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Thread: 2.25 L Diesel - Leaking Fuel Pump - CAV DPA

  1. #1

    Default 2.25 L Diesel - Leaking Fuel Pump - CAV DPA

    The CAV DPA diesel pump on my trusty 1983 SWB RHD 2.25 Diesel started leaking. There is quite a bit of fuel coming out and making a small puddle below the car. The leak seems to originate at the banjo fitting at the top of the pump, then run along the seam of the pump right below the fitting and then drop to the ground. Thing is that I did all the usual fixes to the banjo fitting (cleaning contact surfaces, using new washers), but the leak persists. Could is actually come from the seam between the top and the bottom part of the housing? Is there any kind of seal that could have gone bad? Any leads are really appreciated. I found the attached photo on the web. Someone had the exact same problem ten years ago, but the related thread only contained some guesswork but never came to a conclusion. Any thoughts? Thanks!
    Attached Images Attached Images  

  2. #2
    Join Date
    Jul 2020
    Location
    UK
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    One question, does it leak without the engine running ? The banjo is at injection pressure when running , about 2000 psi so the smallest " hole" will leak. I wonder if the fuel is coming from the union between the injector pipe and the banjo, not the between the bajo & the body . I have know a small crack develop in the flare on the end of the pipe and start leaking. A new pipe would rectify it. There is a seal between the Hydraulic head and the alloy body, which looks to be a an 'O' ring or similar, but it is a relatively low pressure , not injection pressure , see attached cross sectional drawing.
    I think you need to clean it all off again and run it holding a tissue next to each area to find exactly where the leak is.
    Click image for larger version. 

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  3. #3

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    Thanks for the quick reply. Doesn't seem to leak with the engine off, but the injector pipe and the fitting are completely dry, even when the engine runs. The fuel just magically appears on the rim between the pump head and the lower body of the pump, starting right under the banjo fitting. I checked out a YouTube video by Bundy Bear about re-sealing a CAV pump, so my guess is now that the O-ring around the pump head failed. I'm now thinking about ordering a rebuild kit and giving it a go. Much more involved that fixing a banjo fitting, but doesn't seem impossible otherwise. And it would give me my sanity back, after I cleaned the banjo fitting five times with no success.

  4. #4
    Join Date
    Jul 2020
    Location
    UK
    Posts
    180

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    Best of luck with a rebuild, must admit I have always taken mine to the professionals. Note everything must be kept extremely clean, tolerances are in microns.

  5. #5

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    For the benefit of the forum: A leak as shown in my picture is caused by a failing O-ring that sits right under the rim between the pump head and pump housing. There is a great set of videos on YouTube from Bundy Bear Shed with step by step instructions how to reseal a pump. I exchanged all seals, and I'm glad I did, because they were all rock-hard, just as the one that caused the visible leak. The rebuild kit I used is from Sparex item S 57135 but there are others. A few tips based on this experience: Take tons of photos as this will speed up the reassembly, in particular the LR specific items that are not shown in the videos. Also, don't skip the bench-test shown in the videos. This way you know when the pump is working and you can focus on other potential causes if the engine fails to start. In my case, even after bleeding per LR manual, the engine wouldn't start. I finally figured out that you need to pump the gas pedal, not only hold it down at full throttle. With that, the engine quickly came to life. Also, the bleeding screw on the governor housing may not emit a lot of fuel, but that seems to be fine as long as a nice stream of fuel comes out of the other bleeding screw. Hope that's helplful.

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