M62 Valve covers leak

**98OrientBlue** · 06-12-2018, 03:08 PM

It's been a while since I posted. My 98 540 just passed 160k on the odometer and things have been running very smoothly. Except... for smoke that comes in through the dash vents!

The source of the smoke seems to be oil seeping from the valve covers onto the exhaust manifolds. Right cover seems to be worse. I've replaced the VCGs twice in the past few years, (once I did them, then had them done). My mechanic says that that my valve covers have pitted and degraded to the point that they need to be replaced. He says that the magnesium pits easily and makes a tight seal impossible over time. Well, I guess they are 20 years old now!

My question is whether this is a reasonable diagnosis? I found a previous thread that discussed VC painting, but I'm probably going to just get new ones. Has anyone gone this route? Does it stop the oil leaks?

Another question is if I order new ones, are they easily damaged or warped in shipping? Since the smoke seems to be concentrated on the right side, I'm thinking of swapping that out first to see if it helps.

TIA!

**JimLev** · 06-12-2018, 03:23 PM

Most of us are on the original valve covers. They all have pits on the exterior surface, can't recall seeing pits on the insides of any of the ones I've powder coated.
As long as the gasket surface isn't pitted and they aren't warped new gaskets should seal. You could always use a dab of sealant on any pitted areas if there are any.
No, new valve covers shouldn't warp when shipped.
My car is 18 years old and will be getting it's 4th set of valve cover gaskets as soon as I find time.
Don't forget to replace all of the rubber washers too.

**98OrientBlue** · 06-12-2018, 03:30 PM

Thanks Jim for the quick reply! I guess I'll take a close look at the gasket channels to see what shape they're in. I've always replaced everything, including rubber washers, and always with Genuine BMW parts.
Question about putting the cover back on. The shop manual says to coat the gaskets in "glycerine". Is that literally the stuff you buy at drugstores that's used for making soap? Should I use something else?

**JimLev** · 06-12-2018, 06:05 PM

Coat the gaskets with glycerine? Will need to look at the manual again, don't remember ever seeing that.
I've been using RTV at the joints and half moons but have just discovered a much better sealant, Permatex Permashield #85420 that you can get at most auto supply stores.

**98OrientBlue** · 06-12-2018, 06:27 PM

Thanks, will check out the Permatex.

Re, glycerine, see step #8 in this old thread... yeah, it does seem to refer to the stuff you get at drugstores.
https://www.bimmerforums.com/forum/s...ight=glycerine

**StephenVA** · 06-12-2018, 08:48 PM

Plus one on the permatex dabs where the cover needs a little extra coverage. Don't forget the half moons whatever you do.

**98OrientBlue** · 06-12-2018, 09:40 PM

Thanks StephenVA!

**PeterHall** · 06-12-2018, 10:26 PM

I replaced the valve cover gaskets on my sisters car. I also sandblasted and powder coated the valve covers. The channels where the gasket goes gets very corroded so sandblasting cleans them out great. I also put sand paper on a surface plate and rubbed the valve cover over it to level it out. It had warped ever so slightly. Glycerin seemed like it helped the gasket float so it didnt sit funny while installing. I dont know it actually did anything.

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**98OrientBlue** · 06-12-2018, 11:47 PM

Looking good!

**E39540V8** · 06-13-2018, 01:38 AM

No matter what I do, I can't get it to seal at the upper timing cover join, My half moons are fine. Could it be that I have just tightened the upper cover too much?

E39540v8

**scubajim20** · 06-13-2018, 06:20 AM

Yes the glycerin was to keep the gasket from bunching up as you tighten it. Use it sparingly as too much allows the gasket to fall out when inverted.

**JimLev** · 06-13-2018, 08:23 AM

Originally Posted by E39540V8

No matter what I do, I can't get it to seal at the upper timing cover join, My half moons are fine. Could it be that I have just tightened the upper cover too much?

E39540v8

If you replaced the upper timing cover gaskets they usually stick up above the top surface of the cover and the head.
I trim them so they are flush with the top surface then put sealant over them.

**JimLev** · 06-13-2018, 10:11 AM

I looked in the BMW service manual, it doesn't mention using glycerin. The only thing they say to use is Three Bond 1209 at the joints between the upper timing covers and the heads and also on the half moons.

**scubajim20** · 06-13-2018, 11:02 AM

I had seen someone post it as a technical update, I believe. So it may not be in the manual or someone gave erroneous info and I am completely wrong. I did put it on sparingly with a Q-tip.

Originally Posted by JimLev

I looked in the BMW service manual, it doesn't mention using glycerin. The only thing they say to use is Three Bond 1209 at the joints between the upper timing covers and the heads and also on the half moons.

**98OrientBlue** · 06-13-2018, 11:29 AM

Originally Posted by JimLev

I looked in the BMW service manual, it doesn't mention using glycerin. The only thing they say to use is Three Bond 1209 at the joints between the upper timing covers and the heads and also on the half moons.

JimLev, see: https://workshop-manuals.com/bmw/5_s...m62)/page_564/

Installation:
Check seal, replace if necessary.
Coat outer and inner grooves and sealing face of cylinderhead cover all round with anti-friction rubber coating, e.g.
glycerine.
Press internal gasket into groove in cover without torsional
stress, starting at the four corner radii.

**JimLev** · 06-13-2018, 01:16 PM

I've never used it and never had any problems putting the gaskets in the grooves. The leaks usually start when the gaskets got old and dried up, then they started leaking.
So is glycerin suppose to help keep them from drying out?

Some of you other guys need to check in here, we've all changed gaskets many times. Have you ever used glycerine?

**philly98540** · 06-13-2018, 02:01 PM

I have not, but I remember reading about using it.

**98OrientBlue** · 06-16-2018, 12:42 AM

vcbolt.jpg In support of my mechanic's theory, here's a picture of my leaking VC. It appears that there is quite a bit of leakage around the grommets of the bolts that secure the VC to the cylinder head. I think my mechanic is saying that the pitting of the Mg on the surface is what's causing these leaks. Does that make sense? Does that mean that I need to have my heads blasted and powder coated or replaced to avoid the leaking around the bolts? JimLev... anyone?

**E39540V8** · 06-16-2018, 05:23 AM

Originally Posted by 98OrientBlue

vcbolt.jpg In support of my mechanic's theory, here's a picture of my leaking VC. It appears that there is quite a bit of leakage around the grommets of the bolts that secure the VC to the cylinder head. I think my mechanic is saying that the pitting of the Mg on the surface is what's causing these leaks. Does that make sense? Does that mean that I need to have my heads blasted and powder coated or replaced to avoid the leaking around the bolts? JimLev... anyone?

The valve covers have a very course finish on them. This does not cause leaks. The sealing surface under the seals is just fine. The rubber grommets themselves go hard like plastic and don't seal. If you haven't done the upper timing covers, I would do those too. They were leaking for me too and are only one step further than the covers. I had to dig the seals out with a screwdriver (they were rock hard).

E39540v8

**JimLev** · 06-16-2018, 08:56 AM

Those have to be the WORSE set of valve covers I've ever seen. In addition of the paint pealing the surface of the Mg looks very uneven, usually they only have some pits in them that I fill before powder coating. Almost all of the covers I've done had a nice smooth surface after removing the old paint.
New valve covers are pretty pricey, see if you can find a used set.

**98OrientBlue** · 06-16-2018, 10:00 AM

hmm... interesting feedback.

1. Agree that my VCs are not attractive. but aside from aesthetics, is there a problem with that? is the bumpiness of the Mg due to damage caused after the original paint peeled? Or, is it like that from the original casting?

2. Should I be looking for uneven Mg in the wells where the grommets sit? Should I buff those out with a dremel?

3. Would a bit of Permatex under the grommets help? Note, the leak you see here is not due to dried up grommets... they are less than a year old.

4. Yes, I've done the UTC gaskets... and that was a 100% success. I used to lose a quart of oil every few thousand miles. Now, my loss is very minimal, despite the VC problem.

Thanks all!

**JimLev** · 06-16-2018, 10:40 AM

1) Don't know, all the covers I've stripped were smooth except for some pits here and there.
2+3) Clean the paint off where the grommets sit, then use some Permatex.

**BarryM** · 06-17-2018, 05:31 PM

Originally Posted by JimLev

Some of you other guys need to check in here, we've all changed gaskets many times. Have you ever used glycerine?

Only changed my VC gaskets once and applied glycerine during fitting but no gasket sealant. No leaks in 12k miles

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**98OrientBlue** · 06-18-2018, 01:53 PM

Originally Posted by BarryM

Only changed my VC gaskets once and applied glycerine during fitting but no gasket sealant. No leaks in 12k miles

Thanks BarryM. I've ordered new gaskets; will report back when I've installed them. Could take several weeks. :-)

**98OrientBlue** · 06-26-2018, 07:13 PM

IMG_1039.jpg Update on my valve covers. After looking more closely, it's clear that the oil seepage is all coming from the bolt holes and those little gaskets. So, I will focus on those and be sure to apply a little permatex under each one when I reassemble. As you can see, I found a little hole in the metal on the side of the cover (see picture). I'm thinking I can fill that with something like JB Weld Epoxy putty?
After a bit of searching, it seems like "aircraft" paint stripper is what I need to remove the rest of the gold paint.
Finally, is rattle can paint a waste of time? Some of the posts I found say that even with meticulous prep, that it eventually starts to peel, due to the porosity of magnesium. I guess I'd rather leave it unpainted than have cheap peeling paint.