1987 300D lack of power :( - Page 3 - PeachParts Mercedes-Benz Forum

gsxr · #31 09-09-2003, 01:44 PM

Marc- awesome, that is definitely one cause of low power! Get that fixed and hang on to your hat the next time you pin the throttle.

My wrecked car's Garrett turbo always leaked oil out the bottom. It was annoying but didn't impact the function. I was going to get it rebuilt just to stop the minor oil leak, but most people wouldn't bother since it was working fine. I'd ignore it until the leak becomes more severe, and/or your oil consumption gets worse (my cars get 4-6kmi per quart or better).

HTH,

Marcb · #32 09-09-2003, 02:02 PM

Wow! Thanks for the encouragement Dave!

I can't wait until I can change the unit on the car and see how things go! I will definitely let you know how the 603 performs with a clean pipe to the ALDA!

On the oil leak, mine is also a Garrett turbo and it is very annoying and sure does crud up the shielding on the bottom of the motor. On the plus side, my radiator hoses are always soft in the morning and the engine idles very smooth!

In fact, I just switched it over to synthetic oil and all seems great at this time! I think the only leak I can find is on the bottom-side of the turbo. Thanks again and I'll keep you posted!

Marcb · #33 09-09-2003, 02:38 PM

One more thought... since the Garrett turbo is leaking, is the only remedy a rebuild?

gsxr · #34 09-09-2003, 03:26 PM

Marc,

AFAIK, the only solution to a leaky turbo is a rebuild, assuming the leak is from the turbo housing and NOT the oil feed or drain lines (which is highly unlikely on a 603 turbo). You need to remove the turbo & take it apart to change the seals, which is basically what a "rebuild" is, as long as the bearings & impellers are good. It's a DIY project if you're adventurous.

I pressure washed mine from underneath periodically, which helps things stay cleaner, and also lets you monitor the amount of the leak. I could go a few weeks before anything started to drip on to the pan after it was clean. It was enough to make a film all over the bottom of the turbo area, but never enough to make a puddle. Just annoying!

kashbaugh · #35 09-13-2003, 09:26 PM

Well, it turns out I have a genuine 30-year MB mechanic living about 4 doors down from me!!! His kid saw me struggling to replace fanbelts today and told me I should get his Pop to do it. So I did. About 30 minutes and all the belts are brand shiny new!

Then we talked for a while. When I told him about my turbo tribulations - I had verified spin while under the hood today - he bypassed the Overboost relay with new tubing and we went for a spin. Man!!!!

So now I just need the relay!!!

Thanks for all the help!

kma

psfred · #36 09-13-2003, 09:50 PM

He he!

Now you know why everyone wants one of those 87 300Ds -- the 87 190 2.5 diesel is hot too -- 2.5L 602 in a lighter body!

Peter

kashbaugh · #37 09-14-2003, 01:10 AM

I can't wait to see what my milage is, too. I've been getting 25 to 28 non-turbo. If what I think I know about engine operation is correct the turbo should make the system more efficient, too. The extra horsepower should mean the engine has to work less for the same motive power. So I should see an increase in mpg.

Right?

It's amazing how much I am finding out I DON'T know!

Thanks for the help!

kma

psfred · #38 09-14-2003, 11:44 AM

If I stay under 70 on the Interstate, I get between 32 and 34 mpg, once I got 36, but that may be a filling error ( I wish it got 36 all the time!). Higher speeds = lower milage -- the trip to Florida the other year got me about 31 average over the 2400 miles, more or less, but most of that was at 80 mph.

Mixed country open road/city driving gets me around 29 mpg, same as the Volvo TD.

Peter

gsxr · #39 09-14-2003, 07:39 PM

I think KMA has an 85 300TD, not an 87 300D. IF that is correct, the MPG on the '85 will be mid/upper 20's at best, maybe 30 with a tailwind.

The 87 is much more efficient and has a significantly lower coefficient of drag. My 87 will also get 32-34mpg (peak), but my '84 can't get over 24-25 no matter what I do to it...

kashbaugh · #40 09-15-2003, 01:46 AM

Dave,

Yeah, I have an '85, but I'm getting 24 to 28 now. I have enough driving to do Monday that I should be able to get a read on milage with the turbo engaged. At least a first look.

I'll let you know.

kma

#41 09-15-2003, 10:45 AM

Having the turbo working will result in only marinal economy improvement (maybe 2-3%). A 617.91 engine (naturally aspirated 3 liter diesel) produces about 30% less power and almost the same economy (better at low speeds, worse at high speeds). A 617.95 engine without turbo activated fuel enrichment behaves almost exactly like a normnally aspirated 617 engine.

Fuel economy of a 123/126 with a 617.95 engine WILL be lower than with a properly running 603.96 engine (once the trap has been removed).

Marshall

kashbaugh · #42 09-16-2003, 02:19 AM

Must have kept my foot in the turbo too much today. I only got about 23 mpg!!! Maybe by the end of the week I will have quit playing with my new toy so much.

But it runs just dandy!

Thanks for all the help on this. You guys are fantastic!

kma

per eriksson · #43 09-16-2003, 02:31 AM

A variant of piston failure happened to me when I had a -81 300TDT.

Half the piston skirt had broken off so that the piston "tilted" a tad bit in the bore and made contact with the head on TDC.

Power was unaffected but it smoked a little and made some serious noises....
Drove it all the way home 300miles cause the whole car was a heap of junk anyways.

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