: Cooling systm help please on an 88

03-14-11, 06:37 PM
So I still can't figure out how to test cooling fans thru the DIC, hope I haven't altered a setting in the defaults as I've played.. but here's the problem, car keeps getting hot really quick, right up to the high end of the digital gauge, a bar or 2 from the end, then it goes back down and hovers between 1 bar above middle and middle.. there is no "milkshake" in the oil, i did a change a couple of weeks ago and the oil is still super clean, the old oil out of the car was too.
It has always stayed right at middle for the 6 +years I've had it, I have just been throwing fixes a it hoping one would do it. So far I have :

drained and filled the cooling system, as per service manual instructions ( drain radiator, refill run to normal, drain and refill again repeat, then refill as I run the car at 2000rpm with radiator cap off and fill system with proper anti freeze and pellets...

New heavy duty radiator cap,

replaced the cooling fan module from with a used one, even though both fans do and did come on with the a/c on high,,
no cooling fan fault,

the only code I get is eo 47, and I have always had that one show up every few months over the years, even though all injectors are within range, and pass the test when operated individually thru the DIC What else should I do? should I do the thermostat too? I've always thought about putting in one of those fail safe ones that fail in the open position, just for piece of mind, but I really want to diagnose this issue, given the 4100's known concerns, I don't want to risk overheating..
anyone have any advice?

Thanks, MAtt
cadmat at yahoo dot com

03-15-11, 11:05 AM
Does the gauge coincide with the reading thru on board diagnostics? Center on the gauge should be approx 95 to 98 degrees C. Does the OBD reading go up as the gauge goes up? Possible faulty sender? Is the bleed hose from the radiator to the tank clear? unrestricted. The fans should cycle on without the A/C on at approx 110 degrees C. and the temp should drop to under 100 degrees.

03-24-11, 12:08 AM
hey carnut, thanks for responding, yes the bleed hose is clear, and the temp gauge does correspond with the temp in the dic..I have replaced the coolant temp sensor, flushed the radiator, replaced the lower radiator hose, and the radiator cap, as well as a new thermostat. The oils is super clean, and so far nop noticable loss of coolant ( like thru a blown gasket) There never is a cooling fan fault, I have 2 modules now, and both operate properly when tested thru the DIC.
Ok , so here's what I got.. I Drove the car around for a few hours today, A/C off the entire time, both highway and in town. As soon as the car warms up, right at about 9 minutes or so, temp goes up to about 110C ( 2bars over mid point) as I drive around it goes back down, to 95 to 101 ( mid point on gauge) after quick acceleration, or coming off freeway, and quick deceleration it goes up from mid to as high as 113c ( 3 bars above center, and just 1 under the red zone.. Temps outside were around 62 degrees F .. the reason this is all so concerning, is that the car has never gone more then 1 bar over center in 6 years, and when it did it was a super hot day(upper 90's F) and in stop and go traffic.. So is there a problem here? or is this all somehow still normal?

03-24-11, 03:23 AM
Odd as it sounds, I think you still have air trapped in the system. The car is not known to be hard to bleed or burp the air. Remove the cap in the morning with the engine stone cold and off. The coolant should overflow from the radiator neck. With a helper starting the car cold, have him hold the RPM above idle and the heater set to 90 degrees. Eventually the coolant level will drop as the thermostat opens, then quickly add coolant to full and quickly reinstall the cap, THEN allow the engine to come back to idle once the one radiator fan cycles on 1 time. (the fan coming on verifies no air remains) If that has no effect, I would have the radiator flow tested. Years of pellets, I believe, can partially plug the core. The pellets were recommended to stave off seepage while the vehicle was under warranty and if it hasn't seeped in these many years, it wont. I am very adamant about fresh coolant every 24 months regardless of miles none the less!