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      11-12-2018, 02:18 AM   #1
saxonb
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Brown coloured residue inside oil fill / rocker cover?

Only noticed this recently due to a potential buyer pointing it out. His mechanic advises that the engine needs rebuilding (!) but can't provide any detail on what specifically the issue would be.

The engine runs perfect. Has had genuine OEM oil every 5000KM. Any ideas what this residue is? It it is a bit loose and can be wiped off with a finger and turns into tiny black seemingly carbon particles.

My initial research is that it's caused by not enough driving and deposits of moisture and acid which would otherwise be vented through PCV if I were to drive normally at full temperature for long enough. This makes sense as I haven't been able to drive it much for a far amount of time.
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      11-12-2018, 02:19 AM   #2
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      11-12-2018, 02:29 AM   #3
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Yeesh. Looks like you most likely need head gaskets providing that grey sludge is caused by coolant in your oil.

If that's the case, the engine doesn't need rebuilding necessarily, although it would be hard to tell if the diluted/watered down oil has caused any excessive wear to internals.

I'd get a second opinion on that grey sludge, and I wouldn't chance even starting the car again until you do.

EDIT:

Do an oil change first. If the oil looks fine it might just be oil and condensation accumulating around the filler cap.

If your oil looks milky/murky, all signs point to head gasket.
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      11-12-2018, 03:39 AM   #4
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its just the valve cover coating coming off. you can clearly see it flaking off in the first pic. get new valve covers.
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      11-12-2018, 04:28 AM   #5
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Quote:
Originally Posted by roastbeef View Post
its just the valve cover coating coming off. you can clearly see it flaking off in the first pic. get new valve covers.
Is it painted on the inside?
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      11-12-2018, 04:33 AM   #6
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Quote:
Originally Posted by cjm41 View Post
Yeesh. Looks like you most likely need head gaskets providing that grey sludge is caused by coolant in your oil.

If that's the case, the engine doesn't need rebuilding necessarily, although it would be hard to tell if the diluted/watered down oil has caused any excessive wear to internals.

I'd get a second opinion on that grey sludge, and I wouldn't chance even starting the car again until you do.

EDIT:

Do an oil change first. If the oil looks fine it might just be oil and condensation accumulating around the filler cap.

If your oil looks milky/murky, all signs point to head gasket.
There's no grey sludge. It's an orange surface coating with black ashy carbon texture.
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      11-12-2018, 04:43 AM   #7
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It's apparently pretty common. I wonder if the new Shell twin power oil is more suceptible to it versus the Castrol TWS?

https://www.bimmerfest.com/forums/sh...t=rust+oil+cap
https://forum.e46fanatics.com/showthread.php?t=393687
https://www.bobistheoilguy.com/forum...&Number=901313

Might see if the PCV valve needs replacing...
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      11-12-2018, 07:27 AM   #8
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Quote:
Originally Posted by saxonb View Post
Quote:
Originally Posted by roastbeef View Post
its just the valve cover coating coming off. you can clearly see it flaking off in the first pic. get new valve covers.
Is it painted on the inside?
I believe it's a coating process rather than paint.
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      11-12-2018, 08:17 AM   #9
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Quote:
Originally Posted by M3Post View Post
Normal for an S65 motor with stock valve covers. Overtime the valve cover paint "dissolves" and separates from the magnesium valve covers. You can also see it on the outer surface around and near the filler neck. The oil filter catches the flaking (melting) paint though I'm sure the rod bearings probably don't like it. We've all got it to some extent or other. Part of the ownership experience.
OK. I can see this image on ebay showing the same colour internally:



Do I really need to spend $1000 to replace or is this just cosmetic?
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      11-12-2018, 08:19 AM   #10
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I also note that the new one from Turner has a grey interior colour"

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      11-13-2018, 11:41 AM   #11
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As said that flaking quite common on the board. Rebuild engine? Better stay away from that "mechanic" mate.
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      11-13-2018, 12:05 PM   #12
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Quote:
Originally Posted by cjm41 View Post
Yeesh. Looks like you most likely need head gaskets providing that grey sludge is caused by coolant in your oil.

If that's the case, the engine doesn't need rebuilding necessarily, although it would be hard to tell if the diluted/watered down oil has caused any excessive wear to internals.

I'd get a second opinion on that grey sludge, and I wouldn't chance even starting the car again until you do.

EDIT:

Do an oil change first. If the oil looks fine it might just be oil and condensation accumulating around the filler cap.

If your oil looks milky/murky, all signs point to head gasket.
Lol

Cmon man
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      11-13-2018, 12:56 PM   #13
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Milky oil is a sign of moisture, can be as simple as condensation from not warming up enough to burn it off.
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      11-30-2018, 07:15 PM   #14
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Normal.

deansdimmer shared some info on this.

Quote:
Originally Posted by deansbimmer View Post
The covers are indeed a magnesium alloy. Though it is strong and lightweight, Magnesium is one of the lowest in the galvanic series which means it is highly reactive and corrodes very easily in different environments.

These covers are coated in a ceramic oven cured coating. The inside of the covers are not fully coated, which allows contact with atmosphere. The result is corrosion over time, which causes flaking of not only the metal itself, but the coating. If there are pores in the casting allowing oxidation to reach the underside of the outer coating, then the outer coating will bubble also and eventually peel. It happens more often near the oil cap snout because it is not bathed in oil as much as the other areas (which prevents the atmospheric contact).

This can also happen inside the gasket groove which will cause persistent leaks. Since it creates a rough surface difficult for a gasket to seal against, just replacing the gasket won't solve the issue. The key to getting the dealer to replace it under warranty is right here. If you take it back repeatedly for leaking then they will eventually be forced to replace the cover too.

It's not a big deal. "If" small amounts of it fall from the valve cover inside the engine, it will make its way to the oil pan and will be filtered out within the oil filter before allowing any actual harm to the engine. In an oil analysis, it will show up in the magnesium and aluminum counts.
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      12-01-2018, 05:18 PM   #15
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I've seen a lot of cars with sludge. Sludge looks more like molasses. Sludge never accumulate on the valve cover. It usually in the valve train.
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      07-30-2023, 06:20 PM   #16
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Read the posts above. It's not sludge. It's valve cover coating flaking off.

Go to n rw-design.com and order a set of their aluminum valve covers. Lifetime warranty and cheaper than original.
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