135 with Peculiar Diesel Leak

FoodPlotter135 · Jul 6, 2015

I am getting a drip of diesel fuel from the weep hole under the flywheel on my MF 135. It worsens when the tractor is running. No oil in it, just diesel. I know diesel can get into the oil sump, thinning it, and leak from the crank seal but this leak is different as it is straight diesel. Anyone have an idea to the cause or where to look?

DavidP, South Wales · Jul 6, 2015

Hi, it's unusual but not unheard of. Firstly ensure that the engine oil level is correct. Can you be certain that the fuel is coming from the weep hole? Are you sure that fuel from somewhere else is not finding its way to the lowest point? My suggestion would be to start by looking very closely around the injectors and in particular the drain pipe banjo bolts on the top of them and the connection to the return line. If the top is all dry make sure that no fuel is passing the copper seals under the injectors. Next check that there is no leak from the upper body of any of the injectors. Fuel from a leak in this region can run along the top side of the cylinder head and down the back and then find its way between the engine block and backplate and consequently emerge from the weep hole.

If you find nothing there take a very close look at the lift pump and the supply pipe from the tank. The rivetted flange that the tap is fitted into can leak and its in the right vicinity to drop fuel onto the block/back plate join.

Let us know what you find.

DavidP, South Wales

FoodPlotter135 · Jul 7, 2015

Oil is midway between min and max but that's because I just changed it. I am now keeping a close eye to make sure diesel isn't getting in it.

I am certain the oil is from the weep hole. I cane wipe all around clean and then watch the drop form from the hole.

Appreciate all the useful suggestions. I am going to explore them.

FoodPlotter135 · Jul 8, 2015

DavidP

I went to the shop last night and gave things a thorough look before and after using the compressor to blow off dust and dirt in the areas you suggested. I ran the tractor for a good 20 minutes and never saw a drop. This after a steady drip Saturday as well as other times in the past. In absence of reproducing the leak there isn't anything to suggest the leak is from the injectors/drain pipe/return. One area that does raise a little suspicion is the lift pump. I could see wet dirt around it and perhaps flowage to the starter below which provides a path to the flywheel and onto the weep hole.

Last night something else occurred to me that may be entering into the diesel leak out the weep hole mystery. That being the the fuel level. I'm down to less than 1/4 tank. I typically keep it full so with little fuel in the tank, and hence less pressure, the leak may not show itself. That would jive with no leak from an injector (high pressure side) but leaking on the low pressure side at/near the fuel lift. I'm curious if I fill her up the leak will resume. That's my next step.

135 with Peculiar Diesel Leak

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DavidP, South Wales

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