VCG leaks from bolt grommets

[ATB88]

Ever since the first time I've dug into my valvetrain the first time 6 years ago to do my first valve adjustment and vanos lockdown, I've been having leaks from the various bolt grommets that bolt the valve cover down to the head. I've been careful to make sure that I'm torquing them down in the correct order to the correct torque spec, and have replaced all of the grommets, and yet, I've still always had leaks.

I'm wondering if I'm missing something in how I'm going about this, or if this is pointing to a larger problem (warped valve cover, abnormally high crankcase pressure)? Has anyone else had trouble getting this right and figured out a good solution?

I'll be doing a valve adjustment in the next couple of weeks and would really like to have these leaks sorted once and for all!

[maupineda]

Buy original/genuine. Alternative, you can add a washer on those grommets, they seal through the pressure from the fastener to squeeze the rubber to make the seal, if you add a washer you can apply a bit more pressure which would help. These bolts bottom out on the stud so you cannot go crazy or you snap them. When old, these grommets just don’t seal as they are squashed.

[Halftim3]

Yeah as above use original/genuine, but what is the torque spec and is there really a sequence? I just remember them bottoming out.

[ATB88]

Thanks for the suggestions. I did replace the grommets with new OE years back, and I am using the washers under the bolts, but still leaked.

The torque spec and sequence can be seen for example here in this DIY, step 19: https://www.fcpeuro.com/blog/how-to-...-cover-gaskets

I don't remember feeling them bottoming out, so, maybe I've just been under torquing? Would it be a bad idea to ignore the torque spec and tighten to bottomout?

[01SG]

Pictures might help. Are you sure it's leaking from the grommets and not from somewhere else and cascading to the grommets?

Only place I'd think it might leak with the proper equipment and torque is at the half moons where you ought to just a bit of sealant. That wouldn't make much sense that it travels up to the grommets though.

[sapote]

Lube the ID and OD of the rubber so no scratch when installing and turning the cap nuts. Torque unit nut bottom and stop. Lube using grease.

[eacmen]

1. Clean the sealing surface between the rubber and valve cover.

2. as others have mentioned these bolts bottom out so just take your time and torque in sequence until you feel it bottom out. Don't go crazy with it though.

3. stupid question but these grommets are directional. maybe snap a photo to make sure you're not installing them upside down? hard to do but i've seen it before

4. is your CCV clogged up? its the plastic bit that goes between the valve cover and intake. blockage could cause excess pressure in the crankcase

[ATB88]

Thanks, guys. Yeah I'm sure the grommets are facing the right way, and that the CCV pipe is clear. It's possible that my torque wrench is miscalibrated enough that I'm just not torquing them enough -- I've always torqued them to spec, not to feeling them bottom out. I'm just gonna go ahead and replace the full set of grommets, cap nuts, and washers, and make sure that the nuts (barely) bottom out.

[maupineda]

You don’t need torque wrench. A hand driver is enough and you can clearly feel when it bottoms out.

or… your cam cover is warped beyond acceptable. These are not perfectly flat.

[Cubieman]

You don’t need torque wrench. A hand driver is enough and you can clearly feel when it bottoms out.

or… your cam cover is warped beyond acceptable. These are not perfectly flat.

I have never had the grommets leak, but the tube seals are another story, I have genuine everything for seals and cyl. 3 leaks, I'll have to fix that soon.

About the valve covers and flatness, you are right, they are definitely not perfectly flat.
I was worried mine was warped as I could never thread in the banjo bolt for the drain line until I had multiple bolts secure to pull down the cover a bit.

I took out a staight edge and to my shock found that the valve cover was indeed not 100% flat.

I immediately spent ~$700 to purchase a new valve cover and found...it was indenitcal to my original cover and not flat.

Those were the early days when I didn't know much and spent WAY to much time and money obsessing over little things like that.

[ATB88]

I went and replaced all of the grommets and cap nuts with brand new OE, along with a new valve cover gasket. Cleaned the valve cover itself thoroughly.

Things seemed great for a week, but inspected after my last drive and found two grommet cap nuts where oil was just starting to seep out between the cap nut head and the washer it sits on (the washer in turn sits on the grommet).

Disappointing, and really at a loss for what to do? All the cap nuts are bottomed out. Is it possible that a PO (or me in my early days of wrenching on the car) tightened these too hard at some point and damaged/stretched the studs they thread onto? I really just wanna be leak free

edit: photo of seepage so you can see what I'm talking about

[ATB88]

I have never had the grommets leak, but the tube seals are another story, I have genuine everything for seals and cyl. 3 leaks, I'll have to fix that soon.

I also have a tube seal leak on cyl 2 which slowly leaks oil into spark plug well. I've changed seal with OE BMW twice now, no fix (also those mfers now cost $40 a piece on FCP euro now... up from $10 a few years ago). If a new valve cover isn't the answer, whats your plan for fixing this?

[Slideways]

I also have a tube seal leak on cyl 2 which slowly leaks oil into spark plug well. I've changed seal with OE BMW twice now, no fix (also those mfers now cost $40 a piece on FCP euro now... up from $10 a few years ago). If a new valve cover isn't the answer, whats your plan for fixing this?

You might have a positive pressure issue in the cylinder head or there is a defect with your valve cover. How many miles on the engine?

[ATB88]

You might have a positive pressure issue in the cylinder head or there is a defect with your valve cover. How many miles on the engine?

105k. Been pretty well cared for from when I got it at 45k onwards. All components of the PCCV system are relatively new (in the last 4 years/20k miles), including the oil separator, PCCV hose from the separator to the airbox (karb csl), and the airbox side airlines and ICV are all in good shape. Also I made sure to check that the oil return channel in the valve cover that is fed by the oil separator is clear. Anything I can look for to test the positive pressure theory?

[Cubieman]

I also have a tube seal leak on cyl 2 which slowly leaks oil into spark plug well. I've changed seal with OE BMW twice now, no fix (also those mfers now cost $40 a piece on FCP euro now... up from $10 a few years ago). If a new valve cover isn't the answer, whats your plan for fixing this?

I was going to try new spark plug seals, elring this time and maybe even some light RTV on them, but that should not be necessary.

I too wonder about too much positive pressure, my engine came out fine in regards to leakdown/compression tests for what that's worth.

I bought a new oil air separator and vent line from airbox>oil pan even though I don't think there is an issue there, just cheap parts throw at it I suppose.

Ever since I have owned my car there is a slight burning oil smell when the windows are down, I can especially smell it after getting on the throttle them comming to a stop light.
I once even had a friend driving next to me comment on the burnt oil smell after a short stoplight to stoplight race.