Hello,

I have a general question regarding the replacement of piston rings on my 240D.

Is it possible to replace the rings and or remove the pistons with the engine in place.

The lower and upper oil pans will need to be removed to get access.

My workshop books do not mention this, they show engine removal?

please advise if anybody has done this.

brian
240D/250K miles

New rings are very unlikely to fix a low compression problem as the cylinder walls are surely worn beyond specs, and you really need to de-glaze the cylinders to put new rings in anyway.

On top of that, new rings in oversized bores will quickly ruin the pistons. If you need an overhaul, do one, don't bother with "quick" fixes, they almost always end up being more trouble and expense than doing it correctly.

I would not attempt this in place, I really believe it will save considerable time and effort to pull the engine -- they come out pretty easy on those cars, you can even leave the hood on!

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

peter,

Thanks for your input on my post.

I understand what you are saying! However, have you ever removed the pistons with the engine in place?

Thanks

Brian

I suppose you could do it, but no, I've not -- there is a large crossmember under the rear half of the oil pan, and I'd personally not even try to replace the upper oil pan half with the engine in the car, way to difficult.

If you do decide to do this, take a good look at the cylinder bores before you remove the oil pan. If there is a distinct ring ridge and the wall as shiny, no honing marks visible, new rings will do nothing for you.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Hello,

this is an update on my original question re' piston removal with engine in place.

Well, the mercedes workshop manual does in fact have a section for removing both upper and lower oil pans, so allowing access to the crankshaft and its bearings.

this does require jacking up the engine a tadd.

brian