Help: CP3 disassembly!

[mytmousemalibu]

Hey fellas, I have an LB7 CP3 about 80% torn down out in my shop. How the heck do you get the shaft/rotor and pumping elements out I have this strange and bad feeling that all the pump elements have to be depressed to get the shaft out?

Its used of course and may or might not be good, so far i see nothing too out of place, one of the pump element caps and inlet valve was kinda dirty. I'd like to tear it completly apart and inspect and clean it out real good and see if i can apply some ideas ive had.

So if any of ya can help, i'd sure appriciate it! And if any one knows where i can get parts if i need them!

Thanks in Advance, Chris!:hug:

 

[McRat]

You have to hold all 3 pistons up in their bores then the crank will slide out.

It's a total beetch! :barf:

 

[McRat]

There is a special tool for it, but Bosch refuses to sell me one. I'm using screwdrivers.

 

[mytmousemalibu]

Damn! I shoulda known:rofl: After i stared at it and played around foe 5 min thats kinda what i was thinkin. Im a tech at an independant BMW shop and theres all kinds of special EXPENSIVE tools we need, but we hardly ever get them so im the "special tools builder" round there so ill see if i cant pull a hat trick and make somthin

Thanks a million Pat:hug: If i come up with a tool, ill see if i cant make a duplicate and send one to ya!:hug:

 

[McRat]

There is a 3 lobe crank in the center, and in each bore is a cup, spring, and a piston. The spring is maybe 40lbs and it's what you have to push up to get the crank out.

 

[mytmousemalibu]

Ok, will do, i'll go attack it tomorrow, my back and i have given up and gone inside for the evenin I decided that was a good time to stop before i F-up somthin in there!

 

[McRat]

The part you can see right now is the cup, it has some slots in it for fluid travel. If you scratch the face of it, no biggy. Don't scratch the walls though, it's a precision fit in the bores. The piston looks like a valve kind of, but with a bunch of holes in the face. The spring holds the piston against the crank, and allows the pump to flow variable amounts. If their is too much "suction" against the piston, the actual stroke is reduced. The regulator controls the suction.

 

[mytmousemalibu]

Ok, cool, so when the FCA is closed off the suction is greater than the spring pressure and only collapses so far, allowing a small amount of fuel to fill the void and under full open the suction is low enough to let the piston drop all the way and fully fill?

I figured the pistons were pretty small but there smaller than i even thought! Any ideas on what kind of psi the gear pump produces? IIRC Brayden thought it to be around 200psi? I had prevoiuslly thought it was there mainly to draw fuel from the tank to the pump as its primary purpous?

 

[McRat]

Yes, that causes the stroke to be greater or less depending on how much the regulator restricts it's fuel supply.

 

[McRat]

I started to figure out the displacement of the low pressure pump, but got sidetracked. It's more than the CP3 full stroke displacement, but I forget how much. It's pressure is controlled by a check valve IIRC.

 

[mytmousemalibu]

Hmm, I,ve wondered it the low psi pump could be removed all togather if it became a henderance to the main pump. But if it moves more fuel than the pump can inhale, mute point. Like if just a lift pump could supply the fuel feed to it. Course that would depend on what the pressure/volume it makes to dictate that as a possibility.

 

[WICKED DIESELS]

The internal pressure is around 75 psi, pump displacement is 1.1 cc per revolution or 0.068 cid. Or if I am wrong on those specs, the bore is 7.5mm and the stroke is 8mm.
The gear pump can provide around 150 psi, you can starve the internals if you go to high. Excess fuel is used to cool and lubricate the crankcase.

 

[super diesel]

Watch that wear pad (bushing pad) under the crank in the CP3. If you took the aluminum face plate off without something holding the crank down in place the wear pad ears (3 of them) will usually turn and youll never get it together properly (with out free turning with the face on). The wear pad will need to be realigned. You either need to pull the crank to do it or have a special tool to realign it (I made one). I had to do this quite frequently for these pumps a few years ago. There is a thick shim with a taper on it that slides down into place as you rotate the assembly to hold the plungers up in the bores to relieve the pressure off the crank cam so you can pull it straight out. Made one a few years ago. Cant remember the thickness exactly. I think it was like .070 or .090 thick. Made it to go 3/4 or so around the inside of the bore. Worked like a charm. It was some ridgid stuff. Hope this helps.

 

[super diesel]

The internal pressure is around 75 psi,

This rings a bell with me. That's what I seem to remember. I have a test front aluminum cover with ports in it. All the test documentation is lost to time and an angry woman. The pressure varied with lift pump input though. I was thinking with out a lift pump it was aroud 70psi or so. It climbed with the set up and pressure of your lift pump (like a compound). I focused on these for a quite a spell. I remember talking to some one at a turbo shop in Compton on this years ago. Stroking the crank would have no advantage according to him when asked.

 

[McRat]

I haven't tore apart a good pump so far, just a couple of Ebay $25 cores, so it's hard for me to tell what failed. Both smelled like old lawnmower gas though.:barf:

 

[mytmousemalibu]

Thanks Fellas! Much appriciated! I know what ur sayin on the plate/tabs and yea that poped out of place but thats ok, that crank is gonna be coming out, im gonna completly go through it and clean it out and inspect it to the best of my ability, I know the only true test is to run it on a test stand but thats outta my means to test

And Wicked....when you say if psi is to high it can starve the internals, how is that? Too much fuel going into the pump elements and not enough for the internals?

Super Diesel....Got any pics of your shim tools:hug:

 

[super diesel]

Both smelled like old lawnmower gas though.:barf:

YUUUK! I know that smell. Why is that I wonder?

 

[McRat]

YUUUK! I know that smell. Why is that I wonder?

Probably failed from running gas or water through them.

 

[mytmousemalibu]

No Lawnmower gas smells here I'll hafta look again but iirc the "dirty" element inlet valve was the bottom one, makes sense. Hopfully all is well, im gonna clean it up, put it back togather and homebrew me a dual fueler!

 

[McRat]

Thanks Fellas! Much appriciated! I know what ur sayin on the plate/tabs and yea that poped out of place but thats ok, that crank is gonna be coming out, im gonna completly go through it and clean it out and inspect it to the best of my ability, I know the only true test is to run it on a test stand but thats outta my means to test

And Wicked....when you say if psi is to high it can starve the internals, how is that? Too much fuel going into the pump elements and not enough for the internals?

Super Diesel....Got any pics of your shim tools:hug:

When I did my CP3 testing, I used a Dual Fueler setup. I put the test pump in the second slot, and used the engine to drive it at various RPM's hooked up to a flow meter. Cost was about $90 worth of parts, if you have a 2CP3 truck handy.