Does anyone ever have their Wastegate Adjusted?

In your professional expirience, do 300DT owners ever have their wastegates adjusted to compensate for spring wear???

IF EVERYTHING IS WORKING PROPERLY YOUR WASTEGATE HAS NEVER OPENED IN ITS LIFETIME (NO WORRY ABOUT WEAR).
THE WASTEGATE IS ONE OF TWO PARTS DESIGNED TO PROTECT AGAINST EXCESSIVE BOOST.
THE SECOND PART IS A PRESSURE SWITCH ON THE MANIFOLD,WHEN THIS SWITCH CLOSES A SWITCHOVER VALVE ON THE FIREWALL CHANGES POSITION AND DUMPS BOOST PRESSURE FROM THE ANEROID COMPENSATOR,THIS REDUCES FUEL QUANTITY TO THE ENGINE.WHEN FUEL QUANTITY IS REDUCED SO IS BOOST.
MF

Thanks for the reply! I was just curious because the Diesel Forum speaks about adjusting wastegates to get more turbo boost... Adjusting for spring wear, to get to 13.5psi of max boost. Some drivers even put boost controllers in to ensure it! Just wanted a tech's opinion of the matter. Thanks again.

[Jim Anderson]

I just went around on this on my wife’s turbo gas Peugeot, and I’ve had a turbo diesel Peugeot. A waste gate is an integral part of turbocharging an engine. I’ll admit its more important on a gas than on a diesel. The max boost is designed to happen at medium power and the waste gate dumps anything over that around the exhaust fan. I’ve had the waste gate actuator fail on both the gas and diesel with different results. The gas goes over-boost very quickly and the ignition cutoff interrupts the show and the car in pretty much undrivable that way. The diesel on the other hand had a barely noticeable increase in power. I don’t know why the difference, whether the diesel was under boosted, or didn’t care, or was loosing intake pressure cause of the failure, or what. All I know is that the un-waste gated turbo gas could have chased down a 500e before the boost got cut off.


BTW my turbos have a screw adjust for max boost.

[oldsouth]

Mercedes uses a vacuum operated wastgate so they can control boost with the computer. Less vacuum - less boost. The computer does not cut fuel, it cuts boost which in turn cuts fuel through the aneroid valve. Excessive boost does not melt a diesel, excessive fuel does. Low boost rusults in less power in part because the aneroid valve is not opening up enough to let in full fuel flow. At least that is the way it works on a 1995 S-350.

ON THE THE 85 300 TURBO DIESEL ENGINE YOU WILL FIND A "PRESSURE" LINE FROM THE COMPRESSOR HOUSING TO THE WASTEGATE,IT TRANSMITS BOOST PRESSURE TO WASTEGATE.
ON 84 AND 85 TURBOS THERE IS A VACUUM LINE TO THE BYPASS VALVE ON THE COMPRESSOR HOUSING,THIS BYPASS ALLOWS THE COMPRESSOR SPIN-UP WITH OUT CREATING BOOST IN THE MANIFOLD DURING E.G.R. "ON" PERIODS.
THE WASTEGATE AND FUEL CUT-OFF WERE ONLY INSTALLED AS PROTECTIVE DEVICES AGAINST COMPRESSOR SURGE (A VERY DESTRUCTIVE EVENT THAT OCCURES WHEN THE TURBO HAS RUN-AWAY BOOST)
WHEN THIS ENGINE AND TURBO COMBINATION WERE SELECTED CAEFUL CONSIDERATION WAS GIVEN TO PREVENT SURGE EVEN WITHOUT THE WASTEGATE AND FUEL CUTOFF.
MF

[engatwork]

Mike - could you email me please - I have a question concerning your post.
Thanks

95 OUT OF 100 CRUISE CONTROL PROBLEMS ARE JUNK CRUISE CONT. AMPS!
DON'T WASTE YOUR MONEY ON A NEW O.E. UNIT THE'RE JUNK RIGHT OUT OF THE BOX
THERE ARE SEVERAL REBUILDERS THAT MAKE GREAT PRODUCTS WITH GREAT WARRANTEES
MF

[be459]

Originally posted by MIKE FREEMAN
......

ON 84 AND 85 TURBOS THERE IS A VACUUM LINE TO THE BYPASS VALVE ON THE COMPRESSOR HOUSING,THIS BYPASS ALLOWS THE COMPRESSOR SPIN-UP WITH OUT CREATING BOOST IN THE MANIFOLD DURING E.G.R. "ON" PERIODS.
......
MF

Correct me if I am wrong. I thought the bypass valve on the 84 and 85 years is for California only. I am in California and I never have a chance to look at a non-Calif model to verify it. The bypass valve is part of the smog system controlled by an electronic module. I heard that it delays the turbo boost until ~2500 rpm. I do not know how it is related to the EGR but I know the fact that if the vacuum line is disconnected, the car seems faster.

The reason people want to adjust the wastegate because the wastegate is either below specification (due to weakening of spring) or not at the upper limit of the specification. You want to adjust it to the upper limit so you can get as much boost as possible. But the adjustment task is not easy. A work around method is to install a manual boost controller as some of our members here doing successfully few months ago. I am thinking of doing it too instead of adjusting the spring.

The wastgate on these old diesel engines (617) is just mechanical, no electronic stuff involved. I think the way the manual boost controller work is to control the pressure line and allows the pressure to reach the wastgate only when the pressure reaches the upper limit set by you, therefore, prevents the wastgate from open early. Once it is open, turbo boost stops.


David

[h2odiesel]

Original factory spec is .9bar or about 13psi with the over boost switch cutting in at 1.1 bar. In the upper rpm ranges the waste gate is open to bleed off pressure. These turbos will make up to 40psi if not gated. Most that I check if they have not been adjusted make around 9psi. Here is a good link
http://hsb.baylor.edu/html/easley/autofaqs/wgate.htm

[oldsouth]

On my 1995 S-Class diesel, I just had the turbo overhauled. Upon installing I ran the car with no wastegate and the most pressure it would build was about 27-28 psi boost. Could not tell any difference in 0-60 time or feel of the car with wide open boost or 14 psi boost that I adjusted it to. Remember, it is not boost, it is a combination of boost and fuel that make a diesel go.

[h2odiesel]

I couldn't agree more. It takes boost and fuel to make power. I am fairly sure that your model electronically limits the fuel enrichment. I don't think I'd try to encourage the 3.5L to make any additional power. When they are running well they are great. Give a prayer of thanks and enjoy it.