Coolant temp problems

[rn240sx]

Here is how it started:

I had a 98 S14 and had NO coolant problems..!! The car was then wrecked and totalled out, and b4 the insurance company took the car away, i yanked that motor out and kept it in my garage.

6 months later i bought another 98 and drove it for a while b4 i did the swap.... I pulled this motor out that came with the car cause it had 150k miles on it in and i didnt wana turbo it. So we pulled it out and put in in the garage and the OTHER motor that came from the wrecked 240 was dropped into this new 98 along with the turbo.

Went out for a drive and immediatley noticed that my water temps kept rising all the time. It would rise, fans kicked on at 205, temps went down and fans cut off.. then the temp went back UP and fans kick on at 205, temp went down, fans cut off... etc...etc... This would happen no matter if i was at idle speed or 45 mph or at 70 mph on the hwy...

Normally when ur cruising at mid to high speeds and constant air is hitting the radiator, the water temp should stay stationary until u slow down or come to a stop, then the temp will go up and the fans kick on... thats the way it should happen and thats the way it DID happen in my 1st 98 i had....

But for some reason, this car was different. I knew it was not the therm nor the water pump since this motor was fine in the other 98.. The only culprit was the radiator or heater core. So i went out and bought a new radiator and dropped it in and went out for a drive and STILL have the same Fing problem....!!

I also noticed that when i kicked the a/c on, the elec fans would kick over and they were able to get the temps down to 180 deg and hold them there the entire time the fans were on..!! Regardless if i was at a stop light or 70 mph on the hwy.. Once i shut the a/c off, the temps started to rise again.. Now WTF is going on..

I drained and filled it 3 times and nothing changes. The only others things left to check or change is the heater core and the rad cap...

If anyone has ran into a similair problem and found the culprit, please let me know..
Modified by rn240sx at 2:23 PM 10/22/2005

[nismo521]

Sounds like you got an air bubble. KAs are notorious for trapping air in the head. The bubble will keep the thermostat from opening, which keeps the water from flowing through the radiator and getting cooled off.

zerothread?id=120083

Look for my method for bleeding the air in that post. Also, try putting in some water wetter, that seems to help keep the bubbles from forming.