Little or NO power after bottoming out suspension- 1981 300SD
 

My friend was driving his SD on a dirt road and hit a dip, bottoming out the suspension and denting the oil pan.
About a mile later, the car died.

He tried putting on new filters, but still could not get the car to start.
He got it towed home and called me.

I replaced the dented oil pan.
I also replaced the old style (leaking) primer pump thinking that is the reason it would not start.

After about an hour trying to start it, I suspected something was wrong with the injection pump.
I decided to pull the IP and replace it with a known good one.

After trying to get the start of delivery set (removing/replacing the IP three times), I figured something was wrong with the timing device, or something else.
I decided to just put the original pump back on.
After successfully getting SOD set, the engine finally started, however, it barely had any power, and it would only rev up to maybe 1,500 RPM.

I don't want to pull the IP again.
I thought that maybe the muffler was clogged, so I pulled the downpipe off the turbo, and still no power.
It seems to idle perfectly, but barely has enough power to move the car in gear (I can walk faster).

I also found out that the turbo was worn out, and thought that it might be bad enough to keep the engine from getting any air.
I removed both manifolds and the turbo, and started the engine to see if the turbo was restricting the air (had it bolted to the oil feed tube and drain tube to prevent an oil spill), but still no power.

Having ruled out he entire exhaust system, the only thing left is the fuel system.
The filters are both new, and the primer pump is new (new style).
I even tried pumping the primer while it was running to help pump fuel, but still no change.
I also tried clamping the return hose, but that did not change anything either.

Anyone have any ideas?
Like I said, I really don't want to pull the IP again.

There is the possibility that something broke inside the IP from the suspension bottoming out, but I would like to rule everything else out before trying another IP (for the second time).
I already have over 8 hours invested in trying to repair my friends car (his only transportation), and don't want to needlessly invest any more.

Thanks in advance for any ideas or help...Rich

did the timing chain maybe jump a tooth? would the engine self destruct if that happened though? if it idles, but no rev, it makes me think timing, but i'm sure someone with way more knowledge will chime in.

Try running it off a small canister: just pull the feed and return lines, and stick them in there; make sure the canister is secured properly and no diesel can spill out, and take it for a very short test drive.

When the steel fuel lines are 30 years old, they might be clogged from rust knocked loose during the impact. When I started my 200D after 12 years of sitting it barely started; when I ran it off a canister, it started much easier and seemed to rev better, so that could be your problem too.

Are the throttle linkages moving normally (when you put the pedal down, is the movement reaching the IP)?

Did the dip hit the underside of the middle of the car? The metal fuel lines (and brake line) run along under the body and may have been flattened like the oil pan, preventing any fuel flow.

My first thought when I read he bottomed out and dented the pan, was oil pump damage, and oil starvation.

Charlie

+1

I agree with this as a first step. The symptoms sound like fuel. Running off of a bottle (like doing a diesel purge) would take the tank, strainer, fuel lines etc out of the eqution very simply.

Thank you all for the quick replies. I will definitely try running it on a can of Diesel Purge first (I have one in stock). I had not thought of the fuel lines, but I will check them. I also thought of oil starvation to the pump as well. However, I would think the engine would have made some noise from oil starvation long before the IP could get damaged from same. One of the first things I checked was the timing. I pulled the cover to verify the mark on the cam tower and the crank. They both align perfectly. The car was needing a new vac pump anyway, so I checked the IP timer while the pump was out. It seemed to work as intended (turning it against the spring pressure). I also pulled the line to the shutoff, thinking I might have a small amount of vac leaking past the valve on the ign sw. That did not make it run any better. Even though I crimped the return line, could the pressure relief valve cause this condition? I might bring along a known good one and replace it just for grins anyway. Keep the suggestions coming. Thanks, Rich

You said the filters are new, but I wonder if it would be worth putting on fresh ones, just to be sure. I'm a firm believer in taking the simplest things out of the equation before getting into the more complex and costly ones.

The new filters were put on after the car died, and before towing it home. With removing and replacing the IP more than once and using the new primer pump, I am sure the filters are full. However, that is with the tank and fuel lines feeding the system. Diesel Purge as the fuel supply should rule out the filters as well (return flow should be visible).

+2 either pushed up the intake against the bottom of the pan and starved it that way or cracked the oil pump housing killing all pump action.:eek:

(siezed bearings)

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

UPDATE:
 

We ran the engine on a separate can of fuel to rule out the tank and fuel lines. It runs the same- only can get about 1,500 to 1,800 RPM out of it. I figured that the only thing that is left is the IP. The other day we went to a wreckin' yard and got a used IP from an SD. Yesterday I replaced the IP with the used one. The engine runs exactly the same. It was a lot of work, but at least the IP is ruled out. Again, the main fuel filter was replaced with a new one right after the problem started. It has a new style primer pump. I am at a loss as to what the problem might be. The turbo was rebuilt while all this was going on for the last 2 weeks, so it is ruled out as well. Anyone with any ideas?

When the engine was ran on the can of fuel (actually a clear bottle), the fuel flow was evident (pulsing of lift pump). Also, the flow from the drip tube while adjusting the start of delivery showed that it was getting plenty of fuel. The engine idles perfectly, and does not miss at all. When the throttle is wide open, it is very smooth, but only revs up to about a steady 1,800 RPM.

Disconnect the exhaust from the manifold to test for a restricted exhaust system.

I thought of that when the turbo was off, so I blocked off the oil supply to the turbo and fired it up without any manifolds, nothing changed.

Is this an OM603? If so, you can remove the side cover of the pump and run the engine to observe the rack and make sure it's moving in response to the throttle input. Also, try remove the vacuum line from the shutoff actuator to make sure something's not goofing up the vacuum system and causing the shutoff to try to kill the engine all the time.

Check the shut off lever to see that it's in the proper position too.

I've also seen a case where vacuum or blow by (don't remember which) was invading the injection pump and causing the ALDA or shut off to adversely effect the performance of the engine. You can try running the engine with the oil cap off and see of that makes a difference.

It is a 617. The vac line was off when the recent test was done, so that is not the problem. I will check out the blow by by removing the cap. Thanks, Rich

Is there a vacuum/boost gage in the car? If not, hook one up temporary. I did that after putting a used engine in my 85 300D. It wouldn't go faster than 10 mph and wouldn't rev much in N. I knew the engine was good because I had run it on the ground and it rev'ed well w/ no blow-by at all. The boost gage showed 20"Hg manifold vacuum, similar to a gas engine w/ throttle closed, suggesting the problem. I pulled the plastic duct off the turbo inlet and found a wad of paper towels I had stuffed to keep things out of the turbo. Ran great after that. Probably not your problem, but easy to try.

Per previous posts, the turbo was rebuilt in between different tries to fix the engine. It had the same symptoms even without the manifolds or turbo installed.

I don't see how bottoming the suspension could damage the IP.:confused:

I would pull the valve cover off and check the mark on the cam to be sure the chain didn't jump a tooth..It is not likely, but if it did, I think it would create the symptoms you are having

A serious jolt may have moved some things around. Make sure the linkage is advancing the arm on the injection pump properly with the pedal. You may have already checked that.

When the oil pan hit the engine was probably deflected back and perhaps upward a little. May have bent a linkage or disturbed it in some other fashion. You want one person on the pedal and yourself watching the arm on the injetion pump hit it's stop.

On my 74 240d we had a recurring problem of losing power. After pulling the IP four times I took it to a repair shop in Cincinnati that did a lot of mb diesel work.

They finally figured out that the little splined double sleeve that connects the drive on the Ip to the Sprocket on the cam chain was worn so much it allowed the drive to slip a spline. One spline slip would reduce power so you had to floor it to maintain 70 mph, the second spline slip rendered the car unable to exceed 40 mph.

That engine was by far the most worn mb engine I have been into. I think the po must have believed that being a mb it was so durable that it did not need the oil changed ever.

They replaced it with a spline from a sixty something fuel injected gasser mb that they had lying about.;)

I didn't either, but replaced it anyway. Found out that something else must be wrong (see above posts).

Been there, done that. I even adjusted the valves while I had the cover off.

The entire throttle linkage works as it is supposed to. I have operated it by hand and checked to see that it actuates the IP correctly.

The splined collar is perfect in every way. The engine runs exactly the same every time I installed the IP (the third time so far with 2 different IP's)

Whats the oil pressure through all of this.

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?

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?

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.

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.

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

Answered on page 2.

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

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.

Hows the primer pump?

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.

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.

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

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
 

Call me tomorrow.
I think this can be resolved.

.

You didn't have clear lines? (easier to see bubbles in clear lines than just a clear bottle)
Does the engine start with the first crank or does it take extended cranking before starting?

I think this symptom in the first post needs to be scrutinized:

engine died a mile after the impact and will not restart.

Why?

The impact is an up down motion rather than the more common fore aft motion of most impacts. What is more likely to be damaged in an up/down impact? (other than the oil pan)

This is a real mystery. At this point, I'd post a video of it starting and running with the hope that additional sense data provided to the body of minds here, might produce more viable hypotheses.

That's what I meant with the linkages, sorry! There's a few little plastic tabs and rubber pieces around the firewall that might have been damaged, affecting the response between the gas pedal and the engine. If actuating the throttle by hand (in the engine bay) can make it run and rev properly, then the problem should be isolated more and more (not the IP, not the fuel lines... and so on) down to a specific area.

On another note, depending on the location of the fuel lines, they may have been dented in the impact just enough to allow for a normal idle but not allow enough fuel to run past certain demand from the IP. It would make sense in the "limiting" aspect of the problem.

Agreed 100% on the video!

I think ROLLGUY already actuated the throttle at the IP and verified it has full travel motion. He replaced the IP 3 times already!

If the air and exhaust are confirmed clear and open, I don't see what it can be besides fuel delivery. But lots of strange things can happen, hence the need for the video I think, and lots of footage at that.
Have you checked fuel pressure and flow between the secondary filter and the IP?---the reason I ask this is that there's a bypass valve in that secondary filter assembly I think. Perhaps the shock of bottoming out made that bypass valve stick in the open position and it's not delivering enough fuel or pressure to the IP.