Injection Pump Timing--No Drips? - PeachParts Mercedes-Benz Forum

83mercedes · #1 06-14-2005, 12:25 PM

I'm using the drip method of setting the inj. pump timing on an 83 turbo diesel, and after getting the fuel free of air bubbles, it flows, drips once and then no more. Is my pump timing that out of whack?

I'm not sure which vacuum line on the inj pump the manual is referring to, I'm assuming the one on the back of it (towards firewall). Could this be the cause of it? I don't want to adjust it if it's already right...

83mercedes · #2 06-14-2005, 01:02 PM

Just needed to add, did entire procedure by the book, several times, only thing I'm not sure about is the vacuum line (which the manual is referring to). If anyone can give me any advice on that it would be very helpful.

dannym · #3 06-14-2005, 01:09 PM

Hey,
I believe it's refering to the vacuum shut off valve. But you can always remove all of them it won't hurt anything.
Did you remember to wire the throttle open?

Danny

83mercedes · #4 06-14-2005, 01:16 PM

Yes, wired throttle full open, tried with various combinations (and all) vacuum hoses removed, removed spring and valve inside fuel valve and reinstalled with drip tool, got it 23-25 degrees before TDC, loosened fuel union on fuel filter, pumped primer until pure fuel flowed, flow on overflow spout stopped, dripped once, then no more.

I just can't believe the timing could be that off. I guess I'll try moving the pump and remeasuring, but if anybody can spot a problem beforehand, I'd be glad to avoid that procedure.

Pete Burton · #5 06-14-2005, 01:40 PM

just how many degrees do you estimate you moved the IP?

leathermang · #6 06-14-2005, 01:47 PM

And why did you start messing with it in the first place... was the car running badly, or you found chain elongation , or what...
if it was running ok... then it could not have been very far off... so you need to keep looking for an intervening variable....

83mercedes · #7 06-14-2005, 02:28 PM

I have tried advancing the timing, but it will not move towards the engine any further, but it doesn't really move away well either. I loosened all three retaining nuts.

I was checking it in the first place because the car has an excessively rough idle despite installation of a new rack dampener bolt and engine mounts and shocks, is not getting the correct gas mileage, and seems to have slightly reduced power in the last maybe month or so.

It's not filters or injectors or alda adjustment or valve adjustment.

leathermang · #8 06-14-2005, 02:38 PM

Lets back up a little...
Did you set the valves ?
Did you check for chain elongation ? ( using the 2mm movement of the number one intake valve ) ?

83mercedes · #9 06-14-2005, 03:57 PM

If by "setting the valves" you mean to the proper clearances, yes, I did that a few months ago.
If you mean turning the crank balancer to 23-25 degrees below top dead center, then yes, I did that as well.

I just gave up on the procedure after moving the pump to a variety of positions with the same result (no drops, just flow and then stop). Very unpleasant in 100degree weather, direct sun. I found out that I had been forcing the injection pump towards the engine but it was already maxed out that way, so I was just slamming it around for no reason.

I'm just glad my pump still works, and the timing chain didn't get screwed up by those impacts. In retrospect, I can't believe I actually tried to tap the injection pump by force, I guess my mind isn't working very well today.
If anyone can figure out why I was getting no drips, though, I'm still curious if I ever wind up opening the engine enough to have to reset the timing.
Also (this was present long before today and seemingly unrelated to any work), I am having a metallic banging coming from (I think) the front of the engine, not sure if it is inside or out, but if it's out I can't locate it. Maybe in cylinder 1. Any ideas about what might cause that kind of a noise? It disappears at anything but idle.

leathermang · #10 06-14-2005, 04:22 PM

You need to check your ratcheting tensioner and your chain rails and slides...
Also might consider taking the lower pan off and checking your oil pressure valve (if you have one ). That is something talked about in the FSM when " oil noises" are present... several designs of the valve were installed at different times... different lbs of relief and different hole designs... they can fall out....or they can malfuction.
Easy does it when ' manhandling ' the IP... LOL
Did you take anything out of the number one hole on the IP ?

Brian Carlton · #11 06-14-2005, 04:35 PM

I do recall having some difficulty in getting the drip method to work. I never did gain the confidence that I had the pump in the proper position.

I will tell you, however, that trying to move the pump with the fuel lines attached is very difficult. You must, effectively, bend the lines to get the pump to move. So, if you are going to pursue it, you probably ought to remove all the fuel lines. Then, you can move the pump all over the place without the need to use a BFH. The pump doesn't really appreciate a BFH.

But, and this is important, when you go to reinstall the lines, they won't want to go on. This is because the pump has moved. So, you must carefully bend them to fit until you can get the fittings started onto the injectors by hand. These metric fitting are easily cross-threaded. If you can't start the fitting by hand, do not put a wrench to it. Manipulate the fuel line until you are postive it will start by hand. No fun in 100° weather.

dannym · #12 06-14-2005, 04:54 PM

Hey,
This is from another post which I found interesting:

Quote:

While I haven't found it in the FSM I remember reading about the "column" from Stu Ritter almost a decade ago. If I recall correctly it was like a big graduated cylinder and you might have even watched the rate of fuel drop.

In my experience with the timing procedure (using the drip tool) the transition from a fast flow to nothing at all is very fast. I think the "one drop per second" refers not to a specific flow rate but that region between continuous flow and residual drops.

I also remember reading about an alternative method where you dip paper towel into the delivery valve body and watch for the fuel to come out, but I've never tried it.

In my experience with the drip tube method, operating the hand pump and turning the crank at the same time was difficult, and it was hard to discern if the flow at the drip tube was slowing because of the crank angle or because the pressure in the pump body had fallen. Jacking the rear of the car solved this problem well.

Also:

Quote:

I loosened all three retaining nuts.

Don't you mean all 4 nuts? There's one way down behind the rack dampner, which you have to remove to get to.

Danny

83mercedes · #13 06-14-2005, 05:29 PM

Quote:

Originally Posted by leathermang

You need to check your ratcheting tensioner and your chain rails and slides...
Also might consider taking the lower pan off and checking your oil pressure valve (if you have one ). That is something talked about in the FSM when " oil noises" are present... several designs of the valve were installed at different times... different lbs of relief and different hole designs... they can fall out....or they can malfuction.
Easy does it when ' manhandling ' the IP... LOL
Did you take anything out of the number one hole on the IP ?

Yeah, I took out the spring and the little valve piece, then reinstalled.
What do you mean by "oil noises?" More about the banging noise in the engine, if it helps:
1. It usually goes away even at idle after the engine has warmed up for a while.
2. Its severity is diminished somewhat if I shift into neutral at idle.

83mercedes · #14 06-14-2005, 05:32 PM

"operating the hand pump and turning the crank at the same time was difficult"

I didn't realize I had to do both of these at the same time. Possibly the root of my problems. It didn't say anything about that in the Haynes manual.

leathermang · #15 06-14-2005, 05:38 PM

Methods to provide a constant ' head' for your fuel are in the archives... putting something like a boat fuel tank mounted several feet above the IP has been used successfully... better than hand pump in my opinion...

" oil noises" ... I don't know... I am just relating what the FSM says about what might be oil noises... the description of when it happens, and goes away... match the FSM....

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