the easiest way is to buy a CO2 tester for the coolant. you can pick them up at NAPA or any mechanic should have one. it is basically a hand pump with a filter on the bottom. get the car up to temp and put the plunger into the top of the radiator. squeeze the ball at the top of the tool and it will draw gas from in your cooling system through a blue die. if the die turns green/yellow then you have CO2 in your coolant, if it stays blue you are fine. just make sure you don't draw any coolant into the die, because that will make it turn green too.

you can test the fluid by blowing into the bottom of the tool and the CO2 from your breath will change the die so you know what you are looking for. you push air though die to turn it blue again but i usually dump it out after every use.

it is called a block leak tester. should be about $50.



also do a compression test to see where you are at.

 

Thank man. Youve given me alot of info. If this site had rep I would rep you. They are going to check my water pump at the shop tomorow. They did a compression test and cylinder 4 was really low. So they did a leak down test and sounds like air is going out the exhaust so I think we have to pull the head to check the valves.

 

no worries man, i am usually not this helpful. i was just on a mission to 50 posts last week so i could finally post in the for sale section

how low was the compression on cyl #4?

keep us posted, i am curious now.

 

I kinda had a similar issue. It was a headgasket for me. I first noticed when I shut my car off I would hear gurgling, and bubbling coming from my coolant overflow tank. Pressure test it. 3/4 of my cylinders pushed coolant out the cap. Good luck with it. Hope its not that :/

 

well first thing first are you on stock radiator?? if so check the end tanks for leaks....??? next step go to harbor freight or some tool place in your area and buy a cooling system pressure tester....hook it up to the radiator filler neck put coolant in prior give it a few pumps and listen and look for coolant leaks....my guess either ur water pump is leaking maybe ur thermostat is bad check those n report back
dastallion out

 

I would start with a leak down test... good luck...

 

cyl 4 was in the 90s.. my headgasket was DONE!

The head is off the car and on its way to the machine shop. Hopefully thats what was causing the over heating.. will keep you posted when the head comes back.

 

i'm sorry i was right.

good luck man.

 

update on the car? did you get the head back together?

 

Yes, I got the car back together and running friday night. I had the head cleaned, decked, valves reseated and tested etc and new oem head gasket... pulled the water pump and it was fine so didnt change that so we put it all back together and started her up.

Problem is still there but not as bad. The car over heats now only while driving with the ac on. I can get on it full boost and its fine as long as the ac is not on. Im running a slim fan so im going to switch back to a stock radiator fan and hope it puts and end to this headache.

 

hello guys, I got a problem with my evo 8, when it goes over 7000 rpm it star to overheating and then goes to the normal temp, I wanna know how to star to fix this problem. hope you can help me. thanks

 

i bet this is it....because when u run ur ac its off your belt.....replace ur water pump and timing belt while you do your head gasket~

 

lol why didnt you replace the water pump! u had it off, hopefully it dont go out after 10 miles

 

headgasket.

 

well depends on how u hot you got it?? could be somethin as simple as sticking thermostat...best bet first get a temp gun, and measure temp on radiator compared to what it should be, that rules out gauge issue. Second is to pressure test cooling system with car off and find out where the leak is. If no leak, then replace thermostat which is pretty straightforward, and then retest. If still doin it time for a compression/ leakdown test, and cross your fingers.
good luck man