Little or NO power after bottoming out suspension- 1981 300SD - Page 3 - PeachParts Mercedes-Benz Forum

funola · #31 02-17-2013, 03:10 PM

Very strange problem you have there. Was the engine running well before the suspension bottomed out? Did you have clear lines into the bottle of fuel and had no air?

Adv_rider · #32 02-17-2013, 03:54 PM

I know nothing on the topic, but is it possible there is a safety switch that shuts the injection pump off when sensing a big hit ..... Like new cars?

Delibes · #33 02-17-2013, 04:10 PM

When you open up the hood and manually pull the linkages, can you get the engine to rev at high rpms? I suspect it might be something in the linkage mechanism... simple things first. We had the same problem in a non-turbo 300D that we used –very appropriately– as a loaner car.

mach4 · #34 02-17-2013, 04:21 PM

Ok, we're into uncharted territory now. Time to start looking for other factors.

Does the problem happen with the garage door open as well as closed?
Does it happen with light on and off?
Does it happen on odd days as well as even?

Obviously just kidding. You've got a real strange one there.

Despite the weak attempt at humor above, it's got to be something really out of the ordinary.

While I can't imagine what would cause it, have you checked the intake and exhaust manifolds to make sure they're clear, and the intake and exhaust ports on the engine? Did you remove them when you redid the turbo?

The other thing I didn't see you check was the injectors. Try a set of new injectors. And while you've got that apart, pull a compression test. (since it starts right up, it really can't be that, but it would be good to know where we stand) Since we're really "out there" on ideas, swap in a different set of injector lines.

That's all I can think of.

Well, maybe one more strategy, and that would be to start swapping components onto a good running engine to see what causes the same symptoms. A boatload of work, but we're well outside of the normal troubleshooting envelope.

ROLLGUY · #35 02-17-2013, 08:15 PM

Quote:

Originally Posted by Dubyagee

Whats the oil pressure through all of this.

Seems to be normal for the age and miles, about 1.5 bar at idle and going up from there at higher revs.

ROLLGUY · #36 02-17-2013, 08:17 PM

Quote:

Originally Posted by Delibes

When you open up the hood and manually pull the linkages, can you get the engine to rev at high rpms? I suspect it might be something in the linkage mechanism... simple things first. We had the same problem in a non-turbo 300D that we used –very appropriately– as a loaner car.

Answered on page 2.

ROLLGUY · #37 02-17-2013, 08:25 PM

Quote:

Originally Posted by mach4

Ok, we're into uncharted territory now. Time to start looking for other factors.

Does the problem happen with the garage door open as well as closed?
Does it happen with light on and off?
Does it happen on odd days as well as even?

Obviously just kidding. You've got a real strange one there.

Despite the weak attempt at humor above, it's got to be something really out of the ordinary.

While I can't imagine what would cause it, have you checked the intake and exhaust manifolds to make sure they're clear, and the intake and exhaust ports on the engine? Did you remove them when you redid the turbo?

The other thing I didn't see you check was the injectors. Try a set of new injectors. And while you've got that apart, pull a compression test. (since it starts right up, it really can't be that, but it would be good to know where we stand) Since we're really "out there" on ideas, swap in a different set of injector lines.

That's all I can think of.

Well, maybe one more strategy, and that would be to start swapping components onto a good running engine to see what causes the same symptoms. A boatload of work, but we're well outside of the normal troubleshooting envelope.

I'll get back to you on the first 3. I have not looked into the intake and exhaust manifolds, but I don't expect to see anything out of the ordinary if I did. The engine starts right up and idles very well (better with the new IP than the old). I had not thought about the injectors, but I do have a fresh set of rebuilt units with Monark nozzles (was saving them for one of my 617's). I might just try them in this engine as they are handy. I think that is the only thing left to try, as I have checked/replaced everything else on the fuel/air delivery system. Thanks for all the suggestions, Rich

ROLLGUY · #38 02-17-2013, 08:28 PM

Quote:

Originally Posted by funola

Very strange problem you have there. Was the engine running well before the suspension bottomed out? Did you have clear lines into the bottle of fuel and had no air?

The bottle was clear with the lines directly on the lift pump and return fitting on filter. I could clearly see fuel returning, and the feed line submerged in fresh fuel.

colincoon · #39 02-17-2013, 08:33 PM

Hows the primer pump?

barry12345 · #40 02-17-2013, 09:56 PM

Some faults get to the point of not being amusing at all. You have arrived.

When changing injection pumps out etc. You did not get a vacuum line hooked up to the alda system instead of the pressure one? This may pull the alda off further if you did. Really limiting fuel.

The problem with a lot of ideals is this type of thing would just be a contributing factor after the event. Or in otherwords you previously actually already found the problem but would not know with the new condition compounding the issue.

Even though your friend needs the car as it is his primary transportation. It might pay to sit back for a few hours and think about this situation.

When I run out of ideals and that is not all that often. I start to rethink possibilities and probabilities. Things like what have I done perhaps that may be accidentally compounding a situation.

For example at this point I would still be considering what exactly could cause a serious drop in power and rpms after hitting a bad bump? One could almost assume it was not coincidental.

Is the color of the exhaust normal at both idle and the highest rpms curently possible? If fairly clean and normal it would sound like you are limiting fuel. One test for this is. Do the available rpms when using the linkage rise continiously more or less in a linear fashion as you advance the injection pump linkage. Or does it hit the 1800 rpm mark about halfway up and the further linkage given after that does not further advance the rpm?

Especially since it ran no bettter on a temporary fuel supply. Plus other indicators you have that the injection pump is getting a good supply of fuel.

w123love · #41 02-17-2013, 10:15 PM

Quote:

Originally Posted by colincoon

Hows the primer pump?

Read previous posts, he replaced it with the new kind.

colincoon · #42 02-17-2013, 10:46 PM

Quote:

Originally Posted by w123love

Read previous posts, he replaced it with the new kind.

I did, but it doesn't say when it was replaced. If it was done before the accident then it could have been damaged somehow. It also doesn't hurt to double check.

ROLLGUY · #43 02-18-2013, 12:41 AM

Quote:

Originally Posted by barry12345

Is the color of the exhaust normal at both idle and the highest rpms curently possible? If fairly clean and normal it would sound like you are limiting fuel. One test for this is. Does the available rpms when using the linkage rise continiously more or less in a linear fashion as you advance the injection pump linkage. Or does it hit the 1800 rpm mark about halfway up and the further linkage given after that does not further advance the rpm?

I have not considered the position of the throttle at which the highest RPM is attained. I am not sure if that makes a difference anyway. Every time after I do something, the engine runs exactly the same (with maybe the exception of smoother idling with the new IP). I was also told that the exhaust was much cleaner than before, after the new IP was installed

ROLLGUY · #44 02-18-2013, 12:44 AM

Quote:

Originally Posted by colincoon

I did, but it doesn't say when it was replaced. If it was done before the accident then it could have been damaged somehow. It also doesn't hurt to double check.

I replaced it first thing so I could prime the system, as the old pump leaked like crazy. I first thought that was the problem, because of air in the system from the bad primer pump.

whunter · #45 02-18-2013, 01:06 AM

Quote:

Originally Posted by ROLLGUY

I replaced it first thing so I could prime the system, as the old pump leaked like crazy. I first thought that was the problem, because of air in the system from the bad primer pump.

Call me tomorrow.
I think this can be resolved.

.