'08 535xi Coolant light on and running very rough & NOT DRIVEABLE
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(My Mom's car) This all began last week when the crazy cold set in. Coolant light came on and started running rough. It didn't overheat. I was only 1/4 mi away from her condo so it wasn't driven far. Checked level and was just below min. Added small amount of 50/50. It started fine then but had a somewhat brief minimal rough idle. 4-5 days later I went to leave and it immediately was really rough and sputtering and the coolant light came on right away. No overheat. I was only 300ft away from the driveway and it wasn't easy to get it back there because it stalled a few times. Coolant level was fine and no visible leak or residue evidence from what I could view around the expansion tank. I tried to start it yesterday and it started but was still running very rough and there was some smoky exhaust briefly. It isn't driveable.

All knowledge and comments are most welcome!
**We need some additional trusted repair shop referrals in the Madison/immediate surrounding area. The few shops we know of/use are booked til after Thanksgiving. : /
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Although it could be many different things, it could be a bad head gasket. Both times it has happened to me it had very similar symptoms. No overheating, just rough running. While not the most convenient thing to do; draining some coolant from the engine and letting it settle in a transparent container for a few hours will generally reveal if the head gasket is bad and oil+coolant are mixing as you will see oil droplets or a distinct layer of oil on top of the coolant
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So it would need to be put up on a hoist to access/open the the drain plug in the bottom of the expansion tank to drain some coolant out? A head gasket replacement is a pricey repair, right? We (I) do have a reputable mechanic I was referred to by a former BMW tech of 15 yrs and he said he'd be fine with installing our own parts.
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Yes, if it is a head gasket it can be quite an involved repair.
Capturing some of the coolant should not require a lift, just a jack and jackstands. The ideal location to drain coolant from would be from the engine block drain plug (if that engine has one), otherwise a lower radiator hose is fine. By doing this there is a small risk that an air pocket will form in the cooling system that will need to be bled out, but in most cases the air bubble shouldnt be trapped.The mechanic you have a connection with may have the tools/willingness to do a cylinder leak-down test or some more official method for diagnosing the problem as a bad head gasket, but for someone like myself, this is a quick and easy way.
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I can't imagine it's the head gasket. I obviously just have very rudimentary knowledge about this but her car is impeccably taken care of and currently has 92K on it.
One more thing, I don't know if this is related but for the past 2 months there has been some "hiccuping" on acceleration after it has sat overnight. It's as if the car hasn't warmed up yet and you feel like you should step on the gas more, for lack of a better explanation.
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Could be alot of things, water pump failure might be throwing the light, but a bad fuel pump or leaking injector or bad coils could cause the misfire, agree with tsweers, need codes..
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Doubtful its a headgasket. Have never seen one go bad yet. Get the codes read and go from there.
lucky. I have personally had 3.
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lucky. I have personally had 3.
I think he meams on the n54
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I have yet to see a stock n54 blow one lolz
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I think he meams on the n54
That makes more sense. Thanks for the clarification.
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Well...we don't have the diagnosis yet : (
It was towed to the shop yesterday and the mechanic said he'd let my Mom know by then end of the day today. I take it a water pump job will be less costly than a head gasket? Are replacement water pumps usually refurbished and not new due to cost? Please educate. Thanks everyone!
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Have the intake valves ever been blasted?
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No they haven't. I take it that it's recommended? How much $$?
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Well...we don't have the diagnosis yet : (
It was towed to the shop yesterday and the mechanic said he'd let my Mom know by then end of the day today. I take it a water pump job will be less costly than a head gasket? Are replacement water pumps usually refurbished and not new due to cost? Please educate. Thanks everyone!
if its the head gasket then you all owe me a muffin.
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How 'bout a dozen.
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Update: Head gasket is fine. The cooling system is fine too.
Diagnosis is: fuel injectors and repair estimate is
$1400 from this mechanic and that's with a labor rate of only $75/hr. He said that's what has been causing the shuddering, which is mainly felt when the engine is cold.
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