ML320 engine question - PeachParts Mercedes-Benz Forum

Motorhead · #1 02-20-2003, 08:40 PM

I'm a Diesel head but I like the ML 320 for my wife when her 84TDT wears out. Is the engine in the ML 320 an all aluminum engine or is it a cast iron block and aluminum heads?
I just replaced an engine for a friend in a '85 380SE and it is an all aluminum engine with NO sleeves!!

What years of the ML320s are good? Is there anything or years to avoid?

Gilly · #2 02-20-2003, 09:37 PM

It's an aluminum engine with a coated cylinder bore, real tough material.
If I personally were shopping, I'd try finding a deal on a early one and plan on fixing what's wrong. Most everything is repairable. The first 500 or so had a 50:50 ratio transfer case and you can get some vibrations out od it when turning at slower speeds, if this bothers you then stay away from these models, as MB won't replace the tranfer case because of this vibration.
If you aren't so-inclined to buy one with the intention of fixing things, then the newer the better.
I'd generally stay away from the sky-roof models, unless that big hole of a sunroof really turns ya on, then it's worth the wind noises and small rattles.
The 320 engine is "OK" on power, but the 430's are considerably more fun to drive.

Gilly

Motorhead · #3 02-20-2003, 10:20 PM

Thanks Gilly, We had Metric Motors in L.A. do the 380 engine. Did a REAL nice job. I just have a hard time with the aluminum bore. Now give me a Cummins 5.9 (In Dodge Trucks) or a 617 turbo engine, I see durability. What do you think of the long term mileage of these engines? What did they do to better the chain guide problem that the 380 had? (My friends 380 broke a chain guide at 140K and it was a double chain engine).
Do you know the approx. HP of the 3.2ltr V6?
I don't like sun,moon or whatever they want to call it roofs! They are a constant source,(IN MY BOOK)of problems and leaks.
Thanks for your input, Chris

PaulH · #4 02-20-2003, 10:31 PM

Gilly, I thought that I read that the "new" engines are sleeved. If it's just a coating (Silicone?), isn't that how MB has been building gas engines for 30+ years? Motorhead, I love the power that the V6 has. I believe that the V6 gets better fuel mileage than then the V8, but if I were towing a trailer a lot, then maybe the V8. I get 15 mpg around town and 23 on a trip with my 320. So, I guess that you'll have to test both and make up your own mind. Also, I would look at the 2000 and later because I think that the interior ,which was changed in 2000, is Much nicer. Just a few thoughts - -

Gilly · #5 02-21-2003, 09:26 AM

No, they are coated. It takes a special etching process on the surface to give the proper finish to the cylinder wall if the engine is ever bored out. I am unsure how much of a rebore could be done without losing the coating. The coating may be called "Nikasil", not 100% sure if this is correct.

Unsure what was done to address the guide problem that was mentioned, this is a completely different engine than the 116/117 engine. If your friends 380 116 motor was a double row chain, it was converted at an earlier date, which makes the failure of the guide at only 140K kind of confusing. I haven't seen a failure of this type on a 112 or 113 motor, and we have a few in service where I work at about 200K miles. These engines, I would like to point out for all the FSS nay-sayers, have been operated following the FSS plan and not even on synthetic oil.

I would assume under optimal conditions, using synthetic oil (yes, I agree it would have benefits in the long run) and mostly highway miles, probably around 300,000 miles?

Horsepower of the 320 is 215hp@5600. as stated in a 2000 ML owners manual.

We haven't had alot of sunroof problems (on the regular glass sunroof) on the ML's. May as well get used to it if you're buying used, it's hard to find one without a sunroof.

Gilly

G-Benz · #6 02-21-2003, 10:32 AM

Quote:

Originally posted by gillybenztech
The coating may be called "Nikasil", not 100% sure if this is correct.

Gilly

Didn't BMW have problems with their "Nikasil"-coated engines, where many owners had to get complete replacements due to premature failure?

Gilly · #7 02-21-2003, 11:01 AM

G
I know BMW had alot of problems with their 4.0 V8 engines. I believe BMW may use the same coating on the engines, I don't believe "Nikasil" is proprietary to either manufacturer. I am unsure if the coating was a root problem on the BMW engine. I haven't heard anything out of MB that would cast a negative light on the cylinder coating, and again, I am unsure if Nikasil is the correct type of coating, I am fairly sure though.
Some early MB 112 engine had to be replaced, but I believe on the earlier engines it was due to an early engine tolerance problem, resulting in a problem referred to as "keyholing" of the cylinder, maybe there is a machinist who could better address what this is. The FSS "oil sludging" problem seems to be connected to the use of non-synthetic oil and the extended oil change life. We have had very few problems associated with this, as I mentioned earlier. I believe the use of synthetic oil will keep problems to a minimum. The vehicles I mentioned earlier that are doing fine at 200,000 miles on non-synthetic oil and FSS service intervals are vehicles which are driven almost completely for highway use, this may be an important component in why these particular engines are holding up so well.

Gilly

Motorhead · #8 02-21-2003, 01:46 PM

Thanks again Gilly for the info! Chris

mplafleur · #9 02-21-2003, 01:52 PM

Regarding towing. My 6-cyl '98 320 did a terrific job towing an trailer with an '80 240D on it accross the state. It handled well and towed the weight (about 5000 lbs) strongly and without hesitation.

Later the same day, I loaded up a 300SDL (at 6000 lb total) and it was just as strong. I got 15-17 mpg as well!

#10 02-21-2003, 10:46 PM

The BMW problem in the 3.0 and 4.0 V8 engines was the combination of the Nikasil coating and the high sulfur content of US gasoline. The result was that the cylinder walls developed a pitted surface and the cylinders would lose compression. The first sign of the problem was signficant engine vibration at idle. Initially, BMW replaced the EPROM in the DME to increase combustion chamber temperatures and try to burn off the sulfur. This only proved to be a short-term solution. The Nikasil coating was eventually replaced by Alusil which is now used on all the engines. Those owners fortunate enough to have vehicles with less than 100k miles or six years old had the Nikasil blocks replaced with Alusil blocks.