Outer Push-rod tube seals

[ebeeby]

The outer push-rod tube seals are dripping on my R50. This is the same side that had the missing lower outside stud that I recently replaced. I re-torqued all 6 studs correctly after replacing the missing stud.

Does anyone have experience replacing the outer seals? Does the head have to be removed?

[lkchris]

There is no "inner" pushrod seal.

Head has to be removed.

[flash412]

Have you tried re-seating the seals. Sometimes that works. You can do it with a hammer and a screwdriver, hitting the metal collar. But it is better to cut a piece of pipe for the job. Cut the end at about a 45 degree angle and then put a big slot up the pipe on the "long" side. The slot is to allow a place for the tube (in which the pushrods ride) to go. The angle gives you clearance UNDER the cylinder. You can use plastic pipe and make the tool in a few minutes with a hacksaw and/or a grinder.

[20774]

Ebeeby indicated it was an R50...not sure if that's a /2 or /5...I can't tell from his avatar if this is the bike in question. /2 pushrods are above the cylinder; /5 are below. I'd also suggest that this be the last, last resort for this kind of thing. For some model years, the collar is brazed to the tube. Hitting the collar as suggested will only pull the tube out of the head, which creates its own set of problems. Another possibility is that squeezing the seal in this manner can end up splitting the seal, resulting in a much bigger problem. If you can't live with the weepage, then it's best to make the change rather than banging on things...

Kurt in S.A.

[ebeeby]

This is a 1971 R50/5

The outer seals are in the head the inner seals are "closer in" and in the case where the push rod tubes enter.

Interesting idea about tapping the seals to re-seat them from the outside using a plastic pipe.

Still, does anyone know what is involved in replacing these outer seals once the head is (easily) removed?

Eric

[20774]

I'm not sure the "outer" pushrod seals you're talking about are what everyone is thinking of. I'm not exactly certain, but there are o-rings near the outer extremities of the pushrods, under the rocker blocks. The early designed heads needed the o-rings to prevent oil from escaping to the outside of the head. I suspect these are quite easy to do and probably don't require the head to be removed at all.

The "inner" seals you're referring to are a different matter and this is what everyone has been thinking of so far. These are located up against the block and require that the head/cylinder combo be moved away for seal replacement. Some only move the head/cylinder out enough for the job without exposing the piston/rings. A complete top end job would suggest that everything be taken off and disassembly so that a complete cleaning/gapping/checking can be done.

Kurt in S.A.

[flash412]

I'd also suggest that this be the last, last resort for this kind of thing.Then how come there is a factory tool for the job (that I told him how to make on the cheap)?

Oh phooey! Just put the motor on TDC, loosen the nuts that hold the rocker blocks and pull the rocker blocks off, pull the pushrods out, pull the jug away from the block an inch or so and replace the seals. Reassemble in reverse order. Worrying about it won't fix it. It ain't hard. It doesn't take much time and no special tools are required. You won't be disturbing the head gasket. Be sure to re-adjust the valves.

[20774]

I'm still waiting to hear what Eric is really talking about. From what's he's said so far, I think he's not talking about the pushrod seals at the block. He's talking about are o-rings underneath the rocker blocks on the outside of the heads.

Kurt in S.A.

[ebeeby]

I'm talking about the seals (or o rings) in the head. The push rod tube enters the top of the head from underneath and I have an oil leak there. If there is simply an o ring under the rocker assembly that would be great!

Does anyone have any experience replacing these o rings - or whatever is under the rocker assembly?

Eric

[20774]

Eric -

Take a look at this exploded view:

http://www.realoem.com/bmw/showparts.do?model=0260&mospid=47835&btnr=11_1730&hg=11&fg=20

From what I can tell, you'll need to remove parts 6, 7, and 8 to get to the o-ring. The rocker arm itself is connected between the top and bottom #7. Basically, you'll need to remove the rocker assemblies to get to the o-rings. Probably should just do the intake or exhaust at one time rather than loosen all four nuts. Retorque when your done with one set and move to the other set. This all has to be done at TDC on the compression stroke for the side you're working on.

Kurt in S.A.

[ebeeby]

Interesting that line 9 is deleted - is that the O ring?

[20774]

I didn't understand why the o-ring #9 was deleted from the list either. Typically that indicates that it's not used for the given year/model. I have the ETK version of the parts list and it shows the o-ring used on the R50/5 from 02/70 to 8/72.

Kurt in S.A.

[28796]

The push rod tube enters the bottom of the cylinder not the head so that diagram has nothing to do with his leak. The tube is a press fit into the cylinder & if it is leaking at that point the tube would need to be replaced as I doubt it would seal properly again even if you used a Loctite sealant. Removing the tube would require pulling the cylinder off the engine. I'd clean the area & make very sure that is the source of the leak.

[20774]

Certainly, it's a good idea to check to be sure where the oil is actually coming from. But in the early /5 heads, there are steel shafts inserted in the heads for the upper two studs. The oil comes into the valve cover area through one or both of these shafts. There is an o-ring that seals that off because of the way these early heads were designed. It is possible for oil to mist out of this area if the o-ring fails or is missing.

Eric initially said it was dripping (from where?) and that he had to replace a missing lower outside (?) lower stud. I suppose one can assume that the leak is on the lower pushrod tubes which enter the cylinder, but certainly, confirm the source of the leak before proceeding.

Kurt in S.A.

[28796]

Eric initially said it was dripping (from where?) and that he had to replace a missing lower outside (?) lower stud. I suppose one can assume that the leak is on the lower pushrod tubes which enter the cylinder, but certainly, confirm the source of the leak before proceeding.

Kurt in S.A.


Reread his post; he said its dripping from the "outer push rod tube seals" which really don't exist as the seal you describe has nothing to do with the pushrod tube. As you say the oil could be coming from other areas & as I said cleaning up the area and figuring out where its really coming from is the first task.

[ebeeby]

I'll take some close-up photos and post them soon.

Eric

[20774]

Reread his post; he said its dripping from the "outer push rod tube seals" which really don't exist as the seal you describe has nothing to do with the pushrod tube.
I think we're stuck in the on-line world with people describing things they are not necessarily familiar with in the best way they no how, no offense to anyone intended. I'm certainly not a BMW mechanic and don't know the correct terminology all the time. I look forward to seeing some pictures in hopes of narrowing the problem down. Even then we might still be wondering...

Kurt in S.A.

[lkchris]

The push rod tube enters the bottom of the cylinder ...

That's correct, except it's the TOP of the cylinder.

Sounds like a head gasket leak.

[kbasa]

I'll take some close-up photos and post them soon.

Eric

That'd be really helpful. See if you can focus on the underside of the head where the head gasket is too, please.

:thumb

[28796]

That's correct, except it's the TOP of the cylinder.

Sounds like a head gasket leak.

I wouldn't assume that as he says "The push rod tube enters the top of the head from underneath and I have an oil leak there. If there is simply an o ring under the rocker assembly that would be great!"

The pushrod tube enters the top of the head from underneath?????????? Doesn't make much sense at this point as the p/r tube doesn't enter the head at all.

[Friedle]

I can see you now John............ :banghead

Friedle :brow

[ebeeby]

These photos are from underneath the cylinder with the camera pointed straight up. You can see the valve cover gasket edge clearly, as a reference point. You can see the drops of oil on the 2 fins where the push rod tube enters the outer portion (top?) of the head.

http://a4.cpimg.com/image/BC/58/59094204-d2c9-02000180-.jpg
http://a2.cpimg.com/image/D8/59/59094232-0458-02000180-.jpg
http://a2.cpimg.com/image/EC/5A/59094252-849c-02000180-.jpg

[kbasa]

Got any of where the cylinder joins the head?

[20774]

There are 4 tubes on the underside of the head. The two inner tubes would appear to be the pushrod tubes. The outer two tubes are the steel tubes through which the studs pads. These steel tubes were part of the early design before the tunnels were cast into the heads. These steel tubes are the ones that have o-ring underneath the rocker blocks. Given the four tubes, it is essential that the area be cleaned up well so that the first traces of oil can be found to determine exactly where the leak is coming from.

It's tough to tell, but in the lower picture, it looks there's some oil around the pushrod tubes where they go through the fin. It's one of the lowest points and could be just where the oil is settling or moving around as it migrates to the edge of the fin.

Kurt in S.A.

[ebeeby]

After looking again very closely, I am convinced it is the push rod tubes and not the stud tubes that are leaking.
This brings us back to the original question: How are the pushrod tubes sealed to prevent an oil leak? Is there any sort of o-ring for them?

[20774]

As far as I know, no. Consider what John said earlier. These tubes are "drifted" into the head and once loose or dripping, about the only solution is to have them removed and install new ones. I consider it a delicate operation...you have to have the right diameter tool to drive the old tubes out. Then getting the new tubes in requires they be inserted the correct depth. Freezing them probably helps.

If it's the tubes leaking, you're up for some major surgery...the entire head/cylinder has to come off.

Kurt in S.A.

[lkchris]

You can see the drops of oil on the 2 fins where the push rod tube enters the outer portion (top?) of the head.


AGAIN.

Pushrod tube DOES NOT enter the head.

Rather the head gasket seals the joint between the cast-in passages in the cylinder and the head.

Use term pushrod tube ONLY to describe the sheet metal tube pressed into the top of the cylinder and mostly external to it, inserted at opposite end into rubber grommets pressed into engine block.

Cast-in cylindrical passages in cylinder and cylinder head through which pushrods pass are NOT termed pushrod tubes.

AGAIN--this sheet metal tube DOES NOT pass through cylinder and into the cylinder head.

If it's truly leaking at this joint--or at any other place at the head-cylinder interface, you have a leaking head gasket.

Oil, of course, can leak from anywhere and migrate to anywhere, so fact it drips from a certain spot is often not a reliable indicator of where leak actually occurs. Physics would suggest it will collect at lowest spot prior to dripping off. Where it separates when wind is involved is another story.

[paulfinney2]

Try cleaning it all up, then dust it with talcum powder, and trace to origin of leak.

[ebeeby]

This is a 1971 R50. In looking closely at the underside of the *head*, I am not convinced that the tubes are "cast in". I think they are seperate tubes that pass through holes in the fins of the head much like the seperate tubes that the studs pass through in the head.
Perhaps after 1971 they were "cast in". but I believe these are seperate. Since the stud tubes have o-rings, I was hopeful that these (to avoid an argument) push rod *passages* also had a seal where they entered the top of the head but apparantly they are pressed in. I think it is this press fit which is seeping.

Owen Meaney spoke a lot in capital letters - but it had a different effect.

[20774]

Kent -

Look at his first picture. The bottom of the picture shows the valve cover. The white gasket is visible which defines the joint between the valve cover and the head. What are the 4 cylindrical tubes that are passing through the head? I'm pretty sure the two outer tubes are steel and pressed in to pass the long studs. The other two can only be associated with the pushrods...

Kurt in S.A.

[AntonLargiader]

AGAIN. Pushrod tube DOES NOT enter the head.... Cast-in cylindrical passages in cylinder and cylinder head through which pushrods pass are NOT termed pushrod tubes.... AGAIN--this sheet metal tube DOES NOT pass through cylinder and into the cylinder head.
The cast-in passages started around 1975 but they were only for the studs; the pushrod tubes in the heads were still presssed into place and exposed. It's even shown as a separate partnumber in ETK on the early bikes. Later ones show it but not as an orderable part.

Personally I see nothing wrong with calling them pushrod tubes as long as the context is clear, but as Kent mentioned the term "pushrod tube" and "pushrod tube seal" will be assumed to refer to the ones on the cylinder unless you state otherwise. ETK refers to both as "Protection tube."

As for the leak; it does look like the tube is leaking where it joins the head. You can replace the tube but it's not an easy job. Contact Ted Porter at www.beemershop.com.