Preparing to adjust the valves, '83 240D - PeachParts Mercedes-Benz Forum

123boy · #1 09-20-2019, 06:42 PM

Gonna adjust my valves this weekend. This will be the initial adjustment since purchase a few months ago. Although I'm familiar with valve adjustment procedures, and have done many on various other cars, this will be my first on a Mercedes high compression diesel engine of W123 vintage (or any vintage for that matter).
Would like to know member's opinions about the "best" way to rotate the engine (turning the power steering pump pulley, although convenient, does not seem ideal, to me, but what do I know) and if there is a recommended way to relieve the compression to facilitate engine rotation?
I would think removing the glow plugs would be about the easiest route, for compression relief, but wasn't sure if this was the "way to go" or, advisable, for that matter.
This "newbie" thanks all, in advance, for their input.

okyoureabeast · #2 09-20-2019, 08:19 PM

You could remove the glow plugs, but that's unneccessary. Just rotate at the crankshaft with a big breaker bar and do the valve adjustment.

Please double check which direction you want to go. I believe its clockwise. MAJOR engine damage will occur if you do it wrong so please double check!

Edit it's clockwise thanks guys

tangofox007 · #3 09-20-2019, 08:37 PM

Quote:

Originally Posted by okyoureabeast

Please double check which direction you want to go. I believe its counter clockwise. MAJOR engine damage will occur if you do it wrong so please double check!

When viewed from the flywheel, that is correct. But some would describe it as CLOCKWISE, when viewed from the accessory (front) end.

rocky raccoon · #4 09-20-2019, 08:40 PM

If working alone, rotating by the power steering pump is fine. There is a persistent myth that using that nut will "overtorque" the ps pump pulley. That is booshwa. Most of us do it that way.

Rotation is clockwise when standing in front looking into the engine bay. If you miss, go around again. As the Beast says, don't rotate in the wrong direction.

There is no need to remove the glow plugs, just put a little beef behind your wrench. R&R the glow plugs is an un-necessary complication.

The hardest part is replacing the valve cover without dislodging the NEW GENUINE MERCEDES gasket. I remove the cruise control actuator for more clearance but I have a 5-cylinder. You may have plenty of room.

Torque value for the hold-down nuts is very low. Check the value for your engine.
Overtorquing will distort the cover casting and result in an oil leak.

Please report back when completed to let us know how it went.

123boy · #5 09-20-2019, 08:48 PM

ok, thanks. yes, i understand about the engine rotation. It's simply the direction it normally turns when running. Not too worried about the valve cover gasket......I'm obsessed with proper torque values. More concerned about all those darn ball and socket linkages.....

I've also read "here" leave as many connected and unmolested as possible, the majority still attached to the valve cover.

Sugar Bear · #6 09-20-2019, 11:59 PM

Draw a diagram marked I and E with the respective clearance for each valve and keep it in view to reduce any confusion while working.

Valves are not perfectly in position as seats, stems and guides wear. This can cause a tight clearance spot and a loose spot depending upon the rotation/position of the valve. Rotate the valves to find the tightest clearance spot using a feeler gauge and adjust the clearance with the valve in the tightest spot/rotation. This way when the valve rotates it will always have enough clearance. Adjusted on the loose position, if/when the valve rotates there wouldn't be enough clearance.

If the valves are notably out of adjustment, do another adjustment in short order e.g., 2-3K miles

hercules · #7 09-21-2019, 01:36 AM

Easiest way,clip on starter solenoid with push button switch,bump engine
over,adjust valves straight down the line.
Some models may have a tie block on passenger side frame rail that also
could be used. Solenoid wire ties here.Usually one of smaller wires.Apply power from jumper wire.

rocky raccoon · #8 09-21-2019, 06:22 AM

I must disagree with hercules. His method is of course doable and probably with the least effort but ....

I believe it is hard on the starter motor. Replacing the starter on an OM617 is one of the most difficult jobs, mainly because of the reach to the upper bolt. May be easier on your engine, maybe not.

doofus · #9 09-21-2019, 08:00 AM

what’s permissible to use to “stick” the gasket to the valve cover? On VW’s I’d use a little wheel bearing grease, but of course that was a cork gasket. The W123 cover is HUGE and the job looks very awkward. Does it require a helper?

Also, those ball/socket things just pop apart w/a large screwdriver? Then back together w/pliers? I’m worried about messing one up and opening a can of worms...

rocky raccoon · #10 09-21-2019, 09:01 AM

Doofus:
That is why I recommend a Genuine MB gasket. It grips quite well on a clean, dry cover. The aftermarket or "OEM" gaskets not so much and I have tried them all. I have of course, tried grease on a cheaper gasket but it still does not grip well enough. Don't get suckered into using a sealer of any kind. It is a band-aid that will be painful to remove later. You will do this job every 12 to 15k miles.

The Heim joints are not intended to be maintenance-free. They should be popped apart, wiped and lubricated periodically. I do it whenever I am having a slow day, certainly once/year. Some can be re-attached with a hard finger squeeze some will need pliers. You won't mess them up.

Sugar Bear · #11 09-21-2019, 09:09 AM

Never had an issue putting the gasket on and keeping it in place, 240's have working room. Use the best gasket you can get, OE if possible and torque it in place.

Good luck!!!

123boy · #12 09-21-2019, 05:15 PM

OK! Got the valve adjustment completed. As "they" say, it was the proverbial "piece of cake". Easy to build things up in your mind, making them seem more difficult than they really are. It was much easier to rotate the engine than I thought it would be. All valve clearances were "tight", save for one intake. No problems with the adjusting nuts and locking nuts. Buttoned it all up and went for the requisite "test drive". The engine started better than it EVER has (have only had the car a few months). Seemed to have a bit more power on acceleration and the engine ran smoother, too. However....the engine seems to make an awful lot of racket when at idle (always has). Maybe sounds "normal" for these cars? I'll try and upload a video of it idling and get a few opinions here.
Next on my list is the famous, and controversial, "Diesel Purge"! That procedure, along with new filters and strainer might quiet things down a bit, yes?
As always, thanks for the help and advice. Glad the "Pelican" is here to lean on....lol

okyoureabeast · #13 09-21-2019, 05:42 PM

Yeah, the engineers who designed these were thoughtful of those who had to service these engines.

A valve job was probably a only a few degrees more difficult than a regular oil change.

One thing I missed about my w123. Lots of opportunities to inspect the guts before long haul trips.

Sugar Bear · #14 09-21-2019, 06:28 PM

If all of the valves we're tight another adjustment in 3k or so would be good. Depending on what is making it loud at idle it could be good or bad. Too quiet is a sign of low compression, a distinct "clacking" is a sign of good compression.

Glad to hear it went well.

123boy · #15 09-21-2019, 06:48 PM

Thanks guys! Nice to know such great support is always "out there". Amazed, every time I do "anything" on this car, at the high degree of engineering. Especially when you consider that during the same era (70's 80's) American cars were absolute dog crap!!
Definitely a distinct "clacking" at idle. Quiets down as the rpm's go up. I'll re-adjust the valves, per your suggestion, in a couple K miles, or so. On to the purge!!