Cooling Fan Issues, Can't Get It To Cool Antifreeze

smiles855r · Post by **smiles855r** » 12 May 2012, 19:00

My fan won't turn on to cool the system down, so coolant boils over past the cap and all down the sides of the expansion tank. If I turn the AC on the fan kicks on, so I don't think its the relay. Cleaned the three grounds on the front of the block two above the starter and one to the left of it. At this point I can only think that its a wire b/w the CTS, the ECU/ECM, and the relay. Is there a common problem w/ 96 850R cooling fans.

Replaced radiator, thermostat,coolant temp sensor, expansion tank & cap at the beginning of April. Water pump, timing belt and other timing parts replaced 12k ago.

PS. Moving in about 2 weeks to Everett, Wa to work for boeing so I'd to get it working properly before the car is shipped up there.

Post by **jimmy57** » 12 May 2012, 19:55

The fan on temp based on reading coolant sensor is 225F +/- 2 degrees.
I know you have a new cap but does it build pressure in cooling system (upper hose is very firm to touch indicating pressure)?
If the cap does not retain pressure it will boil it out.
The a/c being on makes the fan run when a/c pressure reaches a level when fan needs to run for a/c cooling. The a/c pressure will run fan so often that the coolant stays well below the temp based fan run parameters.

smiles855r · Post by **smiles855r** » 13 May 2012, 20:33

I've replaced the cap several times in the past few months thinking the cap was bad. The upper hose is firm and has actually expanded in size just before the thermo because of pressure. I've done a block test just to be safe and no change in color. The oil and coolant looked fine when I changed the radiator.

Could I run a switch on the inside of the car connected to the center plug on the relay. Center plug because when I connect it either center contact on the relay to the negative terminal the kicks on. So would running it on the low speed help keep things cool or would this make the car run to cool with the fan on all the time?

Rocky · Post by **Rocky** » 13 May 2012, 21:28

Worried that you may have a head gasket leak pressurizing the coolant.

Post by **jimmy57** » 13 May 2012, 22:15

Look at the cooling fan relay and make sure the two wire center connector, has a gray body and is D shaped, has both wires making contact.
The plastic is disintegrating on the wire ends with age and sometimes one of the wires backs out. If the high speed wire is the only one making contact then the fan will trigger for a/c (but on high) and it will boil before the fan is triggered when a/c is off.

smiles855r · Post by **smiles855r** » 16 May 2012, 17:20

Well fan checked out ok, Iat sensor(coolant sensor) working fine, thermo opening when it should. Had a leak down test down and cylinder 2 is leaking, quote from dealer for all gaskets and new bolts is $2070 thats without machine work. If it needs it plus valve job about $2500.

Know if I wasn't moving to Washington in less than 2 weeks I would do it myself but I've still got to pack up my whole life and move. F*** My Life so I'm going to try for a loan or cash my bonds I've gotten over the last/all 26 yrs of my life.