Re: 1993 300SD Turbo Diesel

Problem:

After operating for 20 min +- in cruise--65-70 MPH, turbo boost not evident. Note: Step-down solenoid operational, but turbo boost absent.

Any troubleshooting tips would be graciously appreciated.

Consider-observation: Recently, while replacing the alternator on the aforementioned vehicle, I manually cycled the wastegate diaphram linkage to wastegate in a very quiet work setting. It was then, that I faintly and consistently heard escaping air, or suction, near the LH side of the radiator in the vacuum lines. Normal? Abnormal?

Kindest regards,

Hal

Captain B-737/200/300/400 [retired]

Does the actuator hold vacuum?

Sixto
93 300SD

Thanks Sixto...

Have confirmed actuator/diaphram hold vacuum until the localized area gets warm/hot from engine heat.

Will re-address problem this coming week-- will share solution-resolution.

Hal

Do a search on a forum member who goes by oldsouth. He converted his turbo from vacuum to close the wastegate to the more traditional pressure to open the wastegate. Bypasses the business of the ECU deciding when you deserve boost. Consider emissions laws, of course.

Sixto
93 300SD

Tnx Sixto...

Resolution: Came down to a ground wire torn loose previously by a shredding serp-belt.
Said GRD wire near the two valves under the passenger side headlamp access port.

Like the idea of a non-ECU regulated boost.

Thanks again, will educate self and the investigate further.

haltron

Turns out the grd wire was only part of the problem causing intermittent turbo boost.

Final problem resolution came down to the vacuum 'power converter'--sometimes called ' vacuum transducer' on older models.

To date, the turbo-boost on aforesaid vehicle appears normal.
i.e. plenty of getty-up-and-go.

Plan to clean the EGR later.

Wanted to share this with those of you that have been so gracious to
provide input.

Thanks a bunch...

Haltron

Is the power transducer the electrical solenoid that serves as protection device in addition to the waste gate? On the driver side wheel well?

I bypassed mine - performance went from awful (mid 20s to 60 mph) to around 11 seconds or so - cleaned valve, still performed terribly ... left it bypassed for last 5K miles or so ... am I doing any damage (assuming the wastegate is still operating)?

__________________
George Stephenson
1991 350 SDL (200K and she ain't bent, yet)
former 2002 E320 4Matic Wagon - good car
former 1985 300 CD - great car
former 1981 300 TD - good car
former 1972 280 SEL - not so good car
a couple of those diesel Rabbits ...40-45 mpg

George,

Re: 1993 300SD Turbocharger Wastegate?

The 'power converter' sometimes called a vacuum transducer on aforesaid vehicle is located slightly below the passenger-side headlight.
Yes, this part appears to be a modulating electro-vacuum solenoid controlled by the ECU.
Dealer cost ranges between $125 wholesale, $138 retail.
Simple to install--requires less than 1 hour with metric socket set.

Kudos and good luck,

Haltron