Little or NO power after bottoming out suspension- 1981 300SD - Page 12 - PeachParts Mercedes-Benz Forum

dude99 · #**166** 03-10-2013, 05:45 PM

If you loosened the pump mounts couldn't you advance the pump manually with pry bar or something as someone slowly increases throttle?

kerry · #**167** 03-10-2013, 05:48 PM

This is such a mysterious problem it would also be worth flying in the best diagnostic minds from PP and having them look at it in person. I sure hope the problem gets solved instead of the car just being sold because no mystery is worth a damn without a conclusion.

Brian Carlton · #**168** 03-10-2013, 06:02 PM

Quote:

Originally Posted by dude99

If you loosened the pump mounts couldn't you advance the pump manually with pry bar or something as someone slowly increases throttle?

The range of the adjustment mechanism is quite limited compared to the advance mechanism, however, one could get some idea if this might be the issue if the timing was advanced to the maximum degree possible using the adjustment slots on the IP.

If the engine behaves marginally better with the timing change, it would point the OP toward the direction of the timer again.

The OP must understand that a significant improvement is not possible by simply rotating the IP. The test is done strictly as a diagnostic tool. Any increase in RPM would be considered a successful test.

JimSmith · #**169** 03-10-2013, 06:15 PM

Interesting thread. Quite frustrating to get through the 160 some odd posts and finding no solution.

I hate to be argumentative, but to run an engine that is consuming more than 35hp in friction and not smelling burning oil is a bit hard to conceive of - in fact, it would seem not feasible to me, especially if the load is supposed to be coming from a single main bearing. The normal friction losses for this device are miniscule compared to 35hp. There is no where near the oil flow to keep the machine from melting the babbit on the bearing shells for that kind of load. So, take the oil filter out, cut it apart and inspect the element (the main flow element, and the bypass section) for particulate metallic particles. They will be there if the bearing spun. Or any other source of unusual metallic part wear is contaminating the oil system.

I would suggest if there was a 35 hp or so load on the engine at 2000 rpm or so, there would be some good smoke coming from the tailpipe and the turbo would be beginning to pump out some measurable net intake manifold pressure. And so would a lot of oil smoke if there is a friction load of that size inside the engine that would be obvious with the valve cover cap off.

The problem, if it is friction or accessory load related, the mechanism is speed sensitive. Without the AC on, the bulk of the rest of the losses from belt driven accessories are tiny, even the water pump load is tiny at this rpm (it runs on a cubic curve for speed vs. power, so at less than half speed, the load is less than 12% rated - for this to be 35hp the pump would have to be noticeably difficult to turn by hand, and the same is basically true for the rest of the accessories - in the off position the are idling on a shaft).

The problem is either friction related, and that seems unlikely, but it does fit the trend of increasing load with increasing speed, or it is fueling which also fits the bill because if the fuel delivery rate is limited the engine will speed up until the engine speed limit at that fuel delivery rate is reached, and then stop.

I have had a lot of problems, without bottoming the suspension, with these era throttle linkages. I am less familiar with the 617 turbo engine, but the linkage system appears to be similar to the 240D of the early 1980s. This system has a number of direction changes (from foot actuation to injection pump lever actuation) and a series of devices that can be damaged, and only become apparent by tracing poor engine fueling to the various joints.

I know it sounds like covered ground, but I would disassemble the entire linkage and inspect it, then reassemble and adjust per the previously linked instructions. The same with the ALDA and the associated manifold pressure control system. Old, cracked lines will not get a pressure signal to the ALDA and there will be no fuel enrichment as rpm and load increase. In fact, given the age and the brittleness of the vacuum lines, it is probably a good idea to inspect and replace any and all vacuum lines. A shock load can easily damage these lines.

Interesting thread, hope the solution reveals itself soon.

Jim

JimSmith · #**170** 03-10-2013, 06:24 PM

Quote:

Originally Posted by Brian Carlton

The range of the adjustment mechanism is quite limited compared to the advance mechanism, however, one could get some idea if this might be the issue if the timing was advanced to the maximum degree possible using the adjustment slots on the IP.

If the engine behaves marginally better with the timing change, it would point the OP toward the direction of the timer again.

The OP must understand that a significant improvement is not possible by simply rotating the IP. The test is done strictly as a diagnostic tool. Any increase in RPM would be considered a successful test.

Brian,

I am intrigued. Wouldn't full throttle fuel flow with an improper injection timing setting just make more smoke?

Does this engine, like the 240D, have any intake side or other mechanisms to preclude runaway at idle conditions? Old 220D and 240D engines had some air flow limiting devices that were manipulated by throttle linkages going over and behind the engine. With those older cars, if the linkage didn't work, there was no power as there was not sufficient air. But they did smoke under those conditions.

Jim

ROLLGUY · #**171** 03-10-2013, 08:02 PM

Quote:

Originally Posted by colincoon

Why not just replace the engine? 617's aren't too hard to find, and they aren't exactly expensive. A day's work and a few hundred bucks are worth it to keep it on the road.

We are talking about a guy that has no job, and even if he had one, would have no way to get there (he lives about 2 miles from the closest bus stop off a dirt road). Fortunately for me, he had the car towed (by a chain in back of another 126 for 12 miles) closer to me so I don't have to drive 15 miles to work on it. I am just doing all this work on his car so he could at least get to my house to help me with all the car work I have. Although he says he is indebted to me for the work I have done so far, it still does not make it easy to devote more time to working on this car if a definite fix is not known. Conservatively speaking, I already have at least 15 hours and probably over $100 in parts (oil, primer pump, used vac pump, used oil pan, gaskets, etc). He has put some money into it himself including rebuilding the turbo ($55 in parts alone), and a used IP ($45). This car is a typical 1981 300SD wit ALL the associated flaws (no need to make a list here, as I am only allowed a certain number of characters per post). The car is NOT even worth the $ and effort already put into it, but he has no other option but to sell it for as much as possible, and try to get a car for that amount.

ROLLGUY · #**172** 03-10-2013, 08:10 PM

Quote:

Originally Posted by kerry

This is such a mysterious problem it would also be worth flying in the best diagnostic minds from PP and having them look at it in person. I sure hope the problem gets solved instead of the car just being sold because no mystery is worth a damn without a conclusion.

Agreed, (sort of). This is in fact the greatest car mystery I have ever heard of, let alone been a part of. If someone else could be flown in to diagnose and fix the problem, it would not be because of the car's value, but because of the mysterious nature of the problem. Yes we would all like closure (no one more than me), by economically speaking, we may not get it. However, I am still willing (and the car owner: Brad) to try any and all simple tests to find the problem, and write the final post on this thread. I just hope that day is soon!

ROLLGUY · #**173** 03-10-2013, 08:17 PM

Quote:

Originally Posted by dude99

If you loosened the pump mounts couldn't you advance the pump manually with pry bar or something as someone slowly increases throttle?

That has been tried. I removed the hard lines, and advanced the pump approx 6-8 degrees (maxed out the adjustment on the 3 mounting slots). I had to bend the hard lines to re-connect them. After getting it started again, it was a LITTLE better, but still barely enough to move the car under it's own power.

barry12345 · #**174** 03-10-2013, 08:44 PM

Back to basics? Is fuel being discharged from the return line of the injection pump at 1800 rpms? I have re read all the posts up to current and perhaps could suggest a possible series of events.

A severe bump might shake a lot of the junk loose or stir it up really bad in a dirty fuel tank. This could obstruct the fuel filter and cause the car to quit. The new fuel filter might also get enough of the remaining loose junk to quickly impair it as well.

If the system is clear then the overflow flow from the return of the injection pump should still be present at 1800 rpms. You cleared any involvement of the tank filter when you ran the engine on the fuel container. Actually the only thing that has not really been changed more than once is that secondary or primary filter.

The primary filter may not have been changed even once. Anyways if you have fuel overflowing at 1800 rpm it clears the filters totally and anything else in the fuel supply chain. No overflow is worth investigating further. Simple,simple test. I am not sugggesting you run out and buy filters. Just check for the presence or lack of overflow.

funola · #**175** 03-10-2013, 09:01 PM

Quote:

Originally Posted by whunter

The engine is closer to 38 HP at the moment.

This was a 70+ MPH rolling vertical impact (that did not stop the car).
The lower oil pan deformed in the oil pump pickup area.
This oil pan punched the rubber pickup into itself = cutting off oil supply.

..............................................................................

.

"Cutting off oil supply" is new. Previous to this, it's been reported that the oil pressure and oil pump was fine.

post #13 "The oil pump is fine, the dent just crushed the rubber piece on the bottom. It definitely still has oil pressure."

Would it be safe to say now that the engine stalled a mile after the impact due to oil starvation?

ROLLGUY · #**176** 03-10-2013, 11:17 PM

Quote:

Originally Posted by barry12345

Back to basics? Is fuel being discharged from the return line of the injection pump at 1800 rpms? I have re read all the posts up to current and perhaps could suggest a possible series of events.

A severe bump might shake a lot of the junk loose or stir it up really bad in a dirty fuel tank. This could obstruct the fuel filter and cause the car to quit. The new fuel filter might also get enough of the remaining loose junk to quickly impair it as well.

If the system is clear then the overflow flow from the return of the injection pump should still be present at 1800 rpms. You cleared any involvement of the tank filter when you ran the engine on the fuel container. Actually the only thing that has not really been changed more than once is that secondary or primary filter.

The primary filter may not have been changed even once. Anyways if you have fuel overflowing at 1800 rpm it clears the filters totally and anything else in the fuel supply chain. No overflow is worth investigating further. Simple,simple test. I am not sugggesting you run out and buy filters. Just check for the presence or lack of overflow.

It has return flow, and an entire fuel filter and housing was switched from a known running car. I believe that ALL fuel related issues can be ruled out because of the introduction of WD40 into the turbo at full throttle. There was no change whatsoever in the rpm of the engine with the extra fuel.

ROLLGUY · #**177** 03-10-2013, 11:20 PM

Quote:

Originally Posted by funola

"Cutting off oil supply" is new. Previous to this, it's been reported that the oil pressure and oil pump was fine.

post #13 "The oil pump is fine, the dent just crushed the rubber piece on the bottom. It definitely still has oil pressure."

Would it be safe to say now that the engine stalled a mile after the impact due to oil starvation?

The first fix after the car was towed back to the owners (Brad) house, was to change the oil pan. Post # 13 was AFTER the oil pan was replaced.

Brian Carlton · #**178** 03-11-2013, 12:30 AM

Quote:

Originally Posted by JimSmith

Brian,

I am intrigued. Wouldn't full throttle fuel flow with an improper injection timing setting just make more smoke?

Does this engine, like the 240D, have any intake side or other mechanisms to preclude runaway at idle conditions? Old 220D and 240D engines had some air flow limiting devices that were manipulated by throttle linkages going over and behind the engine. With those older cars, if the linkage didn't work, there was no power as there was not sufficient air. But they did smoke under those conditions.

Jim

Jim, I recall the time when Pete installed the IP 360 degrees out of phase with the crankshaft. The engine started just fine and would idle but would not rev. It heavily smoked the entire neighborhood.

Now, consider a less dramatic situation where the timing is 25 degrees late. The engine might be able to burn all the available fuel without excessive smoke, and fail to make any horsepower due to the injection lag.

We know with assurance that a 617 will run fine at 10 degrees late.............no smoke............just reduced power. The owner doesn't even realize it unless he performs a 0-60 time and finds it's at 18 seconds.

The 617 has no limiting device that would prevent airflow. And, I would suspect heavy black smoke if any serious intake restriction were to occur.

I'm also grasping at straws a bit with this engine because all of the usual culprits have been eliminated and I have serious doubts about any internal damage (crankshaft bearings) on an engine that starts and idles perfectly fine.

Brian Carlton · #**179** 03-11-2013, 12:37 AM

Quote:

Originally Posted by JimSmith

I know it sounds like covered ground, but I would disassemble the entire linkage and inspect it, then reassemble and adjust per the previously linked instructions.

To the OP:

No need to bother with all of that work.

Can the owner of the vehicle simply disconnect the linkage at the IP and move the arm on the IP, manually, while the engine is running at idle?

See if he can rev the engine above 2500 rpm without using the accelerator pedal in the cabin.

Forgive my ignorance if this has already been attempted.

whunter · #**180** 03-11-2013, 12:42 AM

Quote:

Originally Posted by funola

"Cutting off oil supply" is new. Previous to this, it's been reported that the oil pressure and oil pump was fine.

post #13 "The oil pump is fine, the dent just crushed the rubber piece on the bottom. It definitely still has oil pressure."

Would it be safe to say now that the engine stalled a mile after the impact due to oil starvation?

Yes, IMO it is highly likely.
I have been through this scenario on customer cars before, usually it is a parking barrier crushing oil pan to pickup = oil starvation damage.

.