WARNING: Do not use sealant on valve cover gaskets

[gsxr]

The previous owner of our 1994 E420 slathered some sort of brown shellac all over the valve cover gaskets (possibly Indian Gasket Shellac Compound?). Whatever the stuff is, it hardens like epoxy. As a bonus, he also didn't tighten the bolts properly. I discovered this immediately after purchase, but thankfully the minor leak stopped after tightening the bolts so I didn't have to immediately spend time scraping brown crap off the heads and covers. This was back in 2013 when we bought the car, with 114kmi on it.

The oil leak went away for a number of years, but eventually returned. It was very minor so I kept delaying the job, as I knew it wouldn't be fun. Finally got around to the project in summer 2019 at the 150kmi service. Photos below... the brown shellac was on *everything*. It took HOURS to scrape it all off. I'd estimate 8-10 hours over several days, just to clean the sealing surfaces on the cylinder heads, and the valve covers. That did not include the normal time for the rest of the work. What a nightmare. I had already cleaned most of the cylinder head surfaces before I took photos, so it doesn't look too bad in the pictures, but trust me - it was a mess. I got photos of the valve covers before I started cleaning.

While in there, I also replaced all the fossilized PCV hoses/tubes and vacuum lines. I was also able to replace the ETA hose without pulling the ETA, but it took about three dozen attempts before it worked. With new OE/Genuine MB valve cover gaskets installed, plus new copper washers on the bolts, all torqued to spec, the valve covers have been leak-free, 4kmi later.

Please - do not EVER apply sealant of any kind to M119 valve cover gaskets. It simply is not necessary. I've seen this multiple times. The worst is RTV which "glues" the cover to the head, making it difficult to remove without damaging anything - then you get to spend hours cleaning once it's removed.

 

[gsxr]

While the valve covers were off, there was another fun discovery! When the PO had replaced the valve cover gaskets previously, he either forgot to re-install the "fingered" chain rails between the cam sprockets, or they had been missing and he didn't know they were required. Somehow, there was no damage from running the engine like this for at least 40kmi. And no visible evidence that it caused any other issues. No noise either, I had no idea there was a problem for the 6+ years driving the car in this condition.

I measured timing chain stretch while it was apart: 3 cams pinned perfectly at 45°! The passenger exhaust cam pinned at 44°. Can't ask for any better than that. I had already dropped the lower oil pan when the car was purchased in 2013 and there was no rail debris, so a previous owner/mechanic had already been in there at some point. Additional evidence that someone had been in there previously - when I dropped the lower pan back in 2013, the oil sump pickup was the newer/updated style, and still soft rubber, not fossilized. I replaced the oil level sender O-ring at the block again (first in 2013, again 2019) just because it was easy and cheap, and I didn't want to drop the pan again.

In the past I've had issues getting the lower oil pan to seal properly. Using Hylomar didn't help. This time I tried something new, using Right Stuff (or Loctite 5900, or the MB black sealant) between the pan gasket and lower/steel pan. I used *no* sealant on the top side of the gasket against the upper/aluminium pan. So far it has been 100% leak free. I plan to use the same method in the future. I forgot to take photos of this, ooops. If I ever have to remove the pan in the future, it won't be difficult to clean the steel pan on the workbench, and the upper aluminum pan should have little if any residue to remove. UPDATE: As of 2026, the pan gasket is still leak free!

 

[gsxr]

Additional work:

Front crank seal replaced, tips & photos here:
https://www.500eboard.co/forums/threads/m119-front-main-crank-hub-seal-replacement.7000/post-198254

Fixing oil leak from timing cover flange:
https://www.500eboard.co/forums/threads/fix-for-oil-leaking-from-timing-cover-flange.14265/

 

[LWB250]

A couple things:

1.) Plastic oiler tubes? Why haven't you replaced those?

2.) Nice trick with the ETA hose. I'm sorry to say I'm pretty proficient at R&R'ing the ETA, not that it's something I care to be good at.

Why didn't you have the valve covers media blasted or something like that? I would think it would be the most expedient means of removing that goop from the valve covers.

I've got the "pile 'o' hoses" on the shelf for the wife's R129/M119 waiting to be done. I look at it and see that ETA hose and it forces me to find something else to do...

Nice job!

Dan

 

[gsxr]

I know, I know... should have replaced the oil tubes while I was in there. But I only had a few sets handy and they were earmarked for 5.0L engines. I'm also curious how long the plastic tubes will last. If one ever pops, I will replace all 16 with aluminum. At least next time, the valve cover job will be a breeze.

Media blasting would probably have been ideal. Unfortunately I am not set up for media blasting at home, and I don't know any local shops that do this... but I really should find some. I'd also be a little nervous about media particulate getting into the PCV passages, which are sealed with rivets - not easy to clean if anything gets inside. The media would also need to be mild enough to not remove the gray paint on the covers... through about 1994 the covers were painted, but somewhere during 1995 (USA model year) production this changed to bare/unpainted as a cost reduction.

 

[a777fan]

Excellent tips as usual gixxer. Thx!

 

[S70/2]

If there is one thing people love doing its emptying the tube of incorrect RTV everywhere it shouldn't be

 

[JC220]

If there is one thing people love doing its emptying the tube of incorrect RTV everywhere it shouldn't be

The bigger the gob, the better the job!!

 

[nocfn]

Holy crap! That is a mess. I do t know what is worse, the licorice all over the place or the plastic oilers. When I did this job a very reputable shop here in houston did about 5k worth of work getting her ready for the seller. I redid some of their work when I noticed some black rtv on the seals. Not alot, that was in the pan along with the tabs when they replaced the chain guides. So I redid that work and much more, requiring NO RTV, and leak free.

 

[NCCoder]

Permatex... When called for, wonderful stuff (BMW valve cover gaskets, Porsche case halves).

 

[4451533]

Lol

 

[Alphasud40]

Permatex removes with alcohol. Old school crap has no business on a German car. I do however use it when rebuilding Corvair engines.

 

[2phast]

FWIW. Subaru and Toyota use RTV to secure the timing cover and oil pan on the GR86/BRZ. They also used too much, so it squeezes out inside the motor, comes lose and clogs up the oil pickup assembly causing oil starvation. Many of these motors have experienced complete failures due to this.

 

[4psx]

Thank you for all those tips.
What did you use to clean up head and covers? I have plenty of brown as well as blue stuff on my engine

 

[gsxr]

Thank you for all those tips.
What did you use to clean up head and covers? I have plenty of brown as well as blue stuff on my engine

The brown stuff was hard and brittle, and no solvent would touch it. Every bit had to be scraped off manually. Plastic scrapers didn't work so I had to use screwdrivers, putty knives, and razor blades. The valve cover is easier only because you can clean it on the workbench. Be extra careful on the cylinder head, don't dig into the aluminum sealing surfaces with metal cleaning tools. This literally requires hours of work. For the final surface prep you can use a Scotchbrite pad or similar.

If you have softer goop, like RTV, plastic tools and/or solvent may work. Definitely try that before switching to metal scrapers.

 

[Gmach]

Is it OK to use the orange locktite 574 flange sealer (anaerobic) on the cam solenoid and the front cover ?

 

[gsxr]

Is it OK to use the orange locktite 574 flange sealer (anaerobic) on the cam solenoid and the front cover ?

Yes! That is the sealant specified in the FSM:

https://www.500eboard.co/forums/misc/Manuals/Servicev3.2/W124/w124CD1/Program/Engine/119/01-2120.pdf

 

[Gmach]

OK...thanks

 

[gerryvz]

Is it OK to use the orange locktite 574 flange sealer (anaerobic) on the cam solenoid and the front cover ?

Please see this post. Everything is detailed in the thread.

Also note that the bolts MUST have sealant applied to the threads, as shown in the post. 21Nm torque for each bolt.

 

[Benzito]

The previous owner of our 1994 E420 slathered some sort of brown shellac all over the valve cover gaskets (possibly Indian Gasket Shellac Compound?). Whatever the stuff is, it hardens like epoxy. As a bonus, he also didn't tighten the bolts properly. I discovered this immediately after purchase, but thankfully the minor leak stopped after tightening the bolts so I didn't have to immediately spend time scraping brown crap off the heads and covers. This was back in 2013 when we bought the car, with 114kmi on it.
(snip)

That’s weird, I have the same type of gook on my valve covers…

 

[JPM540]

Please see this post. Everything is detailed in the thread.

Also note that the bolts MUST have sealant applied to the threads, as shown in the post. 21Nm torque for each bolt.

Hi Gerry. I attempting to solve a variety of oil leaks. Started with the valve covers, cam covers, etc. For the sealant, I bought Elring Klinger EL-Liq 74...which seems to be the 001 989 89 20 10 equivalent. However, this stuff seems a runny....like it does not have the consistency that I would expect. Do you have experience with this stuff?

 

[gerryvz]

I have only used the MB stuff, but I have the exact same bottle that you show, which I will be using in the not too distant future for sealing the cam adjusters to the front cover of my M104 (G-wagen). I haven't opened the bottle yet, though. Perhaps the @gsxr can comment.

 

[gsxr]

The Elring anaerobic should work fine. If the consistency is odd, shake the bottle and see if that helps (or not). I like to let it cure 24+ hours before starting the engine.

 

[JPM540]

Thanks gents