om602 head gasket job - PeachParts Mercedes-Benz Forum

Phillytwotank · #1 02-21-2015, 06:26 AM

I'm reading up and putting together all the info, tools and supplies to do a head gasket replacement on my '92 300D 2.5

Head Gasket Set - Check

Head Bolt Set - Check. Bought from a local supplier so i can return them if i find that the original head bolts are reusable

Triple Square Driver - Check

Still working on finding a local cylinder head shop. I am tempted to just slap the new gasket in there and go but i should probably find a shop that can perform the most basic of head health checks for me. It would be good to have that piece of mind.

I just have a couple questions for anyone who has done this before.

How do i deal with the "pin" for the timing chain guide?

Any other advice or pointers from those that know??

Thanks

Phil

shertex · #2 02-21-2015, 06:37 AM

Just out of curiosity, how many miles on the car? Mine went at 243k (car since sold).

Phillytwotank · #3 02-21-2015, 06:48 AM

It's at 236k. To be clear, the gasket is not yet fully "blown". Engine was running fairly well in the two weeks I'd been driving it. Used no oil but did use some coolant. I found two places on the exhaust side where coolant is escaping to the outside while I had everything apart working on the turbo. Decided to go ahead and do it now rather than waiting for something to really blow and while a lot of things are already taken apart.

ROLLGUY · #4 02-21-2015, 11:46 AM

Quote:

Originally Posted by Phillytwotank

How do i deal with the "pin" for the timing chain guide?

Thanks

Phil

I use a 6mm bolt that is threaded all the way, and put a flanged nut and washer against a larger nut or spacer (spacer is from the mounting of an R4 compressor on a 617). With several threads in the pin, tighten the nut and the pin will pull out into the hole of the large nut or spacer. You should be able to pull it out from there by using a lever against the head (much easier after the first half inch or so of the pin sticking out)....Rich

moon161 · #5 02-21-2015, 04:33 PM

http://www.peachparts.com/shopforum/diesel-discussion/356840-stripped-allen-bolt-602-head.html

Excavation w/ neat tricks and fantastic dub
https://www.youtube.com/watch?v=xD3TEVzgrF8

Head prep and install
https://www.youtube.com/watch?v=UXSKdN6-KbQ

These were all relevant and useful when I did my OM602 HG

moon161 · #6 02-21-2015, 04:44 PM

And the coolant pipe with the funny connect on the right side of the block. You just have to pull it out after removing the clip. Don't wrench on the connector with the big hex, even tho it is very tempting.

TnBob · #7 02-22-2015, 10:50 PM

You will find that snugging up your head bolts a 1/32 or so turn helps avoid snapped head bolts too.

Phillytwotank · #8 02-23-2015, 05:02 AM

Thanks all for the replies. That 6mm bolt with the collar trick is exactly what I was looking for. So, check that off the list. Sweet!

Just need to line up a head shop now and maybe figure out how to pull the prechambers depending on the head shop.

She'll be riding again soon!

ROLLGUY · #9 02-23-2015, 10:53 AM

Quote:

Originally Posted by Phillytwotank

Thanks all for the replies. That 6mm bolt with the collar trick is exactly what I was looking for. So, check that off the list. Sweet!

Just need to line up a head shop now and maybe figure out how to pull the prechambers depending on the head shop.

She'll be riding again soon!

The last shop I had to do a head job had an oven to heat the head. The prechambers come out really easy that way. I have since purchased from our sponsor the tools for pulling the prechambers. My newest machinist (closer and cheaper) does not have an oven, so I am able to remove the prechambers before giving him the head. You might want to think about buying the tools if your shop is not confident in getting the prechambers out without ruining them.

moon161 · #10 02-23-2015, 12:05 PM

I ordered bolts from PP and from a local MB dealer. In both cases the heads of the bolts were bigger than the originals, and too big to fit in the counterbores of the head that were outside of the valve cover. After much more time than I planned spent on being right, and using the 'right' parts, I just bought a cheap grinder from HF and ground the heads down as required to fit, mostly .01"-.02" per side.

Phillytwotank · #11 02-25-2015, 01:21 PM

All good info here. Thanks!

I think i have everything in place now to get the job done but now there's another setback.

Cracked my damn ribs skiing this past saturday!

I may be feeling up to it by this weekend coming but if not...

Anybody want to me my surrogate mechanic hands??

Simpler=Better · #12 02-25-2015, 01:26 PM

Disclaimer: I've only done this on a 617:

The locking rings are a PITA, clean the threads and use PB blaster.
With a slam hammer the PCs themselves come out easily.

You can always head the head in your kitchen oven, just ramp the temp up slowly & manually to be safe.