OM642 PCV System Retrofit? - PeachParts Mercedes-Benz Forum

JHZR2 · #1 05-20-2025, 01:43 PM

Has anyone looked into the retrofit of one type of PCV for another on the OM642?

I have the (I believe) older unit, which has a metal fixture bolted to the engine, and then a round plastic pick fit to that.

There is another variant that seems to only be the metal section, with I guess more of a valve setup inside of it.

As I understand it, the seals on the section that mate to the engine go bad as well as anything else in there. I suspect that’s why the newer models replace the entire part. But I don’t know if this can be done with the older variant.

Has anyone investigated this?

I’m getting a bit of leakage from the front of the engine (not the oil cooler) due to oil seepage through the intake system. So I want to be sure the PCV is squared away properly first.

Thanks!

87tdwagen · #2 05-20-2025, 03:02 PM

The wear item is the camshaft oil seal that resides in the aluminum block bolted to the rear of the head that the PCV puck snaps into.
EPC shows that the camshaft seal at one point seemed replaceable independent of the housing. I have not been able to find a part number for just the seal tho. So the housing gets replaced entirely just for the seal, there's no other reason to replace the housing as nothing but the cam seal wears. Want more $ I guess.

Next time I do mine, I'm pulling the seal to see if there is a part number molded on it and just replace that.

FWIW another common front side leak area is the oil filter housing, either the seal to the engine block or the mid seal between the housing halves.

Good luck

JHZR2 · #3 05-20-2025, 11:38 PM

Quote:

Originally Posted by 87tdwagen

The wear item is the camshaft oil seal that resides in the aluminum block bolted to the rear of the head that the PCV puck snaps into.
EPC shows that the camshaft seal at one point seemed replaceable independent of the housing. I have not been able to find a part number for just the seal tho. So the housing gets replaced entirely just for the seal, there's no other reason to replace the housing as nothing but the cam seal wears. Want more $ I guess.

Next time I do mine, I'm pulling the seal to see if there is a part number molded on it and just replace that.

FWIW another common front side leak area is the oil filter housing, either the seal to the engine block or the mid seal between the housing halves.

Good luck

If you go to an epc or parts catalog, often you’ll see the two piece older design with the black plastic puck. It does have that cam seal.

if you look up a newer model, it has the one piece with just the metal piece and a cam seal, no black plastic puck…. But the cam seal looks about the same as the one piece Pcv. It has to be unless they changed cam diameters. That’s actually what got me thinking about the ability to retrofit.

The cam seal in parts stores is coming up quite expensive!

Have a look for A0149977146…

Murkybenz · #4 05-21-2025, 07:23 AM

EBay UK around $33 but you would need to contact seller for international shipping etc

JHZR2 · #5 05-21-2025, 11:03 AM

Quote:

Originally Posted by Murkybenz

EBay UK around $33 but you would need to contact seller for international shipping etc

I think I bought it by the PN I gave, on Amazon… I’ll report back what I get.

Would ideally avoid buying the $89 metal part.

Trying to fix this:

But I can’t say that the PCV was that bad. But who knows.

87tdwagen · #6 05-21-2025, 08:39 AM

Thanks JHZR2!
After some searching, I've found it as low as $23.
Crazy pricing though, can't believe how many places offer that seal for over $100, more than the aluminium block WITH the seal already installed. Just crazy.

Going to grab one from kliflex.com for my next PVC service

JHZR2 · #7 05-22-2025, 10:25 PM

Quote:

Originally Posted by 87tdwagen

Thanks JHZR2!
After some searching, I've found it as low as $23.
Crazy pricing though, can't believe how many places offer that seal for over $100, more than the aluminium block WITH the seal already installed. Just crazy.

Going to grab one from kliflex.com for my next PVC service

Got it from Amazon.

87tdwagen · #8 05-21-2025, 12:04 PM

Yeah that seal should reduce the blowby oil considerably.
The downside of the design is that as the turbo spools it also sucks in oil past the camshaft seal, so there will always be some getting in.

A oil catch can plumbed in between will further reduce the oil getting into the intake stream. A fairly easy add-on, but a mist will still get thru.

My experience with keeping a good cam seal and catch can has reduced the oil in the intake significantly, say by 90% compared to what I was seeing before.

If you ever do a EGR delete, this will reduce the sludge in the intake manifolds. I inspected mine about 25k mi after a oil cooler replacement and they're still clean, albeit with a very slight coating of mist oil.