IP wear tolerances

Evening folks, I would like to get some guidance from the forum regarding my db2 IP.
1994 E350 ambulance convertedto camper , Quigley 4x4 4, eod , two tank WVO electric fuel pumps 7 psi , HIH, additional injection line heaters full heated return to tank.

At 95.000 miles, 10.000 miles after conversion hard start, heat soak and then no start.
Ip replaced with junk yard unit mileage unknown. but ran perfect. Thanks for the great write-ups about timing and IP removal. That surely helped.

5000 miles later same problem on second IP. Hard start and no start when hot. On WVO hot start is good.
Batteries good, upgraded starter and ground cables. cranks fast, no air bubbles, fuel comes out of return line while cranking.

I tore the first IP down to find the problem but besides a brown coating from the WVO all seems to be fine. Obviously it was not. I found the rebuild manual but that is not very specific about the tolerances of the plungers and head / rotor.

I have to say , it is pretty cool to take an IP apart.

I can see no damage to any of them and so i am starting to suspect that the problem comes out of the transfer pump?
Can anyone give better guidance how to determine the tolerance in the plungers and head and rotor?

Thank you,

later J

I'm not sure of the exact tolerances and clearances but I don't think it's something you will catch with the naked eye.. They're much like machining a block and to my understanding you have to have special equipment to test them. Maybe Mel or Russ will chime in.

As for transfer pump- are you referring to the lift pump? Easiest way to test that is check pressure at the schrader on the filter housing. I believe 5-7 psi is the magic number.

Thanks Wvdirtroad,

The electric lift pump is set at 7 psi. I wonder if at the cranking speed enough transfer pressure is available to push the plungers apart.
I assume the tolerance are in the range of 0.0002" or 0.0005 MM . That would not visible but I wonder if you can feel it. For instance if i would insert the rotor in the head for 1/4 inch how much wiggle would be allowed.
The heat soak definition although understandable gets me lost a little bit. The material used are all not to dissimilar in expansion coefficient. The only one that really changes is the viscosity of the diesel. That sure I would get.
The other problem I have is that with both IP's the problem appeared in about 200 miles, one trip for me, from being not there to hard start and OK with water on IP and not start about three starts later.
I would think this would be a process of several 1000 miles not several hundreds.
I am in the process of making the transfer pressure adapter "21900" I believe so that I have more data to share.

Later J

I know the issue can come on quickly. The issue may have been preexisting even on the junkyard pump. The fact that you are using an electric pump with a bit higher pressure may have gave the pump a 'dying breath' so to speak from sitting for a while and then being used. You can PM agnem and see if he is willing/ able to discuss clearances etc. He runs conestoga so I'm not sure how much info he'll be able to share in a sense.

Yes I will call him again and see if he has time. It is not to far away, may be a road trip? It is very well possible that the second pump was on its end as well or my WVO is super aggressive. I like to get a good to very good understanding of this problem before I want to invest in a new pump incase that would fail also in a couple of thousand miles.
Later J

Honestly, there is no way to measure that stuff. We build pumps and put them on the test bench, and we can tell how much wear they have by the calibration results we get. As long as they are in spec, we know they will be fine. Occasionally we get a pump that won't test out, and it sucks, but we have to rebuild them with a new H&R, even though the old one looked perfectly fine. Also, now that you have disassembled your pump, if you were to put it back together, your calibration would be gone. Oh it would run your engine, but never as good as it could if it were rebuilt correctly.

Measuring the clearances is really not possible. My feelings are the fuel you are using is ruining the pumps plus you have no idea what condition the junk yard pump was in either. You can test what I think by finding another junk yard pump but this time run only diesel number 2. See if it runs more than 200 miles. Then change back to the other fuel and see how long it lasts. When you run the fuels you made up they have a higher viscosity and that in turn opens up the clearances in the pump.Its like running heavy oil in an engine and then running a light oil.

Thanks Mel, and all

This was a pump that failed earlier and I had no real intend to put it back together.
I assume the H&R wear shows up at the lowest ( cranking speed) and it not being able to pass injector pop pressure.
I was in the hope after reading the inspection chapter 4 criteria in 99009 instruction manual that if you would not have any of the visual scoring damage that it at least would be considered workable.
I will call you today requesting price of a rebuild pump with new H&R.
Thank you
Later J

Hi Icanfixall.

No doubt you are right.
We use our camper on long hauls when I go to inspect our equipment at airline jet engine overhaul shops. Mostly I try to take the wife and kids along and make a roadtrip vacation out of it.
That means we stop along the road and ask restaurants for their waste oil. We on-board filter to 5 micron. We are running wvo in several mercedes 4,5 and 6 cylinders for the the last 10 years and yet have to see a broken pump or engine. We are also running a jeep cherokee 2.1 turbo diesel with 294000 miles on wvo and running strong.
Earlier we made a camping vehicle out of a 97 powerstroke e350 and never had a problem with WVO that we acquired along the road. We changed to the IDI because we thought that the engine was easier to work on in case we would get stranded in the middle of nowhere ( both econolines are 4x4 ). Sofar that thought has not paid off. I have not have to replace an IP on the road. It is a little frustrating that with so much good results with WVO over the last 10 years
the DB2 causes me so many headaches.

The original IP of the ambulance, the one I have taken apart now, had 95000 miles on it, may be the original and so possibly worn out.
It is more the sudden death that concerns me.

I probably have to make a jig on the lathe that holds the pump and see what the lowest RPM of delivery is and still pop the injectors.

Thanks, later, J

Any chance you can "find" some jet fuel when you are doing these jet engine inspection. Just add some lube to it but its really same as diesel. Just a dryer blend cause a jet engine doesn't need fuel to be lubed. I have worked on P&W burner pots and nozzles. Sure lots of nuts and bolts just to slide back the covers to reach that area.

Ha,ha, jet fuel, that would be nice, not very likely.

So, a couple of days later now. I have made up an adapter for measuring the transfer pressure. some date:
engine cold diesel cranking 20 psi, starts well and idling 60 psi. Then the problems start the pressure does not go above 75 psi.
engine hot diesel cranking 10 psi, does not start.
engine hot and hot WVO cranking 20 psi, does start.
WVO or diesel the prssure does not go above 75 psi. I do not have a tacho but that 75 RPM is in second gear at 40 mph. It is revving pretty good.
The electric fuel pump delivers 7 psi and does not fluctuate.

A small observation a made was that the transfer pressure drops 1 or 2 psi from the 75 psi when I fully WOT.
So may be ; the inlet fuel filter / strainer is clogged?
or the transfer pressure regulator is stuck open?

At the least this was a very good learning experience.
No higher pressure means no advance so may be a reason for less power and more smoke at higher altitudes?

Please all let me know your thoughts.
Regards, later J

With the thicker fuels it seems to run fine. Thats a clear indication the clearances are well worn out in the pump.

Yeah, that is sure, now to find which part.
So i measured on my old previous failed pump the vanes width compared to the thickness of the transfer pump and found the vane / blades 0.001" below the thickness of the transfer pump. I regret not having a transfer pressure gauge available when the last pump failed. It would have been nice to see if the transfer pressure was low.
According to the 99009 instructional manual page 1.9 ( diagram of transfer pressure vs rpm) it shows 40 psi at idle?? I am not sure where I picked up 60 psi at idle.
It also shows the pressure as completely linear vs rpm. That must be the result of the pressure fuel regulator.

The next thing would be the leakage at the pumping plungers. Tolerances are 0.00000625" since replacement plungers can be ordered in increments of that number. It seems they just try the tightest non sticking one.
(service bulletin 99687 no 60R8 )

Then there is leakage between the rotor and stator. Nothing can be done here.

To first deal with the hot starting issues turning up the max fuel delivery screw and spring should give more fuel at wot and thus at cranking speed. This might overcome the internal leakage wherever it is.

Another thought that I had is that WVO might contain solvents that attack the sealants used to seal the stator and the inner liner??
Anybody has ideas on that?

Enough for tonight.
I will try to pull the transfer pump and visually inspect.
I will poptest several injectors and see if any thing odd has happened there.

Later J

just a picture of our BULAN

Today I got a PM message from someone else with hot soak issues.

Unfortunately before I could get to a complete detailed understanding of the IP issues we had a serpentine belt failure and an overheat issue. After correcting that issue we blew a head gasket within 100 miles.
We choose not to repair the Van. The IDI was no improvement relative to our powerstroke experience regarding WVO, fuel efficiency and power.
Beginning 2016 we bought a van based skoolie with a powerstroke to continue our journey,

Thank you all for your help, it is to bad that I have not succeeded in resolving the complete detailed mystery of the hot soak problem and a diy solution to diagnose what detail are worn out in the pump.

End.. J

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