318is running hot in standing traffic

[RH318is]

Today, for the first time as I hit some thick standing traffic, the temp. needle passed the 1/2 mark and got close to 3/4. The air temp was in the upper 70s and I mean I could see the needle moving. It happen mostly at a dead stop, when I could move a couple car lengths forward I could see the needle moved back close to the 1/2 mark. The t-stat was replaced about 3 years ago with an M3 model. Driving at any speed brought the temp. back to or close to normal. I also replaced the water pump about 6 years ago.

When I was able I checked the fan and it was spinning. One thing came to mind, a couple months ago (probably some time during the summer) I checked the fluid level in the plastic contain on the left side of the radiator. I opened it and added a little water.

(Don't have the facilities or experience to do it myself), so I'm thinking about taking it in for a cooling system flush. Any suggestions/comments on what else could be going bad or simple things I can do myself to test?

[redhatpat]

Sounds like the fan clutch is failing. Check it for how stiff it is to turn while off, and how easy it is to stop with the engine idling. Use a rolled up newspaper to stop the blade. A good fan clutch shouldn't get stopped by the newspaper at idle.

I had the exact same symptoms, and it was the fan clutch.

[RH318is]

what's involved with fixing that? easy/hard?

[Simon S]

what's involved with fixing that? easy/hard?

i believe it requires (or is recommended) to get a slim 32mm headset wrench from a bicycle shop to get fan off.

reversed threads.
get wrench on and smack w/ hammer.

do some searching on other techniques..

mostly a bitch but do-able.

.

[Simon S]

here's a link to a DIY site - this guy's using a pair of vice-grips


.

[RH318is]

Is the clutch/fan one piece, do you replace the whole fan? Any idea what the cost is?

[AdamF 88iS]

Is the clutch/fan one piece, do you replace the whole fan? Any idea what the cost is?

You only replace the clutch in the center of the fan. Teh plastic blades are reusable.

Beware, this problem can also be caused by poor coolant circulation due to low fluid level or a clogged radiator.

[porsche gt1]

You only replace the clutch in the center of the fan. Teh plastic blades are reusable.

Beware, this problem can also be caused by poor coolant circulation due to low fluid level or a clogged radiator.

If it is only when you are idling at a stop. Then you have a 90% chance that it is your fan clutch. I have heard of it being your thermostat in about 1 in ten cases.

If you have a low coolant level or a plugged rad it would overheat while driving.

[lordofthewaters]

Sounds like the fan clutch is failing. Check it for how stiff it is to turn while off, and how easy it is to stop with the engine idling. Use a rolled up newspaper to stop the blade. A good fan clutch shouldn't get stopped by the newspaper at idle.

I had the exact same symptoms, and it was the fan clutch.

I agree, another easy way to test is to take a paper towel tube and cautiously stick it into the fan while the engine is running. If it doesn't tear the tube to pieces, it is the fan

[Funkmasta]

I agree, another easy way to test is to take a paper towel tube and cautiously stick it into the fan while the engine is running. If it doesn't tear the tube to pieces, it is the fan

*with the engine warm*
:)

[lordofthewaters]

:up:

[AdamF 88iS]

If you have a low coolant level or a plugged rad it would overheat while driving.

Not always. Low level and blockage can be masked while moving with the rpms up. I've had a few customers with this happen to them.

Furthermore, if the radiator is clogged the fan clutch will fail your paper towel tube test no matter what. If the center of the rad doesn't get hot the fan clutch will never hook up.

[Funkmasta]

good point. But if the rad is THAT clogged, the engine will really overheat quickly.
Better to start with a $75 fan clutch, then try the $300 radiator...

[AdamF 88iS]

good point. But if the rad is THAT clogged, the engine will really overheat quickly.

My brother's car had a radiator that was clogged enough for it to get hot in traffic but run fine while moving. There is a grey area.

Better to start with a $75 fan clutch, then try the $300 radiator...

Can't argue with that, though.

[RH318is]

Ok, drove it normally yesterday and this was the response. On city streets and freeway driving it actually ran cool staying at the 1/4 mark. When I exited on a freeway off ramp and went up and over an overpass stopping at the stop sign on the other side of the freeway the temp. had risen to close to that normal spot of just under the 1/2 mark. When I stopped at stop lights it would move toward the 1/2 mark. Didn't go over 1/2 mark all day, but I was never still for more than a long stop light.

I wonder if the t-stat is working with it running at 1/4 while the car is moving?? Someone else also mentioned the radiator thing. I'll try to paper towel test, but what's the consensus on what to start with? I'm tempted to start with the cooling system flush? Your opinions?

Thanks.