Overheating mystery

[91SHOInterceptor]

My car for some reason is still overheating. I replaced the radiator last night with a heavyduty double-core radiator. The thermostat has been replaced twice. All the hoses are new. The water pump was replaced about 2 yrs ago and was checked during the engine rebuild. The car will overheat at idle. When I am on the highway or moving it is at normal type. Also at idle the oil light will flicker on and off. I recently changed the oil and filter after the initial 800 mile breakin period(5W-30). It only comes on though when it is hot at idle. It never comes within danger or completely overheating, it just runs hot in between the "N" and "O" in normal. I figure the oil light comes on since it looses its viscosity when its that hot.

 

[SHOZ123]

The fan should come on at 215F. Is this happening? It's really not over-heating unless the temp goes past this point.

If your oil light comes on when the motor is hot that is because your bearings wore out.

 

[AutoSHO]

91SHOInterceptor:
My car for some reason is still overheating. I replaced the radiator last night with a heavyduty double-core radiator. The thermostat has been replaced twice. All the hoses are new. The water pump was replaced about 2 yrs ago and was checked during the engine rebuild. The car will overheat at idle. When I am on the highway or moving it is at normal type. Also at idle the oil light will flicker on and off. I recently changed the oil and filter after the initial 800 mile breakin period(5W-30). It only comes on though when it is hot at idle. It never comes within danger or completely overheating, it just runs hot in between the "N" and "O" in normal. I figure the oil light comes on since it looses its viscosity when its that hot.

If I were you, I would do this:
(1) Get som thicker oil in there immediately. The oil light typically comes on at less than 4 psi of pressure. I would recommend 10w40 minimum.
(2) Get new rod bearings. When put in the new bearings it should bring the oil pressure up considerably. You can go back to 5w30 after the bearing change.

Try these. Apparently some people have experienced the same symptoms as you just before having a rod bearing let go. Good Luck!

*edit* Just saw your engine was just rebuilt. That changes things. Who did the rebuild? What was replaced, what wasn't? did anything have to be reground (undersize crank, etc..?) There is absolutely no reason for a just-overhauled engine to be running hot. Have you redlined the car since getting the new engine? Or even driven it hard?

 

[luigisho]

How about getting an accurate reading on the oil pressure to be sure the oil pump is working correctly? Was the coolant temp sensor and sender replaced? Is the fan coming on at the approriate temp? At idle that's critical.

 

[91SHOInterceptor]

Everything was replaced basically. All the sensors, bearings, piston rings, gaskets, etc. Nothing needed to be regrounded. I was planning on putting the 10-30 or 40 oil in it since I wasnt having an oil issue since after I changed the oil filter and the cheap oil. The fan is kicking in right when its supposed to be. I really havent drivin it hard yet at all. I got the car put back together like the last week of October so it has about 800 miles on the new engine. I gonna change the oil today and see what else I can find.

 

[Ian]

What's it idle at? Low engine idle can cause the oil light to flash or glow at idle. Just a thought.

 

[sdpatt]

If the temperature is okay when the car is moving, but not okay when the car is stopped, that is an airflow problem through the radiator. In this case it would be caused by the fan not running. If you select AUTO on the climate control and the fan doesn't come on, your fan motor is toast. If the fan comes on in AUTO, but not when the coolant temperature is high, it could either be the temperature switch or the integrated control relay module.

Oil? Get at least 10W-30 in there. It also sounds like your idle could be low. Try resetting the idle speed to be sure. If you still get the oil light after that, you had better heed the warnings about the bearings.