Rocker Arm Replacement Question

[JCarp90]

Long story short, I snapped a rocker arm in my 91 325i. Bought all of the stuff required to replace it including rocker arms, full head gasket set and everything. My mechanic pulled the head to replace the rocker arm and when he was taking the rocker shaft out, they had to use a punch to get it to come out btw, they tapped it and it broke the guide that holds the rocker shaft in place over cylinder 1. My question is if this is a normal thing or if something could have been done incorrectly? I've read quite a few write ups on how to replace rocker arms and it looks like the shaft is supposed to come out the front and not the back. I plan on replacing the head now because it looks to be non-repairable by even a machine shop.

I will post a picture as soon as I get to my laptop.

Cliffs: Broke a rocker arm. Mechanic goes to replace and instead cracks off a chunk of my head. Amidoingitwrong?

[riceh8r]

a bmw mechanic ?? it comes out the front, and one should use a wooden dowell to drive it out. rockers need to off the valve spring so there is no tension on the rod...that said, why did the rocker break ? if a valve taps the top of a piston it will usually break the rocker arm. cracked rod journals is also a major concern when that happens. the cast may have already been cracked. is it possible that you skipped a tooth on your timing belt ??

[MR 325]

The rocker shaft can come out the front of back, it doesn't matter. You need to make sure all of the retainer clips are off each rocker arm and that the large metal clip is removed first on the front side of the head.

No you don't need to use a wooden dowel, you just need to know what you're doing.

[MR 325]

Also, a rocker arm can break from wear and high revving, there doesn't need to be a hidden theory behind why it happens. It's happened to me twice.

Your mechanic owes you a new head as far as I'm concerned. I've been on the other side of things and I do work for a BMW shop and what happened was in his error.

[ttrousdell]

found this helpful

http://www.e30zone.co.uk/e30zonewiki/index.php/Stripping_and_Rebuilding_an_M20_Cylinder_Head

[JCarp90]

It was not a BMW specific mechanic, just a friend that owns his own shop. It's very well possible that it could have already been cracked just due to wear and tear but at the same time, the end of the rocker shaft where they used a punch to move it, was entirely too fucked up. It makes me think they just tried to do it without really looking up how it was done. He's a very knowledgeable mechanic and has always done me right in the past, as well as friends and others I have referenced, but I feel as though he is in the wrong this time.

The way it sounded, they really had to hit it, too. Which makes me think it was their fault when they tried. Isn't there some sort of insurance for this sort of thing?

Also, pics. *Sorry for size*

[MR 325]

I also forgot to mention that all of the valve eccentric should be loosened up on all rockers before trying to tap the shaft out.

I definitely think it's his fault. If you're taking your car to a mechanic he is supposed to know what he's doing. If he breaks shit that wasn't broken, that's on his dime. It doesn't matter if he's a BMW guy or not, he should still be able to handle the M20 head.

[Plastic Emperor]

That sucks...and if you do it right there is almost no tension on the rocker shaft.

You basically turn the cam so that the lobes on cyl #1 face down, remove the exhaust rocker arm clip. Slide the exhaust rocker off the cam lobe. Then turn the cam so that the cam lobes on cyl #6 are both facing down (I can't remember which way to turn the cam here...just be careful not to get the moved exhaust rocker in a bind). There should be no tension on any of the exhuast rockers now...pull the remaining exhuast rocker clips off and the shaft should pull out.

The Intake side is pull the clips off of the rockers that have no tension on them and slide them over the where the exhuast rockers were...then turn the cam to releive the tension off the remaining rockers and remove the clips and slide them over...then the intake shaft slides out.

Dont quote me 100% on that but its the gist off it...its all in the bentley manual.

[nando]

^ that's basically it. you shouldn't have to hammer on anything with enough force to break the head. your mechanic is clueless.

[SpecM]

^ truth, I just tapped mine out

[F34R]

^ that's basically it. you shouldn't have to hammer on anything with enough force to break the head. your mechanic is clueless.

1+ the tube taps out really easy if you do it right. The "mechanic" is at fault, he should replace it.

[jlevie]

When tapping out rocker shafts that have the pressed in end caps, you need to use a hollow driver to avoid damaging the end cap. I don't remember the size, but I a socket and extensions for this.

[NigelStu]

In process of replacing rocker arms and came across an issue.

If a rocker shaft does not slide smoothly into the guides, is this a sign the head is warped? The rocker shafts came out of 1 head easily (and re-installs easily), but does not want to go past journal 2 on exhaust side or even into 1st journal on intake side of the 2nd head (I tried sliding the shafts in prior to full assembly).


-1st head - stock BMW - fully assembled but has a stripped intake stud hole
-2nd head - AMC - sans cam/rockers, has significantly lower miles
-Old head being replaced had broken rocker arm (upon removal of shafts found old shafts and cam journals scored, worn, etc - expect bad maint on PO's part - I basically have some new garage art...)

[E30Gus]

When I bought my engine the head was damaged the same way in the same location. They welded more aluminum in there then drilled it ou the correct size. So I think it is repairable even though I'd definately want another head.