Some issues - PeachParts Mercedes-Benz Forum

bd1308 · #1 09-10-2011, 01:01 PM

Yesterday I drove the 300D about 50 miles just to feel its real condition. It's definitely missing turbo action. Turbo spins freely, but I think something is wrong with the turbo vac lines that I can't seem to track down. The ALDA banjo bolt is clean and the tube is clean. The switchover valve (black box) might also be wired wrong, because i've seen pictures of them where the top rubber tube doesn't have anything in it.

Replaced fuel filter, air filter needs replacing, oil change and valve adjustment all need to be done. But I feel like not having boost is the main performance issue im having now.

jt20 · #2 09-10-2011, 01:04 PM

Bypass the switchover valve.

If you find an improvement, but want to keep the switchover valve in the circuit (not really necessary), clean it out with solvent.

bd1308 · #3 09-10-2011, 03:30 PM

Okay cleaned the switchover valve, and I hear the turbo now but its still not really accelerating well past maybe 3000. Will needing a valve adjustment cause this? I replaced the fuel filters and cleaned out the ALDA line and now the switchover valve. From 1500 to 2500 the acceleration is pretty good, from about 3000RPM its not good at all and from 3500 and up its awful (only happens a few times when I need more juice from the accelerator and i hit the kickdown)

jt20 · #4 09-10-2011, 03:38 PM

look on the passenger side of the IP. There is a lever arm there that controls the IP rack travel. If this is not hitting the horizontal stop bolt when you fully depress the pedal, you need to adjust the linkages.

But regular maintenance items, like the valves, are critical as well. After that, timing might be the next step.

bd1308 · #5 09-10-2011, 03:46 PM

Thanks for your help. These diesels are much different than the gassers ive had before. I love this car though. I'll check that and report back. Any idea why the metal linkages would need adjustments?

tyl604 · #6 09-10-2011, 03:58 PM

Switchover valve from my 81 300SD; think yours is the same. If you have the new style switchover valve, notice the orientation which looks upside down from the way the old style switchover valve was installed. On the top side you put the hose on the nipple that is horizontal to the ground; the other nipple which points to the sky is supposed to be open. The third one is on the bottom of the switchover valve.

When my old one went out, I installed this new style one and got the hoses mixed up. Could not get over about 30mph; it was sluggish and just terrible performance. Went back home, searched the forum and finally found which hoses to connect where. Instantly the power and pickup came back.

You might just have the hoses mixed up. See pic.

bd1308 · #7 09-10-2011, 04:03 PM

My tubes are definitely backwards from your picture. I should change them around? Isnt the switchover valve two way?

tyl604 · #8 09-10-2011, 04:07 PM

Do not know about two way but try hooking the hoses up like mine. Could work. Actually I think the switchover is designed to open and vent to the outside to prevent overpressure in the turbo.

bd1308 · #9 09-10-2011, 04:42 PM

The throttle linkage really does need to be adjusted. it seemed like the other linkages were alright but the linkage to the IP was at like 50% when the throttle was at the floor. I'm going to try and adjust the cap (after seperating the ball and cap socket) and adjust the socket at the firewall? Or is there an adjustment on the accelerator pedal that should be adjusted first?

carnut · #10 09-10-2011, 04:50 PM

Adjust it at the firewall 1st. The rubber at that pivot can be worn out. That pivot hole is elongated, allowing adjustment. Have someone hold the in car throttle to the floor and adjust the pivot point. That is the throttle pedal adjustment

bd1308 · #11 09-10-2011, 10:03 PM

That seemed to help alot...well until I started getting "missing" and running rough today. Guess I need to check the in-tank filter screen or do a diesel purge. Getting things fixed one step at a time...

jt20 · #12 09-10-2011, 10:24 PM

Quote:

Originally Posted by bd1308

That seemed to help alot...well until I started getting "missing" and running rough today. Guess I need to check the in-tank filter screen or do a diesel purge. Getting things fixed one step at a time...

Excellent.

Diesel purge is kind of innocuous. But some like it. I think you nailed it with the tank screen and throttle linkage, so far. Keep it up.

bd1308 · #13 09-11-2011, 04:42 PM

Actually it was the primer pump. Its the white plastic one that is apparently NLA now. I had it closed, and was messing with it yesterday in a fit of ADD and forgot to close it all the way. I'm assuming air in the system will cause all kinds of issues. I closed it and it seems to run better today.

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