I've tracking this ploblem of a sluggish car for a little while and I think I have checked the usual suspects. I ran a boost gauge off the intake manifold yesterday and I only get 3 psi of boost at 4000 rpms. The impeller seems to spin freely and didn'y wobble around or anything. I do have a little exhaust leak in the flex pipe between the two exhaust manifold parts.

Anybody got ideas?

nate

The EGR? Remove it and install an EGR blocking kit.

Then adjust the wastegate actuator spring tension.

Make up a T and get a boost reading between the overboost valve and the ALDA. Report back with results.

My 83 would only make 5 lbs of boost max and I checked all the Alda stuff, Turbo, wastegate etc. Turned out to be a plugged muffler. It ran like a scaulded dog after the muffler was replaced. Boost jumped to 10 PSi in a heart beat. Just something to consider Russ

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1978 300 D 258,000 + miles sold 1995
1983 300 D Turbo 152,000 miles
Thank God for the man who put the white lines on the highway

Wastegates on the 603 engines can get partially stuck open and this prevents boost from forming properly. best way to check for this problem is remove the turbo and work the wastegate while scraping carbon, if its there and the gate isn't closing completely.

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!

Oh yes, BTDT. Does this '87 still have the NASTY TRAP OXIDIZER on it? Even the replacement trap under the car can get plugged too.

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!

Pressure was read at 4000 RPM with the car running down the road or on a dyno, right? If not its not a worthwhile reading

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!

first off thanks for the help. no trap oxidizer, 3psi was running down the road when I did a bunch of speed runs last night.

Okay I went did some more speed runs today with the boost gauge. Now I am confused but happier.
First couple 0-70 at wot I only read 3.5 psi with the gauge hooked to the intake manifold directly.
next I tee'd in between the overboost valve and the alda and got a record 5psi on first run then got it up to 6psi then 7psi on consectutive runs. So I kept doing it(about a dozen throttle ups) and eventually got the gauge up to 11psi.
Did I just do an italian tune up?

nate

I would double check the line going to the alda for restrictions if nothing found disconnect the hose going to the waste gate then try it. If you get propor boost with the waste gate hose disconnected it's not adjusted proporly.

Does anyone know what exhaust pressure should max out at on a turbo diesel? On a gas n/a engine it's about 3 psi max.

Italian tune up yes, and it makes me think maybe there is lots of crud in the cat, that being the new trap thing under the chassis, not the big football shaped trap that originally came on the car.
There is a test in the FSM for exhaust pressure, I believe have seen it there. The plug at the front of the exh manifold comes off just for measuring exhaust back pressure.
There could be crud in the line to the alda and in the intake manifold itself. I saw a recent post by someone that said they saw a 603 with one port of the intake plugged so small you could hardly poke a pencil thru the passageway to one cylinder!

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!

Sorry, don't want to hijack this thread, but I'm just curious - could someone comment briefly on what it takes to take off the intake manifold?! I wouldn't mind checking around in there as my Banjo bolt was full of Crud - I can just imagine what the insides of the IM ooks like... is that something that can be cleaned fairly easily?!

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1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K

Just a combo wrench on the back of the manifold. They're usually full of crap.



FWIW on the 603s from '87, I gutted my under car cat also. One less thing to have to worry about down the line... simple job, just messy and time consuming.

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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 think he meant remove the entire intake manifold. On the '83 its not a heck of a lot of work, it straddles the exhaust manifold. Take care with the studs if any seem stuck don't break them off. Use copper clad nuts when replacing.

On the '87 its a bunch more difficult thanks to it being on the drivers side and the injector lines run under and along side of it.
You may find like I did that it takes a boiling out in the parts tank plus a can or so of Carb Cleaner to get the gunk out. Its inevitable that gunk will build up there again, but a bb in the vac line or blank off plate (for testing purposes) to the EGR valve will help a lot to prevent it from getting plugged again.
And don't even think about using carb cleaner on the manifold while its attached to the engine!

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!

Ohhhh okay! Yes, the 603s are a bit harder to remove due to the stuff in the way. Not too bad, but a bit harder. If you're pulling it, replace the glow plugs and crank the ALDA up. About one full turn CCW seems to be a good starting place.

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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]

Remove the fuel filter, drain it, and fill it with the injector cleaner of your choice and put it back in. I used SeaFoam. Then I did my speed runs. On the third things started picking up and I was putting out a HUGE cloud of black smoke. By the 5th I was doing 10-12 second 0-60's with little/no smoke. Injector cleaner can do wonders.

-Jim

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1995 S350D, Green with black leather interior.
Bought January 2008 w/ 233,xxx miles.
I did 22,000 miles during the first year of ownership.