0m606 valve job - PeachParts Mercedes-Benz Forum

jhunt253 · #1 10-09-2011, 01:05 PM

doing a valve job on my 606 and am wondering how much can be removed before you get into trouble with the hydraulic lifters and can this be measured/determined without assembling the cam? also if an adjustment is needed, can it be done with stem removal and if so how much?

thanks, hunt

engatwork · #2 10-09-2011, 01:39 PM

You got access to a manual/cd? All this information should be covered in the manual.

How many miles are on it?

Jeremy5848 · #3 10-09-2011, 01:51 PM

For starters, why do you think the engine needs a valve job? What year car is it in and how many miles are on it? Do you already have the head off?

I recommend getting a manual and learning more about this engine before you get in too deep. Anyone asking about an "adjustment" of hydraulic lifters definitely needs help.

Jeremy

jhunt253 · #4 10-09-2011, 07:02 PM

first of all, we have not been able to find a manual for this car-engine. we did find a cd on ebay but even the wisest in our neck of the woods has been unable to make it work, therefore my question on this forum.

the car has 390k on it and because it became difficult to start i conducted a series of test, one which was compression. the results were poor, 250 on #1 down to less than 100 on #6. leak down pointed to the intakes as did a soap test. i have not removed the head yet as i am finishing up one of my spare heads. i decided to do a valve job on it
[the spare] since it leaked fuel on #6 and 3 intakes.

hydraulic lifters can stand a range of stem length. basically when you exceed that range the hydraulic lifter becomes like a solid lifter. this happens when your valve sinks into the seat, the valves are ground too much, and or your seat is ground too much. on our airplane engines, such as a lycoming 680 which has hydraulic lifters this range is kept in check by a rocker arm adjusting screw,[the valve is adjusted by taking the spring tension out of the hydraulic lifter and then setting the clearance] other engines use different length push rods. removing stock from the valve stem after a grind is also commonly done.

my question was, how much can i get away with before an "adjustment" needs to be made? that adjustment might be a new seat, stem stock removal, lifter stock removal, a new valve, or a combination of the above. i have since answered that question by some measuring the components and their interaction.

engatwork · #5 10-09-2011, 07:09 PM

I will try to fire up my w124 cd and see what I can dig up. I am sure there is some info in regards to this matter in there somewhere. The reason I am interested is because I have two 606 engined cars and am always interested in seeing what all happens at different mileage.

Just for kicks, put the cd in and see if you can look at the files on the cd. If you can then you should be able to find a section on the 606 engine.

engatwork · #6 10-09-2011, 07:19 PM

PM me an email address and I'll email you a pdf file on the subject.

It is in the "programs" file on disc 1 .

The pdf provides a sketch and directions on where to measure and what to do. Easier to email than to spell out here.

jhunt253 · #7 10-09-2011, 07:24 PM

i suspect the valve on # 6 in the car is "sunken" as it appears to be off the seat by shinning a light down the port. i have been told that is a common problem with the 606. i don't know what causes that to happen. the other engine[the spare] has 230k on it.

engatwork · #8 10-09-2011, 07:36 PM

I'm always curious to see what goes on with these engines at higher mileage. I have two, one with 285k and the other around 227k. Both received new head gaskets a couple years ago with no machine shop work done. As you will see in the pdf recommendation looks to be replacement of the valve seat or head based on if there is other wear/damage.

Jeremy5848 · #9 10-09-2011, 08:24 PM

OK, misunderstood what you meant by "adjustment." Your compression and leakdown tests are pointing you in the right direction. I don't believe there is anything to adjust as on your airplane engines. If the 606 is similar to the 603 in this respect (and I am not sure) then there is a range over which the hydraulic element in the valve cap will compensate, after which you have to rebuild the head. Do you know if others have done work on the head in the past?

In the 60x engines, the cam sits over the follower, which presses down on the valve stem to open the valve. A hydraulic element in the follower takes up the slack and keeps everything tight. The 606 has two cams while the 603 has only one but I think the mechanism is the same. Burned valves and/or valve seats would be my first guess based upon your tests. I have not heard of valve problems being "common" with this engine; it certainly has not been discussed frequently on this forum or I would have seen it. My 606 has only 280,000 miles but it is as tight as new or so it seems although I have not had the head off.

The factory published a DVD on the W210 cars that included the OM606 engine. It is no longer offered but should be available used somewhere. The OM606 engine in the 1995 E300D is very similar (you still haven't told us the year of the car). The factory offered a 2-CD manual for the W124 including the OM606 engine. It also is no longer available new but again should be available used and maybe even on-line somewhere.

One thing I just learned is that Mercedes no longer recommends use of a magnet to lift the cam followers out because the followers tend to become magnetized and they attract tiny iron particles that damage the cam and follower. Instead, they now recommend a suction cup.

Based on the miles on this engine, I recommend pulling the head and having a valve job done (or doing it yourself if you have the necessary tools). Try Books4cars.com for either the 124 or 210 manual. Even a Haynes manual is better than nothing.

Jeremy