IP Element timing check
 

So, I gather that the individual elements on the injection pump are adjustable. I s there a way to see if they are in adjustment? Could the crank pulley be marked every 144° and the "weep" method used to confirm each element or is much greater accuracy needed?

Andrew

Yes they are adjustable but better let a pump shop do it. At present there are several tests that may indicate it is needed. For starters what leads you to believe your sequential pump timing may be out? In effect an injector in poor condition might cause a simular suspicion. Plus perhaps several other things. To establish if you even have a problem reading the glow plug output voltages might give some indication. Have you done your engine to pump timing yet? In otherwords suspicion of pump problems is your last resort because of cost and usually it will be something else. As to your degrees on crankshaft between element discharge it would be every 180 degrees I believe. Accurate enough for a general test I think using the well up method. Worst part of the job would be getting a degree wheel mounted on the pulley.Plus a pointer as well. But quite possible in my opinion.

That would be correct for a four stroke, four cylinder engine. 144 degrees for a five cylinder. (Assuming crankshaft angularity is evenly spaced.)

.......LOL.......one of his rare mistakes............:D

Well, the reason I asked is because I have a sound I am trying to diagnose. Yes, valves are adjusted as is pump timing. All the nozzles are new and dialed in to within 30 psi of the high spec for breaking pressures. Still there seems to be one cylinder that has a very pronounced diesel "marble on the plate" sound. Perhaps I will loosen injector lines and swap injectors prior to checking the pump, as it's easier to check the injectors...

Yes, mine is a 5 cyl.

Andrew

My apologys, here I thought all mercedes were four cylinders.:D even though I own two five cylinders as well.:silly: I would assume you know the suspect cylinder. If not or even if you do read the milli volts output of all the plugs. See if the problem is being reflected in a cooler running cylinder.Reflected by a lower milli volt reading. . If you can establish you have a cooler cylinder then rotate your pump timing a little back (retard) and do your voltages again. For extra insurance roll your pump a few degrees advanced as well and check those voltages one more time. You do not want to adjust the element timing unless verification that the individual element is off by the bad cylinder not tracking the recorded voltages in a lockstep fashion. Meaning if you find the cylinder does increase it's voltage to equal the best you got on the other three cylinders with the overall pump timing at normal it is pretty conclusive. At this stage you might want to try to fine tune that element with your disk on the crank. Even if you are not succesful you at least have not much to loose and have already proven the element is badly timed in relation to the others. It is a little too early to recommend doing the adjustment by the milli volt method really. But if the rotation of the pump to a slightly retarded position increases the suspect cylinders output voltage much more than the other cylinders you have your problem verified. The marble sound indicates your problem is one element is advanced rather than retarded if it is a problem. The other voltages should have fallen off a little of course during the retarding proceedure if the test is sensitive enough. There seems no reason not to reset the pump primary timing and make a slight adjustment of the elements position until it equals the other voltages. If you were to totally mess up and that is unlikely in my opinion you have proved beyond a doubt the pump needed sequentially timed earlier anyways so it would have been on it's way to a pump shop. But primarily you will have proven it is or is not the element timing by the swing method that it is the underlying fault. I also think the disk on crank method is a good way to locate the problem but a bear to try and rectify using it as the element adjustment is usually so small and you might get tired with the repetative moving of the element and checking the disk by rotation of the engine everytime. The milli volt method is used with a running engine and your ear will tell you when you are going in the right direction with the milli volts verification of when you reach the other cylinders values to back it up. A member just loosened his two nuts a very little and using a pry bar moved his a small amount till the engine sounded better and the milli volts output of that plug equalled the others. All above statements should be valid in my opinion but I can only suggest them not recommend them. One other thing if you find several elements off sequential timing I would send the pump to a shop for a retime at this point. Swapping glo plugs around to make sure of their equal output might have to be done in the proceedure to verify their refference output by comparison... But on one element it does seem a reasonable home proceedure to me.Or at least worth trying if the voltage indication is there. Several indicated elements out of timing is another kettle of fish. To be fair though it is still a little early to deal with anything in an absolute fashion when it comes to this proceedure. Your reporting back again is so very important long haul for a lot of other members on this site. Good or bad. I also fully realise that I have left a lot of potential variables out as well. They are becoming less of a factor that I originally suspected so far.