New valve stem seals installed - Page 2 - PeachParts Mercedes-Benz Forum

rs899 · #16 02-11-2009, 06:24 AM

any oil consumption observations yet?

WINGAS · #17 02-11-2009, 06:41 AM

Yes, my bio-buggy's oil consumption went UP after I had the cylinder head redone.

winmutt · #18 02-11-2009, 07:26 AM

And still less smoke? Man I really need to do this for my car.

Ether · #19 02-11-2009, 09:04 AM

I can't really give an accurate answer on oil consumption until I do my ceremonial 1k check and refill to my reference point on the dip stick. That should be about the middle of next week so I will report then.

Yes winmutt still dramatically less smoke in stop and go traffic and none on cold starts.

Stevo · #20 02-11-2009, 10:47 AM

thanks for the feed back, keep it coming.

KAdams4458 · #21 02-11-2009, 09:58 PM

This report gives me great hope that my engine is not completely trashed! Less pressure in the valve cover? My car had a similarly seepy cap until I replaced the gasket, but tightening up the gasket on the cap made the fresh valve cover gasket seep. There is so much pressure inside of the valve cover that it blows oil through the vent and directly in to the intake in rather large amounts.

I'll be on the edge of my seat until the oil consumption results are in. This is really exciting!

leathermang · #22 02-12-2009, 04:38 AM

This is a valuable maintenance job which should be done more often than it is...
While one has it opened up to that level for the valve stem seals I would suggest new valve springs and valve rotators at the same time... and perhaps new locking and top caps for the valves.... these are things suggested by the FSM on a periodic basis and it makes sense to save the labor of taking it back down to this level by doing it while it is opened up. These things are amazingly cheap compared to their value to an engine.

Dionysius · #23 02-12-2009, 04:17 PM

Quote:

Originally Posted by KAdams4458

This report gives me great hope that my engine is not completely trashed! Less pressure in the valve cover? My car had a similarly seepy cap until I replaced the gasket, but tightening up the gasket on the cap made the fresh valve cover gasket seep. There is so much pressure inside of the valve cover that it blows oil through the vent and directly in to the intake in rather large amounts.

I'll be on the edge of my seat until the oil consumption results are in. This is really exciting!

This is a very important thread. The results will be very welcome and then we will have to explain what is going on. If the pressure in the Valve Cover is reduced by the Seals an explanation will be required. The Seal is more likely to prevent ingress of oil and some pressure into the Stem Guide interstitial zone but I am not as clear as to how it can hold pressure back from entering the Valve Cover. Any ideas??

winmutt · #24 02-12-2009, 04:20 PM

I would think gasses passing the seals when the exhaust valves were open, although there is a good amount of pressure coming up, do the valve guides seal as well?

Shawn D. · #25 02-12-2009, 04:29 PM

You know, folks, that blowby comes from rings as well. In fact, rings are probably the major culprit in almost every case.

Dionysius · #26 02-12-2009, 04:51 PM

Quote:

Originally Posted by Shawn D.

You know, folks, that blowby comes from rings as well. In fact, rings are probably the major culprit in almost every case.

If the Seals make a noticeable reduction in Valve Cover pressure what I am saying is that it will be difficult to explain. The challenge here is to keep an open mind and analyze the data we get from Mr Ether who is doing a great job in providing us with the data.

jt20 · #27 02-12-2009, 05:40 PM

On engine heads with fair mileage it is quite reasonable to believe that the valves do not seat as crisply or uniformly as the they once did on a freshly ground head. These gasses pass into the head ports and add to the existing pressures- most likely minimal by comparison due to the volume that passes.

The minutia of surface area available at the valve steam seal on the combustion side may allow the seal to effectively retain the pressure of exhaust/ intake gasses that are found in the manifolds and their respective parts. The valve guides and stems do some sealing but after time clearance accumulates and sections of the valve movement have more clearance in the guide / stem interface.

Whereas older seals do not have the elasticity to allow the tensioning ring to function as designed.

...just a guess.

pizzachef · #28 02-12-2009, 05:52 PM

I have a considerable amount of smoke at startup and a little bit just driving around with the car fully warmed up. This is on a '74 240D.

NHDOC replaced the valve stem seals in his '75(ish) 240D and in this thread, he said it didn't reduce his oil consumption much:
Valve Stem Seal Question

Hopefully your results are different. I'd like to do this on my w115 as well, so I'll be waiting to see how you make out. Thanks for letting us know!

Bajaman · #29 02-12-2009, 06:03 PM

I would assume that any appreciable blow by from the valve stem seals is going to be fresh air from the turbo, or exhaust... neither having anything to do with valve functionality.

jt20 · #30 02-12-2009, 06:13 PM

which is greater: pressure from the piston on its exhaust stroke or pressure from combustion? They are both plumbed into the same region. Any, even small amounts, combustion gases passing the valves will add to manifold pressure. - there is always a cylinder burning while another is exhausting, combine them.

Surely, it is negligible. Agreed, that the pressures in the manifolds are exhaust back pressure / turbo boost and are the same pressures working on the valve seals.