kylekratzenberg

So the other day I was driving my 95 z28 (six speed manual) and the temp Guage started to climb. Since then I've replaced the thermostat with an lt1 180 degree thermostat and bled the system. The car ran well for a couple days and then the same issue started to happen again. My fan motors seized and since then have been replaced with new ones. The car has also been running rich could this be the coolant tempensor in the water pump? Also after the first time it over heated while limping it to a friend's house it had very little power below 2000 rpm then would suddenly gain Power again any help is appreciated! Thanks

Injuneer

Could be the coolant temp sensor in the water pump. Do both fans turn on at low speed at 226*F? Do they go to high speed at 235*F? What actual numerical temperature do you mean by "temp Guage started to climb."?

Is SES light on, have you scanned for codes? There are codes for the fan control circuits.

Might be time for a complete PCM data log using Scan9495:

https://www.camaroz28.com/forums/com...95-lt1-874306/

.... free download, buy a 16-pin cable from ALDLCables or Red Devil River. One of us can help you interpret the data log if needed.

The stock t'stat in an LT1 is 180*F

kylekratzenberg

The temp will go from mid Guage to the red in just a couple blocks of driving. The fan motors are both new and so are the pig tails connectors to the fans. Both fans kick on a around 212 and high at around 225. There is no check engine light on but the low coolant light is on even though the system is full and bled of air bubbles

Injuneer

Ignore the low coolant light. The sensor is damaged. The coolant seeps through the seal, into the printed circuit board, and ruins it. If you keep a visual check on radiator level, unplugging the level sensor harness connector will turn the light off.

If your fans turn on at those points, based on the dash gauge reading, either the CLT sensor is not calibrated correctly and needs to be replaced, the dash gauge is "off", or the PCM has been reprogrammed for fan on/off temps. Was the t'stat you removed a 160* model?

If both fans are running, and the temp increases like that in a couple blocks driving, either the cooling system is badly crudded up, the front of the radiator is blocked, the cooling system is not holding 18psi, or possibly a head gasket problem. And, since both fans are actually running, it would appear that when the fan motors seized up, the fusible link that supplies power to them did not blow.

kylekratzenberg

Thanks for everything! A friend of mine and I are going to try and replace the various hoses for the cooling system most of them are beginning to dry rot anyway. I think you're right about the system being crudded up the guy I purchased the car from must have put just water in the radiator. It could be a blockage caused by bits of corrosion or something like that. The thermostat I pulled out was a 160 degree thermostat. Does the fan kicking on at a lower temp really have any negative effect in the long run? Should I try and get them reprogrammed for the 226 and 235 temps?

Injuneer

If the fans come on at the temps you indicate, no problem. Most people that install a 160* t'stat will reprogram for the fans coming on in the range of 185-200*F. That would be a problem, since a 180* t'stat isn't fully open until about 200*. But if they are set to run above 210* you are OK.

Since this seemed to have happen all of a sudden, just for the heck or it, check to make sure a plastic bag did not get sucked up into the front of the radiator. And, if this is mainly a problem with freeway driving, check to make sure the plastic air dam under the front bumper is in place. If that's missing, temperatures will climb at freeway speeds.

kylekratzenberg

Problem solved! The hose from the radiator to the overflow was clogged and there was a few pin holes on the inlet to the water pump which was pulling air into the system. I replaced all the coolant lines which was pretty easy fix for such a big problem. Thanks for helping me with possible causes!