720 D

J Bouchard · Apr 21, 2018

Am contemplating removing fuel delivery system, transfer pump/ injectors and fuel pump system from my 720 D to have rebuilt. Have had issue with fuel dilution in motor oil. Though it does not seem that complicated to remove, how difficult will it be to reinstall when rebuilt? Would it be best if I had a mechanic to also remove? Though I have some mechanical skills, I have not had the pleasure of working on these diesels before.

Bob · Apr 21, 2018

Unless you have a ton of extra money to spend, check a few things FIRST...

A leak at the transfer pump shaft seal is common.

High pressure injection lines can crack or leak at the fittings.

There's gaskets involved on the low pressure side, as well.

Once you've ruled out the transfer pump, at least have a good look around under the top cover and valve cover for signs of fuel.

Dieseltech · Apr 21, 2018

Most two cylinder pumps I see in for repair have eroded pump delivery valve gaskets too. Not bad going back together when using the service manual, and taking your time. MAKE SURE when setting the timing, turn the flywheel slowly and check that the timing mark DOES NOT leave the pump body opening. If it does the pump cam lobe is worn, and when the timing is set on the worn lobe the full cam lobe lift will move the plunger too far, and risk severe pump damage. I purposely set the timing about 1/8 inch back, then turn slowly to make sure mark is still visible. If so then set it to the correct location, and re-check at full lift.

Patatrcc · Apr 23, 2018

Since we're on the subject of fuel transfer pumps, do they make a rebuild kit for them? I have a 70D that needs either a new pump or a kit. I would rather rebuild the one I've got, but not sure what to test, fix or replace.

Pat in Montana

720 D

J Bouchard

Member

Bob

Well-known Member

Dieseltech

Well-known Member

Patatrcc

Member

Similar threads