injection pump
 

The injection pump on my 300d seems to not be putting anything out on the #1 cylinder. Yes, I pulled the injector, nothing comes out the tube from the pump. It began running rough and blowing blue smoke at the same time. Just had a new timing chain and the valves done, worked good for 150 miles or so and then just started doing this while running at about 65mph. Is there something that could have slipped or am I probably looking at a new pump ($$$$$)?

Been there, done that.

Maybe you can get very lucky like I did. After overhauling my daughters 300D, number one would not hit at all. At first it scared me, thought I had no compression. A compression test showed 370PSI on all five, whew!

I then pulled the line for number one, and removed the fitting at the top. Then pulled out the spring and plunger below that, and then the sleeve and copper washer below that. I cleaned everything very well and reassembled. Number one then came alive. I considered myself lucky.

Do not loosen the two nuts on the plate that surrounds the fitting, you will lose the calibration for that cylinder if you do.

Best of luck,

Unfortunately I already did that, I had a guy that works at a diesel injection shop come by and check it out, he had no idea what could be wrong, everything looked ok to him. He thought that maybe it was getting pressure back to the pump from one of the cylinders but we couldn't tell. The funny thing was that when the tube going to #5 was cracked open it ran smooth and #1 would come somewhat alive, I wish someone could explain this. I'm going to take it by Tyler Fuel Injector next week to run a test on the injectors and try to figure out what's going on.

When I started inquiring about this when I had the problem, it was suggested by one of the pros that I remove the injector and let it spray into a cup while watching the spray pattern at the injector.

Be careful with this, because this high pressure stream of fuel can cut you.

Good luck,

It smoothed out when you cracked the #5 line because numbers 2 - 3 - 4 when firing are a bit more balanced in thier firing order than when #5 is included in this order. Do as Larry has said, and pull the pre-delivery valve assembly from #1 on the injection pump without moving the outer hold downs so the calibration won't be altered. carefully inspect clean and re-assemble the valve to pump in the correct order. Start and run engine without installing #1 injector line. You should have fuel comming from the pre-delivery valve at the fitting for the line. If no fuel, pump is at fault and will have to be repaired or exchanged. If fuel is present, pull #1 injector and switch it with #3 injector, start engine and run for a few minutes to get any air out of lines, if miss changes to #3, injector is bad. Make sense.

Rob

For the sake of safety, I must expand on Larry's previous comment:

If the high-pressure jet from an injector hits you, it will cut you. If diesel fuel gets into your bloodstream, even in a tiny amount, you will die.

"Be careful" is an understatement. Unless you have the proper tools and training for checking injector spray pattern, don't try it. Leave it to the professionals.

- Nathan
'83 240D "Steiner"
'00 New Beetle TDI

There is no, repeat no, high pressure at the injection pump with the line to the injector disconnected. pressure is only built up against the pintle valve of the injector when it is installed in the line.

Thanks for the warning but I'm going to take it to a diesel injection shop, nothing comes out of the #1 tube. If I pull the stuff out of the pump, actually I had a guy from the shop I'm taking it to do it, and put it back together it "spits" a little bit but not as much as the others. Long story short, I need to get it fixed and I want to have it done right, hopefully I'll accomplish this by taking it to a professional. I just hope it's not going to be expensive.

The thing that really still makes me wonder is that when #1 is disconnected from the injector and #5 is cracked open #1 starts putting out some fuel. I can see why it might run smoother but why I start getting fuel on #1........something doesn't make sense.

#1 sleeve set and #5 sleeve set aren't connected except by the camshaft, so I have no idea why you get more fuel when #5 is open.

Sounds like your #1 plunger spring is broken, so the plunger stays up instead of re-filling with fuel for the next injection. Not an expensive fix, but the pump does have to come apart!

Peter

Sounds like your #1 plunger spring is broken, so the plunger stays up instead of re-f
 

Are you referring to the spring which keeps the pintle valve (or pressure valve) closed? The small spring under the 15mm threaded housing?
Or are you referring to the small diameter "piston" underneath the pressure valve which is connected to the camshaft? Is there a spring under this? or is it hooked onto the camshaft?

I guess I need to see a blow up of the pump, huh...

The reason I ask is because I cannot get any pressure on my #1 injector.:rolleyes:

Ed:

Do you get any fuel delivered with the pressure valve spring out? If you do, the seal is shot -- its underneath the steel "sleeve" that the pressure valve and spring fit onto.

If not, you have an internal problem with the pump and will have to have it serviced -- it simply is not possible to do this at home. The two most likely causes are a broken return spring or a scored plunger, niether of which can be replaced without complete pump disassembly and recalibration.

I repeat, it is NOT possible to do a pump repair at home -- if you take it apart, you will have a non-funtioning pump. Yes, I know all sorts of folks claim to do injection pump repairs on the workbench, but I've yet to see one properly working when they were done!

Peter

Peter,
Depends upon what is wrong with the pump. I had injector pump on 1970 220D fail to feed to #4 injector. Rear camshaft ball bearing had come apart allowing the camshaft to drop so that #4 plunger would not operate. A $7.50 ball bearing fixed the problem. This problem occurred at about 200,000 miles---this pump now has a little over 720,000 miles, having survived two short block replacements. When working on injector pump and removing parts a clean work surface is essential. And as has been pointed out, some parts you don't mess with---like the two nuts that hold each holding flange at element assembly (not present on the 220D pumps).

Peter,

Thanks for the input!
I found my problem, there was no seal under #1 injector,(my fault), so I wasn't building pressure...

Now it fires, but only above 200 rpm, hmmmmm.:confused:

Peter,

...that's 2000 rpm!:rolleyes:

Ed:

Same thing my 300D did -- in my case it was because the pressure valve holders weren't torqued down properly. I could unscrew one by hand! Either you need to re-torque the #1 holder, or better yet, pull it again and inspece the copper seal for deep scores, etc.

Make sure the seating surfaces are very clean and that the pressure vavle holder isn't cracked or chipped -- if it is, it will never seal properly!

Proper torque is 30-35 N/m or 20-25 ft/lbs.

Peter

Peter

Well I found that when this #1 line has new copper seal, and new O ring, AND new injector seal, it does fire but only above 2000 rpm, yes!

I found my real problem today though. I went to Kragens and bought a $40 compression checker which reads to 300 psi only. And unfortunately found only 80# on #1:mad:

SOOOOO, off with her head!!!:eek:

Alas...

Before you pull the head, I would make sure your valves are still adjusted correctly or for one that is sticking open. It sounded like you had recently adjusted them, but it doesn't take much to check for a stuck or misadjusted valve.

Good luck!

Frankly,

Thanks for that tip, actually I was hoping the valve had tightened up or I had goofed, but nooooooo.

What throws me is that the #1 starts firing when the revs go up, I guess it's enough piston speed to raise the compression just enough...?:confused:

Ed:

If you have any way at all to pump compressed air into #1 at TDC on the compression stroke, do a leakdown test -- set crank to TDC on #1 with both valves closed and apply air pressure, then listen for where it leaks out -- if into the exhaust, bad exhaust valve, if into the intake, bad intake, if into the crankcase/valve cover, bad rings. Much easier than taking the head off. You can probably use a bicycle pump for a severe leak.

Triple check valve clearance (although I would bet you've got it correct), then check to make sure the valves can be rotated when closed. There is a little ball bearing dodad under the valve spring that spins the valve a little each time it opens to even out the valve seat wear. If the valve stops rotating, it will wear unevenly and leak.

If this seems to have been a cronic problem, you may want to set the #1 valves somewhat loose and drive it a bit and see if they close up -- if it is firing above 2000 rpm (and you aren't 'making' oil!) you may be able to burn some of the crap off the valves and get them to close. You will know quickly, as there will be a tremendous difference in performance when #1 fires properly.

And don't forget the obvious things like a missing injector seal or dirty glowplug seat letting the compression leak out.

Otherwise, decapitation will answer all the questions!

Oh, and yes, it will fire better at higher speed -- the pump is going faster, the unburned fuel will help seal worn rings, and the cylinder will be enough warmer to get some combustion.

Peter

Wow!

Peter, thanks so much for these comments!
It sure is better to try these things first, then pull the head.:rolleyes:
What is throwing me a little, is the condition of the engine!
With the valve cover off, it seems obvious that a good oil regimen was maintained...(unless diesels don't build up oil gook like gas engines do???)
The other cylinders seem very healthy indeed. The car can maintain speed on the freeway, but I can feel one cylinder sort of cut in and out, not a full miss but more like it's not convinced it should put out 100%.

What would cause a valve problem????

If the valve was say, sticking open because of poor adjustment, it wouldn't get burned, right? Because certainly no burning is taking place!!!

When I checked my valve clearance, I wiggled each cam follower and they were the same wiggle as some others which were off cam. So no apparent problem there.

As to valve rotation, I wouldn't be able to tell unless the engine was running and I was watching it...?

I doubt it has carbon buildup after my blast to Lake Tahoe, a round trip of 500 miles.

Ball bearing thingy?:eek:

I haven't pulled it into the garage yet, so I am interested in any other diagnosis procedure there may be.

As to the pressure test, I could rig up something using the nifty hose which came with the compression tester and some compressed air. Looks like the same 1/4inch fitting...
It will be a few days for that though, as it is back to work week!

Ed:

Don't run the engine with the valve cover off unless you want to spray used diesel oil everywhere!

You can rotate the valves with a wrench on the adjusting nuts -- be careful not to loosen them, just rotate the valve. You can also use the large "nut" underneath. The valves must be free to rotate on the valve seat in the head, otherwise they "burn" -- that is, get slots eroded in them as the burning mixture leaks past.

Burned valves on MBs usually have a deep circular groove eroded in the sealing face -- only in really severe cases will they be blackened and bent.

Having the valve adjustment too tight for a long period will cause the valve to fail to seal after a while, even if it is properly adjusted later. Even a small leak between the valve seat and valve will leak off most of the compression.

Intermittant loss of power can be a valve failing to completely close (sticking open) due to crud on the valve stem. This can be caused by ERG related oil coking in the inlet extending down into #1 intake opening. Believe me, it won't stay open very far, as the piston will hit it and shove it closed!

A valve not completely closed will burn because the fuel is still sprayed into the prechamber, and it will burn at high speeds, with the flame running past the unseated valve. This will get the valve very, very hot, and since valve cooling is via contact with the seat, no cooling takes place and it overheats. Bad.

Other nasties can happen to just one cylinder, too -- a piece of glow-plug can break off and get into the cylinder, beating the piston to death, as can other stuff from the intake, like a spare nut that got dropped in, etc. Pre-chambers can crack or burn, too from bad injectors, allowing a chunck to break off, etc.

The valve rotator is a ring that fits between the valve spring and the head -- you won't have seen it unless you have taken a head apart. If it fails, the valve stops spinning and starts wearing funny, and usually starts to leak.

Sudden appearance, intermittant improvement make me think of a non-rotating or tight valve. Especially check to make sure you haven't got the intake valve set as an exhaust and vice versa -- I've done this, and lost compression on that cylinder until I fixed it.

Peter

Peter,

Thank you very much for taking the time to type all these comments, they are very informative and may solve a problem with less work than pulling the head. I am not adverse to pulling it, but hey...

When I purchased the car, all 4 cylinders worked, started quickly, but had no power!!! That was about 600 miles ago. About 350 miles ago, it started hitting on 3 at idle.

The no power thing was quickly sussed to be the bracket on the firewall which holds the throttle rod. Instead of opening the throttle at the pump, the rod was deflecting sideways instead of transferring the movement to the pump. $12 at the dealer!!!!!!
I was figgering at least $65, so there you are.

Then, I couldn't get it rev and that turned out to be the defective vaccuum pot on top of the IP.

So, I shall check the rotator on the exhaust valve and check the clearances, noting the intake and exhaust correctly. Perhaps if I rotate the valve and drive it, it will seal up! And I will later win the Lotto, and find her, and, and,....
Well first things first.

I've been a professional bus driver for 35 years, and driven I-dunno miles in front of a Detroit Dripper. For the last 23 years I have been a charter tour driver all over the west, and have noticed an odd trait amongst my fellow drivers. When we are near our buses, say we are waiting for the group or whatever, instead of talking normally, we invariably end up shouting at each other because we have drifted to the rear of our idleing coaches! I pointed this out to several drivers and they just stopped, cocked their heads and said, 'say, you're right!'.

Diesel sickness is fascinating. There is something very comfortable about the mechanical clatter which is very satisfying.
Sooo, I dunno...;)

Ed:

It must by something psychological -- after all, there isn't anything logical about driving a 3600 lb car that only produces 65 hp!

Those Detroits are a strange breed in their own right! Quite different from the MB diesels -- if I remember correctly, they are two stroke supercharged direct injection, narrow rpm range engines -- just about the opposite of what one would expect in a road vehicle. No way to argue they don't work well, because they do -- forever. Noisy, smokey, drip oil, and go and go and go!

I still lean toward a bad valve in your 240 -- ring problems simply don't appear that fast unless something fell in!

Peter

Whew....just to follow up....I found that the plate on top of the pump, I don't know the name of it had been bumped when the chain was replaced, the bolts apparently were a little loose. I could see where it had been before from the dirt etc. around it and put it back there. Still ran bad and really smoked. I then pulled the valve cover off and fond a bent rocker arm, the mechanic that had replaced the timing chain and gear on the cam had not gotten the bolt into the cam tight enough and it backed out allowing the cam to slip back bending the rocker. Luckily I found a good MB tech that was able to get everything back the way it should be. He "adjusted" the ALDA and now it runs better than ever, not even a hint of smoke. The moral of this story is, find someone who really knows what they are doing or do it yourself.