7520 fuel pump problems

[jrchafin]

Hello all, have a Mahindra 7520 with 700 hrs on it, about 6 years old.

Using it the other day and I noticed a diesel fuel smell, found a leaky gasket in the bosch injector pump. The leak was on a gasket underneath a plate that was facing the engine block, so I had to take the pump off to fix the gasket. I have no idea why this started leaking, but it was running fine otherwise.

I removed the pump, and replaced the gasket as well at the other gaskets involved in the removal. I reinstalled it, and cracked the line that enters the pump, running through the filters and hand pump to the top of the injector pump. I hand pumped until fuel came to this point and then re tightened that line.

I knew the pump wasn't bled completely, but decided to try and start it. I cranked it and it ran great. put it at full throttle for a minute or so, no problems, no leak. I shut it down thinking I was done.

The next day it wouldn't run at all, just cranks and cranks with the starter, a little grey smoke coming from the exhaust. I figured I was air locked, so I removed the high pressure lines and tried to hand pump fuel through the pump. I have pumped that thing probably 50 times or more, and it feels like it's pumping, I can hear a hiss, but no fuel comes out of the high pressure ports.

What am I missing?

Thanks in advance.

 

[jrchafin]

Ok, got the pump bled, and got it running again, and it promptly started leaking again through the same gasket. Not just dripping here and there, but squirting out. It is coming from a gasket at the bottom right side of the pump toward the engine block, so it is hard to see exactly.

So now my question is, has anybody else had this problem? What's causing it to blow the gasket and what's the solution? Pump overhaul? UGH!

 

[SPYDERLK]

Ok, got the pump bled, and got it running again, and it promptly started leaking again through the same gasket. Not just dripping here and there, but squirting out. It is coming from a gasket at the bottom right side of the pump toward the engine block, so it is hard to see exactly.

So now my question is, has anybody else had this problem? What's causing it to blow the gasket and what's the solution? Pump overhaul? UGH!

Yes! ... Mine has it and Iv not fixed it. When I do I plan to put in some extra small bolts to limit clamping span and help squeeze the gasket uniformly. Is the rear steady bracket on your pump intact. I found mine had come loose -- maybe a contributor to failure? Any pointers you can give on pump removal and re timing?
larry

 

[jrchafin]

Any pointers you can give on pump removal and re timing?
larry

Yeah Larry. This pump is not difficult to deal with the timing. Just don't turn over the motor or spin the pump when they are separate. It bolts to the pump gear with a nut, keyway, and a tapered shaft. It's a bit of a wrestling match to get the tapered shaft to free up. The service manual talks of a "special tool" to remove it, but doesn't say anything else, like what the tool is or the part number. Brilliant. So I used a puller I had on hand as a pusher actually. I took some spare bolts and threaded them into the front cover plate bolt holes securing the puller in place, and then spun the center bolt of the puller tight against the shaft of the pump. This shaft has a dimple in it, so it works perfectly. Keep cranking on the puller bolt until enough tension builds that it pops the tapered shaft loose. When reinstalling just have to make sure the key on the shaft goes into the keyway of the pump gear.

 

[jrchafin]

Larry, I'm trying to decide if I should just get a new gasket from the mahindra dealer, or take the pump to be rebuilt. The gasket I put in the first time was just a basic gasket that I cut myself, not strong enough apparently. I guess my question boils down to this. Is it leaking because of too much pressure, ie: something wrong with the pump? Or is it just leaking and needs a new gasket? I've heard that the recent changes in diesel fuels are causing a lot of seals to fail, and maybe that's the cause.

 

[Navasot]

Have the pump rebuilt if your taking the time to have it off... no reason not to.... keep some good fuel treatment in the fuel and it will help lubricate the pump to keep this from happening... low sulfur sucks

 

[jrchafin]

Turns out mahindra doesn't supply any parts for this pump, according to my dealer. I found a company that will work on it, but would have to send it away and would cost big money. They sold me a new gasket for $12. Last one lasted 6 years, maybe this one will last another 6. Only takes me about 30 minutes to get the pump off, twice that to put it back on, so I think it's worth it to just replace the gasket and cross my fingers.

Larry, the business I found is just north of Lynchburg if you are in that area and want to have yours fixed up or get parts. valley fuel injection services, in madison heights, VA.

 

[SPYDERLK]

Yeah Larry. This pump is not difficult to deal with the timing. Just don't turn over the motor or spin the pump when they are separate. SNIP.

Thanks!

Larry, I'm trying to decide if I should just get a new gasket from the mahindra dealer, or take the pump to be rebuilt. The gasket I put in the first time was just a basic gasket that I cut myself, not strong enough apparently. I guess my question boils down to this. Is it leaking because of too much pressure, ie: something wrong with the pump? Or is it just leaking and needs a new gasket? I've heard that the recent changes in diesel fuels are causing a lot of seals to fail, and maybe that's the cause.

... But it is the gasket leaking, right? My impression w/o seeing it off is that there is a cover plate gasketed and bolted to the back side of the injector pump. I project that the bolted/clamp points on the plate are too far apart considering thickness/rigidity of the plate. The stock gasket works for a while - then leaks. Im guessing your home made replacement was not quite as compliant. :confused3:

-- All guesses, but when I take mine off Ill be looking at whether the span between clamp points is too much. Perhaps the center points of the spans have room for using a hi strength #4 or 6 capscrew to increase clamp force and make it more even.
larry

 

[jrchafin]

Thanks!

... But it is the gasket leaking, right?

Yep, definitely. But the cover plate is quite heavy, 1/4" thick, looks like grade 8 steel. Pretty beefy. Of course, additional bolts would give more even gasket compression, but I would worry about drilling and tapping into the pump. It's a pretty complicated mess in there, don't know how much room you would have to drill without messing something up. But sounds like a great fix.

 

[SPYDERLK]

Yep, definitely. But the cover plate is quite heavy, 1/4" thick, looks like grade 8 steel. Pretty beefy. Of course, additional bolts would give more even gasket compression, but I would worry about drilling and tapping into the pump. It's a pretty complicated mess in there, don't know how much room you would have to drill without messing something up. But sounds like a great fix.

Yeah. Ill have to size it up. Theres gotta be a way to actually fix it. I hate doing things twice. ... Was the rear brace point on your pump tight? Mine was loose - and may be the excuse.
larry