This is whats going on. I just had the car engine rebuilt and it runs fine, except that after driving for extended periods of time it overheats. I'll be sitting at a light and I will see the rpm go up (at idle) and then the gauge will start to rise. I start driving and it will cool off. The fans are working. Im not losing water, in fact the overflow tank was past the full line, so I already took care of that. I am going to flush out the system and redo the water.
I had installed the water lines to the turbo from the heater core lines. I don't know if that would have anything to do with it.
Anyone know what could be the deal?

 

accidentaly install the thermostat backwards?

 

never took it out

 

well at least I dont know if maybe my dad did when he was working on it. But it doesn't do it all the time.

 

You said that you came from the heater core to the turbo with the water lines. does that mean you completely robbed the lines from the heater core, or just patched into them?

 

I patched into them. They are still connected to the heater core

 

who re-built the engine? will they look at it -- warranty
also why did it get re-built - performance or did it overheat originally?

 

there is a ground wire for the coolant temperature sensor located on the drivers side that bolts up to the cylinder head. it sounds silly but if that wire isn't grounded that gauge goes crazy. i used to have the exact same problem; i added a ground to wall of the engine bay and the problem stopped instantly (the original ground wire was rubbing on the cylinder head, the casing melted off, and the ground got fried). also, double check to make sure the whole coolant system was reinstalled properly as well.

 

Did you get air in the lines, Make sure you bleed any air out of the cooling system. A bubble will block water from moving. Also, I known you just had the engine rebuild done, did you replace wwater pump when in there. We generally recommend water pump replacement when timing belt or engine rebuild. Cheap part but a lot of labor costs.

 

Have you had the fan controller recall done at a dealership? That or the ground wire could be the problem...

 

if the problem was with the water pump the car would overheat under load conditions as well...this sounds electrical.

EDIT: check the coolant temp when the gauge reads normal operating temperature; drive around and pull up in your driveway and let the car idle. if the problem is consistent the car will overheat in the driveway. check the coolant temp then as well. it may very well be the same...if it is you will know that the problem lies withing sensors and/or the electrical system.............please be careful not to burn yourself...it's usually not a good idea to open up the radiator when the car is running or hot!

 

Good stuff! Thanks for all the input guys.

The fan is aftermarket and it works fine. The thing is when the temp goes up so does the RPM. This weekend I'm redoing the water. Its been cool here and I haven't had to sit in traffic.
Hey coma, I'll definitely check that grounding wire here in a minute. I def won't burn myself....
Aight guys, hopefully I'll have this thing fixed this weekend. Thanks again

 

Thermostats are all garbage, thats where I would look. I've had a few that have a "hitch" in them in other cars, Mazda, Ford and recently a Toyota, you can feel it when you take them out and push it open with your fingers and it only affects you in traffic.

As a temporary fix you can always push the AC button and that forces both fans on.

 

I always drill 2 holes into any thermostat I install, 12 and 6 o'clock, lets enough through to help if the t-stat sticks, but not enough to dramatically affect warm-up

 

^^ i never heard that one before