So we had our Gathering of Idiots this past weekend and the event was simply fantastic. Great weather, people and location. Thank you Ron for all you do and thanks for being my wing man.
My trek to the event was a bit stressful, so I thought I would "share" it and leave you with some valuable knowledge. All of the following was due to a $20 part.
I left home to meet with Ron north of Allentown, PA which was a 169 mile sprint. About 80 miles into it, temp gauge started to creep northward. Pulled into a rest stop and inspected everything. All looked good. having replaced the coolant tank and cap prior to Sharkfest, I began to doubt if I had bled the cooling system...So I cracked the bleeder and she burped a couple times. Temp gauge drops back to normal
Headed on to Ron's thinking all is well in the world (well, my world) and it was, for about 30 miles...gauge starts creeping again. I pushed on to my destination with the gauge staying in the "white zone" barely.
Upon arrival we did the ole shove the roll of paper towels in the fan test and the fan clutch failed. After a few calls, we confirmed Fernando had a fan clutch and would have it in tow. Now, in the back of my mind I was thinking a crapped fan clutch should have little or no impact on cooling at speed, but I was in denial and drinking rapidly, so who cares.
Before leaving for Mass in the AM, I jumped the wires to the low speed aux fan circuit to provide a little extra air while in flight. I figured why overtax the fan in high speed if low would get er done. Right?
The drive Friday morning was good for a short time period when the gauge started to creep up again. As the morning grew warmer, so did my cooling system. A brief period at idle for the toll booth at the Hudson got her damn near the "red" zone. We pulled over immediately and jumped the high speed fan. That got me another...11 miles and we ended up exiting the interstate for a NY State Police Station (thinking the only safe place to leave my car) but was told I could not leave it due to policy. OK. Fortunately there was a small auto repair shop just across the street (the second safest place?). They were very nice and there I left her. Prior to piling all my crap into Ron's car, I checked under the hood and thought it was "odd" my coolant recovery tank was nearly full to the cap...Hmmm
That's when the light bulb came on. If the aux cooling fan on high speed could not bring the coolant down to normal operating temp, then there must not be any coolant there to bring down...THERMOSTAT!!!!!!!!!!!!!!!!!!
Sunday on the return trip, we REMOVED the thermostat and swapped my fan/clutch for Fernado's (cause his was a Sachs and mine was a Behr and I think the Sachs is a better unit, but anyway) topped up the coolant and the problem was SOLVED. The trip back to Ron's and subsequently home was about 260 miles with no incident. NONE.
So, the thermostat I took out of my car was a Wahler that I had replaced back in 2008. Funny thing was it was stamped "Made in W. Germany" When did the wall come down?
So the moral is, replace your thermostat every 3-4 years (not 6...) and don't replace it with one that says "Made in W. Germany" ...
'84 Euro 635
'88 M6 (Gone but not forgotten)
Ahh, good times. Very glad to be there any time, George.
Oh well...but all's well that ends well. Another great story to tell this winter while sitting in front of a roaring fireplace.
Recall just having met my bride to be and I was smitten. She had a Jeep CJ7 and it was winter, no heat. Chivalry was not dead, I changed the thermostat outside in a snow-covered parking lot, about 15 degrees. Ahhh to be young and dumb(er) again.
Rob E3
Yeah now we're Idiots.
Great story, George. Glad it all worked out and your car was not damaged.
Randall Morin
COL(Ret), US Army
Hagerstown MD
I was enroute to Oxbow, NY, doesn't that take the prize? Thanks Jody for asking me wtf I was driving to NY!
I really need to get my car sorted so I can take a summer trip to your side of the country. Ill have a rat rod by then at this rate but hey who needs clear coat. Theres a relatively large e24 following here in the Bay area. Probably more than the 5 peope Ive met who are <25yrs old and have clean examples. We have a young lady with an m6. Id love to set up a caravan to Bimmerfest east. Maybe Cameron (Garma Zabi) will join me on my trip.
I think the Bimmer Gods feel like I've dealt with enough overheating BMWs with all the two dubs I've had. I replaced the original radiator in my '85 a couple of weeks ago just because the upper water neck was broken off - after nearly 30 years. The old car ran reasonably cool - below half on the gauge at highway speeds and would finally creep up to the high speed fan kicking on in traffic in the Alabama summer heat.
After the new radiator, cooler thermostat sand a new fan clutch it stays about 1/4 on the gauge, may have to put the "hotter" thermostat back in before this old 6 freezes to death!
On our return trip from SESF this past year one of those in our caravan developed an overheat issue within a half an hour from our departure. I think it was Todd (AlpinaCSI) that knew of a local contact where the car was towed. The driver thought he was going to need a head gasket replacement and the rest of us continued on our way. Fortunately it ended up only needing a thermostat replacement. Funny how the problem can happen so suddenly.
I had a similar situation a bit over a year ago. Cruising down the freeway on a Sunday afternoon. All of a sudden the charging light came on and the temp gauge started to rise. Pulled off into a gas station, checked it out, and the fan belt had disappeared. Which seemed strange because I knew I'd replaced it not very long ago. Get the car towed home. Get a new belt the next day and put it on. Try it out and it squeals like crazy. The water pump has frozen up solid. It never leaked, just suddenly froze up and, of course, burned through the belt.
And that's why for no good reason at all I replaced the water pump on my '85 just because. I've had this car for a little over a year, got it from an old friend who had it for 15. He seemed to remember putting on a new pump but wasn't sure how many years ago. It wasn't leaking, wasn't noisy, car ran cool - so I put a new one on.
just because.
Well, over the weekend with the "Idiots" the 6 developed high speed brake wobble.
Sooo--changed the 8 yr. old Potenzas and put on Michelin's Pilot Super Sports
and upper control arms. Wow, what a change--smooth ride and no wobble.
I'm a happy camper. On to Lime Rock for Fridays track day.
Thanks to all of the "Idiots" for their advice
George,
got to thinking about your fan clutch test. With the water in the radiator being cooled by ram air and elec cooling fan, and not having hot block water being introduced to it from the blocked tstat, the clutch would not have sensed heat being drawn through the rad enough to engage the fan. This was certainly a confirmation that the Tstat was blocked. Engine temp hi , Rad temp low. Clutch thought it was dealing with cold air so was freewheeling. You mistook this for a bad fan clutch when it fact it was reacting properly.
'88 635, '92 325IC
Bimetallic strip is on the clutch facing the radiator. Makes sense that it works from the radiator heat.
FWIW, I am surrounded by brilliant idiots. What a pleasure! I love the crowd.
Yes, Todd is correct. Bimetallic strip in clutch center facing the rad moves a pin or metering shaft in and out varying the oil inside of the spinning clutch to engage paddles much like an automatic transmission torque converter. You will sometimes see the oil leaking out of the center hole on faulty ones. Some clutch designs have a coiled bimetallic spring (much like the electric chokes on carburetor cars)which rotates the shaft when hi temps hit it expanding the metal and some have the single strip that rises and falls with respect to length and pushes pin in and out. I bet a 6 pack that George's old clutch was probably still good. A Bad clutch would not fail such that you would see a spike in the engine temp while driving. Afan is not needed while driving hence no mechanical fans on some cars. In fact you wouldn't even notice it was bad unless you were starting to see a noticeable rise from normal temps while sitting in traffic only. Once you got to highway speeds though, the efficiency of a correctly operating cooling system would cool it back down. Not so with a blocked Tstat though. Instant engine temp rise and cold radiator no matter how fast you were driving.
'88 635, '92 325IC
Over the years a lot of crud can build up on the fan clutch and bimetallic strip, acting as an insulator so the unit does not respond properly to heat from the radiator. It's worthwhile to clean it with brake cleaner spray or a pressure washer.
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