rocker shaft bushing gone AWOL

masraum · 11:18 PM

Hey, a while back I noticed an oil leak at the front of the engine, driver's side, (farthest rear in car, cyl 1?) that had no obvious source. It is a minor leak, so, because I haven't had much time I haven't bothered with it yet (Porsches leak, right

). I just changed the oil and found some metal parts on the magnetic drain plug. Looking around I believe these to be pieces of the bushing that goes in the end of the rocker shaft. If I've been running like this for a while (couple of months) what are the possible consequences? Should I replace that whole shaft and it's assorted parts? Wish I had more time or more money (or I guess both

)

Thanks

PS I haven't gotten into it yet, but I am pretty sure that's what I've found. And from reading past posts the rocker arm shafts can be a major leak causer, right.

Bobboloo · Bobboloo's Garage

I would pull the valve covers and find out. If it is what you think then get to it pronto. Loose metal parts in a motor are a bad thing.

If it is the bushing then I would replace the rocker arm, shaft and the bushing. To do otherwise is to gamble with your motor.

Have you already refilled the motor with oil? If so then you'll either have to drain it again before you pull the lower valve covers or jack the car up on the side that your pulling the lower cover so thet the oil runs to the other side.

Lastly, I wouldn't feel comfortable until I found all the missing pieces. But that's just me.

Bobby

ChrisBennet · ChrisBennet's Garage

Steve,
What do you mean by "pieces of the bushing that goes in the end of the rocker shaft"? There is a tapered "nut" on the far end of the #3 (left side, closest to front of car) rocker arm shaft. Is that what you mean?
If that was the case, I would make sure the rocker shaft is in the correct position in the bore, replace the nut and find the missing pieces.
-Chris

masraum · 09-22-2002, 07:37 AM

It's the "bushing" at the head of the allen bolt that keeps the oil from getting out past the head of the bolt.

ChrisBennet · ChrisBennet's Garage

Hi Steve,
Hmmm, never heard of one of those breaking but I don't get out much.

That bushing and the bushing/tapered nut on the other end, expand the ends of the rocker shaft to hold it in place. They are on the "dry side" of the engine and should not be able to get into the oil supply. If they broke up the pieces would fall down toward the heads, possibly into the spark plug hole but they can't get into the engine.
Rocker shafts certainly like to leak and seals exist to cure this but I would take a closer look at the part you have. Post a picture to the list - you know how we like a good "what is it?"
-Chris

masraum · 09-22-2002, 04:00 PM

Back to the front page, and now with pictures.

OK, here are the parts, from both sides. Pretty scary to find in your oil, I gotta say, but hopefully it won't be too pricey to fix.

The first picture has one of the two sets reversed from the other. It was hard to tell, but on the second set because of the pattern I got the orientation right. The pieces seem to have a curve to them as well as a bit of bevel at one end. They look to be about 7mm tall and I would guess the cylinder would have been somewhere in the range of 10-20mm around if it was in one piece. Actually what clued me in was a photo from Waynes project book. (page 42 bullet#5)

BTW, if you think the parts are something else please let me know.
So besides the fact that I used his directions to swap my wiper park he's also helped with my engine. Way to go wayne. If your next book is as good it may actually rejuvenate motors just by being in the garage with them.

ChrisBennet · ChrisBennet's Garage

I'm still looking Steve. It's hard to tell without having it in my hands. What would it look like if you sliced it and looked at the exposed sliced edge? Does it look like any of the following?

masraum · 09-22-2002, 08:14 PM

well, it's worn pretty thin right now, but it looks most like option A.

masraum · 09-23-2002, 06:17 AM

OK, back to page one since it's Mon and everyone is around. Another note. Someone on the Rennlist said the bushings are bronze. The pieces that I have are definitely iron based because they are magnetizied from being on the drain plug.

The pieces are approx 7mm tall and about .5-1mm thick, but I would think they could have been thicker at some point. Any thoughts guys? Come on, I wanna order parts so I can work on this next weekend (assuming Isidore isn't paying us a visit here in South TX then.

ChrisBennet · ChrisBennet's Garage

Steve,
I'm still stumped Steve. You can pull your valve covers and look but I don't see any way that the bushings or anything from the valve train could get into the sump.
Rocker shaft bushings are steel.
Bearing material is magnetic though I don't know why. I thought it was mostly lead and copper.
good luck,
Chris

masraum · 09-23-2002, 06:56 AM

When I pulled the parts out I was hoping that they were left over from a mechanic working on the car in the past. I guess I'm still hoping that's what is going on, but I don't want to assume that and have a bigger problem later. Any ideas, anyone?

I wish I was more familar with a 911 engine, i would probably know what this part is from.

Tim L · 09-23-2002, 07:09 AM

I think you might have a bigger problem. Those pieces look like parts of a rod bearing to me. They are definitely not parts from the rocker shaft. Do you hear any noise under hard acceleration something like an exhaust leak but a lower note?

Tim

masraum · 09-23-2002, 08:01 AM

IIeeeAAAaaahhh! Don't say that. I don't believe I have heard any rod knocok sounds? Are rod bearings iron? Will they stick to a magnet?

john walker's workshop · 09-23-2002, 08:30 AM

they do look a lot like chunks of a spun rod bearing, but i would think there would be a hell of a rattle because of it. you didn't mention any noise. they're not rocker shaft related.

MBAtarga · 08:35 AM

I've never been into one of these flat six engines. (EDIT: John Walker beat me to the punch, but my post has pictures

)
Based on the size you estimate and looking in PET, my guess is this:

Tim L · 09-23-2002, 08:34 AM

They must have some iron in the bearings because they stick to the magnet. There aren't many pieces inside the motor that look like that except bearings. It could be the intermediate shaft bearing as well. On the brighter side when my bearing went there were a lot more pieces.

Tim

masraum · 09-23-2002, 08:34 PM

Well, ladies and gentlemen. I believe we have a winner. I believe Walt Fricke of the Rennlist has the answer.

The drawing is the end of the rockershaft itself which may wear and fatigue and crack from many expansions. Now all I have to do is find out if that was old debris from a problem that was fixed long ago, or verify that ther is currently a problem.

Thanks to all with suggestions and thoughts.

82SC · 09-23-2002, 09:49 PM

well having my engine open down to the rockers shafts at the moment...I guess it could be rocker bearings...looks similar to my rocker shafts...

they would fall off and drop down to the oil return tubes...then be at the bottom of your crankcase near the drain plug...and be magnitized there keeping it from doing too much damage

I would guess it is a exhaust bearing since it is closer to the oil return tube...but it could be the intake too...but that would have to pass by a rapidly spinning cam

if I were you do a drop or a partial drop take the rocker covers off...buy the seal and nuts kit from pelican...if the bearing really came out the rocker would be moving all over the place...there is absolutely no play in componenets when I opened it up...that is a very easy procedure and will set your mind at ease...

hopefully it didn't do too much damage...it is better then having something in the comb chamber or it being a rod bearing or a crank case bearing

let us know how it goes.

MJ

911pcars · 09-23-2002, 10:38 PM

Here's my guestimate.

The cross-sectional view looks like a valve retainer lock to me. Perhaps it was dropped into the crankcase at some point in time. It doesn't look like a lock (normally half round) because it looks like something smashed the living s@@@t out of it. I have no idea what the crunch source is other than the rotating mass.

Have you counted the valve locks in the engine? If you only have 23, this may be a potential problem.

The oil leak below no. 1 might just be a coincidence with what you found in your tank; totally independent. I'd look for a leaking cam oil line fitting on the driver's side (both ends), then pull the valve covers and check the valves and rocker arm shafts; make sure all the piece are still there.

Sherwood Lee
http://members.rennlist.org/911pcars