Help on Improving 0-60 82 300sd - PeachParts Mercedes-Benz Forum

82300sd · #1 01-30-2007, 06:35 AM

Hi All,

New oil change.
New air filters.
I've had this car for a year now and drive it daily but I have not really focused on improving it's performance. Current 0-60 is at 50 seconds. My kickdown cable is broke since I got it. Mechanic just tied a wire to secure it properly and said it should be ok. My top speed using the GPS is 125kph. Any suggestions on where I first start? Cheapest and easiest to do first.

TIA

Ara T. · #2 01-30-2007, 06:50 AM

Jesus christ..

First thing I'd do is change fuel filters (both), diesel purge, adjust valves, check timing. Probably in that order. You are revving the engine all the way right? Should spin up to at least 4500 RPM.

82300sd · #3 01-30-2007, 06:55 AM

Sorry...I have already replaced all fuel filters. The pre filter, main filter, and the one at the fuel tank. My tach is not working.

MS Fowler · #4 01-30-2007, 07:11 AM

Wow, 50 seconds!!

Well, the problem is not the broken tach. My 82 300SD also has a broken tach, and probably gets to 60mph in under 12 seconds. I'll have to check that next time I have it out.
I think I'd check the line from the manifold to the ALDA, and the elbow, too. I might even run a temporary tube to a pressure gauge in the cabin so I could monitor boost pressure.

winmutt · #5 01-30-2007, 07:38 AM

Adjust and clean the alda, check your boost. Also is the muffler new/old?

RUN-EM · #6 01-30-2007, 07:44 AM

Adjust valves,CLEAN THE BANJO BOLT ASSEMBLY, do Italian tune up, run diesel purge, adjust alda to achieve more fuel delivery. Replace the shift levers in the linkage unit on top of engine. Then you might borrow a boost guage and check if you are getting more than 7-8 lbs. boost. These old boogers were set factory for about 13-15 lbs. of boost...and unfortunately, the old pop off springs get tired. You can either reset the old spring unit on the turbo, or buy a simple mechanical boost limiter off of e-bay for a few bucks (prolly less than $25.00). Then adjust the boost to the 13-15 lb level and let it ride. The best hp/$$ investment I made on old SPARKY was the banjo bolt cleaning. Oh, yeah, plug the egr valve....it dilutes the intake charge with pre-burned mix and will sticky up the intake system if nothing else.

Regards

RUN-EM
1983 300 SD--aka--SPARKY THE DIESEL

pawoSD · #7 01-30-2007, 08:19 AM

By kickdown cable do you actually mean bowden cable?

The kickdown on these cars is electric, and is simply a switch on the floor of the car under the throttle pedal.

I think you have no boost...50 seconds sounds about right for a "Naturally aspirated" 300SD

Clean the line from the manifold that feeds boost pressure to the injection pump, it is likely the source of your problem.

82300sd · #8 01-30-2007, 08:35 AM

Quote:

By kickdown cable do you actually mean bowden cable?

It's the cable connected on top of the engine cover with a groved rubber cover. I don't know how it is called. Does it have any effect on my 0-60?

Quote:

I think you have no boost

Does this mean my turbo is not kicking in? How do I know if my turbo is working? This could be the possible culprit since I can only top 125Kph.

Quote:

The best hp/$$ investment I made on old SPARKY was the banjo bolt cleaning.

Bajo bolt cleaned less than a year. How often should it be cleaned?

Quote:

Oh, yeah, plug the egr valve....it dilutes the intake charge with pre-burned mix and will sticky up the intake system if nothing else.

What is the effect of plugging the EGR? How do I go about it. My mechanic recently replaced the vacuum valves on top of the cover and connected my EGR back. Said my car should run faster but I still get the same 0-60 aftewards.

I will have the boost line checked tomorrow and update you guys.

pawoSD · #9 01-30-2007, 09:01 AM

Quote:

Originally Posted by 82300sd

It's the cable connected on top of the engine cover with a groved rubber cover. I don't know how it is called. Does it have any effect on my 0-60?

Does this mean my turbo is not kicking in? How do I know if my turbo is working? This could be the possible culprit since I can only top 125Kph.

Yes, that cable is the bowden cable, if it is broken the car could very likely be immediately shifting into 4th gear, do you ever feel it shift? I am betting it goes....standstill -> 1.2.3.4, and then all your "acceleration" is taking place in 4th gear potentially. The bowden cable holds the transmission in each gear longer based on how depressed the throttle pedal is. Does the engine ever actually rev up? Is the throttle linkage in good adjustment? I just got a 300D that has so much slop in the linkage that pressing the pedal halfways down barely gets the engine above an idle....I'd check that too.

The turbo likely is working fine (they rarely fail) but the Injection Pump might not be getting the boost pressure signal, meaning no extra fuel and then it acts like it has no turbo.

Check:

1. Bowden Cable, replace if broken
2. Throttle Linkage, make sure its moving the full travel smoothly
3. Boost line

barry123400 · #10 01-30-2007, 09:38 AM

This car may have had no basic attention other than filters for a dog's age. I would start at the beggining and go through a total tunup procedure. Read lots of posts in the archives for guidance. Plus ask questions. These are tha kind of cars that a new thread is posted somewhere along the road that the timing chain is gone. So easy to prevent but almost impossible to fix the damage after the fact.
I agree the car probably has no boost as well. Wiring on the bowden cable does not sound too proffesional but might be. I also do not think it limits your top speed although could have a major effect on acceleration. The top end would still be normal though and yours is not. But to overlook everything else and just focus there is a bad ideal. You want your complete engine at maximum efficiency. As well you also want it to stay together. The valves are supposed to be checked for clearance every 15 thousand I believe. The chain stretch and injection and pump timing and timing chain and chain guides. Every 60 thousand as well or is it 30 thousand? Maybe a lot of the items I mention where checked in recent history. If you do not know they where they should be checked.
On quite a few cars I have seen with no service history these items could not have been checked in less than the last 100k miles in my opinion. No better way that I can think of to become familiar with your car as well. Do it yourself with the help of this site and a friend with some mechanical aptitude to help if reqiuired .You will save yourself a fortune over the years.
Even on old guy like me would not live with a 0-60 time approaching 50 seconds.It is dangerous for starters even in a rural area like I live in. These cars are also so easy to learn on it's not funny with a little help. You may also want to find another mechanic more familiar with mercedes diesels if you do not want to do anything yourself. Again I do not think these are the cars to keep running to mechanics with. Much better to learn yourself. Save your money as you will be needing it for other things as time goes by.
Get to know your car. Just my two cents worth by the way. You and others might feel differently.

rrgrassi · #11 01-30-2007, 10:57 AM

Along with the Banjo bolt, check the turbo switch over valve and the hard lines as well. The turbo switch over is between the banjo bolt and the ALDA. Just follow the hard lines.

82300sd · #12 01-30-2007, 12:27 PM

Quote:

The chain stretch and injection and pump timing and timing chain and chain guides. Every 60 thousand as well or is it 30 thousand? Maybe a lot of the items I mention where checked in recent history. If you do not know they where they should be checked.

Valve adjusted within 10k miles. It still does 30miles to a gallon on highway runs proving its efficiency. I'll probably look first at the boost. I believe this is what i've been missing since my previous 1979 300sd 10, which I had 10 years ago, accelerates faster than my sd now. I hope there will be no major trouble when I have it checked later

.

benzforlife · #13 01-30-2007, 02:14 PM

to check if ur turbo is working, with the car turned off stick ur hand into the turbo and spin the wheel to check for play, something is definetly not right, it could be your injection pump?

Hatterasguy · #14 01-30-2007, 02:39 PM

In peak tune you should be able to do 0-60 in about 12 seconds. Look at some of the above suggestions and try those first. Timing it is probably a good idea as well.

MS Fowler · #15 01-30-2007, 08:31 PM

According to a road test on an early non tuirbo 300D in Road and track, 1975, 0-60 was 20.1 seconds. If your car is taking 50 seconds, something is definitely amiss.