Cylinder head removal

[dirkbalter]

Normal compression on a 130 (280SL) is 10-12 atu  (roughly kg/cm2).
With a difference of no more than 1.5 atu between cylinders.
If I were you, I would take the motor to a specialist for evaluation and than decide on the necessary work to be done. Kevin already pointed out the procedure for properly measuring the cylinders and the minimum tools required.
You don't want to do this kind of work twice.

[ja17]

Normally A M130 engine with less than 150K miles just needs the cylinder head rebuilt and a new timing chain.

[Sens]

Thanks for your comments,
guys!
I will ask the guy where I will bring the cylinder head.

I think I will attack the cylinder head first and then rebuild the engine. The chain does not shows any play, but since I am there…

Overhauling the total engine is better of course, but a much, much bigger project. The risk I am willing to take is that I need 2 head gaskets in the end…

I wiil keep you updated.

Halvor

[stickandrudderman]

It's very importaont to have the bores measured properly by someone who knows what they're doing. A compression check isn't sifficient.
The absolute best way is to measure manifold vacuum with the engine running but of course, you don't have that opportunity now.
Did you manage to seperate the 2nd manifold from the downpipe?

[Sens]

Thanks for your comment!

Yes, measuring the vacuum in the manifold is difficult now…

As indicated above I did not insist separating the down pipe and the manifold; I was afraid to break it.
I simply cut the two down pipes and I will reconnect them later on.

Suppose the diameter of the bores is to high, that would mean a complete engine overhaul, right? The big thing…

[Sens]

Hello again,

I measured the distance between the ridge and the bore itself by inserting a feeler gauge in the small gap. (see picture)
I know that you will tell me that this is not the correct way to measure this, but at least it is an indication. 

I was able to insert a gauge of 0,05 mm, meaning that the bore diameter is at + 0,1 mm approximately.
And that is far too much, since Haynes tells me it should be lower than 0,022 mm!

I am afraid I will have to go a few steps further than just the cylinder head overhaul.
The wear of the valve guides indicated already to me that the engine had made its km's.

I my reasoning correct?

Thanks for all your support!

Halvor

[dirkbalter]

https://www.youtube.com/watch?v=VXiN1lNZ7TY

Also, get yourself a workshop manual aka BBB and read up on the chapter. (00-5) 

[ja17]

The top of the cylinder bore does not wear since the piston rings do not travel all the way to the top. If you thoroughly clean the carbon off the cylinder at the top, it should measure out to the original cylinder diameter. Lower in the cylinders, is where all three or four rings travel in every stroke and this is where most wear occurs. The wear may also occur more on one side of the cylinder than the other. Cylinder bores can actually wear oval and the rings adjust by wearing themselves to fit, as the cylinder wears. Just installing new round piston rings in worn oval shaped cylinders usually results in an engine which uses a lot of oil. So evaluating the condition of the cylinders is critical. It seems that the factory uses very hard rings, and the cylinders are worn out of spec before the rings are depleted. This seems to happen around 150K to 200K miles with conventional oil. Longer engine life can be achieved with modern oils, good maintenance and good driving habits. One quick way to evaluate the wear of the piston rings is to examine the bottom cast iron oil control ring. It has a double ridge and the valley between the two ridges almost disappears as the two ridges wear down. By this time the cylinders are usually worn beyond factory specs also. As you realized, the factory does not allow much cylinder wear before calling for a cylinder boring with new pistons. If your engine has less than 150K miles consider just reconditoning the cylinder head first. 90 percent of the time, most oil consumption problems and compression problems are cured or made much better.

[Sens]

Nice Video Dirkbalter!

Thanks for the link.
I have access to the link https://vdhflipbooks.de/books/WHB/WHB1959-Band-1/#94.

In fact that is the BBB chapter you mentioned.
Indeed, I had studied the pictures about the different defaults in the cylinder bore.

In my case no scratches or so, but a polished surface and a diameter probably out of spec...

Best regards and thanks again.

Halvor

[Sens]

Hi Joe,

Thanks again for your very helpful comments!

I think I will go for the head repair first, knowing that in fact the total engine is due.
However, my goal was to solve the oil mist problem after idle and that wil probably be solved after the head revision.

After that I have some other projects for the car: radiator, rear axle overhaul, etc.

So step by step will bring this beauty back to where it belongs!!!

Halvor.

[dirkbalter]

Yup, if you can read German, the flippbooks are better than the single volume BBBs that are available now.
Good luck

[Sens]

Hello again!

After inspection of the cylinder head by the machine shop they strongly recommended a total overhaul of my engine.
I found however an overhauled 280 sl engine, done by the same shop for reasonable price. The engine was sold by the guy from whom I bought the car 5 years ago. I have great confidence in him.
So I will do the swap in the near future and I will let you know.

Thank you so much for all the support so far!
Great forum!!!!

[Kevkeller]

I’m curious how they can tell how the rest of the engine needs to be rebuilt without seeing it. I guess if the valves are all good and there’s burnt oil all around they can deduce the oil scraper rings are shot.

[Sens]

It is an assumption, but I think they are right.
In fact they will not do the head only, just the total engine.