Is There Something Inherently Slow About the '85s? - PeachParts Mercedes-Benz Forum

rs899 · #1 09-22-2006, 10:09 PM

I test drove an '85 300CD for my good buddy, who is out of state at the moment, but is looking for one of these. It had issues, one of which was that it was dog slow off the line compared with our 83 300D. Hell, it was slower than my 240D stick (maybe even the auto). I know they had a different torque converter and tranny than the earlier ones, but I don't recall any performance complaints. It wasn't starting in first- I shifted manually to be sure.

Any ideas ?- other than the clogged pressure line off the intake.

Rick

TheDon · #2 09-22-2006, 10:12 PM

fuel filters? i doubt the fact that the 85's are a lil bit more lean on the fuel than the previous years... or maybe...

rs899 · #3 09-22-2006, 10:28 PM

I don't think its filters. The car looks well maintained and the guy who is trying to sell it says it has always been that slow, and he has compared it to other turbodiesels

#4 09-22-2006, 10:34 PM

It does have a higher gear ratio (2.88) than the 82-84 (3.07) so it may be a little slower off the line. If it's really slow, I would suspect it has other issues. My 617 is very slow if I turn the ALDA down too much, try giving it a turn CCW and see what happens.

Wodnek · #5 09-22-2006, 10:43 PM

Does the car get good power around 30 mph? My 85 is dog slow to 30, then it pulls like a train after that. Shifting it manually and winding the gears to 40 helps alot. Also check the banjo bolt on the back of the engine.

rs899 · #6 09-22-2006, 10:51 PM

Wodnek-

Yes- that seems to be what is happening on this one. And the tach is not working so its a seat of the pants feeling (or lack thereof). The ALDA is still virginal, I noticed.

This is a pre-purchase inspection. I can't do anything yet, except make a recommendation to my pal to buy or pass.

MBeige · #7 09-22-2006, 10:57 PM

Check that the throttle linkage has no loose connections. Usually the culprit is a 10mm bolt. It was on mine. No amount of adjustment to the bowden cable or ALDA changed it so I figured it must have varied with the modifications.

Jeremy5848 · #8 09-22-2006, 11:06 PM

I assume that, being in Florida, the car is not a California version? Burdened with the trap ox or trap cat, those engines get fewer horses and more opportunities for clogged tubes.

rs899 · #9 09-22-2006, 11:12 PM

No, didn't see a trap ox, but there were quite a few extra lines around taht I don't have on the '83 300D. A couple coming from the front of the turbo.

Bama1 · #10 09-22-2006, 11:22 PM

Just a thought but my first guess would be algae in the fuel system...even in a well maintained vehicle.

Given the Florida humidity, temperature, and the potential for water infiltration, their environment is absolutely perfect for algae production. Most common algae fouling results from an algae bloom stage that rapidly propagates but in an accomodating environment it can also be so persistent that it just resides in the fuel and the negative performance impact is so gradual that it seems as if "it has just always been that way". Kind of like a low-grade fever...won't go away until the cause is gone

That is specially a possibility if fueling is done through the same distribution supply chain set of refinery, storage, wholesaler, and local dealer(s).
(Highway/distance travelers seem have less problems since each tankful is likely from a different source )

If not that, could it be from a problem with the injector timing, nozzles or Injector pump?

Motor On

MBeige · #11 09-22-2006, 11:41 PM

Now that you mention the vacuum lines on the turbo, I understand that the 85 had the vacuum device on the turbo. It seems like the vacuum lines all merge into the blue disc in the engine bay that provides amplified vacuum (like a storage). Maybe the vacuum from the turbo has a leak, possibly? I'm not familiar with this mechanism yet but do check those out too.

my123ca · #12 09-23-2006, 03:03 AM

If it was slow ever since then that would mean more engine life for that car(hopefully). My car was like that when I first got it. MB dealer couldnt fix it. I wouldnt lend it to my father since it was dangerously slow. After the warranty expired, I brought it to an independent(who stole my service records-we had the same car

). He adjusted the bowden cable and the turbo came to life. Ive picked up a few tricks and tips especially in this forum to speed it up a little bit more.

Lostyankee · #13 09-23-2006, 09:03 AM

Does this model have the dreaded football shaped gizmo on the exhaust? I believe MB will still replace these on recall. My notes list 85 TD's but nothing for this model. If so you may have a trud covered gem waiting for the refit.

TheDon · #14 09-23-2006, 09:14 AM

Quote:

Originally Posted by rs899

A couple coming from the front of the turbo.

probably the ARV like on my 85.

rs899 · #15 09-23-2006, 08:17 PM

The dreaded football-shaped gizmo would be the crap er trap oxidizer. I didn't see one , but I will check again and for other easy solutions in a few days. My pal will be in town next week and we will have another look. This car has inside-out rust issues. Bad seals- waterlogged-rusty floors. Common issue in Florida.