grankin

OK, I've reported earlier that the belt sensor has failed repeatedly, and that I was going to get a new one and see about replacing the bearing for a real one. Instead, when the new part arrived, I looked at it & thought a bit. There appears, BTW, to be a bearing ID there on the wheel. It says "*** 626RS NT" That's an actual bearing, findable at <http://www.seekpart.com/bearings/***+Deep+Groove+Ball+Bearing+626-RS.html>, but that won't do you much good when it is the shaft it runs on that fails.

There was a nice hole down the center of the shaft the sensor wheel rides on, what looks like a bolt head pressed-in to the forward side, and the shaft peened-over on the aft side. <thinks to self> Betcha I could find me a bolt that'd go through there, a couple of washers to bear any loads and a nylock to pull it all together. </thinks to self> So I went to a local hardware store and bought a button-head cap screw, M3 in size, 20mm long, 0.50 pitch. Then two M3 0.50 fender washers and a M3 50-pitch nylock. The cap screw doesn't fit a 2.5mm Allen, as the photo purports, but really a 9/64 Allen key.

So here are some photos. First, what it looks like from above:


And from closer-in and from above (with zip-tie):


And closer-in from another direction:


Note that the wheel's gone and the end of the shaft looks pretty rough. That's what contacts your belt when the wheel takes off. Not good.

Here're the parts from Ace Hardware, a total of $1.31 worth:


The new part, from the peened-over aft side:


And from the pressed-in bolt forward side:


Cap screw & washer on the bolt side:


Nyloc nut and washer on the peened-over (aft) side:


Tightened-down:


And now seeing both sides:


My theory: the washers will keep the wheel from wobbling (as I assume it does) which causes the peened-over end of the shaft to fail. The whole thing is not drawn up all that tightly, just enough to hold it together, so as not to add new stresses.

Any thoughts or observations before I install it?

darth

very resourceful!

Goughary

bigger pics maybe? I can barely see them,,,

Good job btw...

grankin

Edited the original post with bigger images - once I figured out how to do that.

Goughary

nice! Thanks

martin964

genius! I have had 3 go within the last year.....

Jacke2c

Great job... go for it!

grankin

Progress report:

Over a year later, and the repair continues to stay ... errr ... repaired.

BHCfarkas

Amazing.. these really fail that often?

grankin

They did for me. Either bad design or bad materials. My 'fix' is cheap and appears to have longevity.

911Jetta

Fan belt light came on this weekend!

I had both kids in the car and we were 10 miles out in the country, so I definitely had an "oh-****" moment for a second. Turned off the car and popped the lid to find the the fan belt sensor wheel was missing and the plastic sensor arm was rubbing against the fan belt. Pushing the sensor arm back actually kept the sensor from rubbing the belt, at least for minutes at a time until is decided to spring back and contact the belt.

Picture of the wheel-less sensor


So, got home safely and was easily able to disconnect and remove the sensor.... but, where in the hell did the bearing and little wheel go?

Looked everywhere around the belts to make sure there was no shards there, then continued to scoure the rest of the engine bay and couldn't find any evidence of the wheel or bearing. It looks like this situation is somewhat normal (I've also already replaced the unit once years ago), but it really bothers me that I can't find the wheel or bearing. My engine bay tins and seals are all in great shape, the only thing missing are the two little plugs below the engine mounts... I just don't believe it could it have escaped through those holes?

Anyone been here before and know where the wheel and bearing are hiding?
From the first post, the bearing is "*** 626RS NT"... but it looks like I'll have to buy a new unit just because I can't find the wheel!

Vandit

Maybe it broke into pieces and either fell under the crank pulley or maybe even got sucked through the engine fan.

911Jetta

I was looking forward to what you would say... that said, I don't like either of your answers though!
I spent a lot of time looking around the crank pulley, but saw nothing... I'll check again, with a magnet.

crg53

Good fix. The only thing I would like to add is, make sure the inner race of the bearing is held tight, you do not want that to turn on the brass shaft, so as long as the fender washers are only touching the inner race, I would cinch the nut and bolt up tight, may even use a little blue Loctite on the thread.

grankin

Annnnd ... a progress report: here it is, nearly 3 years after I "rebuilt" the stock sensor wheel using a couple of washers and a bolt. It continues to function properly.

So my advice to anyone whose sensor has lost a wheel? Don't bother trying to repair it, nor to find the parts that have run away and hid somewhere. Buy a new unit, then read what I wrote at the top of this thread. Cheap, easy, and (fingers crossed) permanent.