Hey Guys,

Ok, so i have a problem...

which has been an annoyance for a few weeks now.

Basically, i did an engine swap almost 2 months ago... putting a 2.2l motor from an 04 into my 01. The car that it was swapped from had a turbo kit with AEM ems. It also has a modifry, designed for my ap1 dash. All of that was swapped as well. The car ran perfectly for almost 2 months until maybe 3 weeks ago...

I drove home from a drive of about an hour and i pop the hood to do my post drive inspection and i see my coolant tank to be completely full. I find this interesting because it had been running fine for almost 2 months. THe next morning i pop the hood of the now cool engine and see that the coolant is still at the same level. So i remove half the fluid and go about my business. I drive about 2 minutes and check out the coolant level and see that it getting higher and higher with no stopping... I pull over to the side and turn off the motor for 10 minutes and then restart the car and let it idle until the fans come on. All the while i am running the heat full blast. THe fans come on and the temperature stabilizes at 4 bars... which is normal for my car just sitting. I drive on and the coolant temperature is fine and i drive back on the highway to my destination...


Basically to make a long story short, the car overheats when it has been sitting over night, basically if the motor and coolant have cooled down. I had bled the system multiple times, using the bleed screw and the rubber boot at the far end of the heater line to get all the air out...

Now here is the thing, if i let the motor warm completely up and let the fans cycle 2 times the car is fine... i can do highway pulls, drive in stop and go traffic etc... but as soon as i let the car cool down over night and just get in and drive the same thing happens again...

Earlier this week i did a complete coolant change and put another s2000 radiator cap on the car... The difference i foudn with that one was that it didnt pressurize the system... it would idle fine, but when driven would overheat... i chaulked that up to a faulty cap and put the original one back on... I then thought it might be the thermostat... so i took the thermostat from an ap1 block i had in my garage and put that in the ap2 motor in my car... I did another thorough bleed and had the heat on full... and got full heat... I then drove it for an hour and was completely fine... drove to my friends house and hung out for 4-5 hours and came back outside and saw that the overflow container had exactly the same amount of coolant that was in it when the car was hot. I didn't open the cap to see if there was enough coolant in the radiator as i didnt want to jinx myself.... So i set out on the way back... drove on local roads watching my temp level... then got onto the highway... it just steadily rose up, without stopping... I had the heat on full and it didnt get hot at all... I pull over and reach down to the bottom radiator tube and its cold... i let it idle for 5 minutes and feel the tube get hot... and as that happens the air from the heater gets hot and the fans come on... the temp goes back to 4 and i go on my way... with the temps going back to three when on the highway...


I am really confused as to what is happening? Is it my cap that isnt letting the coolant to get sucked back into the system when it cools? Should i get another cap? Please someone help me... this is killing me

 

would the radiator cap prevent coolant from flowing back to the radiator when it cools down?

anyone have any insight?

 

Sounds Like you may have a bad water pump. Also make try to flush out the block with a high pressure hose, you may have gotten something lodged in there while doing the swap. Check the head gasket as well that may be the culprit. Check to make sure there are no restricions in the hoses and they dont collapse easily. Some times they get to soft a collapse on them selfs and block the flow of water. While you are at it, you may as well pick up a new thermostat and a tuner rad cap. maybe a spon or somthing. They hol a little more pressure. Good luck!

 

Check to make sure your coolant reservoir cap has a siphon hose going to the bottom of the reservoir. I can't check my car right now to see how it's configured, but there has to be a tube that sucks the coolant back into the radiator through the radiator cap when the cooling system cools down.

Also, make sure you don't have some oily residue in your coolant reservoir. If you do, you have a blown head gasket.