CAV Injection Pump Leak MF255

[samsclub91]

I'm trying to figure out an injection pump leak on a new to me MF255 with the Perkins 236 diesel. When I bought this tractor a few weeks ago there was a small leak, about one drop every 4-5 seconds. After messing with it I've successfully worsened the leak to a pretty steady drip and cannot figure out how.

I've thoroughly cleaned the entire pump off and unless I'm missing something major the leak is coming from the very bottom of the pump, either from the circled bolt or where the rear most section meets the main body of the pump. Someone before me appears to have tried to fix this too and thought it was the bolt because there was a fairly new copper washer before I started working on it. Now, the leak worsened when I removed the bolt and installed a new copper washer trying to fix the problem which leads me to believe the bolt is the issue but no matter how tight I get the bolt it still leaks. I've tried 3 different copper washers now and none of them will seal up.

My questions for anyone who knows something about these pumps are:

A) Am I trying to seal the indicated bolt correctly with a copper washer like you would seal a banjo bolt?

B) I'm assuming there is some kind of seal between the two sections of the pump, is it at all common or possible for a leak to develop there?

C) This is the first time I've ever looked at an injection pump, am I just missing something simple?

Thanks in advance for any info.

 

[4play]

Ive got a 245 but it's basically the same pump. I went through all the leaks a couple years ago, olives, gaskets, washers, everything leaked, finally the last leak was right where you see drips. There's an o-ring seal where that cylinder fits into the aluminum housing. I pulled the injector pump off,, took it apart and resealed it

 

[samsclub91]

Ive got a 245 but it's basically the same pump. I went through all the leaks a couple years ago, olives, gaskets, washers, everything leaked, finally the last leak was right where you see drips. There's an o-ring seal where that cylinder fits into the aluminum housing. I pulled the injector pump off,, took it apart and resealed it

Is replacing that seal something you think a fairly handy individual could tackle? Until I started messing with that bolt I felt like it was the seal but I do wonder if the pressure of taking that bolt in and out could have flexed the housing just enough to make the already failing seal worse.

 

[MF#1]

Probably the best thing is to remove the pump and have it resealed by a pro, dieseltech comes to mind.

 

[Texasmark]

I'm trying to figure out an injection pump leak on a new to me MF255 with the Perkins 236 diesel. When I bought this tractor a few weeks ago there was a small leak, about one drop every 4-5 seconds. After messing with it I've successfully worsened the leak to a pretty steady drip and cannot figure out how.

I've thoroughly cleaned the entire pump off and unless I'm missing something major the leak is coming from the very bottom of the pump, either from the circled bolt or where the rear most section meets the main body of the pump. Someone before me appears to have tried to fix this too and thought it was the bolt because there was a fairly new copper washer before I started working on it. Now, the leak worsened when I removed the bolt and installed a new copper washer trying to fix the problem which leads me to believe the bolt is the issue but no matter how tight I get the bolt it still leaks. I've tried 3 different copper washers now and none of them will seal up.

My questions for anyone who knows something about these pumps are:

A) Am I trying to seal the indicated bolt correctly with a copper washer like you would seal a banjo bolt?

B) I'm assuming there is some kind of seal between the two sections of the pump, is it at all common or possible for a leak to develop there?

C) This is the first time I've ever looked at an injection pump, am I just missing something simple?

Thanks in advance for any info.

Yes I know a lot about that problem. I just spent $650 to get it solved....a new pump. My problem was just like yours. I looked and looked and decided as you have where the leak originated. Considering we are dealing with a diesel pump that has exacting specs and that it would have to be removed and torn down to be fixed and I was not equipped to tackle that problem and pump rebuilds run over $600 and that fact that I would have to disconnect the pump and remove it anyway.

So the money is spent. The pump was installed without a lot of hassle as I decided it was my best option so I had a positive attitude. I bled the pump. Bled the lines at the injectors, hit the starter and it fired right up, bled the lines at the injectors one more time for good measure....ran like new and no leak.

Good luck.

 

[samsclub91]

Yes I know a lot about that problem. I just spent $650 to get it solved....a new pump. My problem was just like yours. I looked and looked and decided as you have where the leak originated. Considering we are dealing with a diesel pump that has exacting specs and that it would have to be removed and torn down to be fixed and I was not equipped to tackle that problem and pump rebuilds run over $600 and that fact that I would have to disconnect the pump and remove it anyway.

So the money is spent. The pump was installed without a lot of hassle as I decided it was my best option so I had a positive attitude. I bled the pump. Bled the lines at the injectors, hit the starter and it fired right up, bled the lines at the injectors one more time for good measure....ran like new and no leak.

Good luck.

@Texasmark do you happen to remember where you bought your pump from? I'm finding them for just over $800 online including this site. I've known I may have to replace it and have accepted that but wanted to explore any possible repair options before just replacing it. Part of me hates to replace a perfectly working pump over a little leak and I probably would just live with it if it were leaking anything but fuel!

For the cost of rebuild kit I may try rebuilding it myself with the full expectations of having to buy a new one if I screw something up. Best case I save some $$$ and learn something new, worst case I'm out the cost of the rebuild kit and a little of my time + a new pump.

 

[Dieseltech]

I'll bet the leak is higher up, like most I see in for repair.

 

[samsclub91]

I'll bet the leak is higher up, like most I see in for repair.

I certainly won't say you are wrong but I can't find it if its higher up. I've cleaned the entire pump with brake clean and am 100% sure its not coming from the top cover. I cleaned it off then ran it and wiped a clean shop towel all over the top cover and the main body of the pump. My rag only got wet when I arrived at the very bottom where the drips are. I don't THINK its any of the banjo fittings on the rear of the pump as they all appear quite dry.

I've seen a suggestion of using baby power to find the leak but haven't tried that yet. Any other suggestions for tracking down or confirming where the leak is?

 

[Texasmark]

I'll bet the leak is higher up, like most I see in for repair.

Nope on Dieseltech's reply! I spent too much time drying out things and measuring this and that.....it was lower on the pump!