my 300sdl has only 3 to 4 lbs boost. Our local independent mech say's it's a bad turbo,but the turbo spins freely, by hand and when air is forced in. Have everything off ready to pull the turbo, but don't want to if there is a possibility of another solution. Thanks for any help

How did you measure the boost?

What's the 0-60 time for the vehicle?

The mechanic did the test. Never checked 0 to 60. mechanic has one just like mine and it's much faster. also lots of smoke.

We don't have a very high regard for mechanics...........they typically haven't a clue what they do..........just replace parts until the problem goes away..........or not.

Without any data, others will take some wild guesses............just like the mechanic.

Clogged cat (trap) could slow it down.

How can i check for this?

You could remove the plug in the exhaust manifold around the #1 and 2 cylinders. This may relieve enough back pressure to make a difference, if clogged. Easy to do and does not cost money.

My car was lazy above 3000 rpm. Removed exhaust pipe and emptied the cat.

Check throttle linkage for full operation. Change fuel filters. If tank filter is clogged, switching feed and return lines will bypass it.

Overboost relay can be full of ****, mine was and made my car a slug. Then my cat was also plugged, gutted that and the car runs fantastic.

I would purchase a simple vacuum/boost gauge so you can do your own testing. You need vacuum to set the trans system on it and boost, to you know... see how much you are getting. It could easily be making proper boost... or not. Spec is about 13psi. A bad turbo (think seized) would make NO boost and the car would barely be able to run due to the exhaust restriction.

I second inspecting the throttle linkages, the ones by the firewall have a small nut. 10mm? That likes to become loose over the years causing lack of travel to the IP making the vehicle slow. I had this on my SDL and SD, both would necessitate a running start to merge into city traffic when I purchased.

Hell, you could have a bad ALDA preventing fuel enrichment.

__________________
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]

pulled the bolt on the manifold, and blew it out. Where exactly is the overboost relay? Guess will gut the cat. Glad didn't order anew turbo. Thanks