Got another deisel!!!! - PeachParts Mercedes-Benz Forum

jerryyoung · #1 08-29-2003, 11:18 PM

Bought another 84 300DT today!! SHMBO saw it sitting in a driveway while she was out doing her yard sale thing. Called me at work saying it was in really good shape and that I should buy it!!!! Think I'll keep this girl!!!

The car is in real good shape, no rust, idles smoth as glass!! Good interior, paint (repaint), over all great shape , 215,000 miles, new transmission! Paid $2300, I think it's a good deal.

One problem - VERY slow on initial acceleration, I mean slow!! I have another 84 300DT and it goes when you press the accelerator. This one will get you run over!! After the engine reaches 2000 RPM, it goes like stink! Before that, look out. What do I need to check for this problem? I found no vacuum lines off, don't see anything visual wrong. Car has been serviced by Mercedes and/or supposedly competent independent shop. Seller said it has always been that way, thought it was normal!! Not so as my other 84 jumps (for a diesel) off the line.

The car has a 1 year old transmissiom, works very good.

So what could be causing the VERY slow initial acceleration?

Thanks

jassz · #2 08-29-2003, 11:28 PM

Congratulations! May you have many happy years together.

We had problems with acceleration when we first got Belinda. For us it turned out to be a problem with the throttle linkage. There was a tear in a rubber component. Fuel fliters could be another thought, but 'always been like that' makes me think it's not that (probably would have been replaced at some point, and if not, it would have gotten worse). Maybe the turbo?

It's like solving a whodunnit mystery... good luck Columbo!

#3 08-29-2003, 11:46 PM

Your ALDA could be set wrong.
Charlie

Plantman · #4 08-30-2003, 08:49 AM

What's an ALDA?

#5 08-30-2003, 10:08 AM

I would suggest

1. Change the air filter
2. Change both fuel filters
3. Clean the turbo boost line. (search to find out how)

Hold on and away she goes.

have fun

bob c

jerryyoung · #6 08-30-2003, 04:02 PM

Thanks!!
I'll try the above suggestions and report back.

mercedesmatt · #7 08-31-2003, 07:00 PM

if your ALDA lines are all clear, including the banjo bolt in the intake, you can adjust the aneroid valve on the i.p. to increase the respose time. very simple to do.

mercedesmatt · #8 08-31-2003, 07:02 PM

opps, i mean decrease your response time, sorry.

JimSmith · #9 08-31-2003, 08:36 PM

If the engine runs "like stink" after you get to 2000 rpm, and that means it has some power, I would not get too wrapped up in looking at things like the ALDA. The ALDA adds fuel to account for the increase in air being pumped into the cylinders when the turbocharger starts to build intake manifold pressure, when you push on the throttle. The ALDA is regulated by the increase in intake manifold pressure and throttle position. From your description, the engine is responding to throttle input fine when the turbocharger kicks in.

The problem you are experiencing sounds like sluggish performance before the turbocharger kicks in. Which is probably a throttle linkage problem. I would try readjusting the throttle linkage or at least verifying it is not interfering with something from full closed to full open. Also verify the full open position is really at the stop in the opening direction. Good luck, Jim

P.E.Haiges · #10 08-31-2003, 10:19 PM

Jerry,

Fuel and air filters would affect the engine power more at higher engine speed. If either will pass enough fuel and air when the engine is putting out full power, they will not affect low speed performance.

Does the transmission start out in low (1st) gear? If you start out in second gear, the acceleration would be less quick. Have you tried a manual shift to "L" when accelerating from a start? The transmission should stay in low until the engine reaches maximum RPM at about 25 MPH when you start out in "L".

P E H

Plantman · #11 08-31-2003, 10:50 PM

What's an ALDA? second time............

Lycoming-8 · #12 08-31-2003, 11:43 PM

Plantman.

The ALDA is an altitude compensator located on the top of the (IP) injection pump. It causes the IP to add extra fuel when the turbo causes boost, based on a signal from the intake manifold. Fuel add is supposed to be proportional to the boost level.

Plantman · #13 09-01-2003, 08:58 AM

Thanks.

#14 09-01-2003, 12:48 PM

Now I must conceed that there may be other causes to the problem but I do think that it is imperitive to change out all the simple causes first.

I forget, is this a new car. IF it is then you should change those filters out anyway.

Diagnosis of the problem is alot easier when you eliminate the easy stuff first.

IF the new filters and cleaning all the boost lines dont cut it then look toward the alda and turbo.

I would not adjust the alda or turbo waste gate until I knew for a fact that it was getting all the fuel and air it needs.

THe filters will cost you about 30 bucks and take less than 1 hour to put in.

And you have a good chance that it will solve your problem.

DO NOT ADJUST ANYTHING UNTIL THAT STUFF IS CHANGED OUT.

just my opinion

good luck

bob c

jerryyoung · #15 09-01-2003, 01:10 PM

All,
Thanks for all your suggestions. Yes, I have tried starting out in Low - same results. The transmission is starting out in Low as it shifts 3 times.

I will do all the filter changes, check linkages, etc. before I touch the ALDA. I am currently getting SWMBO's Jag airconditioning operating, then I can get back to the Mercedes.

Thanks for all suggestions, open to more if someone has one (I ain't proud, I ask before I break something!!)

I'LL post results as soon as I get back to the problem.