Just bought my second w124 30. My first is an 87 om603 that I bought for $500 and fell in love with.(installed a Keychain and have been driving it since)

My 90 2.5 turbo that I just bought is not cooperating however.

Car has 285k. Starts immediately with no smoke or hesitation.

Turbo is spinning at idle but is very quite, almost too quite. The 87 turbo sounds like a jet engine, not this one. Normal?

Car doesn't smoke if you floor it. Has torque to about 2k rpms then hits a wall. Will rev to redline but takes a scary amount of time to get there.

I've been stalking this forum for awhile but I'm still getting used to mercedes diesel jargon.

My guess is the turbo isn't boosting. I tried to move the wastegate by hand when it was off but I couldn't budge it.

I have an adapter coming to attach my boost gauge Wednesday but until then, any suggestions where to start?

Welcome to the forum!
I would start with fuel filters. Change them one at a time, starting and idling for a minute between changes.

I would change the prefilter first, then the spinon.
If no improvement, move on to the fuel tank vent, or the intake pressure tubing, and safety circuit, known here as the ALDA hose/banjo bolt and over boost solenoid.

After that, the linkage should be checked for travel and stop.

Pictures?

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

1987 300TD
1987 300TD
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Thanks! All the filters are new, fuel vent seems okay. Linkages all seem to move easily except the wastegate. I'll post pics in a bit

Does this car have a switchover valve? If so, might need a new one or it might be unhooked.

On the left side of the intake manifold you will see a large electrical sensor, this is the boost sensor. Directly below that is a little hose fitting. This hose fitting connects to the Alda, which senses boost and enriches fueling accordingly. The fitting is a good place to attach a pressure gauge to measure boost. Just plug your gauge in and goose the engine. If you don't have boost, then remove the fitting and make sure it's not plugged with sludge, which would prevent the Alda from adjusting fuel. Then we'll go from there.

If your '87 whines like a jet engine, the turbo is toast. You really can't hear any turbo whine with these motors.

One thing to try is hook up the wastegate acutator directly to a vacuum source and go for a test drive. If performance improves, there's a problem in wastegate vacuum control. Don't leave things this way unless you have enough discipline to not drive with the pedal to the floor. Spare yourself needless diagnosis and go straight to - http://www.peachparts.com/shopforum/diesel-discussion/212097-wastegate-actuator-swap-om602-962-a.html

Sixto
MB-less

Sorry I had a brake line go so I've been screwing around with that.

I think the 87 turbo is fine, when I took the boot off that one there was no play. Maybe there's less baffling that year. I hope nothings wrong, it's sounds awesome.

Here's the 87. Best $500 I've ever spent. Looks like ****, droves amazing and I've spent no money on it. Easily the ugliest on the forum!

And the problem child. I'll test the boost tomorrow then I guess the fuel pressure then Alda?

According to my boost gauge, I have 3psi under full load...

I'll double check my fittings and readings tomorrow.

I did however get new Pirellis on today, so I got that going for me which is nice.

Remove the fitting from the manifold and inspect it for sludge. it's probably nearly clogged.

I'll do that but I just installed it all new like 24 hours ago lol

Have you done sixtos recommendation with the p2 flap?

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1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

Not yet, is the p2 flap the wastegate?, how much vacuum does it need? Does the vacuum keep it closed? Do they open when you turn the car off? It sat for a long time before I bought it.

So on my 91, there are 2 ufo's around/under the air box, currently I have them bypassed directly to the wastegate. See if that works for you as well. I have spare UFO's, just havent had a chance to test/fix.

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http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

How much vacuum does the wastegate require? I did another run after checking everything boost gauge related... I have 3 psi of boost.