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Topic: Leaking Lift Pump (Read 1024 times) previous topic - next topic

Re: Leaking Lift Pump

Reply #20 –
Baaad kitty.... >:D

Re: Leaking Lift Pump

Reply #21 –
Mike,

Thanks for the great writeup.  I'll plan to pull and check the pump when I get home and then install with a new gasket.

Rich

Re: Leaking Lift Pump

Reply #22 –
Rich,
You are more than welcome,I also did not know about this design when I was searching for an early 2000 vintage RV, but quickly found out about it. As I diy all of my own equipment, I learned as much as I could about the design, its weaknesses as well as ways to improve if possible.I even spoke to a few old Cummins guys I knew, whom all talked about the system in the same respect. CAPS fuel injection was not exactly a very proud moment for Cummings back in that day, evident by the fact they did not stay with it very long. But at the same time, not a reason I would walk away or avoid an 8.3 of that vintage. The 8.3, not fully electronic controlled engine has a strong reputation for being a long haul bullet proof engine and still somewhat easy for the DIY to work on. Every piece of equipment in this world designed by man has a weak link somewhere. For these its this goofy lift pump gasket.

What fascinates me is how MOT, whom really seems to care for its customers and the overall condition of our coaches, seems to be very non informed on the subject. When I asked about it, they replied I must have gotten 3rd world misinformation they know nothing about such an issue. These engines were used in countless vehicles around the world, not just RV's. And there have been countless incidents of failures, and well documented cases and write ups on the subject. Even Cummins TSB's published so I was told. (Limited write ups/info in the RV forums world). To state that they knew to tighten the bolts as a temporary fix, clearly shows they know about it. To me, if they  know to tighten the bolts, they should also inform the customers of the History of the issue as well as a suggested fix (replace gasket or pump or upgrade) Not just slap a band aid on it and let the customer head on down the road to a possible very bad situation.

FYI.....it not a terrible hard Job, lift your bed and look for the top of the lift pump, located near the front end of the engine passenger side.
Obtain your Gasket or Gasket material before you  start.

Disconnect the electrical connector from the pump, thats usually quite fun as it probably never been removed and full of gunk on the locking slide.
 The bolts are probably hid under a bunch of wire tied cables/hoses etc. I found it easier to deal with after I cut a bunch of wire tires. Get you a large tote that will also fit under your engine as while you work on this thing you are going to lose about 1-3 gallons of diesel fuel. Raise the coach on safety stands will give you more room for the tote. The 3, 1/4 bolts are in a triangular pattern probably crusted up black in crud. Loosen but not remove them so that the fuel within will start to come out into your tote below.

You will need two large box end wrenches seems I recall a 1" and a 7/8" was what I used, but now that I think more about what I did, you will probably only need to remove the Supply fuel line which is the larger of the two. The closer to the block is the return line and is not in the same liquid path as what you will be working on. You might could just drain the fuel bowl on the filter by the batteries that feeds the pump. However you do so, you need to make sure no fuel is going into the pump body and that you catch it.

 Once fuel quits dropping from the pump remove 2 of the bolts, with your other hand and a large rag wrapped around the pump and still holding onto it, or use a box or something to catch it, remove the last bolt and lower the pump body straight down out and up. I state this particular way as it may come down with the body and gasket stuck to one another or it may come down with the gasket stuck to the fluid path manifold. If it does the latter, small parts could hit the floor. (another reason for a large tote) The fuel impeller with its movable vanes can easily drop a few parts and pieces if you tilt it. If it does, dont worry the Vanes are rounded on both sides and it really doesn't matter which way they go back. Get it all on the bench, While out clean the pump body in a parts washer making sure not to get much if anything inside of the pump cavity. I used a can of carb cleaner and gently blew out the  pump cavity and the impeller vanes before reassembly. The impeller goes in if I recall on a shaft, the veins slide into ports on the impeller. I tiny dob of grease on the back side of each vane where it goes into the impeller would help hold them in place and not hurt the situation as it will dissolve in diesel. Put the top impeller plate back on, it will have a circular worn pattern on it, the worn side mates to the impeller, topped by the NEW gasket. Now me personally, I never install a solid rubber, paper or cork gasket without a tiny bit of adhesive on both sides wherever they mate with metal bodies. Permatex #2 is prefect for this application.

Using acetone or similar, clean the Fluid path manifold where the new gasket will mate.....this ain't easy as you have to do it by feel and a mirror. Or maybe lay under the rv and reach up IF all diesel has quit dripping.
If you have a helper, have them on top to do the screws while you perfectly vertical lift the pump body into place. (this is where those vanes might jump out of the impeller if your not careful.) Once in place and screw started tighten until you feel a good snug fit, if I had to give a torque spec I would guess 89-98 in/lbs. Me personally I put a small amount of the blue locktite on the screws for added back out security.

Reconnect the electrical connector to the lift pump.
reconnect the fuel line, or filter bowl.
Using the ignition key, but not cranking. Run the pump through 3-5 pre start cycles, where it will run 30-45 seconds . This will get all the air out of the system and put fluid path back into its proper operating state. As your cycling this little pump quite a bit ( more than its used to), Maybe wait a minute or two between each cycle so as not to overheat or stress it. **Note** the very first cycle will sound a bit noisy from the pump as all of its internal pieces realign and the diesel start to lubricate the parts.
On the last one go ahead and let the engine crank. Check for any obvious leaks. Clean up the mess all the dripping diesel created.
I road tested and checked several times over a few days.

I am glad my shared information helped you. I surely appreciate it when others do the same for me.


Re: Leaking Lift Pump

Reply #23 –
Mike,

Sorry for the late reply.  As you probably noticed, I got distracted yesterday with another problem. 

Thanks for the great writeup.  I'm sure it will help others besides me.

Rich
 

Re: Leaking Lift Pump

Reply #24 –
For what it is worth, after spending most of my working career as a machine designer and assembler, if you don't have any blue Loctite handy, silicone sealer makes a good insurance adhesive against bolts coming loose on their own from vibration.
We used it a lot because of the limited shelf life of most Loctite products at the time.