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I changed another IM bearing..... by rabbitman on 04 Feb, 2011 00:57
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I was helping a friend get an '85 jetta td (Garrett T3) on the road and after changing the clutch (the pushrod had at least a 1/8" slop in the bushing and seal
) , heater core, reattaching the exhaust manifold that had two nuts missing and the rest loose (hopefully it fixes the lack of boost issue) and lots of other little stuff I started changing the t-belt.
Got it all apart and was changing seals and checked the outer IM bearing for flaking. It was terrible, half the width was gone at the wear point.
Luckily I stock two sets of bearings just for such occasions as this, the first set is for try one and the second for attempt #2 which so far has worked. So I drove it in with a hammer and screwdriver while my friend held it from falling into the oil pan with his finger.
For installing the new one we oiled it, lined up the oil holes and using the IM shaft, seal holder/retainer and longer retainer bolts, pressed it in by tightening the bolts little by little. The retainer hit the block slightly before the bearing was completely in so we used a large washer between the retainer and IM shaft to hold the retainer back and then pressed it in the rest of the way.
After the bearing, shaft and retainer where back in the shaft turned easily by hand
Compared to the last attempt this was a breeze, last time I ruined a bearing by pounding it in with an ill fitting pipe cap and after waiting a few days for the new bearing to arrive I pounded it in "gently" this time and deformed it just enough that the shaft wouldn't fit in without "machining" the bearing out with sand paper.
Of course, using the shaft as the guide won't work with the inner bearing but from what I've read it rarely needs changing anyways. -
#1 by dyoungen on 04 Feb, 2011 20:55
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I have both bearings to replace on my 1985 Jetta n/a Diesel. Does the outer bearing go out more than inner? I haven't started on replacing mine yet, just waiting on the time to do it. When you replaced yours, did you have the engine out or did you have the engine still in the car? I'd like to replace mine with the engine still in the car, if that's possible.
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#2 by rabbitman on 04 Feb, 2011 23:33
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The outer bearing has the t-belt pulling against it so it's life considerably shorter.
We lifted the engine up, removed the rear mount and then lowered it enough to slide the shaft out. I also did it on a MK1 with the engine installed, just had to undo the pass side mount, front mount and I think the rear tranny mount too and then lower away.
It wouldn't be a bad idea to check the inner bearing while you're at it, but to do that you have to drop the oil pan. -
#3 by rabbitman on 04 Feb, 2011 23:47
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I have a question.
You all know the oil port for the outer bearing is at the rear and slightly up in the bearing bore, and the belt pulls the shaft away from the port. On a gasser the belt pulls the shaft towards the oil port and afaik they don't have flaking bearing issues.
I'm thinking that a groove inside the bearing, running around the circumference and through the oil port would allow oil to flow to the loaded side better, thus preserving the bearing better.
Thoughts? -
#4 by RabbitJockey on 05 Feb, 2011 07:57
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I have a question.
You all know the oil port for the outer bearing is at the rear and slightly up in the bearing bore, and the belt pulls the shaft away from the port. On a gasser the belt pulls the shaft towards the oil port and afaik they don't have flaking bearing issues.
I'm thinking that a groove inside the bearing, running around the circumference and through the oil port would allow oil to flow to the loaded side better, thus preserving the bearing better.
Thoughts?
thats brilliant! i don't know that a groove would carry it like it should, maybe a goove on the outisde of the bearing that would then carry the oil to the other side of the im. or is that what you meant -
#5 by rabbitman on 05 Feb, 2011 09:29
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thats brilliant! i don't know that a groove would carry it like it should, maybe a goove on the outisde of the bearing that would then carry the oil to the other side of the im. or is that what you meant
Well, I was thinkin' a groove inside the bearing would even out pressure centering the shaft in the bore with a good film of oil completely around the surface rather than the oil pushing the shaft away from the oil port and then maybe getting around to lube the loaded side.
Seems like most of the oil would leak out of the bearing surface long before it gets around the shaft and any bearing wear would way speed up the wear process.
I've got a few new inner bearing's maybe I'll experiment with and try to get a picture up. -
#6 by theman53 on 05 Feb, 2011 10:02
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A grove just like the main bearings have only not as deep or wide I bet would work. Too wide or deep might make the original surface not get oiled and wear faster. Maybe 3 rings on the inside a couple thou deep and 1/16 wide.
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#7 by truckinwagen on 05 Feb, 2011 10:15
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the main reason gassers dont have the IM bearing failure issue is that they run about half a much tension through their timing belt while running.
-Owen -
#8 by rabbitman on 05 Feb, 2011 15:59
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the main reason gassers dont have the IM bearing failure issue is that they run about half a much tension through their timing belt while running.
-Owen
That's true, also the belt doesn't wrap as far around either.
I think this would still help though. I'd do one groove maybe 2-3 thou deep and 1/16th wide at the most, the only reason for the groove would be to get the oil to the other side faster losing the least amount of bearing surface as possible.