Problem with my 3kGT it overheats to 3/4 of gauge!! Help?

[Fernandoz3kGT]

So i just bought a 1999 Mitsubishi 3000GT with 116k Miles on it Pearl White, its a really nice car and i really like it but not even a day after having it i noticed the temperature gauge goes up slightly at idle mostly. I was driving home from Home Depot about 2 miles away from my house and saw the temp gauge go up to as high as 3/4 and would drop when the fan would kick in but not all the way back to normal, again it does this slowly and not right after start up.

I can start the car cold from overnight and drive for a mile or two and then the issue starts again. Today i replaced the Thermostat, Gasket, and did a flush. Topped it off with 50/50 antifreeze. Also i replaced the 180 T stat with a 170 and did improve a little temp stays under half point but after the 2 mile drive or after about 10-15 minutes it happens again.

Extra info::::::::
`The Waterpump seems fine since it doesnt leak any kind of fluid and Timing components were done at 90k.
`BOTH RADIATOR Hoses stay hot once engine reaches operational temp.
i know that the inlet or top one is usually hot and bottom one should be cooler but in this case they are both hot.
`Headgasket seems ok i do not see any i mean ANY signs of coolant/oil mixture in the crankcase or dipstick. Oil is fine.

Anything else i can look for?????
Any help will be highly appreciated!!!!!!!

My next guess is the radiator itself which i found for $90 new but before buying it i want to have confirmation from you guys.

Also the easiest way to reveal the issue is starting up the car let it get to op. temp and rev engine to 3k RPM's and temp goes up. i shut off the engine every time.

Guy who sold it to me seems pretty honest and said he hasnt used the car in a week or two and hardly drives it. Doesnt seem like he knew about the issue when i asked him so all that is left is fix it.


Thnaks in advance!!!!

[Fernandoz3kGT]

So i just bought a 1999 Mitsubishi 3000GT with 116k Miles on it Pearl White, its a really nice car and i really like it but not even a day after having it i noticed the temperature gauge goes up slightly at idle mostly. I was driving home from Home Depot about 2 miles away from my house and saw the temp gauge go up to as high as 3/4 and would drop when the fan would kick in but not all the way back to normal, again it does this slowly and not right after start up.

I can start the car cold from overnight and drive for a mile or two and then the issue starts again. Today i replaced the Thermostat, Gasket, and did a flush. Topped it off with 50/50 antifreeze. Also i replaced the 180 T stat with a 170 and did improve a little temp stays under half point but after the 2 mile drive or after about 10-15 minutes it happens again.

Extra info::::::::
`The Waterpump seems fine since it doesnt leak any kind of fluid and Timing components were done at 90k.
`BOTH RADIATOR Hoses stay hot once engine reaches operational temp.
i know that the inlet or top one is usually hot and bottom one should be cooler but in this case they are both hot.
`Headgasket seems ok i do not see any i mean ANY signs of coolant/oil mixture in the crankcase or dipstick. Oil is fine.

Anything else i can look for?????
Any help will be highly appreciated!!!!!!!

My next guess is the radiator itself which i found for $90 new but before buying it i want to have confirmation from you guys.

Also the easiest way to reveal the issue is starting up the car let it get to op. temp and rev engine to 3k RPM's and temp goes up. i shut off the engine every time.

Guy who sold it to me seems pretty honest and said he hasnt used the car in a week or two and hardly drives it. Doesnt seem like he knew about the issue when i asked him so all that is left is fix it.


Thnaks in advance!!!!

[DIEBOG]

The temp sender could be malfunctioning giving a false reading. When it "overheats" does it push water out of overflow bottle? If its not blowing water out into bottle, then I would guess that its probably not past the operating temp because if it were the rad cap would let pressure by after it exceeded the safe operating temp. There might be a way to check sensor with olhm meeter but I don't know for sure. Or you can get a replacement. A few years ago I had the same type of thing happening. Car wasn't boiling over and I replaced the temp sender and that was the problem.

It seems like you have check all the starting places for overheating, how did inside of rad look? Depending on what the previous owner put in it, there could be a buildup on cooling tubes. Some people don't know to use distilled water because of all the minerals in tap water. Its a possibility, I have seen some nasty rads in cars that you would think were fine. You might be able to have rad professionally cleaned, I believe the hot dip and rod it. Not 100% sure though.

[Fernandoz3kGT]

Thanks for your reply!! Well actually under the radiator cap it looks pretty cleaning haven't checked the radiator itself but it seems fine too. When I did the flush I flushed the radiator out individually with water first and then with antifreeze. When the car "overheats" there is no bubbling anywhere or noises of smells. Only thing are the hoses that I know shouldn't be that hot nor both of them should be. Also today my friend told me that between the radiator and chassis of the car they were a lot of leafs stuck in between? Don't know if that would affect much but will clean it up tomorrow. And I might just replace the coolant temperature sensor it's easy and cheap and might be it but do you know why BOTH hoses get hot? If you need any pictures to help I will take and post.

Thanks for the help!!!!

[DIEBOG]

Well normally both hoses hot are a sign of a working thermostat. If a thermostat is stuck closed one hose would be cold, and if it is stuck open operating temp would be to cold for optimum operating temps. When your car or any auto for that matter reaches its operating temp, you shouldn't be able to hold on the hoses too long. The water in there is 180+ deg which would make the hoses hotter then most could stand to hold onto. I would venture to guess that if the overflow inst boiling over assuming you have proper psi rad cap, then everything should be working fine. Except for most likely the temp sender. For water to boil over into over flow,(cap at 15 psi) the temp of 50/50 water antifreeze would be around 265. Most say that anything over 240 is time to shut down and/or crank heater inside cab up to help cooling.

So if you definitely don't see water blubbing into overflow bottle, I think you are ok here. But to make sure you could get an infrared temp gun and point it at rad or hose to get a generic temp to see how hot it actually is. It wont be exact but it should be close.

[Fernandoz3kGT]

Ok thanks i will do that tomorrow and get back at you here with results, i just want to make it run and dont have to see that needle go up. I think im going to just spend $20 on a new rad cap and coolant temp sensor, after that ill do the temp reading with a gun and go from there and once more ill check the overflow tank if it boils which i highly doubt.

Thanks for all the help!!!! If this doesnt work I'm going to just buy a new radiator because the car has very low mileage and looks very well taken care of. Maybe it wasnt driven enough and rad passages got plugged up? idk but i just need it running reliable enough asap.

[speedy25]

Its the radiator. Look at the very bottom. You will see the fins rotted away from the core. At least thats what I have found in every case like you describe. Low mileage is only a part of the aging proccess. Parts still fail because they are old and not used up.

-SP

[Fernandoz3kGT]

Thanks speedy25 i think i will post up pictures of the motor and bottom radiator itself and have you be the judge since i honestly dont know much about these cars i just know my basics. The car isnt throwing any codes nor has any other issue at all, ac needs recharge blows little bit cold and heater is working good very good. I didnt find any signs of add-ons in the cooling system like stop leak etc.. But hopefully with pictures you guys can help me out and confirm that way i order the necessary parts.

Thanks once again for a reply to my issue!

[kelvinTurbo]

Do yourself a favor and check to see if the fans are actually running
I recently had this problem where the fans would just stop running at idle, when they are needed due to a mistake made in the wiring by a shop, took me a while to figure out why it would overheat at idle only

[Fernandoz3kGT]

Thanks for the input but they are working properly when my temp raises almost to H the fan turns on and temp drops slowly until it shuts off and rises up again and fan turns on once more. AC fan works aswell. Also at idle it does it very slowly and after running it for 5 minutes it slowly does it on the road too. Its like if the radiator isnt cooling enough anymore because everything else seems fine.