I plan to pressure wash the engine compartment at the self serve car wash. I remember when I had a GM diesel the owners manual said not to wash the engine unless it was cold since water getting on a hot injection pump could cause it to crack. Any similar suggestion for this car? I rather not wait 2 hours at the car wash until the engine cools down.

I have washed my 617 diesel while hot on several occasions, and nothing bad has happened...yet. Your post alarms me though, as the GM warning seems to make sense.
I really like to keep my car clean; inside, outside, underneath, and in the engine. It is so much easier and more pleasant to work on clean parts that arent caked in crud...but this injector cracking warning..
I never considered that. I will monitor this post to see if anyone has advice.

I have found that even with a cold engine I can get a very clean engine and bay by spraying simple green everywhere under the hood, letting it soak for a few minutes and then hosing it off with water. From time to time I will aslo get under the car and spray the underside of the engine and all the trans that I can get to. Really helps to see if there are any more drips than normal (for my car!)

There have been no problems with dry rubber products and my driveway is cleaner for it. Plus it is cheap in bulk and better for the environment too.

I always use caution when spraying the water on the turbocharger. It get quite hot.

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Jim

That's what is nice about simple green on a cold engine. No temp. difference to worry about and no cracked parts $$$. May take a washing or two but well worth the time and little effort.

I normally wash (and dry major puddles with a towel) the engine before the body of the car and I have run the engine while I am finishing the exterior wash. That way I have a clean engine bay and outside of the car to go with it

I've been using "gunk" on a cold engine and underneathm where it is more oily. Also spray warm water/dishwasher detergent on everything else, wait a bit, then wash the whole thing off with garden hose. Keeps my engine nice and clean.

anyone think that the gunk stuff will harm rubber parts like hoses?

Nic

By the way I found the turbo statement interesting; as a side note; I have a 300D N-T, and I also have a turbo BMW. The KKK turbo on the BMW is air-cooled and my mechanic thought this was unusual as all the turbos he saw before (American cars) were engine coolant cooled. Is the Garett Air Research Turbo air or coolant cooled?

Adam
ATLD

What - engine coolant cooled?? The W123 turbo diesels use the engine oil to lubricate and cool the bearings. I can't say I have ever heard of a turbo that was engine coolant cooled.

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Jim

American Cars;

As an example, a 89' chrysler lebarron has a seperate coolant line that feeds the turbocharger as well as an oil line (if you don't believe me, check Chiltons). The coolant only cools the turbo bearing, not the turbine, which I don't think could be cooled nomatter how much coolant you have.

My mechanic (not my MB mechanic, my independent BMW mechanic) thought exactly the opposite. He thought that every turbo was coolant cooled and was shocked not to see coolant line going to my BMW's turbo.

ATLD

What is Simple Green?

Simple Green is a biodegradable general-purpose cleaner/degreaser. It works pretty well and isn't caustic at all. It's available at Wal-Mart, major auto parts chains and a variety of other places. Not surprisingly, it's green. There is also a Simple Green automotive formula, which I've found is a better degreaser than the standard Simple Green.

I used to own a 1985 Dodge Shelby Charger and it had a water-cooled turbo. It was a great car, but not exactly at the pinnacle of automotive engineering or quality. So I was very surprised when I was replacing the air cleaner mount on my 1982 300D and found only oil lines going to and from the turbo; no coolant lines.

It was always my understanding that a water-cooled turbo was less sensitive to a hot shutdown than a turbo that is only cooled by engine oil. I have also heard that, often, turbochargers can be run either way. In the '80s, I remember seeing cars that were aftermarket turbocharged with turbos that had provisions for a coolant line, but no coolant line was attached.

Obviously, turbo life isn't a problem on a well cared for Benz diesel, so I don't worry about it. I would like to know what percentage of turbocharged vehicles being currently produced have water-cooled turbos, though.

Aaron

I know that the new Porche Turbo uses a turbo that is almost the exact same model as the KKK turbo on my Bimmer, so it is also air cooled; I guess.

If Porche does, many are soon to follow...

ATLD

Not necessarily. You don't see a whole lot of other rear-engined cars running around, do you? Or cars with horizontally-opposed engines (except for Subaru)?

How about air-cooled engines? Porsche employed them for years in the 911, and finally gave in to convention with the 996 (newest 911).

Porsches are great cars, but the unique engineering that goes into them doesn't always encourage a whole lot of copying by other automakers.

Aaron

I regularly powerwash my 300SDL's engine at the do-it-yourself carwash. I usually wash my car (15 minutes) then wait a few minutes with the hood open, spray on the gunk, then wash the engine off.

You want to wait a little bit for the engine to cool off, you dont want to crack anything (head or block!!).

John

I have used Simple Green too and it works well. Recently, I tried that Orange type cleaner and found it works even better though. It seems to melt the grease away and does not seem to hurt the paint under the hood.

Used to use Gunk but it was too hard on the paint under the hood.