E90 330xi head gasket failure

[LateFan]

Wow.

Do they not warble and rattle like a normal water pump while they're failing? Or is not a bearing issue - it's an electric motor that just quits?

If so, it seems like there needs to be a better warning, or a back-up system, or a way better motor in it! Was there ever a service bulletin on this?

[dnguyen1963]

The warning system is the temp gauge...stop driving when it wanders into the red zone.

[LateFan]

Yep, exactly. His email says "I got an overheat signal and lost power." So I'm not sure how much warning he had, but then he decided to keep going...

[nando]

The warning system is the temp gauge...stop driving when it wanders into the red zone.

there's no temp gage. the N52/N54 have an electric thermostat/pump and they vary the temperature according to driving conditions (from 80-110c). it sounds weird but a temp gage actually wouldn't have made a lot of sense.

The motor itself doesn't seem to fail or leak. it's something in the control circuit. I took one apart and everything was really clean inside, no signs of leakage or anything. probably some flaky component they decided they would save 10 cents per pump or something. I'd like to have a look again and figure out what exactly is failing, and maybe the pump can be rebuilt.

there are error codes for the pump (for overcurrent, underspeed, etc) but you would never see them unless you scanned the car. I figured out how to get them to trigger the CEL but I'd already replaced the pump on my wife's car by that point (95,000 miles, so it had a good life). you could also lower the threshold for the first yellow warning lamp but I doubt it would help much.

[dnguyen1963]

^ This is true! No Temp gauge in N52/N54, but there is a hidden menu to get to the water temp.

For instructions to unlock these hidden menu, read this:

http://www.e90post.com/forums/showthread.php?t=4135

[LateFan]

Seriously…no temp gauge?

So, you could have a perfectly functional water pump and some electrical glitch shuts it off and you cook your engine unless you shut it off right now?

[slammin.e28]

IIRC Standard you get the MPG deal. Think I saw one with oil temp....probably mistaken.

I have seen temp gauges on e90s, but for the most part they lack it.

[nando]

Seriously…no temp gauge?

So, you could have a perfectly functional water pump and some electrical glitch shuts it off and you cook your engine unless you shut it off right now?

There's a yellow warning light when it shuts down that turns on at 115c. you wouldn't cook your engine unless you kept driving it. a red light comes on at 120c. the engine can run under normal conditions at 110c. I think you could safely drive it up to about 125c.

it also beeps at you and cuts power, it's pretty obvious that you shouldn't continue driving, but the engine will keep going regardless.

so your buddy drove 17 miles with the red light on, it beeping angrily at him, and up to a 90% power cut. it's the same as driving with a gage pegged to the red - I don't think it would have mattered if there was one or not.

[nando]

IIRC Standard you get the MPG deal. Think I saw one with oil temp....probably mistaken.

I have seen temp gauges on e90s, but for the most part they lack it.

no cars with electric pumps have a coolant gage. the turbo cars get the oil temp (and M cars of course).

[slammin.e28]

no cars with electric pumps have a coolant gage. the turbo cars get the oil temp (and M cars of course).

That explains it

[LateFan]

There's a yellow warning light when it shuts down that turns on at 115c. you wouldn't cook your engine unless you kept driving it. a red light comes on at 120c. the engine can run under normal conditions at 110c. I think you could safely drive it up to about 125c.

it also beeps at you and cuts power, it's pretty obvious that you shouldn't continue driving, but the engine will keep going regardless.

so your buddy drove 17 miles with the red light on, it beeping angrily at him, and up to a 90% power cut. it's the same as driving with a gage pegged to the red - I don't think it would have mattered if there was one or not.

I see, thanks. Bummer. All to save a 17 mile tow.

[mrmckie]

damn...and here i thought only the 335's gave trouble..

[nando]

any car would blow a gasket if you drove it 17 miles with no waterpump. :p

[LateFan]

Thought I'd add the frustrating conclusion to this -

I wrote him to send him links for nice used cars and ask what was happening with the engine.

The mechanic's phone person kept putting him off. "Just a few more days," she said. "He's out test driving it right now," she said.

"Finally the mechanic just gives up. His assessment of the situation is: "It stutters a little on start-up. It needs to be relearnt (honestly, he said relearnt). Can't relearn it here. Need to take it to BMW." "

He went to pick it up. The CEL is on. It stumbles on cold start, then the computer takes over and it compensates. He made it home. Competent independent Shop A says they can fix it for $2800+. Competent independent Shop B agrees.

A big (non BMW) shop says the car has 13 codes, including alignment. He's on his third set of run-flat tires and can't keep it aligned. Brakes need service.

The small town mechanic who repaired the engine put a part in backwards.

SO….his old truck is wearing out with 185,000 mi, and he was putting off getting a newer one. An unnamed large domestic dealer will give him a huge trade-in on the BMW, 25% more than he expected. They say they can make money on a 58,000 mi BMW even with the repair costs.

So he bought a new truck. I kept sending him nice old Alfas - he wasn't going for it.

[nando]

that sucks. but, BMWs aren't for everyone. A lot of people that don't know anything about them mechanically will get burned like that, especially if they're in a rural area and a shop takes them for everything they're worth.

At least he got out of it!