Figured I'd post this in here also. Not really sure where to go from here. I think I still have a Mercedes manual for my 300sd I used to have I'm going to look for this weekend

I'm starting to think I need to replace my injection pump: (
I know it's a rare problem but I'm not sure where else to look. I've got a best beautiful 81 300d. It's got 125k and by the look of the rest of the car I think it's been well cared for, I even have original purchase receipt from Lubbock Texas. From the time I bought it about a month ago it's shaken like a paint shaker and I cant seem to get idle to lower enough by adjusting idle adjustment. I'm not sure what it is but it's obviously a little high and when in drive it wants to push the car almost. I've changed both fuel filters, changed injectors with another set off another car(and new heat shields, did valve adjustment, I checked injection pump timing and it's good, engine compression check showed even in all cylinders, engine mounts replaced, it also has vibration driving down highway slightly. I don't see air bubbles in the hard lines. What else can I check? I'm running out of ideas. Not my first one. I've also got a 240d and used to have a 300sd with an odometer that stopped at nearly 300k. That car ran great! I was really excited about this one. It's a beautiful car

I'm in the middle of this. Air in fuel lines, injectors, rack damper bolt, compression, injection pump delivery valves, timing, idle speed.

__________________
85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

Try the rack damper bolt first. Easy to install.
Fixed the shaking in my engine when I first got the car.

Jeff

__________________
1984 300SD 300,000 miles--two tank WVO setup
2.88 diff & 500SEL anti-squat rear end

How are your motor mounts? A car will shake with poor motor mounts, also.

W.

It is an '81 300D which should be non-turbo, so no rack damper bolt.

__________________

All Diesel Fleet
1985 R107 300SLD TURBODIESEL
2005 E320 CDI (daily)

LOTS of parts for sale!


EGR block kit
http://www.peachparts.com/shopforum/diesel-discussion/355250-sale-egr-delete-block-off-plate-kit.html

1985 CA emissions 617 owners- You Need This!
Sanden style A/C Compressor Mounting Kit for your 616/ 617 For Sale + Install Inst.

Sanden Instalation Guide (post 11):
http://www.peachparts.com/shopforum/diesel-discussion/367883-sanden-retrofit-installation-guide.html

Rich, Thanks....see what I know. Never had a non-turbo.
I keep learning stuff on this site all the time.

That rack damper bolt, though, is an amazing little invention.

Jeff

__________________
1984 300SD 300,000 miles--two tank WVO setup
2.88 diff & 500SEL anti-squat rear end

It might be worth checking lift pump supply pressure. If the lift pump is worn, or the overflow valve is stuck open, low supply pressure can certainly cause a rough idle or fuel starvation issues.

Since this is a 61x engine, make sure you have the upgraded style of primer handle. The early style seem to be prone to air leakage. Air is your enemy in the fuel system on these things!

For what it's worth, I went through rough running issues on my SDL. Different engine, but similar fuel delivery system. In my case, the rocking and rolling at idle was leaking/worn delivery valve seals. The car tended to run "ok" when cold, but was very rough on startup for the first 5-10 seconds. As it warmed up, it started to idle on 5 cylinders and would smooth out above 1000 RPM and nailed loudly up until around 1400 RPM.

Replaced the copper washers and springs in the delivery valves and it's had a marked difference on how my car runs. I went from an intermittent 5/6 cylinder with a VERY LOUD injector nailing to be smooth and refined and a full time 6 again. Fuel economy went up 3mpg too, so win-win all around.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Junkman has a thread going with a perhaps similar issue. You might want to find his current thread labeled does head temperature matter?


On page three of diesel discussion as we are waiting for his compression check. We have no ideal if his car is worse than yours.

I agree that what you experienced for some reason possibly age is becoming more common. In this posters case really nothing is known yet other than he has decent compression.


You can go a lot further in establishing what it is far more likely to be as a fault. Before starting to spend money to isolate it. Or at least really narrow it down. When you do I just think it might be. Then it turns out not to be the problem it is demoralizing to some extent.


For example it is always a good ideal to record any compression numbers or voltage readings because as you correct things you are far more likely to get all the faults. Many times on older engines that have not had proper maintainence. In the end there will be the primary fault fixed and perhaps others still there that could easily be improved as well.


Say for example you had a poor set of injectors. I am not stating you have. A systemized approach will tell you this is the case. The sooner guys get a handle on a systemized approach the better things should be. At this time it could be at least several separate things that are creating your problem.


Doing all the readings properly allows you to get the engine running like new again in many cases. Instead of just a lot better.

Did you change the air filter?

Did you change the crush washer and o-ring on the fuel filter hollow bolt?
There should be no air in the clear(ish?) hard lines.

Did you replace the rubber fuel lines?
If you can rotate the rubber fuel lines by grasping and twisting them, air can get into the IP.

Do you have the old style primer pump?
They seem to leak very readily.

Maybe clogged in-tank fuel filter screen?

See Disc 2 of the online FSM for info on your 1981 300D.

Adjust the linkage (FSM job 30-300) before you adjust the idle (FSM job 07.1-100)

Keep at it and you will get is all sorted out.

__________________
78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022

Wow thanks for all the quick replies! Yep no rack damper bolt, yes air filter is changed. New style priming pump and no air bubbles that I can see in the lines. The lift pump is something I need to check. I assumed the problem would get worse at acceleration on highway is this was the problem but I suppose it could act better when the pump is running faster. I guess the best way is to tee off from line going from lift pump to injection pump and and run a fuel pressure gauge? I need to read up on that

Oh and temperature does not seem to matter

take a look here:

Thinking about 617 MW delivery valves

read through complete post also...

valid for w123/w126 M/MW pump

__________________
w126 500SEC gen II euro, powered by OM617 turbo stolen from 84 300SD 2.88 diff,EGR blinded
next wish/project: w114 coupe OM603 powered

I haven't even looked at the others except for number one when I did IP pump timing. One could be stuck or in backwords or worn I suppose. I guess they are kind of a one way check valve makes sense that one not working right could cause major vibration.