[W126 Coupe] oil, oil, oil

[kirk erichsen]

Contrary to BPs response to the US Congress about some 5/8ths of the Gulf oil spill just 'evaporating,' when your engine runs low on oil over time, it's either leaking out of a joint or being burned in the combustion chamber. You don't have to see any blowby to burn oil. If you don't have any obvious oil leaks, that leaves oil consumption through combustion and a high probability of the cause. While the issue is sometimes conflated with the oil ring binding in the piston lands (happened to me intermittently, quite maddening), the likely cause in this case points to valve seals and/or valve guides. If the valve seals are original, they are guaranteed to be petrified. The new seals of a better material (fluroelastomer/flurocarbon, aka "Viton") which can operate at much higher temperatures and neigh impervious to oil and all common additives. Valve seals can be replaced with an air compressor, some fittings (or the tool to hold the valve in place from the spark plug hole, less commonly practiced) and a spring compressor as the primary tools. A shop can do it for you and once down to the naked valves can evaluate if the valve guide clearance is within reason. Valve seals are fairly straightforward, but the guides are not. If the guides wear past a certain point, the valve seals can only slow the excess oil getting down the intake valve stem. When that comes, you pull the head, address any imperfections to the valve inlets and seat and bore out the guides. I prefer to have them drilled out vs. pounded out with a drift as this is less stressful to the head and the new guides don't need near the machining to get them squared away. You should also consider freshening up the cams if the lobes are worn, checking the clearance on hydraulic tappets and shimming springs as necessary - also don't forget to replace the maddening little brown plastic clips on the oiler tubes which invariable get brittle, break and can find their way to the timing chain and lodge themselves well enough to jump the sprocket. 

For your sake, hope for a valve seal only remedy.  

Pray tell what does the inside of the air filter housing look like? Any oil pooling near the draught tube from the valve cover? That was my hint when my oil scraper on #6 was intermittently sticking.

-K


-------------------------
Kirk R. Erichsen
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> Date: Tue, 9 Nov 2010 13:37:47 -0500

> From: pfc at nyc.rr.com

> To: mbcoupes at mbcoupes.com

> Subject: [W126 Coupe] oil, oil, oil

> 

> i don't seem to be blowing enough smoke to believe that i'm actually 

> burning the stuff, and there are no leaks to speak of.  where is all my 

> oil going???  i'm told that these alum engines just "use" it.  yes?

> -- 

> _______________________

> David Leonard

> Director

> pfc Opinion Research

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