Hi all,
I've had several 617's over the last 15 or so years (and still have a 82 300sd), so almost a year ago I bought an '87 300d and I love it, but alas I'm not as familiar with all the monkey motion yet as I would like to be.
First, I would like to thank gsxr, babymog, sixto, brian carlton, jeremy and all the others whose posts I've been reading lately. You guys have been a huge help to me to understand the 603.
Now the problem: My car still starts like a champ, idles very smooth, accelerates great UNTIL about maybe 2500 rpm, then it falls flat on its face. Just a total loss of power, kinda bucking, like its not getting any fuel. I can lift up outta the gas and slow down, and its smooth as silk again.
Sometimes I don't drive the car everyday and it sat for about a week before these symptoms started. It was fine before, adding to my confusion.
Things I've done so far:
Remove the gas cap (as I did notice a vacuum hissing, thought the vent was plugged) no change (NC)
Change both fuel filters (they were due anyway) NC
Hooked up a bottle of fuel (thinking maybe the tank screen was plugged) NC
Cleaned ALDA lines, switchover valves, press. sending unit. NC
Removed ALDA NC
Installed another (used) fuel pump NC
Checked exhaust pressure by installing a gauge where there is a plug on the manifold ~ maybe 2-4 psi. From this I guess the cat. is OK
Also, I connected a pressure gauge to the intake manifold and the most I got while driving was about 7 psi. Now I'm wondering if the wastegate is possibly stuck. But it still kinda feels like it could be a fuel starvation issue.
So I guess my question is is there a way to check the wastegate while its on the car? Or maybe someone has a better idea of what I should try next.
Sorry for the long winded post and thanks again for all the valuable info here.

Have you tried driving with the exhaust plug removed? Caution, it's loud (duh)!

Sixto
87 300D

Are you sure it's a KKK? Both my engines have Garret turbos. Hook a Mighty Vac/Pump to your wastegate line and verify rod/gate movement. The Garret turbo uses a pressure wastegate. Have not fooled with a KKK on a 603. Use the Mighty Vac/Pump and pressurize the ALDA directly, should hold 20 psi with no leakdown. If it does not hold pressure, remove the ALDA and drive the car again. If it holds pressure, install a boost gauge right at the ALDA with a "T" and pull it out where you can see it. Drive the car HARD. You should see 13 psi or more. If not you have a leak somewhere.The ALDA allows fuel enrichment under boost conditions. Let us know what you find.

KKK has banjo fittings between the compressor housing and wastegate actuator so testing the wastegate is tedious. The wastegate itself is enclosed and tucked under the turbo so it's difficult to access and impossible to verify as operational (that sentence didn't come out right).



If he already tested the car with the ALDA removed, what more value is there in cleaning and testing the ALDA?

Sixto
87 300D

Was the hard wastegate line a KKK feature? The lill KKK KP24s on my ECOdiesels had hard lines too.

-J

__________________
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Sorry, skipped over that part where he pulled the ALDA. Like I said, I have not fooled with a KKK equipted 603. From what the OP is describing, it sounds like fuel starvation when the boost comes on. Are the KKK turbos pressure actuated through the hard line with nothing else external?

bdtsr: yes, its a kkk like the pic sixto posted after your reply. I removed the alda completely and the rod that goes into the ip is moving freely. I drove it and all i could get was 7 psi at full throttle. (this is where it was breaking up at about 2500 rpm.)
sixto: no, I didn't drive it without the plug in the exhaust. I throttled up but didn't drive with the gauge installed and only got maybe 2-4 psi. Yes, your pic is the (possible) guilty party that's on my car.Thanks for confirming that.
Also, I forgot to mention that I removed the box under the air filter and wired the flap completely open just in case something had caused that to be closed, but again no change.

Ok. Maybe a tap or two with a small persuader on the housing might help? Was there a lot of black smoke with the ALDA removed and the pedal to the floor while driving?

I can't say for sure how much I was contributing to Al Gores greenhouse effect at full throttle. I really didn't see a big black cloud behind me but there must have been some. But I'll say this : I have seen more in the mirror when I'd kick it down a gear to pass someone. (before this problem started.)

Can you rev beyond 2500 rpm in neutral?

Sixto
87 300D

It revs freely and normally in neutral, all the way to the redline if it had one.

I'm tempted to suggest the IP pressure relief valve is sticking open. I don't know how to test it without replacing it until the engine won't start. Has anyone tried a FPR on the fuel tank return line?

Sixto
87 300D

sixto: I thought about that too and I have another complete ip with one in it. But I talked to an old master of rebuilding the bosch ip's and he said they very rarely go bad because its a metered orfice with a relatively weak spring to begin with, as opposed to the one on the 617 which actually has an adjustment in the fsm to stretch the spring. But I should probably put my other one in anyway I guess.

The weak spring is the problem. If the ball sticks open, there won't be enough pressure in the IP to feed the injectors under load.

Sixto
87 300D

May I suggest that you send a nice friendly PM to ForcedInduction .
He probably knows more about your turbo than most of us combined.
I dont think its the turbo that is the problem though.

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1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
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