JD450 Surging and Mouse Turds?

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Big Chris
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JD450 Surging and Mouse Turds?

Post by Big Chris » Wed Sep 26, 2018 7:15 am

Hello, new to the forum and my first post. Our dirt bike club has a 5 acre motocross track that we maintain with a 1972? JD 450 dozer. It does not have a letter designation, and has dry clutches. Its an in-line 4, non turbo 6 way blade, no winch. Ol' Bessie is an old girl and until recently ran well. I am the chief operator and have probably logged 200 hrs on this machine in the past 8-10 yrs. She lives at the track and stays under roof in a non heated pole barn.

When I operate the machine, I usually set the throttle to about 1/3 lever and just run the machine. Recently, the engine has started surging when being operated (throttle setting remaining constant). Seems like going uphill makes this worse. Ran the machine with the fuel cap loose, no change. Filters are recent, fuel is clean. On Monday, she died. She'll start with ether, sometimes run for a minute of two then die. When I open the bleeder bolt on the high pressure pump and crank the engine, clean fuel comes out.

We did have a fuel leak on the bottom of the 2nd filter (not the glass bottomed one). The leak was at the little plastic drain screw, the seal on the plastic screw was damaged. It was only a very slight drip, leaking a single drop maybe every 3-5 minutes. This has been repaired.

I searched mouse turds, I am assuming there is a component in the injector pump that gets shredded and the debris resembles mouse crap. Talk to me about this, and any other suggestions you might have for what may be causing our symptoms.

Thanks in advance,
Chris

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Stan Disbrow
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Re: JD450 Surging and Mouse Turds?

Post by Stan Disbrow » Wed Sep 26, 2018 10:18 am

Hi,

There is a ring inside the injector pump made out of a plastic called Pellethane. It deteriorates and comes apart in small pieces which resemble mouse turds. This, in turn blocks the fuel return line to the tank. This, in turn, blocks the fuel flow thru the pump and so it won't inject enough fuel to run. Fuel locked, as it were. The return fuel is the difference between what the lift pump supplies and what the governor sends to the injector. This happens in waves, so your surging was very likely the onset of the return line plugging.

I would set the timing to TDC on #1 and then pull the IP and take it to the IP shop. Others on the board fix their own. This would be a good time to replace the injectors as well.

Stan
There's No Such Thing As A Cheap Crawler!

Useta Have: '58 JD 420c 5-roller w/62 inside blade
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Big Chris
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Re: JD450 Surging and Mouse Turds?

Post by Big Chris » Wed Sep 26, 2018 11:31 am

Thanks for the reply Stan, so I guess step 1 would be to disconnect the return line from the IP and inspect for debris?

Sounds like I'm need of a IP pump rebuild. Are there other members on the forum who might share where they sent their pumps to be rebuilt, and a rough idea on cost? I think I read in other threads around $400-$500, are these number still accurate?

Not that it really matters, I am in Pa.

Thanks, Chris

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jsal
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Re: JD450 Surging and Mouse Turds?

Post by jsal » Wed Sep 26, 2018 5:14 pm

dcp diesel care and performance is in TN $414.00 round trip no shipping just sent one out yesterday had others done locally for 600.00 I am trying them out JIM

Big Chris
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Re: JD450 Surging and Mouse Turds?

Post by Big Chris » Fri Sep 28, 2018 6:18 am

Thanks for the info guys, I'll let you know what I find.

Should get to work on her on Sat, if it ever stops raining.

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77 Ford
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Re: JD450 Surging and Mouse Turds?

Post by 77 Ford » Fri Sep 28, 2018 7:02 am

I had one done at DCP in memphis, could not be happier.
JD- 450C track loader
Serial #208336T

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