CLutch fan?

[lance]

Hey guy's it's been awhile since I been on here but anyways I just picked up a 1995 gmc sierra with a 5.0 an 5 speed runs good an all but the only thing I'm having trouble with is my Temp. gauge isn't working right only comes up just past 100 degrees. I replaced the temp. sending unit in the head an that didn't fix it, so I replaced the thermostat thinking it was bad but still didn't fix it was thinking maybe the clutch fan? What do you guy's think? any help would be appreciate it!!

 

[someotherguy]

Actual measured coolant temperature is = ???

Richard

 

[lance]

Not sure how would you check this?
Also Went to the mall with the wife an when I came had a huge puddle under the truck looked like it was dripping out the weeping hole of the water pump...
So I just replaced it also....

 

[someotherguy]

Infrared thermometer ("temperature gun") aimed at the intake below the thermostat. With a warmed up engine you should get a reading very near the thermostat rating. 195F is the factory piece...and what is strongly recommended unless you have a custom tune that is designed for a colder stat.

I'm sure ambient temp in WV is pretty chilly right now but it should rise up above 100F for sure unless the thermostat is stuck wide open (I did read that you already replaced it) or the fan clutch is stuck engaged. Usually you can tell with reasonable accuracy if the clutch is stuck (or sticky) while the engine is cold and off, you try to spin the fan by hand and it has a lot of resistance.

As a very short-term test that doesn't cost anything you could remove the fan and clutch then re-install the nuts to hold the pulley on, fire it up, and see if it comes up to temp without the fan installed. I wouldn't do this though without the temp gun handy because if your gauge still has problems registering correct temp, you could overheat it and not even know until it's too late.

Richard

 

[great white]

I'm waiting for results of water pump replacement, but if that's not the problem try placing a piece of cardboard over the radiator and go for a short drive.

If the temperature doesn't come up, it's not the clutch fan. Likely not the thermostat either. You're into "weird" territory at that point.

I'd be looking at the actual temp sensor or the gauge.

If you were OBDII I would suggest you monitor the data stream to see what temp the ECM is seeing since the gauge and the ECM use different sensors. I'm not sure if anything does real time for OBDI. But you can run a data log with an ALDL cable and a bit of software, then look at it later.

If the ECM sees 190 or so, the sender or gauge are suspect.

I've never trusted those IR guns. Anything you can buy at the "hardware store price" are mostly garbage. I've got one in the garage and it's wrong more than it's right....

 

[TylerZ281500]

clogged coolant passage or something blocking a correct reading of the temp sensor? pull that off and run a hose through it for a while see if anything unnaturally large or disgusting comes out replace the sender and try agian?

 

[someotherguy]

I've never trusted those IR guns. Anything you can buy at the "hardware store price" are mostly garbage. I've got one in the garage and it's wrong more than it's right....

I didn't say to trust a crappy one. I've got a Fluke 62, nice piece of equipment. I use it for all kinds of stuff.

Richard

 

[lance]

I'm waiting for results of water pump replacement, but if that's not the problem try placing a piece of cardboard over the radiator and go for a short drive.

If the temperature doesn't come up, it's not the clutch fan. Likely not the thermostat either. You're into "weird" territory at that point.

I'd be looking at the actual temp sensor or the gauge.

If you were OBDII I would suggest you monitor the data stream to see what temp the ECM is seeing since the gauge and the ECM use different sensors. I'm not sure if anything does real time for OBDI. But you can run a data log with an ALDL cable and a bit of software, then look at it later.

If the ECM sees 190 or so, the sender or gauge are suspect.

I've never trusted those IR guns. Anything you can buy at the "hardware store price" are mostly garbage. I've got one in the garage and it's wrong more than it's right....

What do you mean by Actual Temp. Sensor?

 

[great white]

What do you mean by Actual Temp. Sensor?

There is a sensor for the ecm and a separate one for the gauge.

By "actual" I meant the temp sensor itself. Bit too wordy I guess.

 

[lance]

Ok. I replaced the water pump an that stopped the leak, an drove it around town an the Temp. Gauge never came past where it normally sits (just above the 100 degrees) but when I hit the interstate for a little bit the needle went up just a bit further but when I got off the interstate an back driving threw town the Temp. gauge went back down to where it normally sits.
I checked the anti-freeze in the radiator an it's full.
I meant to check the fan today before I went for a drive but forgot so I'll check it tomorrow.