oil consumption valves issue?

[Rodolfo]

Dear collegues,

In general I am very satisfied with my 230sl 1966. It is very sober: around 10,3 l/100 km or 23 mpg. Went to 170 kmh and it stills accelerates, but I stopped there. Acceleration is very good. It means compression is good, and ignition is spot on. There is also no blue smoke of oil burning.

But:

It does consumes oil, and if a put a paper after the exhaust, black oil gets on it. So I assume it good be the valve guidings letting oil through to the exhaust?

What could be the cause? What oil consumption would be normal?

If the oil goes through the valve guidings, I should let overhaul the valve guides?.What would be the normal cost? I can myself dismount the cilinder head and regulate valves.

Thanks in advance,

Rudy

[garymand]

The usual sign of worn intake guides and seals is at 100Kph foot off the accelerator for a few seconds, like slowing for an exit.  Then accelerate again.  the oil is sucked past the guide seals with the high vacuum and a nice puff of smoke comes out the exhaust.  Yes it sounds like unburned oil getting past the exhaust guide/seals.  Wow, nice power, well tuned motor.  I've never tried just replacing the seals. 

[w113dude]

Why don't you just replace the valve guide seals first to see if it makes any difference. Then move on to more complicated things. It's cheap and in a couple of hours will be done.

[Benz Dr.]

That's a waste of time for the most part. You will see smoke while doing this test if the intake guides are worn. Exhaust valve guide wear won't always show that much smoke because it gets burned in the exhaust system and generally less oil will leak down the exhaust guides than will be seen going down the intake guides. There is very little vacuum to pull oil down the exhaust guides.


If it's really bad or it simply bothers you, get a valve job. Costs depend on what parts you need. If you need valves, guides, rockers, ball studs and a gasket set, plus all of the required machining, it could be 3 - 4 K.

[ja17]

Hello Rudy,

Yes, I would try to recondition the cylinder head first. Good chance your oil consumption will greatly decrease.

[Rodolfo]

To Ja17: do you mean with reconditioning the full machining and new valves and val guides, or just the valve guide seals?

To w113dude: do I need the special crow tools for this?

I will better buy first a seal for the cover, so I can open it to have a look inside: I will probably see then better if the exhaust valves are leaking oil, I guess.

Thanks for feedback

Rudy

Another question, I saw a 250 sl cylinder head refurbished for sale. Does it fit or does the 230 sl has hotter cams and is not completely compatible?

[w113dude]

I don't know what condition the head is, if you haven't done this level of work perhaps it'll be good idea to take it to a specialist, but if you feel comfortable that you can do it yourself then there is a lot of info in this site that can walk you through it.
The cost of redoing the head all depends on what are the things that need to be changed.
The ones I have done (not that many of them) cost four to five hundred dollars in parts if the valves, valve guides, guide seals had to be changed and the head had to be shaved.

I suggest taking the head out, either way you have to do it, then you'll see it more clearly of the work involved.

[ja17]

Most often, just replacing the valve seals will not help. To re-condition the head, it must be removed. All parts are inspected to make sure they are within factory specifications. The head casting is checked to make sure it is flat.

Any parts worn beyound acceptable factory specifications should be replaced.

Most often new valve guides are installed, all the valves and valve seats are reconditioned and re-checked to make sure they are within specs. The head is milled "cut flat" if warped. All new valve seals are installed. Parts like ball studs, rockers and camshaft are inspected. The head is re-assembled and installed with a new head gasket.

Automatically replacing parts like ball studs, vlaves, rocker arms etc. is great if cost is no consideration. But closely inspecting the parts and following Mercedes guidelines on wear limits, and replacing only the bad parts will save you lots of money.

It is important to find a good experienced machine shop to inspect the head casting, install the valve guides, and grind the valves and the valve seats.