My M42 is over heating! help!

[iamcreepingdeath]

Here is the situation:

A while ago i noticed my temp gauge doing funny things like bouncing around.  I started a thread on it.

Recently, the temp gauge has been much more steady in the high region.  I thought it was my thermostat so i took it out.  I am now running thermostatless.

Now my car runs super cool on the highway, like at 1/4 position, but if i get into traffic, the temp gauge goes to the half position.  If i park and let the car idle, the temp gauge will go all the way to the 3/4 position.  If i rev it up parked, the temp gauge doesn't really do anything, just stays at 3/4 and threatens to go higher.

help???

so its obviously not the thermostat, it may be the fan or the water pump.  what do you guys think it is?

Thanks so much

[rob_e30]

I would replace the fan clutch and the water pump.

[HATER-PROOF]

Yeah-it does sound like your fan clutch according to your description.

[iamcreepingdeath]

hmmm.....  that's what everyone is saying on R3V too.....  i will do the "roll of newspaper test" and see what happens, i am so broke that i would hate to buy parts that i don't need, although otherwise i love buying parts and putting them on my car....

[rob_e30]

These parts will be a lot less expensive than a head gasket or new motor.

[iamcreepingdeath]

These parts will be a lot less expensive than a head gasket or new motor.

true.

Is there any chance it can be the coolant temp sensor?

[monty23psk]

The coolant temp sensor will cause the engine to work differently as it is associated with the computer. But if the temp itself is going up, there is either air in system, no circulation, or not enough cooling from the outside. But first is to make sure that the temp reading is accurate. Without that, you can be guessing most of the times. You can measure the temp of the coolant when it is getting hot.

But from your description, looks to be fan clutch.

[xwill112x]

fan clutch. if that doesnt work, get a shroud, if that doesnt, get a new radiator.

[iamcreepingdeath]

The coolant temp sensor will cause the engine to work differently as it is associated with the computer. But if the temp itself is going up, there is either air in system, no circulation, or not enough cooling from the outside. But first is to make sure that the temp reading is accurate. Without that, you can be guessing most of the times. You can measure the temp of the coolant when it is getting hot.

But from your description, looks to be fan clutch.

what is the best way to measure coolant temp to see if my temp gauge is working properly?

fan clutch. if that doesnt work, get a shroud, if that doesnt, get a new radiator.

The consensus seems to be my fan clutch or my water pump.  I am going to try the rolled up newspaper fan test tomorrow.

btw i have a shroud.  Radiator looks ok too, i took the shroud off and took a good look at it.

[monty23psk]

With out getting fancy, you can open the cap for the radiator and stick a long thermometer. Other option is find out th specs on the temp sensor on the head and check it witha mulitmeter.

[iamcreepingdeath]

UPDATE!!!!   it is most definitely the fan clutch.  Not only can i stop the fan with a rolled up newspaper, i can stop it with my pointer finger.  And i can hold the fan still as i rev the engine.

BUT....   the car was warm, but it was just after i power washed the engine, so the engine may have cooled.  Would this make the fan do this?  should i re-try the test when the engine is fully hot?

[xwill112x]

your fan clutch is bad, no question about it.

[monty23psk]

You can try, but just get a new fan clutch. FYI, I can get them brand new Sachs for $62 plus shipping. $10 cheaper than Pelican Parts.