M35 Leaking IP

[builder77]

I am thinking I have left a trail of drips behind me on my current Thanksgiving holiday travel from Richmond, Va. to Raleigh, NC. My injection pump is leaking around the hydraulic head. To me it looks like it coming from the very top of the IP like under that thin plate that is ontop of the hydraulic head. So I am thinking either the center bolt for the head or one of the fuel lines is the problem. Any suggestions, and is it ok to tighten up that center bolt in an effort to stop the leak? Oh the truck is operational, but is perhaps a bit down on power. Are there any o-rings that would be susceptible to VWO damage in the IP?

This may have been caused by running the last of my WVO mixed with gas as with these cold evenings it might be too thick in the mornings. I will have to install a proper two tank system before I run any more WVO to insure no future problems.

 

[cranetruck]

The center "plug" is tighteneded to about 50 ft-lb, no gasket there, just metal to metal seal. The fuel lines are ferrule type compression fittings, nothing that would be bothered by WVO. The thin plate is only a way to label the lines, the leak could come from any of the above....

 

[Massm35a2]

Be careful. I think it may be one of your injector lines. I have been stranded by this same thing. Once you touch them they can get way worse. On mine, water must have gotten down around the furrels and pitted them. I tried to tighten them, but got a worse leak. Once it looses a certain amount of pressure, your injectors will not open and you are stranded

 

[builder77]

I am thinking that it probably is an injector line too. I have one that has no rubber boot over where it goes into the IP. Perhaps the furrel got corroded. Are the ferrels replaceable? Any good sources for them and the rubber boots? Anyways I am not going to mess with them until I am at home. I may lose some fuel, but I can deal with that just fine. Oh now the starter did not want to work for a few minutes too. Perhaps a wire was loose, or I was looking at the wiring diagram and there is a fuel pressure switch.

 

[cranetruck]

Ethan, don't know which wiring diagram you are using, but the CAD one on this site has some errors in it. The fuel pressure switch may not be present on your truck, mine doesn't have it and the start relay does not go to the start solenoid contacts as shown....
Check/clean all battery cable connections.
To fix a bad injector line, the best way is to replace it.

 

[builder77]

Well the plot has thickened with my IP head leak/injector line leak. I got home ok, and am just about back to diesel fuel. I noticed thhat my IP did not leak at startup, but only after driving a few miles. I don't know if this is casued by thinner fuel or expansion of the metal parts. It appears that third injector from the front has developed a sudden leak at its top. It somehow managed to squirt fuel through the radiator and up over the hood to hit my windshield which I am still confused how that is even possible. I can't imagine that a leaky IP could cause a leaky injector, so could a clogged injector cause a leaky IP head due the increased pressure? Is each IP fuel line different?

I am not sure which wiring diragram I have in my truck. I remember found several out there here, on OPCOM's site, and elsewhere. I had trouble printing on one page though, so whichever I managed to make work is in the truck. I don't think my truck has a fuel pressure switch from following the wires. One of the wire studs would rotate which is usually not a good thing, so I will be working on obtaining a spare. It started though.

 

[cranetruck]

If you start the engine on a mix of veggie oil and diesel you may develop coking of one or more injectors, unburned fuel clogging the openings and it's possible that a pressure build-up causes the leak you are seeing.
Remove the #3 injector and take a close look at and around the holes. I have pictures somewhere or they may even be on this site, come to think of it....

With a dual tank system, heating the veggie/bio fuel, the engine is always started and warmed up on 100% diesel so chances of coking are reduced dramatically.

 

[whatadeuce]

View attachment m35 diag. in word .docxHello cranetruck, And I am just checking a M35A2 and find there is no magnetic start relay installed. Did these trucks start by wiring conductor # 74 right to the starter solenoid? 

 

[whatadeuce]

sent wrong diagram, will try again,,,

 

[cranetruck]

View attachment 532528Hello cranetruck, And I am just checking a M35A2 and find there is no magnetic start relay installed. Did these trucks start by wiring conductor # 74 right to the starter solenoid? 

There is supposed to be a starter relay to reduce current demand on the start switch, typically 1 amp vs 30 amp.
These are the wires required respectively.

 

[whatadeuce]

Thank You cranetruck, and I see on this vehicle wire # 74 is all burnt up. Its no wonder. I guess someone did thisnas an emergency procedure, but I have the magnetic starter relay and I am going toionstall it.

 

[cranetruck]

Good, and you may also need to replace the start switch.
In addition, I would recommend that a diode is added as shown here, typically 1N4003 or equivalent. It will protect the start switch from electrical spikes produced by the inductive load (start relay).