E90 330xi head gasket failure

[LateFan]

I have a friend with a 2006 330xi 4 door (E90?). He's an engineer by training, and a careful guy. He took an xmas trip from MT to Texas with it. On the way back, almost home, he got an overheat signal, lost power, and pulled over. He figured it was in limp mode maybe, so he got it to a local shop, left it, and headed home in another car.

He's been told it has a blown head gasket. With 57,000 miles. No oddness or signals before that.

It has no dipstick, which pisses him off, and he doesn't trust the level sensor lately.

Is that the N52 engine? Have there been problems with that engine? Seems pretty outrageous for a newish straight 6 to go pop like that at such low miles.

Thanks -

[DrJosh]

You would be better off consulting one of the larger BMW forums instead of the E30 specific one.

[nando]

his water pump probably failed. so, he drove some unknown distance with no water pump. yeah, I could see that causing a blown head gasket.

but I'd get a second opinion, because I drove our E91 about 15 miles with no pump. the temp stabilized at about 130c, swapped the pump and it's just fine.

[slammin.e28]

N52 already have issues with headbolts breaking off. If it gets hot....goodnight sweet prince.

IIRC, Usually the WP or T-stat will toss up a check engine lamp when the go poo poo.

[nando]

they don't trigger the CEL, but you do get a cooling warning signal (first yellow, then red) and it cuts power up to 90% in an attempt to save the engine.

I haven't heard of head bolts breaking often, have you seen that at your shop a lot?

[slammin.e28]

they don't trigger the CEL, but you do get a cooling warning signal (first yellow, then red) and it cuts power up to 90% in an attempt to save the engine.

I haven't heard of head bolts breaking often, have you seen that at your shop a lot?

Yup. There's one in particular, near the oil cooler. Have N52s come in and it's been a running thing to check that bolt. 3 of the last 4 through here have been broken. The bolt head is usually down against the cylinder head.

Not my pic, but this is the one:


I read they can break inside the head as well. This, and the whole belt eating thing makes me regret telling mom to buy her e90....

Had and x3 come in with a replacement engine from BMW....obviously a used engine....but it was replaced in August due to eating the belt after the oil cooler seal leaked all over it....and that bolt was broken.

[nomansland92]

I believe that has the electric driven water pump, my mom has a 07 328xi and hers failed under 50k.

[LateFan]

...you do get a cooling warning signal (first yellow, then red) and it cuts power up to 90% in an attempt to save the engine.

This is exactly what he described.

I've been reading about N52 head bolts. On several forums, people are confusing steel head bolts with aluminum valve cover bolts, which seem to break regularly. People also confuse a head bolt with a bolt head.

But, are there two or three aluminum bolts at the front of the head to the front cover? I've read about the bolt heads snapping off and jamming in the chain wheel and making a real mess.

[nando]

Yup. There's one in particular, near the oil cooler. Have N52s come in and it's been a running thing to check that bolt. 3 of the last 4 through here have been broken. The bolt head is usually down against the cylinder head.

Not my pic, but this is the one:


I read they can break inside the head as well. This, and the whole belt eating thing makes me regret telling mom to buy her e90....

Had and x3 come in with a replacement engine from BMW....obviously a used engine....but it was replaced in August due to eating the belt after the oil cooler seal leaked all over it....and that bolt was broken.

That'sa valve cover bolt. ;)

The head bolts are steel. There's no valve cover bolts on the inside..

[slammin.e28]

Nope. Valve cover it above that. That's the intake mani to the right, and intake mani bolt above.

http://bmwfans.info/parts-catalog/E90/USA/325i-N52/2005/browse/engine/cylinder_head_attached_parts/#pos_2

Can see where it goes right under the #1 intake port.

Although it appears I may be incorrect on the inner headbolts.....but I do recall reading somewhere they like to break as well....will try to dig it up.

Bolt in questions is part of the #2 set of alum bolts.

[nando]

#2 is not a head bolt, lol. :p

the head bolts are part #1. also note it doesn't say anything about aluminum like part #2. and you can see the weight difference is significant.

[slammin.e28]

It's a bolt holding down part of the head and it breaks.

While it doesn't show it on the BMW pic, a pic of the HG shows a hole for the bolt to go through to seal the oil passage (flange that drops down on left of the gasket)



It serves the purpose only of clamping the head at that place....so headbolt.

But is not the same as the bolts that hold the head on the block to seal the combustion chamber.

[LateFan]

Right - holding the head to the front cover.

I am reading that the block is magnesium and the liners aluminum and there have been head bolt problems. Or is it just these front alum bolts failing and leaking oil on the belt?

The electric water pump failing is a separate issue.

I'll ask him what kind of shop it's at - it's a fairly little town.

Here's a guy where the head of those bolts broke off and jammed behind the timing gear..

http://forums.edmunds.com/discussion/14128/bmw/x/2006-bmw-525i-n52-possible-wide-spread-defect

[LateFan]

Update and explanation -

He says the water pump failed. He suspected water pump and was going to tow it, but his bro-in-law was so sure it was the thermostat, they drove it 17 miles back to the next town, stopping three times to let it cool. Those 17 miles blew the head gasket.

[Todd Black 88]

Had the wp shit the bed on my n54. Cut power to zero and shut the car off in the middle of an intersection. Light came on 2 seconds before shut down.

Car has 55,000 kms on it...soooooo. 35,000 miles?