720 D

J Bouchard · May 13, 2017

Started my tractor this spring after winter storage. Noticed the following, swirling of sediment in the fuel bowl while running and leaking of fuel from the base of the fuel transfer pump. Last year the seal of the transfer pump was replaced. Am I dealing with an injector issue causing increased pressure in the fuel system to cause this? Is so do I just replace the injectors or do they get rebuilt? Any guidance on this is appreciated.

Dieseltech · May 13, 2017

I just cleaned a pair of 730 injectors, but not for what you describe. Injectors will not cause your trouble, fuel may or may not swirl in the bowl, but any fuel leak needs repaired.

J Bouchard · May 13, 2017

So the fuel leaking around the transfer pump base is from a failure of the gasket F 1755R or the seals on the pump shaft AR 395R? I notice that there are 2 seals used. Do they both install the same way or is one facing out and one facing in to seal both directions?

Dieseltech · May 13, 2017

Most likely the shaft seals. If I recall there are two, facing away from each other.

J Bouchard · May 13, 2017

Thanks for the followup, will look to replace those shaft seals and go from there. Is it a big deal to have the injectors removed and repaired? I'm thinking that I should do that anyhow.

Dieseltech · May 14, 2017

If the diesel engine runs well with little smoke injectors are OK. Both are under the valve cover. I have the JD Woodring & Wise test stand to reset the injection pump calibration too. Just finished up on the pumps/injectors for a 730.

Mike M · May 14, 2017

I also have noticed swirling in my sediment bowl. Mine has the return up thru the top inspection cover and into the bottom of the tank. I think this is normal. The transfer pump shaft might be too worn as most are. Was it replaced along with the seals ? Also the new type thin seals if not held into the housing with some sort of hardening sealer can get pushed back and leak. Can't remember for sure but may of even had to make a metal retainer to hold some seals in ? Seals go back to back. A later style pump is better as they have a bleed hole back to the suction side of the pump to help relieve pressure off the seals.

J Bouchard · May 14, 2017

by saying seals are back to back , you mean that one seal faces inward, and one seal faces outward? When seals were replaced the shaft was not but did not seem excessively worn. I did not measure it however.I did not use a seal retaining compound and this is possibly an issue. It did not leak initially when they were replaced last year, though the tractor did not run much either.

Mike M · May 14, 2017

Yes seal lips opposite. I'm betting once you get it off you will see the seals have moved letting it leak out the weep hole. I had one do that before.

J Bouchard · May 14, 2017

thanks for the help, I hpoe that takes care of the problem

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