300SD acceleration problems - PeachParts Mercedes-Benz Forum

BenzOil · #1 03-15-2007, 11:24 PM

This is my 1st time posting here after a referral from the biodiesel & svo discussion forum. My 300SD was converted by a mechanic to run on an Elsbett 1 tank system. There's been a few minor maintenance issues that kept me from driving it much, though it has just 185,000 miles.

After replacing the filters from clogging after the mechanic road tested with wvo, I noticed the acceleration from a stop was noticeably slower than usual. The air was purged from the system and it seems to idle fine. However, it takes a long time to feel the tranny shifting.

I'm sure the cause is a vacuum leak in either the fuel lines or transmission. I've been told there's a way to defeat the vacuum switch by shifting the gear lever to 1st (how can that be done when the lowest gear on the console is 2nd?). If I can "defeat" this switch, it would tell me if that's the problem, or if it's with the fuel.

I'll admit I have very little experience with diesels, but I've driven a 300D non-turbo and the acceleration was faster.

kerry · #2 03-15-2007, 11:27 PM

I'd guess a fuel delivery problem or perhaps an accelerator linkage problem. Seems unlikely that it's a vacuum problem.

bellyboy · #3 03-16-2007, 10:38 AM

i would encourage you to do a search for "banjo bolt" and "alda adjustment"

- it made a big difference for me

rrgrassi · #4 03-16-2007, 10:41 AM

Also check the hard lines between the intake banjo bolt, turbo switchover valve and ALDA. Also check the turbo switch over valve for proper operation.

Also check the wastegate and make sure it's not stuck open.

GRIESL · #5 03-16-2007, 11:36 AM

Quote:

Originally Posted by BenzOil

This is my 1st time posting here after a referral from the biodiesel & svo discussion forum. My 300SD was converted by a mechanic to run on an Elsbett 1 tank system. There's been a few minor maintenance issues that kept me from driving it much, though it has just 185,000 miles.

After replacing the filters from clogging after the mechanic road tested with wvo, I noticed the acceleration from a stop was noticeably slower than usual. The air was purged from the system and it seems to idle fine. However, it takes a long time to feel the tranny shifting.

I'm sure the cause is a vacuum leak in either the fuel lines or transmission. I've been told there's a way to defeat the vacuum switch by shifting the gear lever to 1st (how can that be done when the lowest gear on the console is 2nd?). If I can "defeat" this switch, it would tell me if that's the problem, or if it's with the fuel.

I'll admit I have very little experience with diesels, but I've driven a 300D non-turbo and the acceleration was faster.

Did you change tank strainer when you did filters? Mine clogged and had same symptoms. I would set up a fuel cell under the hood wiith a gallon jug and then observe performance. The next test would be like as has been mentioned with the alda and overboost valve. You should be able to find archives on this list regarding testing the valve by disconnecting the hoses. I've never done that test, so I don't have details on it. Good luck!

BenzOil · #6 03-17-2007, 08:28 PM

ALDA adjustment done, slight improvement but the car really doesn't get up and go until it hits 2nd. Less smoke, engine seems quieter, but it still takes 10 seconds or so to go from 0-40 when 2nd engages.

GRIESL · #7 03-17-2007, 09:29 PM

Quote:

Originally Posted by BenzOil

ALDA adjustment done, slight improvement but the car really doesn't get up and go until it hits 2nd. Less smoke, engine seems quieter, but it still takes 10 seconds or so to go from 0-40 when 2nd engages.

Ten seconds to 40 isn't that much more than what mine does--I'm gonna check it tomorrow. I get to 60 in about 16 seconds (on petro--18 secs on b100), which I thought was about normal. What color smoke do you have? Does the SD still seem drastically slower than the N/A 300d you've driven?

mespe · #8 03-17-2007, 09:30 PM

10 seconds from 0-40 is pretty close to allright, gotta remember starting form 0 it takes a few seconds to get going. hows the 40-60?

BenzOil · #9 03-17-2007, 11:32 PM

Once the car gets to 40, it takes off. The non-aspirated 300D I drove had significantly more power, quieter than any diesel I've ever heard before. The SD would spew some grey smoke on startup, smelled like pure veggie oil, but it's been reduced by the ALDA adjustment.

I forgot to mention that when I bought the car, it was already running half diesel, half vwo without modifications and there was very little smoke on start up, acceleration was good. Have not checked tank strainer, don't have the proper place to work on it.

GRIESL · #10 03-18-2007, 05:33 PM

Quote:

Originally Posted by BenzOil

Once the car gets to 40, it takes off. The non-aspirated 300D I drove had significantly more power, quieter than any diesel I've ever heard before. The SD would spew some grey smoke on startup, smelled like pure veggie oil, but it's been reduced by the ALDA adjustment.

I forgot to mention that when I bought the car, it was already running half diesel, half vwo without modifications and there was very little smoke on start up, acceleration was good. Have not checked tank strainer, don't have the proper place to work on it.

EEyikes, wvo with no mods? You may want to look at a thread called 300td cold compression check.