260psi cold is a GOOD number. Minimum spec is 18bar ( approx 261psi ) hot so it will be within spec when hot. MMO does NOT work unless the coking is very light. BTDT. I took an OM603 cylinder out with stuck rings and soaked it in MMO for a week, nothing. Soaked in solvent, surface coking dissolved, basically nothing. Need to break the ring loose with slight hammering and scraped the coking out by hand. Even this was a lot of hard work. This piston may be the extreme but I do not think MMO works magic as most members believe.

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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.

I agree. I don't think it did any good. But won't hurt either.

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1991 350SDL 350k+ miles

At those low temperatures no actual chemical action will occur for all practical purposes. Seventy degrees F is the threshold basically. Leaving the block heater connected may get the engine warm enough.

. I just do not know.

Recently, the camshaft on my 603 broke at highway speeds. Pulled the head and took it to the machine shop. The number 3 piston is marked, but not damaged. So while the head was in the shop, I soaked the pistons with MMO as stated in earlier post. Ended up having to pull the pistons in order to hone light scuff marks in number 3 cylinder (honed them all and replaced rings). Found more carbon build up on the piston than normal in number 6 and 1 stuck compression ring. I'm glad now that I went ahead and pulled them. Thus my reason for thinking the MMO didn't do much good.

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1991 350SDL 350k+ miles