valve job? - PeachParts Mercedes-Benz Forum

allenying · #1 12-18-2017, 05:41 PM

hi, my engine is running rough, with intermittent kicks, and smoking, seems like oil burning.

valves have been adjust a couple times.
rack damper idle adjuster spring bolt has been changed and adjusted.
a few cans of diesel purge have been run, as well as startron.
each gave a small improvement but not complete fix.
there is injector knocking coming from 1st valve, 1st 2 injectors have been been tested for pressure and spray pattern.

compression tests and leak down tests have been done. it seems that there is a leak in the 1st valve, and the compression is lower on it than the other 4 valves.

basically it seems like most things have been ruled out, and the next step is a valve job.

has anyone paid a shop to do this? if so, how much?
i'm going to get a couple estimates, from my shop, and one that comes highly recommended, but i want to be able to gauge if they're over quoting.

also i'm a little worried that i'll end up spending the money on it and for whatever reason it wasn't the problem. based on the info i've given, would anyone have doubts?

thanks in advance,

Diseasel300 · #2 12-18-2017, 05:46 PM

If you're going that far, it may be worth your time just to source a rebuilt head or farm yours out for a rebuild. Have it checked for warpage and cracks, valves and seats ground, check the wear in the valve guides, valve guide seals, etc. Be aware that you're talking about a head gasket job in the works as well. If you're paying someone to do the work for you, expect a fairly hefty bill (north of $1000). The cost to refurb the head will depend on what is worn and what needs to be done to it. If the valves are worn and you need new ones for example, it's going to cost several hundred more than if your existing ones can be reused.

dkr · #3 12-18-2017, 06:00 PM

I would get a used head and replace it if that turns out to be the case. There are lots of heads available and most of these parts do not just easily wear out.

Dkr.

jamraw · #4 12-18-2017, 06:01 PM

Quote:

Originally Posted by Diseasel300

If you're going that far, it may be worth your time just to source a rebuilt head or farm yours out for a rebuild. Have it checked for warpage and cracks, valves and seats ground, check the wear in the valve guides, valve guide seals, etc. Be aware that you're talking about a head gasket job in the works as well. If you're paying someone to do the work for you, expect a fairly hefty bill (north of $1000). The cost to refurb the head will depend on what is worn and what needs to be done to it. If the valves are worn and you need new ones for example, it's going to cost several hundred more than if your existing ones can be reused.

I just went through this on my om602 turbo. I had a machine shop check everything out. They said the valve guides needed replacement and the exhaust seats were pitted needing replacement. They were able to reuse both intake and exhaust valves. Shop did the work and cleaned up the head real nice all for 400 bucks. I provided the parts...valve stem seals, exhaust seats, and valve guides.

Sent from my Z963VL using Tapatalk

Junkman · #5 12-18-2017, 06:23 PM

You will want to be certain that rings are good. It would b disappointing to find out after the head was reinstalled.

allenying · #6 12-19-2017, 01:56 AM

$400? that would be lucky i guess...?

hmm, well a good machine shop would be able to find out for sure what is wrong? the main thing i don't want to do is spend money on something that wasn't the problem.

is finding a replacement head really that easy?

i'm not super knowledgeable or have had a lot of experience on these things.

thanks!

Diseasel300 · #7 12-19-2017, 10:15 AM

617's are like cockroaches, they're everywhere! Ask nicely in the "Want to Buy" section of this site, and you'll probably be able to pick one up pretty easily.

When I had my 603's head redone 2 years ago, it ran me right at $400. I had all 12 valve guides replaced and the valves all re-ground. My seats and valves were still good enough to be re-used and the head did not need skimming.

Are you capable of performing the head gasket job yourself, or will you be paying a shop to swap the head? If you're paying a shop to do it, expect a staggering bill - it is not a trivial task.

dkr · #8 12-19-2017, 12:33 PM

Quote:

is finding a replacement head really that easy?

There are a bunch of used engines out there in various stages of repair/disrepair. The issue with a lot of the engines is you just don't know what condition they are in. I would be very hesitant to just pull an engine out of a pick a part and trust it not to have problems, but the heads are all over the place and generally are in good shape unless the last owner overheated the engine.

I was the junkyard a few weeks ago and was thinking of pulling the head on one since it was a 40% off day, but I didn't because they are so many and the thing is heavy to lift.

Dkr.

allenying · #9 12-20-2017, 06:54 PM

so swapping out a head like this?

https://www.ebay.com/itm/Mercedes-Benz-OM617-Cylinder-Head-Good-Condition-No-warping-Free-Shipping/302539769869

and wouldn't you be risking running into other problems with it?
my engine is at 175k...

i will not be doing and head work myself...

thanks

dkr · #10 12-20-2017, 08:49 PM

I would personally be ok with it if it is not warped. I would get a magnifying glass and look all over it for any signs of micro-cracks starting and if you can't see any, it should be ok. I don't know where you are physically, but you could probably do better with the price. I would imagine shipping is a big part of the seller's asking price. If you can find a local seller, it would be better as you can inspect it on-site, avoid the shipping cost, and maybe gain some confidence in the car it came from.

Dkr.

Sugar Bear · #11 12-21-2017, 12:08 AM

Consider rebuilding the head that is on the car now. It is lower mileage @ 175K, not overheated, probably never been milled and definitely the right one. Have a valve job done on it, replace worn guides and it should be like new. This saves the expense of another head, reduces the chances of getting a bad one and has a fresh valve job.

Find a shop that does Mercedes diesels in case it needs to have the pre-chambers removed if it needs to be milled/planed. Confirm they know the minimum allowable thickness and that they measure it before and after milling.

Good luck!!!

allenying · #12 01-08-2018, 01:05 AM

thanks all,
i've been too busy and it's been too cold to take it in yet,

i'm not sure if it's the cold, or something else, but the smoking and kicking has reduced gradually over the last few weeks. usually there's still some smoking and kicking when cold, but once warm it's much less severe than before, less severe than before the new idle adjuster bolt was put in, and less severe than right after it was put in.

also it's interesting that people have had good experience with lubro moly or liqui moly motor oil saver. on other forum threads they say it has resolved their oil leaking and exhaust smoking. it's probably just hopefully thinking but seems worth a try since i'm not in a rush to get the valve job done.

funola · #13 01-08-2018, 10:09 AM

Interesting! Maybe the tight #1 exh valve that's been adjusted twice, or was that 3 times, has finally settled? Or maybe it was due to something else?

So you've decided to get a valve job done? What kind of quotes did you get?

leathermang · #14 01-08-2018, 01:22 PM

The FSM suggests replacing the cap and lock nuts on the valves ... particularly if one will not stay set as long as the rest of the engine...
The cap nut is softer than the valve top... so hopefully it is only play caused by wear on the nut .... and thus fixable.....just as a r and r ....
Would be very lucky if that is the cause...

allenying · #15 01-08-2018, 08:32 PM

i have a few theories, maybe the valve adjustments settled in, like now the engine wants the valve has to be not exactly as spec since it was far from spec prior to adjustment... maybe it's just the cold weather, and when it's warm the problems will come back, though once the engine is warm it shouldn't matter what the temp is outside.

i'm not really sure at all, the problem is not completely gone, but it's much less severe that i can live with it for now. i do want to get the valve job, but i just keep waiting, and i haven't gotten quotes yet. i'm going to try the liqui moly motor oil saver that claims to rejuvenate seals.

the one thing that is just as loud if not louder is the nailing, what sounds like injector nailing, which is occurring despite having pressure and spray tested them.

my theory is also that the 1st cylinder is still having lower compression, which would explain everything else, including the winter issue i'm having that on a cold start, it stalls when i let go of throttle, until it's warmed up a bit. my workaround has just been to give it slight throttle to 1000 rpm.

how big a job is changing the cap and valve nuts?