You may also want to use Hylomar on your valve cover gasket on both sides. It is a non-hardening tacky gasket compound that has excellent sealing qualities and yet does not harden like most gasket maker compounds, allowing for ease of disassembly.

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Stable Mates:
1987 300TD 310K mi (Hans)
2008 Jeep Grand Cherokee OM642 165k mi (Benzrokee)

I've used Hylomar over the years on other projects and I'll keep it in mind for this.


Dan

I'll be watching this one. I just put an OEM MBZ valve cover gasket on my truck and it's still marking it's territory inside the shop. I still need to sort out my breather system, so can't blame the valve cover gasket entirely.

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617 swapped Toyota Pickup, 22-24 MPG, 50k miles on swap

Ok sounds good, I'm curious to see how a 617 handles 40 psi.

Might consider just getting another valve cover....
Obviously, the head surface is machined flat (well, it should be). Your OEM gasket is as good as it gets. All that’s left in question is your VC

Mercedes actually did get 230hp at 4,500 rpm out of their experimental 617 back in 1978 in the C111 running it at 200 mph getting around 15mpg at that speed.

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'83 SD, 2x '85 SD
You are entitled to your own opinions, you are not entitled to your own facts.

That was cool!

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I haven't installed the MB gasket yet so that's the next step after I look to be sure the cover is coming down to the head as/per previous discussion. Several things to try. Tom offered me a cover and I have one on my backup engine so there are options. Thanks for the thought.


Dan

I've run at 26PSI for several years w/o issues. The turbo I just took off had a big cold side and nearly zero pressure differential between the hot and cold sides so I can stand a bit more pressure drop and still be OK (everything I know about sizing turbos I learned from Tim @Tim's Turbos). So we traded more boost pressure for a bit more pressure differential. There's a useful limit on how much pressure differential (it's called "pressure ratio") you can stand but we're pretty sure this one should be OK. IIRC, Tim doesn't want more than 1.5:1. In Tim's defense, I asked for 25 to 30 PSI when I ordered up the last one and that's what he built. Then I saw that I'm still overfueled so rather than dial back the pump we're dialing up the boost. I'll find out how much is too much then dial it back a tad.


Dan

If you look on Mutt's build thread you can see how I handled my breathers. It seems to work.


Dan

Someday I need to make a trip up to see your truck etc, you're only about 2.5 hours away.

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Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

Come on over! Love to have you and Wilmington is a great place to visit.


Dan

I got into it today and you're right - except......



When I flatten the cover it takes an equal amount of material off the standoffs built into the cover as it takes off the gasket surface so that relationship is still intact. By working the whole cover on a super flat surface you "machine" it exactly as MB did when it was in the factory only no doubt they used a fancy surfacing machine (which I can only wish for......)


BTW - close inspection of the studs does show a step at the head surface as in your drawing. I toyed with the idea of taking the studs out and taking them to a machine shop and having them remove maybe 0.0020" from the step just to squeeze the gasket a bit more but I think I'll try the new gasket first. The step looks to be 0.125ish (maybe 8mm or so) but I'd have to pull one to get a proper measurement (sorry - I have a non-metric brain).



Pics:


1) The "machined" (actually sanded flat) surface. Notice that the boss where the hold down bolt goes was sanded down at the same time and the same amount as the gasket surface.


2) The cover face down on my flat surface. That old cast iron saw table is pretty much dead flat and that's what I stuck the strip sandpaper to do my "machine" work. I hope you can see that there's pretty much zero warp between the cover and the table and I couldn't get my thinnest feeler gage between the surfaces (0.001 IIRC).


3) The high-dollar Mercedes gasket. The old one was 4 or 5 seasons old and was a cheapie to start with so I guess it doesn't owe me anything.


Dan

Attached Thumbnails

     

Wasn't the idea to remove material form the standoffs only so that the cover fit tighter to the gasket?

No argument on the non-metric brain. 0.125" is nowhere close to 8mm.

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When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.

Nope. The idea was to flatten the cover as it was decidedly warped when I built this the first time. I'm pleased that it's still pretty darn flat. And yes - I slipped a cog - 8mm is about 5/16 not 1/8. I get to blame old age.

Dan