Ok, I've been driving this thing for almos 2 weeks trying to decide if I want to buy I from a friend. It's a 1987 300D turbo sedan with 250,000 miles and some appear to have been less than kind. It drives well and has good power. I think the only things working in the vacuum system are the brake booster and the shut off solenoid - rest is unplugged and not working. Tranny shifting is all screwey as to be expected by vacuum issues.

It does have a 14 head. Seems to have no crack symptoms - hose goes soft when it cools off, doesn't build pressure too fast, etc.

I hooked up a boost gauge today and drove it some. Seems to me to have massive boost lag. Takes about 3 - 4 seconds from flooring to build full boost. When it finally decides to come on it builds quick to about 13 - 14 psi. Once boosting a little it comes on fast and makes good power. Car is not slow overall, but painfully slow 0 - 15 mph. Oh yeah, tranny is starting in first and alda is removed. Puts out black smoke until boost comes on.

The trap oxidizer is long gone. The exhaust looks like a factory system, and only has what I assume is a resonator and then muffler at back. Did the update have a cat or trap in the system? Would the thing I assumed was a resonator be a cat or other type of trap?

So - any thoughts on the boos lag?

The update has a cat in the downpipe. Remove it.

Also, your 0-60 time would help in diagnosing.

Should have a cat but it wouldn't be plugged if you make good power on the top end. Black smoke indicates rich and properly atomized fuel, white is poorly atomized fuel. I think the first thing to check is a leaking egr valve.

Good compression and proper IP timing should handle acceleration through about 2000 rpm. You should have at least 5 psi by then and max boost by 2500 rpm.

Remove the turbo air inlet pipe and check for play in the turbo shaft. The impeller blades can cut you so watch what you're doing. Anything more than just perceptible radial play is bad, any axial play is bad.

Remove the ALDA temporarily to see if the IP has more to give as is. It's your choice whether to adjust or shim the ALDA or go without it.

Sixto
87 300D^2

3-4 seconds to build 15 psi and that's unsatisfactory?

A gasoline powered sedan with a big V8 is in your future.

YOU NEED to get to that next red light faster than all the other DB's out there..........have to do it!!!!

Actually I have had vehicles at both ends of the acceleration spectrum. My '84 ranger diesel was pretty slow. This 300 does not feel like a slow car at all - you don't drive it floored at all. But, it's completely dead from a stop for the 3-4 second lag then you're immediately backing off the throttle. It simply doesn't seem right. It makes it ackward pulling out into traffic because it's so slow to take off. Genrally if you have enough fuel to make black smoke you've got enough exhaust heat to spool fast...

I guess I was't entirely accurate in the way I described the boost building. The 3-4 seconds is completely boostless, then it VERY quickly builds to max boost.

Thanks for the input - I haven't had a chance yet to see how the turbo clearances are.

Sounds like it is running pretty normal to me. You have a 250000 mile, IDI Diesel that had 143hp when new. It is a fuel miser, not a street racer.

I suppose you could check the throttle linkages. Gut the cat. Check the IP timing as stated also. Verify the EGR is closed.

If you are unhappy with its performance, you may as well skip its purchase.

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I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG]

I accelerate into traffic at exactly 2000 rpm...........WITHOUT BOOST..........and the SD gets to the destination (the next red light) at the same time as every moron who must mash the pedal down and slam on the brakes.

On the highway, I accelerate at 2000 rpm until the set pedal position allows the engine to slowly climb to 2600 and 62 mph. The DB's can pound sand behind me.

I get 29.5 mpg.........on average.........over 10 tanks......there's a reason for that.

My GF's '85 OM617 wagon will kill my '87 OM603 sedan off the line and I'm pretty sure my 603 is running about right. However 4 seconds of "turbo lag" is wildly excessive. My car would already be catching the aforementioned good launching '85 TD in 4 seconds.

Removing gunk from my prechambers and replacing my injector nozzles made a huge difference in how quickly boost would build in my 603.

Thanks again for the useful responses to my legitimate question! Between this thread and a few others on here I see the error of my ways - asking a question that has any relation to performance of the car seems to always elicit an obnoxious response from a member that also seems to be pretty helpful in other posts as long as performance is not mentioned. I'll be sure to not make that mistake again! Sorry!

I'm not a speed demon - obviously would not be interested in this car if I was. I have a 2100lb gas V8 powered sportscar when I wish to go fast. I'm about to turn 40, old enough to be over driving crazy. On the opposite side I don't drive like I'm pushing 80, either, having to watch the rear view mirror in fear of getting run over...

Ok, back to the actual question. I pulled the crossover pipe off, and it wasn't built up much inside. With pipe off i started it up - basically no airflow from turbo until revving it a little. Most vehicles i've done this on mov some air at idle. Pulled the air cleaner box and turbo inlet hose and was surprised at how nice the bearings felt. I've checked a lot of turbos and this one feels like it must have been rebuilt recently.

So, I guess Mercedes sized the turbo such that it does nothing at idle and even light load. Or could the waste gate be not closing all the way? Might even be that it's all working exactly as designed by Mercedes - that's why I went on a Mercedes board and asked....

Btw - would someone please clue me in on what DB stands for??

Oh - forgot to ask. How far down the exhaust system did they put the oxidizer on the updated federal systems? I have a muffler at the very back, and what I assume is a resonator near the differential. That seems too far back to be anything but a muffler / resonator. No sign of modification / removal up closer to the engine.

DB isn't Daimler Benz

The cat is the first item along the exhaust pipe under the car. It's just aft of the transmission before the flange.

Sixto
87 300D^2

I'm thinking no cat on this one then.

I have two 300 617 Turbo powered vehicles at this time. The 300D accelerates like the very devil is behind it. The 300DT doesn't accelerate much at all but is within the 4 second spec.

I have yet to figure out why - been working on other more important things on the wagon. I think it has something to do with the shifting of the transmission.

Try manually shifting your car and see if it gets up to speed faster. If so, you may need to adjust a few things.

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Codifex
1981 240D ChinaBlue (Got her running with a donor engine.)
1983 300DTurbo w/sunroof.
1984 300TD manual sunroof. (Electrical Gremlins)

if your car does not have a cat close to the turbo, you may still have the trap-ox on the system... look at your motor. does it have a large football shaped metal can above the exhaust manifold?

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!