Ouch!! Broken Rockerarm. What is the next step?

[NWDriver]

1990 535 / m30 / Automatic

OK Drove to work just fine. On way home lost all power and heard knocking, 5 blocks from drive way, I nurse it in. Pop Rock Cover and find out 1 and 4 Rocker arms are broken on the intake side.

I was informed that the upper end was rebuilt 30k ago. I do not belive this now as the cam shows much more ware than 30k. Car has 230K on it. Have a receipt for a new head gasket in 02. But no docs on new parts besides gasket. So I now want to fix it right. Please help in guidance.

What would cause break? Or is it just age?

What is the best fix? Pull head and rebuild?

Is there a place that I can order a new head/rebuilt rdy to go head?

I am in Seattle WA. Is there a good BMW Head guy around in the NW?

Can you guys help point me in the right direction on next steps?

Thank you in advance.

[Rigmaster]

It's like deja vu all over again!!

Sorry to make light of your trouble, but the same thing happened to us in the wife's '91 535iA at about 130k miles. PO had a "rebuilt" head installed at approx 80k for some reason, but it was a POS rebuild- the head casting was all scarred up in one of the combustion chambers and they reused the rockers. On our car, it looks like one of the valve seats failed and put alot of stress on that rocker, so it failed + broke.

IMHO, the only way to do it right is to pull the head and do a complete top end rebuild. This means pulling the head, having a competent machine shop check it for cracks or other damage, check for warping and resurfacing if necessary, perform a "valve job" which is basically cutting a fresh surface on the valve seats + grinding the valves to fit, replace ALL of the rocker arms, check + replace rocker shafts if necessary, then reinstall using a new head gasket.

I am lucky to have a good machine shop locally that is familiar with BMW heads, so I have no experience with purchasing "rebuilt" heads- but the head that we had to fix was from a "reputable" source installed by a high-end independent shop- YMMV.


Good luck, I'm sure we can help walk you through it if you need help.


Bret.

[NWDriver]

Thank you for such a quick response. I am mechanial enought to pull the head and I have a Bently manual to help guide. I do not have head work experience, so that part is a bit scary.

Is there anyone out there that can recomend a good machine shop in the greater Seattle Area?

Also where to buy parts? BMA? Other?

[Kalevera]

You probably want to talk to the Bellevue crowd on the board before doing anything. Some of those guys are M30 experts. I also *think* Dave535Phoenix had a similar problem/broken rocker arms recently, so it might be wise to contact him....

....yup, I was on the money:

http://www.bimmer.info/forum/showthread.php?t=8797
http://www.bimmer.info/forum/showthread.php?t=8824

BMA's the best place, IMHO, for the parts. You probably already know that.

Best, whit

[Martin in Bellevue]

There's Mike, at Kirkland Machine Shop, 425 822-8216.

I liked Phil, in Renton, at Highland East Auto, 425 288-6364. The address is 4616 NE 4th St, Renton 98059. I spent about $400 with Phil installing new guides, resurfacing head, grinding valves & some such.

I remember Erick using a machinist somewhere in downtown hippieland.

Wonder why the thing broke rockers after 30k miles?

[NWDriver]

Thanks for the contacts in the Seattle area. I do not belive that there was any upper end work done except for the gasket 30k ago.

I was wondering though as I am about to start to tear it down. What all should be replaced. And should it all be OEM or is there a better substitute.

I would assume that doing the timeing chain at the same time would be a good idea?

[epj3]

Think the motor could've over revved? That's usually the only thing I hear of causing this problem.

[NWDriver]

I could have been pushing 6k in the last few days. Had some fun weekend dirving. But not this morning. So my guess is that I might haved damaged the Rocker Arms a day or two ago and it failed today. It is a theory any how.

[niall]

ah memories, memories,

its a full top end rebuild for you
sorry mate ;)

[Rory535i]

Same thing happened to me about a year ago. Was just driving along and all of a sudden I noticed a loss of power and a knocking noise. I wasn't driving hard or over revving it, it just happened. Took the rocker cover off and #6 exhaust valve rocker was broken. Ended up with a top end rebuild as the cam was worn and it was due a head gasket. Anyone know why the rocker arms break? are they just a bad design?

[Jose]

wrongly set valve gap is a known culprit. Puts too much strain on the rocker. I'm surprised to see so many of you had this problem.I've been driving M20/m30 engines for over 10 years now, and I never had this problem. Guess I've just been lucky.

[niall]

yeah what happens is when the valve - rocker clearance is
set incorrectly, the rocker actually slides off the top
of the valve, this hammering action causes fractures.

[JonE]

So, are we talking too loose a gap or too tight or both that might cause this breakage?

[Jose]

too tight without a doubt. There are a lot of us out there who don´t want to hear the slightest valve rattle and tighten the valves too much, causing unnecessary strain on the valve train and killing the smoothness so well known to the M30 engine.

[Jeff N.]

Unless the timing chain has a link (the factory one will not), it's not easy to replace the chain. You need to remove the lower cover to get it off which in turn means removing the crank nut (325 ft/lbs).

Most people don't replace the timing chain with a head job. That said, I think you're on the right track to take a close look at given what happened.

Some things you may want to while the head is off include:

- replace the injector o-ring seals, 2 per. BMW charges a fortune. Order from BMA or consider use Ford Mustang 5.0 seals.
- if you have crap in the intake manifold runners, consider having it dipped.
- replace the water hoses that run under the intake manifold. Easy to to it now, PITA to do it any other time..
- be sure to order two of the special hose guides for the water hoses above, they will break. You'll need two. Attach to base of the intake manifold.
- Replace the ICV hose and the 3mm vacuum hoses running to the FPR and valve cover vent.
- Plan to get new fuel rail plastic clamps (3 total). Yours will likely bust when you pull them.
- It's a great time to put in a new water pump; $50.
- New distributor cap and rotor is a nice idea ($60 or so)
- Get a 6 pack of BASS and call Martin. He'll be happy to do at least half of the work for you. :)

Where are you? Martin and I live in the Bellevue area. We've been known to lend a hand to foolish souls.

Jeff

[NWDriver]

Thank you for all the advise. I am getting rdy to do the big order from BMA for all the parts. (gasket kit, distributer, hoses, etc..)

I have two options for the head.
1. Aluminum Head Rebuilders of Portland. Reworked head with a 12month or a 12k miles warnty for $650 (complete replacement. price does not include core charge of $300)

2. Local rebuild $820 including new cam and rocker arms all around.


Any sugestions?


Fred
West Seattle

[pundit]

Same thing happened to me about a year ago. Was just driving along and all of a sudden I noticed a loss of power and a knocking noise. I wasn't driving hard or over revving it, it just happened. Took the rocker cover off and #6 exhaust valve rocker was broken. Ended up with a top end rebuild as the cam was worn and it was due a head gasket. Anyone know why the rocker arms break? are they just a bad design?
I read somewhere that later M30's (92-93?) were more prone to breaking rocker arms than the earlier ones. I'll see if I can find the article. ;)

[niall]

yeah dam right man