what are these pits in my cylinder walls?

monkfish75

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what are these pits in my cylinder walls?





I discovered them after taking off the cylinder head to replace the gasket. Are they the death of the engine?

The reason i took the head cylinder off is because there was alot of pressure in the cooling system and oil in there too.

HELP :( :( :(

sorry its a 1991 2.0 190E
 

Robby

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They don't look overly healthy, but its hard to gauge the depth. An old 2 stroke bike trick is to polish them gently with a brillo pad and see if it cleans up the face. Your choice whether or not to try it on an MB.
 
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monkfish75

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well they are in the two that we can see the inside walls of so probably in all 4 then yes. Is it possible that they could be going all the way through the wall and this is how oil was getting in the cooling system?

thay are quite rusty and my dad said that there was stuff seaping out, looked like rust, when the head came off.
 

Benzowner

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Are the cyclinder on mercs lined, I thought most alloy engines were. In which case you could get the bores relined. Your pics certainly show an edge to the cylinder bores at the top. If they are cylinder liners, it could be the welded joint breaking down of the liner
 

230K

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Geoff2 said:
Are the cyclinder on mercs lined, I thought most alloy engines were. In which case you could get the bores relined. Your pics certainly show an edge to the cylinder bores at the top. If they are cylinder liners, it could be the welded joint breaking down of the liner

I thought the 190 had a cast iron block. Those marks are from the gasket me thinks.

230K
 

Dieselman

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I suspect they are rust marks caused by water leaking into the cylinder from the gasket.

That looks like a cast block with dry liners, so there shouldn't be any direct path through to the water or oilways, unless the block has corroded right through, unlikley.

Only a pressure test will really tell you.

If the liners are scrap you could have new ones pressed in.

The marks are evenly spaced due to the water sitting in the ring lands whilst the engine is off. The engine will always stop in a set number of positions as compression builds in each cylinder, hence the corrosion in set places.

Looking at the pictures you can see where the gasket has blown between the two waterways then leaked down into the cylinder, hence the decoke of that part of the liner. You can also see pitting on the same part of the piston crown.
 
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monkfish75

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so do you recommend putting the head back on and then doing a pressure test after?

how much does it cost to get new liners pressed? and where would do that?

thanks for all the replies too.
 

Glideman

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I'd agree with what Dieselman said about the water settling in the bores. Interesting to see the honing marks still showing, how many miles had the car done?
 

wiggy

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136k!!!! thats kin impressive would have expected about 40-50k, agree with the others, I think thats just corossion marks where water has run down lookin at where the blow was an the position of the steam cleaned bit of the piston
 

Ian B Walker

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136K miles, take it back to the stealers and have it done under warranty, not run in yet :rolleyes: :D :D
 

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