Pushrod tube position

[SeanW]

probably an old chestnut...

is there such a thing as a BMW-recommended position for pushrod tubes relative to the barrel, or, more likley, a position that people have found works well most of the time?

eg top of tube flush with head gasket end of barrel/ 5mm lower than this position etc?

when I did my winter rebuild I obvioulsy fitted new grommets, and stainless tubes in the one side which still had manky original tubes (fitted in exact same position as removed originals)

But I still ended up having to readjust the height of the new stainless tubes to get a snug but not over-compressed grommet fit (luckily this coincided with having to restrip that side for other reasons anyway), and now it looks like I'm gonna have to do the same on the side that the tubes were left alone as well, as the inlet side has split as a result of being overcompressed (it looks like to me anyway) and the exhaust side doesn;t look much happier either.

have all the bits to do it, but thought it might to get a guideline for a good sensible position for the tubes before I start smacking them about...

ie, it might be that I just ballsed up installing them cleanly the first time round?

 

[richie moore]

Did you buy your grommets from BMW, if you did not file them under B for BIN.

 

[SeanW]

got them from motorworks - so probably not OE?

 

[Beemerboff]

Is there any way of telling which are the good ones.

I have two sets, one with no markings, and the other marked with three overlapping 0s then 2961- 34.

First set were from Motorworks, second from Sherlocks.

Looks like I need another set, and I assume the marked ones are the way to go!

 

[VAL. H.]

probably an old chestnut...

is there such a thing as a BMW-recommended position for pushrod tubes relative to the barrel, or, more likley, a position that people have found works well most of the time?

eg top of tube flush with head gasket end of barrel/ 5mm lower than this position etc?

when I did my winter rebuild I obvioulsy fitted new grommets, and stainless tubes in the one side which still had manky original tubes (fitted in exact same position as removed originals)

But I still ended up having to readjust the height of the new stainless tubes to get a snug but not over-compressed grommet fit (luckily this coincided with having to restrip that side for other reasons anyway), and now it looks like I'm gonna have to do the same on the side that the tubes were left alone as well, as the inlet side has split as a result of being overcompressed (it looks like to me anyway) and the exhaust side doesn;t look much happier either.

have all the bits to do it, but thought it might to get a guideline for a good sensible position for the tubes before I start smacking them about...

ie, it might be that I just ballsed up installing them cleanly the first time round?

Sean, I did a couple of these down at the Airheads weekend a couple of years ago. I found that some will reseat just fine when the new tube is located in the exact same place as the old tube. However some did not relocate propperly in this way.

I had to adjust the length of the tube to suit the new seal to prevent over compression of that seal. I'd say that most importantly you will need to make sure the tube is located in the correct place and not over compressing the seal, which will more than likely involve removing and readjusting a couple of times to get it right.


Val.

 

[(RIP) Arkwright]

When I put push-rod tubes in it is to within 1mm of the top of the barrel (I have had to shorten them when the barrels have been shortened) and a very small smear of silicon on the seals to help them pull in to the block properly.

 

[SeanW]

if anyone's interested, I readjusted the pushrod tubes on the leaky side at the weekend so at their "lowest" point relative to the barrel head gasket face (ie measuring the position of using the part of the tube that is closest to the piston), they were 5.5mm inset from the face. On the side that is furthest away from the piston, they were obviously much closer to the face, due to the tube's angle, but I didn't measure this.

The grommets look correctly seated, and didn't leak on the ride into work this morning.

We will wait and see....