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1994 K75S High-pitched chirping noise when hot?

Right you are, Don. In my dilemna and advancing age I got sidetracked by the blocked fuel return line and actually forgot about the stethoscope until Ted piped in about it later on. I am getting a bit more senile at age 61 than I would have expected (absent-minded more than ever lately; I think my 88 year-old dad is sharper than I am!

Oh, well, at least I have an almost completely new fuel system going and the bike is running great otherwise (and I didn't damage anything important by operating the bike while screeching; it was only a fan motor bearing).

I just noticed that Beemerboneyard sells just the fan motor (Bosch!) for $79 so I immediately ordered one minutes ago. :dance Now I'll look into what I need to remove in order to install it asap...

Thanks again for your help and I'm sorry I spaced out acting on your excellent advice.:thumb
 
Well what do you know about this...!

Another slightly incorrect diagnosis cropped up this afternoon as I removed the radiator assembly and loosened the two bolts holding the fan in place.

When I swung the fan up and out away from the back of the radiator I discovered that a small section of the radiator elements were bent and mashed down maybe 1/8th of an inch---looks like the fan motor shaft was rubbing itself into the radiator! Maybe the motor bearings were not bad after all (will hook up to 12v and test soon)

Fortunately, when I drained the radiator earlier the Mercedes (or maybe it was Swiss) blue anti-freeze I had put in about three years ago still looked very clean and translucent. There was also plenty of it---so no apparent leaks.:thumb

Tomorrow I'll take and post a picture of the radiator damage and hope to get some opinions on how to best avoid a repeat scenario after I install the new fan motor. I'll also try to gingerly pry the radiator fins apart and straighten them out as best I can. Otherwise the radiator seems to be in great shape for an 18 year old bike.

Even if the old motor is OK I'll still gladly install the new one. Here in the desert I can probably expect a slightly longer fan life and my K will be all the better in the long run.
 
Radiator Fan Blade Damage

The damage radiator elements you talk about, are they in the centre opposite the fan spindle?

I have read that in some instances, radiator fans have been known to come loose and "helicopter" themselves into the radiator, drilling a hole causing the bike to lose coolant.

ghyber
 
Yes, that's what would have happened eventually---but I caught it in time.

I can't see how the fan spindle made such contact but maybe it worked itself forward just enough to mash the radiator some. Otherwise the mounting seems fine.:dunno

I'll post some pix tomorrow.
 
Radiator damage from fan spindle; how do I prevent this?

Here are pix of the radiator damage caused by "helicoptering" of the fan motor spindle into the back of the radiator.

ANY IDEAS ON HOW TO PREVENT THIS OCCURING ASAP ARE SO WELCOME! I plan to put it back together today if possible.:eat Btw, the old fan appeared to mounted correctly!



DSC_9830_zps71f8c405.jpg
 
ALL FIXED AT LONG LAST! (Unusual problem to begin with)

The screeching should be gone for good as the culprit was the fan motor---but not the bearings going out at all---the fan motor was fine after I pulled it out.

It WAS, however, the fan propeller "helicoptering" into the back of the radiator causing all the blasted screeching and chirping plaguing me for the last many months!

I fixed it with a small patch of Fast Steel epoxy putty to protect the radiator core from further damage should the propeller center nib try to head into the radiator again.

I posted pix over in my "helicoptering" thread ajacent to this one.

Ironically, it has been way too cold here to even think about going for any sort of test ride but I am already convinced that this problem is solved. It is supposed to warm up into the 60-65 degree range the rest of this week so maybe I will get to take Berlina out for a spin soon, though.

Thanks to all who responded in my time of need!

:bow
 
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