This is my first real effort to revive a mal-maintained ’80 300D [na] and I need a little help with a low power problem. This baby has less power than my 240D
(1) Adjusted the valves... checked for chain stretch... OK !
(2) Ran ~3 cans of Diesel Purge direct through the engine IP and injectors,
(3) Had the injectors rebuilt at a local top notch diesel shop, and
(4) Changed both fuel filters,
Each of these have helped some for I started out with a max speed [straight and level] of ~55 mph and now it is up to 70 mph… but she really dies on the slightest hill… e.g. from 70 it dies back to 55 on just a moderate hill. A hill that the 240D tops at 55 mph, this 300D is lucky to top it at 35-40 mph. It clearly lacks power.

The engine reportedly has only ~85,000 on it !

Which of the following do you think we should try next:
Q1 – Compression test?
Q2 - Check IP governor [no tach on the dash ]?
Q3 – Check IP timing on #1?
Q4 – Take IP into shop for testing timing on all elements?
Any help will be appreciated.
Sam // Novato, CA

It really sounds like it's not getting proper fuel or the fuel is injected at the wrong time.

So, if it has not been maintained, odds are that the IP timing has never been set and it's probably five degrees late. This will affect performance.

But, the engine seems to be even further down on power than what IP timing would suggest. Any chance that the tank screen is partially clogged? Might be a benefit to drop it and make sure that it's clean. You can do a quick test by running the engine from a can of fuel under the hood. Or, you can blow compressed air back through the supply line to temporarily provide some additional flow through the screen.

What's the blowby? Is the engine quite tired or does it appear to be in good shape?

You probably don't want the headache with owning one of these cars - especially one of these low mileage vehicles. Are you sure you don't want me to take it off your hands.

I would suggest pulling the tank screen and cleaning it. Get as much fuel out of it as you can prior to removing it. Nose around this site to find pics/instructions. How does it run otherwise?

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Jim

Did you remove and clean the tank filter? Also have a look at the exhaust sytem critically. Look for any serious dents in pipes as well. You may want to loosen header pipe on manifold to eliminate exhaust restriction as a possibility. Although there may be a fitting to check back pressure on the exhaust. A plug fitting on manifold if that year has it. Did previous owner by any chance say if problem happened quickly or slowly over time if he knows. Also would not hurt to remove gas cap and blow high pressure air back down the fuel line to tank. The fuel line might have some crud in it. Come to think of it have a look at fuel line for serious dents as well. In otherwords I would eliminate any and all other possibilities before pulling the pump. Also one very last thought. Are you getting the linkage movement to the full stop? 240s are famous for that gem and I have seen a few with about half power because of it. In fact one of mine had that problem and the previous owner had driven it for some time that way. In fact he was not really aware of the problem until I took a minute to fix it and it astounded him. I believe he had drove the car about five years that way.

Wonder what his fuel mileage did after the fix.

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Jim

YES:
Q3 - First, Like Brian said.
Q1 - For peace of Mind.
NO:
I did Q4 and think I wasted my money, for this reason - the IP on these seems incredibly durable and rarely needs any adjustment (my experience).
Q2 - don't think so, never seen a single thread on this subject.

AND.... you did not mention a new air filter, should I assume you have a new air filter ?

My 300D NA engine does great at 70 to 80mph, the RPM's seem higher than I'd like, but otherwise does have decent top end speed.

__________________
80 300D 340K Owned 30 yrs
83 300SD 440K Owned 9 yrs - Daily Driver 150mi/day
02 Z71 Suburban 117,000
15 Toyota Prius 2600 miles
00 Harley Sportster 24k
09 Yamaha R6
03 Ninja 250

As already mentioned, the simplest and quickest thing to check is the linkage from the accelerator pedal to the injection pump. Especially check the condition of the pivot rotator on the firewall. Have someone press the pedal to the floor while you watch the linkage turn - then grab the linkage and see if you can turn it further by hand.

Often the linkage gets taken apart to remove the valve cover, and then people put it back wrong - then you only get 1/2 full IP injection or so.

And, that pivot point can wear out making that part of the linkage loose, and again you don't get full injection.

Very simple thing to check and seems to happen fairly often.

Ken300D

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1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles

It was an ebay transaction that required the fix when I went to pick up the car. I backed the car out of the owners garage and of course noticed no action on first 1/3 or so of pedal movement.Plus little apparent power. Model was 1982 vintage. Lifted hood and repaired with a couple of short lengths of fuel hose and a couple of twist ties. Got back into car and floored the petal. Previous owner was actually speechless and after he recovered said the engine had never reved like that as long as he owned it. Think car never was much past a fast idle in years. About five years or longer in fact. He must have thought all 240ds were that slow I suppose but perhaps it was going through his mind that he had suffered the low power for so long and perhaps thought it was normal . Yet so simple and quick to rectify. Car averaged about 25 miles per american gallon on the 1100 mile trip home. It was in the depth of winter and driving conditions were poor for about 700 miles of it. I really believe if car had not had the problem or he was aware of it even being a problem he would not have sold it. He drove the ultimate turtle car.

that I/we also:
(1) had replaced the air filter and checked to see that nothing was obstructing the air intake,
(2) removed and cleaned the screen filter at the tank and blew air into the hose at the prefilter back into the tank, then flushed an additional 5 gal through the tank out through the bottom.

I'm working [ and learning ] with an experienced independent M-B mechanic who owns his own M-B only shop and although he does not "go all the way" and do the more intricate things I suppose some might tackle, "Karl" strikes me as more than competent.

No I'm not ready to sell it yet... I'm just trying to make it safe and run well enough to turn over to my Banker Son !

The car was sitting outside for many months and possibly for more than a year and then the owner did the minimum to get it running for the sale!
I was shown bill for replacement engine ~90K ago... but know nothing more !! I paid my mechanic $100 worth of looking it over before the sale so I think I have him on my side as we struggle a bit with this power problem.

Although the mechanic checked and adjusted the throttle linkages, I'll bring that up again and also check into it myself... especially the pivot point.
Will look for dented fule line as suggested.

A couple of final symptoms:
(1) I smokes black just a little at idle,
(2) It smokes black at full throttle but only if you press down that final little bit... and stops smoking as soon as you back off just a little.

I'm surprised no one voted for a check of the govenor !

Mechanic off on Hawaii vacation until April 17.

When he returns I think I have him convinced to get the electronics that attaches to the injector fuel lines and then to a timing light to enable faster IP timing checks. "Ferret" brand timing lights have such a system.

Q - Does anyone any experience with timing light systems on M-B diesels?

Sam // Novato, cA

We recently did a back to back comparison of the M/B RIV timing lights with the pulse timing system that attaches to the #1 injector line.

With the SD set perfectly at 15ATDC via the M/B RIV timing, the pulse timer registered 13.5° BTDC. So, I would presume that the n/a 300D should be close to this value.

Your last post was more helpful. The black smoke indicates you are not really underfuelled probably. It is possible injector pump timing is way late and would account for your description as well. Perhaps some previous owner messed with the pump setting for example. Or even just a result of wear and tear over the years. An awful lot of the older cars have not had really essential things checked for many years. It's part of a good general tuneup anyways and should be done. Things do age with time. By the way even a standard drip test in your situation should be more than adaquate. No real need to go higher tech really.

Perhaps the measurement of the Glow Plug voltage to indicate whether some cylinders are not operating as hot as others would give an indication of the possible problems

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Tony from West Oz.
Fatmobile 3 84 300D 295kkm Silver grey/Blue int. 2 tank WVO - Recipient of TurboDesel engine.
Josephine '82 300D 390kkm White/Palamino int.
Elizabeth '81 280E, sporting a '79 300D engine.
Lucille '87 W124 300D non-turbo 6 cylinder OM603, Pearl Grey with light grey interior


Various parts cars including 280E, 230C & 300D in various states of disassembly.

Next I'll probably:
(a) pull the IP high pressure lines,
(b) pull the injectors,
(c) do compression test… dry and then wet, and finally
(d) check timing on #1 before I reassemble !

The timing light thing is just my trying to help him out because he is getting so much diesel business he knows he needs to be able to check IP timing more quickly than by the old school method. Continuing on this same subject, when I talked to the Ferret tech support people they talked about how their equipment was used and it is best if the light you use has the feature that allows you to dial in the desired timing + some kind of "fudge factor" that compensates for the particular engine.
Questions:
Q1 - Brian - What did you mean by "M/B RIV" timing lights?
Q2 - Are there posts in the archives that I can go back and read that would help my education on this subject?
Q3 - Does anyone else have useful input for my education on this subject?
Sam

The RIV timing light is a M/B tool that allows you to install a probe in the side of the IP. The probe senses the notch in the rotating shaft in the IP. When you are nowhere near the notch, no lights are lit. When you approach the notch, the "A" light illuminated. When you are dead on the notch, both "A" and "B" illuminate. When you pass the notch, ever so slightly, the "A" light goes out. The spec for the engine when you use this tool is 15°ATDC. Not all engines have the capability to use this tool. The older 616 and 617 engines did not have the port in the side of the IP. The '80 vehicle would probably not be able to use the RIV tool.

You can certainly search "timing" and "injection pump" and read for hours. Also check out the DIY section where the most relevant posts are indicated by section.

If your mechanic gets the pulse timing tool, the spec would not be 15°ATDC but would be 13.5°BTDC which is the correlation that we established on the SD.

Tony the wizzard, the reading of the glow plugs voltage output is not really as far fetched in my opinion as some believe. If a little research was done and results from normal engines logged it would provide a guide. For instance if output voltage is lower than average examples across the board at an established rpm it would indicate pretty conclusively that primary timing was late. Perhaps also that engine was unable for whatever reason like obtructed exhaust to utilise the available fuel energy properly. Or as you suggested any sub standard reading from any glow plug in comparison to the others should be grounds for some investigation to find out why that cylinder is cooler. So fast to read the running glow plug voltage directly from the harness plug as well. Possibly much more refined indication than listening for rpm drop by loosening each injector line in turn. It will take time if there is really any merit and change is always met with resistance. If you were to simply benchmark all of your engines individually and record the readings. All at operating temperature of course. At some future date reading them again may give an important clue of something amiss. This area needs a lot of work.