cooling system help needed on an 88
 

Hi Gang,

I posted this on another forum too, but as of yet had no response, so hoping someone here can help me,

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, 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, Lately, 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

sounds like possibly a bad thermostat andit would have been a good idea to replace it when doing the coolant flush. You cant change the fan settings through the dic, the PCM is what regulates when to turn cooling fans on or off. So you should be ok on that note. I would replace the Thermostat and go from there and let us know what the out come is.

still showing hot at times,
 

I did replace the thermostat with a fail safe unit ( one that fails in the open position, ) and all seemed well for a day, now I'm getting the same symptoms, gets hot a few bars above middle and then drops down if I put on the ac... any other suggestions? is it possible the new thermostat is bad too? ( it's a slant brand, 195 temp).. I'm going to take a look at the lower radiator hose today, last looked ( several months ago) it was pretty soft, but the spring inside was still intact, I know it's been on there at least 6 years, so as a preventative I will attempt a replacement, even though no one has pre-molded ones, I have to play craft class and whittle me one..