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Discussion Starter #1
06 530i with 152k.

To make a long story short, I think I have oil in my coolant and would like to get ideas on what would be the likely cause? The long story is below.

I saw smoke/steam coming from under my hood one rainy day waiting at a stop light. I thought the car was overheating even though no codes were being thrown. I let it cool down, popped the cap on the reservoir, and saw some brown stuff in the coolant. I drained the coolant and yup, clearly some contaminants in there. I replaced it with the correct coolant (did the whole circulation pump thing) and I can still see brown stuff in the coolant reservoir (maybe wishful thinking but it does seem like less is there).

I think it might be the head gasket similar to the issue here ---> https://www.bimmerfest.com/forums/showthread.php?t=1320251&highlight=oil+coolant

But I am hoping it could be something else.

Any advise, diagnosis help, etc. will be appreciated.

Pictures below are some of the old coolant in a bucket and new coolant with contaminants still present in the reservoir.
 

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N52 engine? Would be good if you could locate the smoke/steam from under the hood.

Yes, that looks like oil in the coolant. Could be from several sources.

Worst case is blown head gasket.

Lesser culprits could be oil cooler gasket (or failed oil cooler internals). Has that gasket every been changed? It should have by now.
If you change this one change the oil filter housing gasket at the same time.

I imagine the transmission oil cooler and the power steering oil cooler could also be at fault.
 

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Discussion Starter #3
Yes, It's a N52.

I was unable to reproduce the smoke/steam from the engine compartment and am thinking some water just got into the engine compartment (no codes were thrown so I am not too worried about it).

Reading you response I am thinking to replace the head gasket, oil cooler gasket and oil filter housing gasket. Hopefully this will fix the issue.

It will take me a few weeks to get enough time off to make this happen but I will update this thread once complete.
 

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Blown head gasket would be unusual on an N52.
Is there oily grease all on the front of the engine? That's one sign of a degraded oil cooler gasket.
 

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Discussion Starter #5
Yes there is. I was planning on cleaning up the oil (now mostly in the form of gunk) from the engine while doing this job. I guess I can do the oil cooler gasket first and see if that changes anything. . . thanks for the follow up, you may have just saved me $150.00 that I will likely spend elsewhere on the car.
 

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If the front of the engine is all gunked up, it is important to clean it up. The nightmare scenario is that the serpentine belt comes off and wraps around the harmonic balancer. The risk is the belt can get pulled into the engine though the front main seal. I used some Gunk or similar spray and carefully cleaned up the front of the engine. Plenty of hosing it down afterwards. Replace the oil cooler and oil filter housing gaskets. Replace the serpentine belt.
 

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Discussion Starter #8
Has anybody re-used the 3 bolts from the oil filter housing before? I'm trying to get this done tomorrow and it doesn't seem like I will get the bolts in time. It looks like they have the belt at the "chain auto store" closest to me but not the pulley tension assembly. I'll replace that when I get it and have time. And thanks for the comments, I appreciate them.
 

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The bolts on the oil cooler and oil filter housing are steel and can be reused. No need to replace them at all. They are not one time use aluminum. They screw into the cylinder head, which is aluminum, and steel bolts in aluminum is fine. If they were threaded into the crankcase superstructure, that is magnesium, and then they would be one time use aluminum bolts.

I would say be sure and use Torx sockets and not try and get buy with a hex head socket. Also, the rear bolt on the oil filter housing is hard to reach if you don't unbolt the intake manifold. You'll need some 1/4" drive extensions, with a swivel in-between the two extensions and a 1/4" drive E10 Torx socket. The 3/8" drive E10 I had was too fat.
 

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Also, check this cylinder head bolt that is right near the oil filter housing and to the left of the intake port. There is a little well there. On my car that bolt head was popped off and just sitting there. I was able to unscrew the bolt and put a new one in. It is the only (I think) externally visible cylinder head bolt. All the others are under the valve cover.

 

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Discussion Starter #11 (Edited)
Whelp. I got the the oil cooler off just fine but the lower front bolt for the filter housing assembly seems to be wrecked. twh, you are absolutely right about the 3/8 socket being too big, so now I will have to wait until a 1/4 drive socket arrives. A curious note is that the gasket for the oil cooler looks new or very lightly used. Another note is that the front of the engine is literally caked with oil/grime in certain area's. I am wondering if there was a catastrophic part(s) failure in the past and somebody replaced some part(s) but didn't bother to clean the engine up. I have attached pictures but they don't do justice to the issues.
 

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I have a 2006 530xi. The grime on the front of my engine looked the same. You should heave cleaned it off first with degreaser.
 

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Just throwing this out there, a 1/4'' 8 mm swivel socket with a 6'' extension will get the E10 under intake runner and an 8 mm boxed end wrench will get the E10 next to coolant pipe in the oil filter housing. I'm sure everyone knows if you try and remove the coolant pipe bolted to the head pulling it out will break the plastic in front of the o-ring so I never take it loose I just use a wrench to loosen the bolt and screw it the rest of the way out by hand. The wrench will get stuck between the plastic on the hose and the bolt if you try and use the wrench the whole way.
 

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Discussion Starter #16
Just throwing this out there, a 1/4'' 8 mm swivel socket with a 6'' extension will get the E10 under intake runner and an 8 mm boxed end wrench will get the E10 next to coolant pipe in the oil filter housing. I'm sure everyone knows if you try and remove the coolant pipe bolted to the head pulling it out will break the plastic in front of the o-ring so I never take it loose I just use a wrench to loosen the bolt and screw it the rest of the way out by hand. The wrench will get stuck between the plastic on the hose and the bolt if you try and use the wrench the whole way.
Well to make a long story short. See the pic. I now have a new issue to fix. Haven't looked up this part yet and am hoping it's reasonable.
 

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Discussion Starter #17
GeorgeBush234,

I did not. it looks like I will have time to do it this weekend while I am trying to fix my last mistake though.
 
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