The engine on my 84 300D is really dirty, caused mostly from a leaky value cover gasket. I plan on replacing the gasket, but feel that I need to (steam?) clean the engine first. What, if any, precautions do I need to do before I clean it? Also, what type of cleaner do you recommend? Thanks!

Engine degreaser and HOT water. Do not spray the exhaust manifold, turbo or injection pump as the rapid temperature change can crack them.

I usually buy a can of aerosol engine degreaser, and take it to a quarter-type car wash. (Not anymore, since we got a pressure washer..., but I've done it this way several times.)

I pull in and shoot the degreaser all over everything... letting it cool as long as I think I can get away with without looking suspicious - feed my quarters, put it on the soap cycle, and blast away. Haven't had any problems yet.

***If you try this, and if something DOES crack from the temperature shock, you were fairly warned. I said that I never had a problem doing it. I didn't say that science has proved it's a safe thing to do.***

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~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL

Does the engine have to be at temp for this to work??? If Engine were cold then no cracking.....explain.

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Dionysius

Engine is hot or cold when you do this???

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Dionysius

I just used Engine Bright on mine a few weeks ago. Just cover up anything electrical. Use as directed, very sparingly. Rinse sparingly, then start the car and go on a long drive to the water all evaporates.

jeff

Cold or mildly warm engine, it's fine to spray anything and everything (except obvious things such as uncovered fuse boxes, etc).

A road temperature engine... although I have chanced it a time or two and gotten away with it - I suppose would be at risk of cracking if hit by a jet of water.

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~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL

The cheapest way I know of.... buy a gallon of Gunk concentrate... mix with 4 gallons of kerosene... coat the warm ( but not hot ) engine with it...and leave overnight.... spray off with thumb over hose end...... I really don't believe in using high pressure washers since they can get into electrical connections and cause problems later...
This combo will last a long time... but keep closed ...
To do a second round on really greasy engine.. .you have to let the water dry off before putting the Gunk on again... run the engine to dry everything each time anyway...

I have read that you shouldn't use high-pressure cleaners on engines because the water could disturb or get past gaskets and seals. It probably would be OK if you backed off and didn't apply pressure directly with the spray nozzle right next to the engine.

A warm engine should be easier to clean. You can allow the car to sit for 15 minutes after driving it and the exhaust system will cool a lot faster than the block. That should reduce the risk of damaging anything.

Note in this post the use of the weasel words "should" and "could." Caveat emptor.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

I use engine-brite on a cold engine with good results.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

I've done quite a bit of degreasing, especially after my oil cooler line incident, but detailing it to the point you can eat of the valve cover scares me.

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1985 500SL Euro w/ AMG bits 130k
1984 300SD Turbodiesel 192k
1980 240D Stick China 188k
2001 CLK55 AMG 101k
2007 S600 Biturbo 149k Overheated Project, IT'S ALIVE!!!

bglots sells bisel foaming bubbles bathroom cleaner. spray on till foam stands. let sit. rinse. can be done cold. really thick stuff. brake parts cleaner to loosen it up then foam.

foam will clean hands tooo. spray on rub around wipe off. great for those road side repairs where you can't get to water, but you need to show up clean like nothing happened.

I always do this after my car has been sitting over night so its cold. I spray the engine with a degreaser, wait 5 minutes and wash with a hose at low pressure. I have heard a lot of stories about cold water on a hot IP and I am not going to take the risk so I do it when the engine is cold.

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1983 300SD
200000miles

I've used engine bright in the past with good results but I now use just Simple Green.

Whatever you choose, be sure that you read the label. Greased Lightning, Purple whatever it is called will ETCH aluminum - not good.

Also, be sure to regrease the ball sockets on all your throttle linkage. If you degrease them, the ball sockets will bind they can stick your throttle WIDE OPEN!

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~shell
As of 2/2010:
2001 CLK55 0o\=*=/o0
13.6 @ 106mph
10K mi
1984 300SD
260K mi and going and going...
97 S600
46K miles
1991 Sentra SE-R (extremely dorked with)
www.se-r.net

Simple Green Max, available at autozone and others, detergent not solvent, works better than any of the foaming sprays etc. I've used. Rinse thoroughly.

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Gone to the dark side

- Jeff