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IP problem for the experts

cranetruck

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Background:
The governor and associated parts of the IP on the LDS465-2 appeared very sticky a couple of days ago, so I removed the FDC and exrecised all the parts and lubed them liberally.
This morning I cranked the engine and it started nicely. The "gas" pedal was very responsive and all linkages worked well.
Oil pressure was 45-50 psi in the beginning and dropped to about 40 after 1/2 an hour. Generator right on the tick mark on the gauge, air pressure at 90 psi, power steering working well and engine op temp rising normally to about 130°F when the engine stalls out.
Cranking it produced nothing, no smoke, nothing. Fuel flow in good condition, no air in the lines and plenty returning to the tank.

I removed the plug on the hydraulic head and found the plunger in the up position. Tapped on it with a metal rod and small hammer, still stuck.

This is very reminiscent of the problem I experienced in Joplin, MO last year, where the steelsoldiers came to help with a new hydraulic head (Jason Curtis, Cabell and others), which we replaced in the parking lot at the Flying J.
Anyway, that hydraulic head has a plunger, which is so tight that it will not return to low position by spring power.

Question: How does the plunger seize up and what is the cure?

Yes I can tap harder, but if it rides on the cam, it won't help. I had to loosen it up last year also, prior to starting the engine at that time, so it will probably happen again.

Image shows IP location and the cab may have to come off to access it so that the head can come off. Big job.

It ran beautifully for 1/2 hr, though, idled at 725 rpm and revved to 2,000 several times. Transmission in neutral and transfer in neutral.
 

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Westech

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Thats what I would be guessing at would be the WVO. Some sort of build up in the pump. I run all sorts of stuff in my tank and never had any problems with "sticking". maybe trying using some Diesel 911 once a year or so. That stuff really seams to help remove build up and "gunk".
 

cranetruck

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We are talking about the xm757 8x8, which hasn't been operated since 2001.
The fuel now is almost 100% low sulfur diesel with some canola oil (fresh from the store) for lubricity....maybe I need more veggie oil. :)
The problem is that the plunger isn't returning to its low position. I put some CLP on it for the time being....
 

Westech

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It could be just from sitting. I know mine acts a little funny if I let it sit for 6 months but after a min or two she is all good. I still would dunp some good old nasty Diesel cleaner in her. One thing I have been doing alot is adding a bunch of used (filtered) ATF in the fuel. That might not be a bad idea for ya if the truck is going to be sitting a bunch... if its stuck that ATF will clean her right out.
 

cranetruck

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To summarize what we have so far, the fuel plunger moves up and down by the action of the cam on the main shaft of the IP.
It is also rotated by a guide, which according to the manual, will shear if the plunger "freezes" in the bore.
All surfaces of the plunger and bore are lapped for a near perfect fit.
It's lubricated by the fuel.
Engine runs good at rpms varying from 700 to 2,000 for about 30 minutes and suddenly dies for lack of fuel.
The fuel plunger stuck in up-position. Don't know if it still rotates...

The hydraulic head from the engine serviced at the truck stop in Joplin still rotates the fuel plunger, but the spring is very slow at returning the plunger to the bottom position, so the guide has not sheared.

I don't like to tap the plunger back down, there is always a possibility of deforming the end...perhaps by using a softer metal rod, more forceful taps can be permitted. Also, what action can be taken to keep it from happening again?

Is it safe to assume that all hydraulic heads are the same regardless of the motor, need to check on that?
 

cranetruck

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As usual, a small problem leads to more and more "work", in order to trouble shoot the IP and remove/replace the hydraulic head, I need to turn the engine over by hand and since the automatic transmission effectively hides any access to a drive shaft to turn, the radiator had to come off.
It came off yesterday. Good thing too, need new drivebelts, coolant hoses and removal of another 1/2 dozen mud dauber condos.

Of course, this leads to the need for more tools....1-11/16" socket for the crankshaft and a special puller for the compressor pully (to replace the belt).

Am I correct in assuming that drivebelts don't come in "matched sets" any longer?
 

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5tonpuller

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The years I worked on trucks and equipment when this happens ether some crud or something else jammed it up. When that
happens it always leaves a bur. Once stuck, now it will and you might never know when the next time will be. This makes peace
mind fun drives really had to enjoy.
My $0.05 worth.
Matt
 

gringeltaube

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Re: RE: IP problem for the experts

cranetruck said:
Is it safe to assume that all hydraulic heads are the same regardless of the motor, need to check on that?
Check these charts, Bjorn. Several IP head models, some do interchange, some don't! Wish I knew what the differences are!
According to the manual yours would be an A code pump.
The heads offered at SMINC would be good for C, D andE code IPs only!?

Lots of patience and good luck!

G.
 

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cranetruck

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RE: Re: RE: IP problem for the experts

Thanks, I have one to practice on, so maybe I can fix the one on the LDS465-2. The fuel delivery spring can be replaced and if repolishing the fuel plunger works, I should be okay.

I don't have the 1-11/16 socket required to turn the crank shaft on the engine, so there is a little delay in further trouble shooting...
 

Westech

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I have not seen matched belt sets in a long time. They pop up on ebay for the deuce but your set up looks a touch different. As long as you get the same part number belt you should not have a problem. We replace a ton of double alternator belts here at my shop and we never have a problem. I think 50 years ago the belts were made a little "looser" and that's why you needed matched sets, but with today's drive belts made to a much tighter tolerance you should be good to go
 
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