1972 r107 350SL Inlet valve

[Isdyldan]

Will I be able to see the valves if I remove the inlet manifold?

 

[LostKiwi]

You'll be able to see this much:


(Assuming it's an M117 engine).

 

[Isdyldan]

Hi - I'm just struggling to get the inlet manifold off - I've removed everything mentioned in the Haynes manual and all the bolts but its still stuck down. Is there a technique to budging it please?

 

[Isdyldan]

Ah - its loose now. Unfortunately the head broke off one of the bolts under the AAV. It was very tight and I have been soaking it and trying it all week, until it finally just broke on me this morning. I thought it would just pull up over the stud, but the bolt is actually stuck in the manifold. I just need to wiggle it off over the next few days. This one bolt is becoming a pain!

 

[Isdyldan]

Hi - last week was a battle to remove the inlet manifold which I finally managed today after drilling out most of the last bolt. I could just see a tiny bit of wire stuck in the valve, but as I managed to free it, it fell down into the cylinder. I'm guessing its about 1mm x 3mm long, and there is a squashed bit in the middle. I can see it down on the piston using the camera but so far have been unsuccessful removing it. Very hard to see in the photo, but the tiny silver thing centre of photo. Any suggestions would be most welcome please! Dylan

 

[LostKiwi]

Try spinning the engine over and see if it gets carried out the exhaust.
Now the wire is gone from the valve area it may be worth doing a compression test.

 

[Isdyldan]

Yes I did consider just putting it back together and hoping for the best. There's quite a lot disconnected though at the moment - water ways etc, also a metal pipe at the rear of the manifold - maybe oil pressure gauge? What are the chances of it getting stuck again?

 

[LostKiwi]

Just spin it over as is (first ensuring nothing can go down the ports). I suspect the metal pipe at the rear of the manifold is a vacuum line.
At least then you'll be able to see if the compression is still bad (at which point the head will need to come off.

Disconnect the fuel pump before turning ignition on.

The lack of water won't be an issue - you're not going to start it.

 

[Isdyldan]

Hmmm the saga continues - still no compression. I'll need to check if the valve clearance is still ok I think. I got this car running in the state it is now so it's possible someone has set the valve clearance with the valve not seated properly. Or it could be the damaged looking piston, but air did seem to be getting past the valve when I pressurised the cylinder.

 

[LostKiwi]

Sounds more and more as though the head needs to pulled off.

Shine a bright torch down the spark plug hole then look for light in the inlet port with the valve shut.

 

[Isdyldan]

I can't see any light. Maybe my pressurising the cylinder plan was flawed somehow. Maybe I'll try it again tomorrow. I'll check all the other cylinders for compression before I remove the head. May be flogging a dead horse. The one next to it (number 6) was fine.

 

[Isdyldan]

I think I'll have to end this thread now - thanks for all your help and advice. I've been wrong about the valve - its leaking past the piston. I'm assuming the engine needs to come out to fix that, so I may just put it back together and leave it be for a few months.

 

[LostKiwi]

If it's leaking that bad past the piston I'm surprised it's not smoking.

Yes the engine will need to come out.
Whilst out I'd definitely be replacing all piston rings and bearings as a minimum and depending on what you find pistons as well.
Once done though it will be fabulous for years to come.

Rebuilding an engine is a great winter project.

Don't be tempted to run it as is - if the rings are broken up you risk scoring the bores which could significantly add to rebuild costs.

 

[Isdyldan]

Thanks.