M20B27 coolant temp rises at idle or while in traffic.

[bigredguy]

I have a 1987 325 with the M20B27, or eta, motor and like the title states at idle or while in heavy traffic the coolant temperature rises. It has been happening since ive owned the car for a little over 2 years now, but since I rarely drive in heavy traffic it hasnt been much of an issue. I have just recently began to fix all the little things wrong with my car and this is one of them on the list.

Does anyone have any experience with this or have had the same problem? Through research, I have noticed that many people have needed to replace the sensor, but I dont think it is a sensor problem because if I turn the heat all the way on the temp gauge begins to go down.

I have no clue what could be causing this, so any information would be helpful. Thanks

[camip]

Worn out cooling system. I'd just replace the simple stuff that should be done every once in a while thermostat, water pump ect. I'm pretty sure all cars run warmer in stop and go traffic not enough air being rammed into car.

[bigredguy]

the water pump was just replaced over winter when the timing belt was done. Still didnt help at all. Its not that the car just runs hotter, the coolant temp gauge will be pinned in the red if I am in traffic too long, which is what worries me.

[bimm3r82]

sounds like your clutch fan is shot.. do the newpaper test.. stick a loosely rolled up newspaper into the clutch fan while its running and if the newspaper stops the fan its no good and needs replacing.. example:

http://www.youtube.com/watch?v=qUN17UEUWmc

[bigredguy]

sounds like your clutch fan is shot.. do the newpaper test.. stick a loosely rolled up newspaper into the clutch fan while its running and if the newspaper stops the fan its no good and needs replacing.. example:
http://www.youtube.com/watch?v=qUN17UEUWmc

I will try that out tomorrow. How difficult is it to replace the fan clutch?

If that is not the issue, keep the suggestions coming so I can get this figured out. Thanks

[mr.vang]

Use a thin 32mm wrench, whack it with a hammer toward the driver side. After that removed the fan shroud and pulled it out.

[bigredguy]

Use a thin 32mm wrench, whack it with a hammer toward the driver side. After that removed the fan shroud and pulled it out.

ok thanks. will I then replace the whole fan if it is in fact the clutch, or do you just replace the fan clutch. Also if I do need a fan, is there any better fans that can just be a direct substitute and will bolt right in and hook right up?

[SmokeE30]

You could upgrade to an electric unit to free up a little power but a new stock mechanical fan clutch should be fine as long and your radiator is up to par

[saturnv7890]

With the fan clutch, it's much easier to have the right tools. I guess you'll probably know this from doing your water pump, but you'll want a thin 32mm wrench (previously mentioned) and the holder tool which grabs onto two of the nuts on the water pump.

You can find them at any forum sponsor I'm sure, and ebay, both for cheap compared to the headaches

Holder tool:

[bigredguy]

I dont think the radiator was ever replaced, and was told that it was leaking when I took it in to a bmw shop, but they wanted 600 dollars to replace the radiator, and said the radiator costs 300. Thats an easy decision for me to say fuck that and do it myself, but the leak stopped on its own so I just let it go.

[saturnv7890]

From my own research, no personal experience yet, but I hear the ebay aluminum ones are great stock replacements, and at ~$100 you can't go too wrong

[RGCintha29073]

From my own research, no personal experience yet, but I hear the ebay aluminum ones are great stock replacements, and at ~$100 you can't go too wrong

Do you have a link to a specific one?

[saturnv7890]

Do you have a link to a specific one?

I've heard good things about the cxracing one:

http://www.ebay.com/itm/CXRacing-Aluminum-Radiator-88-91-BMW-E30-M3-MANUAL-TRANSMISSION-DUAL-CORE-2-ROW-/290648951174?pt=Motors_Car_Truck_Parts_Accessories&hash=item43ac070986&vxp=mtr

However, I might jump on a z3m radiator as I might go to track days and the z3m is a direct drop in with 3 cores

http://www.ebay.com/itm/3-ROW-FULL-ALUMINUM-RACING-RADIATOR-98-02-BMW-Z3-M-COUPE-ROADSTER-E36-3-2L-L6-/190792148395?pt=Motors_Car_Truck_Parts_Accessories&hash=item2c6c1925ab&vxp=mtr

But this is all based off research alone, someone else can jump in here and give some experienced reviews.



.

[bigredguy]

so if going with a replacement, the z3m is considered upgraded? What are the upsides and downsides to running one of these?

[saturnv7890]

Based a little on research and a little on intuition, here's my somewhat developed opinion:

OEM: Perfect fit, all the cooling you could ever need for street, track, etc. Plastic will likely rot out after about 20 years (...), and may not have the cooling needed for a super hot day, or a track car making some serious power. And supposedly the thermal shock or something on the track isn't good for the plastic. So aluminum might be better here. Oh and this is crazy expensive.

Ebay aluminum: Aluminum won't dry rot like plastic, can handle rapid temperature changes seen on track better than plastic, really no added cooling though, much lower cost, fitment can be so-so, but still very useable, as tolerances don't need to be tight for fitment. I hear a guy had to bent the barb for the tube that goes to the reservoir. Oh and maybe the welds aren't as high of quality?

Ebay aluminum z3m: 3 cores means more cooling capacity, can handle track cars making serious power probably? A little more expensive and it might not be necessary. I think the only downside to the z3m over the stock would just be the extra cost for efficiency that might not be needed.


And once again, my intent isn't to spread misinformation, I'd talk to people with more first hand experience rather than base a purchase off my own research