So Mazdaduece isn't the only one with German head bolt issues...

Agh! We have a BMW 128i (purchased CPO from the dealer)... just four months out of extended BMW warrantee. I had a shop help diagnose a suspension sound I was having after installing my Koni's (duh! Sway bar link was loose), and they noted an oil leak from the top of the engine. On closer inspection, they found one of the N51 head bolts was sheared off next too the oil filter.

Since I had just had the car in the dealer (fully serviced under the BMW service plan) just in December for "oil leaks" and they replaced the oil filter housing gasket, I thought this might be covered, but sadly not.

It appears the N52 engines in 2006-07 had an issue where the front three head bolts (with torx head bolt heads, not sockets) are made of aluminum and shear off. What I've read is that there was a design change since then and this isn't as common, but here we are.

I'm not totally sure (but it sounds like) they are all three of the bolt heads are gone on my engine. The head by the oil filter falls off externally, the two under the valve cover fall down the timing cover into the engine pan....

I'm waiting on final word from the service manager, but right now there's no help from BMW about this...

If it's just the one bolt head that fell off externally, I'm fine with replacing the bolt and going on (some oil is coming out around the stud). Performance of the engine has been fine.

If all three heads gone, with two in the pan, would you pull the complete head and replace the gasket PLUS pull the oil pan and fish out the leftovers? Or would you replace all three without pulling the head and pull the oil pan?

The price is sub $6000 for the first option and sub $4k for the second...

I'm really hoping that some goodwill will come of conversations and I get a price break, but I'd like a plan on how to proceed.

Sounds like the valve cover bolts snapping problem.

Personally, if it were mine, I'd try to E-Z-Out the remaining piece of bolt and then just replace them with a steel bolt.

Yes, yes, I know, BMW used aluminum bolts because they thread into magneisum and blah blah blah. Over-toilet-trained engineers. There are tons of BMWs on the road where people have replaced the broken aluminum motor mount bolts with steel ones and the world hasn't ended. Volkswagen has thread steel bolts into magnesium valve covers and engine cases for DECADES without galvanic corrosion problems. BMW magnesium is nothing special and the aluminum bolts are silly.

Is it a head bolt or valve cover bolt? I'm lost a little here.

This engine series has had both issues. Mine is a headbolt.

I'd check everything. Last thing you want is parts playing ping pong in the motor...

Aluminum head bolts, tho? WTH were they thinking?

I'd ignore the errant bolt heads. They would have done whatever damage they might have done as soon as they escaped, and now they are settled to the bottom of the oil pan. If they haven't come out during an oil change already. The only bad thing I can think could happen on the way down is lodging in a timing chain and causing it to jump a tooth. They aren't going to climb back up the oil drains for another chance to do that

The official word for aluminum bolts is because they won't corrode the magnesium structures they are threaded into. Which is BS, given the Volkswagen precedent going back to, what, the 1940s?

Porsche, over the years, used many different materials for head studs on air cooled 911s. Ends up that old school steel is as good as, if not better, than the rest. Pull those aluminium POSs and replace with steel.

Wow, that sucks. Does the head need to come all the way off? I know there have been several people with the Mercedes engines who have replaced the bolts one by one without removing the head with success. Of course you have a missing lot head already so the easiest thing might be to pull the head so you can easily remove the offending bit. Is there an updated part?

If the others haven't broken, why wouldn't you replace them??

This board is not a good emissary for the German auto industry.

I love the way my BMWs have driven, the balance of capability and comfort, and the attention to making routine maintenance relatively easy, but this is just one more example of how ridiculous their engineering has become in recent years. I cannot imagine having to deal with anything newer than my E39, and even that's a bit of a stretch sometimes. If I could find a rust-free M30-powered E34 I'd probably keep it for life, and I would have every expectation that it would last for decades with simple maintenance, but the newer generations are seemingly engineered to last a few years, then break expensively.

I'm with you 02Pilot. I loved a lot of things about my current E30, my old E36 and my dad's E39, but sometimes the engineering was a bit of a head scratcher, like water cooled alternators?! Give me a break.

I have never understood aluminum bolts of any kind, they have given me a few issues. My E36 had an aluminum drain plug bolt, which I sheared off once and had to use an E-Z Out to remove, was pretty annoying.

I'm not convinced theres a new bolt design, but even Pelican Parts has a "how too" on this one bolt..External Head Bolt repair

I'm still awaiting word from BMWUSA on the repair good will. The valve cover hasn't been removed (yet), so any thoughts of internal head bolts being broken is conjecture on the SA part. I'm hoping they'll lift the valve cover, see all is fine there, and then replace the one broken head bolt for me. I've had good experiences with BMW so far, so keeping my fingers crossed.

I know though... I love the drivers experience, and up to now, it's been fairly reliable. However, broken bolts don't give me a warm fuzzy. Although, unlike Porsche and the IMS issue with their water cooled flat 6's, I haven't really heard too much about the N52 engine (actually, mines a SULEV so it's a N51 technically) giving fits to every owner... just I'm the "lucky" one right now.

To be continued next week.....

Just read the Pelican article. Cams have to come out to get to the other ones. Yuck. Good luck man.

NOHOME wrote: This board is not a good emissary for the German auto industry.

^^^^This. Every time I start thinking about a used German vehicle these things scare me away.

Just a follow up. BMW offered to cover 70% of the dealer cost of the repair. They found that all three of the bolts had broken, so they took the head off, replaced the gasket, and then used "updated" bolts for the repair. My out of pocket was $750, so not as bad as I thought it might end up.

I had a nice loaner for the time, and picked up the car today. I did miss driving my car!

I do have to say if it wasn't my wife's DD, I was prepared to dig in and do it myself, but in reality, $750 was money well spent that I didn't have to do it. Sad that I had to spend anything at all, but glad I wasn't looking at a more expensive bill. Other local shops were willing to do it for approx $1500, which is where I was prepared to take it if I didn't get good will from BMW. I'm glad there was a positive resolution to my problems.

I do have a 3 year 50K mile guarantee on the work too.

That's a bargain on that fix. Good on BMW.