed the cooling system

[Derek Olding]

ya i watched it but was a little confused because i am not seeing a bleeding valve anywhere on my particular car lol

[rick]

not all cars have a bleeder. if its not overheating then thats more than likely not your problem anyways. try to backflush the heater core if you feel comfortable to do so.

[Derek Olding]

ya i feel comfortable doing it….but i do have a question…do you think it would hurt to switch the heater hoses in the reverse order? im thinking if you reverse the flow, it may lossen stuff up then i cood do a complete flush and all be good….ya the car never overheats

[Josh]

You need to bleed the system out. The bleeder valve you don’t actually need. Just have a funnel on your radiator, turn the car on, put the heat on max, and rev to 2500 rpm till your cooling fans come on. While your holding rpm at the throttle you can feel the heater core hoses; both should be warm to the touch. If not you may have to watch Eric’s video on how to un-clog a heater core. I had to do the same thing to my car a 95 subaru legacy when I replaced my radiator. I don’t have a bleeder valve and just followed Eric’s video step by step and my car is happy and cool again. Even have excelent heat through the heater core. But before you do any of this I would recommend you do a coolant flush. If it’s the same coolant that it came with from the factory it’s in dire need. Also change your spark plugs.

Hope this helps you and keep us posted 🙂

Here is the heater core video:

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