My turbo works sporadicaly on my 85 300SD. For the past week it ran fine and then today it stopped working. If i let it sit for a few days it will work again. I know that there is a vacumme line that runs along the firewall to the intake manifold and sometimes that gets clogged. I checked the line and cleaned it out and there isn't a blockage. What could it possibly be? thanks, stephen

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68 250s SOLD
78 300d non turbo SOLD
1980 240d manual SOLD
1981 300SD 360,000 miles I think she's doomed for a parts car but has a good engine SOLD the engine to spamman
1977 300d non turbo SOLD
1985 300SD california car
1978 240D Manual

Can you describe the symptoms that indicate the turbo is not working? Have you checked the wastegate?

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

The noise that the turbo makes is a very distinct sound. the absence of this spooling sound as the RPMs increase and the lack of power that she normally has tell me that I have no turbo. What is a wastegate?
-Stephen

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68 250s SOLD
78 300d non turbo SOLD
1980 240d manual SOLD
1981 300SD 360,000 miles I think she's doomed for a parts car but has a good engine SOLD the engine to spamman
1977 300d non turbo SOLD
1985 300SD california car
1978 240D Manual

It's a pressure relieving valve which stops the turbo from overboosting. Maybe yours is sticking open. A search here will probably turn up a picture of it and its control mechanism.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Did you remove and clean the banjo bolt that is threaded into the back of the intake manifold (at the end of the line).

Did you ensure that the overboost protection valve is clean and that air will pass through it (solenoid at the other end of the line).

I did not take off the banjo bolt. so the solenoid is the thing on the IP side that has a vacumme line to the IP and is attached to the fire wall and has an electrical connection to it right? So i blow through one of the vacumme line to see if it is going through the solenoid. if that is the culprit....can i clean it to make it work or just replace it? thanks, stephen

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68 250s SOLD
78 300d non turbo SOLD
1980 240d manual SOLD
1981 300SD 360,000 miles I think she's doomed for a parts car but has a good engine SOLD the engine to spamman
1977 300d non turbo SOLD
1985 300SD california car
1978 240D Manual

Problem number one is the banjo bolt.

Problem number two is the overboost solenoid. You can clean it with brake cleaner.........but, don't go crazy..........it's plastic.

As a test, you can also bypass it. Run the line from the manifold directly to the ALDA............if the vehicle is transformed...........the problem is the solenoid.

IIRC....i cleaned the banjo bolt over the summer when I replaced the starter because that vacumme line was so brittle it broke when I was trying to get to the starter. I will check the banjo fitting and then the solinoid tomorrow. thanks, stephen

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68 250s SOLD
78 300d non turbo SOLD
1980 240d manual SOLD
1981 300SD 360,000 miles I think she's doomed for a parts car but has a good engine SOLD the engine to spamman
1977 300d non turbo SOLD
1985 300SD california car
1978 240D Manual

There is supposed to be no Vacuum in your Intake Manifold.

Some of the Older Mercedes Diesels without a Turbo have Fuel Injection Pumps with Pneumatic Governors have a Butterfly Valve in the Intake Manifold to create Vacuum for the Governor.
Otherwise Diesel Engines do not create Vacuum in the Intake Manifold unless something is restricting the incoming air (plugged Air Filter or as stated that Butter Fly Valve).

When was the last time the Air Filter was changed?
If you have a CA car for sure you have an EGR. The EGR could be opening a little at the wrong time or sticking.
On mine the EGR is controled by those White Plastic 2/3 Way Valves (correct name?). May be those valves are sticking and keeping the EGR open when it should not be.
When your car is running good pull the Vacuum hose off of the EGR Valve and plug the hose. Drive the car and see if your symptoms go away.

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84 300D, 82 Volvo 244Gl Diesel

Vacuum and EGR have absolutely nothing to do with the intermittent behavior of the turbo.

This morning I took the banjo bolt off, cleaned it, and it had some crud in it but after a test drive did not help the turbo. I connected the vacumme line directly to the ALDA and still nothing....Originaly i stated that it works intermitantly....now it has not worked for a week, cold or hot. Any other suggestions?
-Stephen

__________________
68 250s SOLD
78 300d non turbo SOLD
1980 240d manual SOLD
1981 300SD 360,000 miles I think she's doomed for a parts car but has a good engine SOLD the engine to spamman
1977 300d non turbo SOLD
1985 300SD california car
1978 240D Manual

What about the waste gate hose? I've had mine break with age and heat.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

..........and, without a wastegate hose........what happens?

Answer: No loss of power unless the head gasket fails due to excessive boost pressure

You're going to need a boost gauge for further tests.

where do you attach the boost guage...to the wastegate hose? i was reading that the the turbo not working could be the cause of an exhuast leak...how much of an exhuast leak make the turbo not work? Before the turbo stopped working i noticed that the wastegate hose was cracked and at the time didnt know what it was, regardless i replaced the hose. the time that hose was broken, could that have has an ill effect on the turbo? How do I take the wastegate off to diagnose? thanks, stephen

__________________
68 250s SOLD
78 300d non turbo SOLD
1980 240d manual SOLD
1981 300SD 360,000 miles I think she's doomed for a parts car but has a good engine SOLD the engine to spamman
1977 300d non turbo SOLD
1985 300SD california car
1978 240D Manual