Can I Change Valve Seal Stems Without Using Comressed Air - PeachParts Mercedes-Benz Forum

maurinquina · #1 08-03-2004, 07:47 PM

I have a w126 and bought the seals already . I need the valve compressor but also info on doing job,if possible w/o compressed air because I don't have that available. Smokes only when idling when engine is warmed up .Thanks !!!!!!!

Gilly · #2 08-03-2004, 08:42 PM

You can rotate the engine so the piston in the cylinder you're working on is near bottom dead center, then put in a length of rope (I am guessing a few feet of about 1/4" nylon rope) in through the spark plug hole, then bring the piston back up as high as it will go without being forced, and the rope will hold the valves up. Be sure to do this on the compression stroke, not the exhaust stroke. Then you can gently back the engine up to enable the rope to be removed. When you are done with all the cylinders, be sure to rotate the engine forward (normal direction) again before attempting to start the engine, you don't dare try to start it after a reverse rotation.

Gilly

maurinquina · #3 08-03-2004, 10:22 PM

That's a great idea, Gilly ! That takes care of the main problem but
I'm still without a Spring Compressor . I can't buy one because they're too expensive for one-time-use . Are there places that can rent a W126 specific valve spring compressor ? My 88' 560 SEL has 213k on it and I can't wait to see how engine runs
"without" smoking !!! Thanks again .

Gilly · #4 08-04-2004, 08:38 AM

When you're dealing with engine issues, you have to "drop" the chassis number (126) and start using engine nomenclature. I belive you have a 560SEL, that's a 117 engine, so you need something to remove valve springs on a 117 engine with the head installed.
That all being said, I'm not sure where you could just use or rent one. Maybe ask the closest dealer if they will. Unsure what else to offer. Maybe someone else knows of a place or a cheaper solution rather than the factory tools.

Gilly

Jeff Hartmann · #5 08-04-2004, 09:14 AM

I don't know about the 117 engine, but I did my seals on the 103 with a compressor (screw type) from Advance Auto ...I think it was 19.95.

Jeff

afmcorp · #6 08-04-2004, 01:24 PM

i believe Performance Products will rent the compressor for a week for a fee. don't know if you have to buy something or not. worth a call though.

afmcorp · #7 08-04-2004, 01:30 PM

some one a few weeks ago made a statement on stem seal replacement on either a 420sel or 560 don't remember.

the comment was that his mechanic only replaced the stem seals on the intake side. because that is where the sucking of oil is. further said something to the effect of...the exhause side doesn't suck and would need the extra lube from the leaking oil.

that comment caught my eye because there is some sense in the intake being the sucker of oil.

anybody got anything to add to comment good or bad

donbryce · #8 08-05-2004, 09:21 AM

I had the problem of oil seeping by the seals when the engine was at rest, leading to large puffs of smoke at start-up when the accumulated oil in the cylinders burned off. There was also some smoking when accelerating, which I would take to be the result of the 'sucking' described by the mechanic.
- If the oil is seeping down from the top of the cylinder head, past the seals while the engine is not running, it would go down the stems of both the intake and exhaust valves.
- Either valve open with the engine at rest would admit oil to the combustion chamber, which would burn off on start-up.
- A closed exhaust valve, engine not running, would have accumulated oil expelled with the burnt mixture on start-up as it exited the cylinder.
- A closed intake valve, engine static, would, as the mechanic says, 'suck' the oil in when it opened, both at start-up and while the engine was running.

I'd think that seals would wear fairly uniformly across all cylinders. Why would anyone go to all the trouble of setting up a seal replacement operation and then only do the intake valves?

And since the subject is open for discussion, if the seals are on the top of the guides, how does the valve stem get lubricated? Are the seals supposed to let just a certain amount of oil past for this purpose?

Craig: That's one beautiful trio of MB's in your stable.

Cigar Havana · #9 08-05-2004, 09:35 PM

If anyone is in the Toronto area, I would be willing to rent my valve spring compressor, for a M116 engine (420SEL 1986-1991). I think it will also work on a M117 (560SEL 1986-91).