Scavenge Pump Cover

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who_gives_a6 · #1 Post by **who_gives_a6** » Sun Oct 23, 2011 2:59 am

Putting new Timbo worked parts in an engine I picked up that seemed to have a monkey build. When I removed the scavenge pump I noticed loose bolts. Wasn't ridden after built a few years ago or I'm sure would've grenaded. I got the new crank in and everything good till the scavenge pump. I noticed that the first two pins were damaged and wedged in there, the inner rotor had a bad burr, and the pump cover bottom left bolt housing was cracked.

I put in all new parts, o-rings, cover, and all seemed good. Spins freely as manual says up until finger tight. But as soon as I torque the bolts to manual specification it is impossible to spin; completely locked. I even swapped out covers again to try with same result. It seems the cover pushes down on the rotors, freezing them in place. The washer is in the cover also.

The only thing left I can think of is the cartridge plate being bent maybe. As said, the bolts were not torqued down when opened up. The cover had a small gap in it because of that. Any suggestions here? I can try another plate, just haven't yet. And wondering if I'm overlooking something simple. The last two I put together went without a hitch.

Also, I need two scavenge pump covers, both the inner pins on the shaft, and the inner rotor if anyone has some they want to get rid of cheap.

Edit: I can only torque down the top cartridge bolt. The other bolts for the pump cover wont go to the specifications. I cracked another pump cover torquing them down.

claas900 · #2 Post by **claas900** » Sun Oct 23, 2011 10:04 am

Sounds like your torque setting is wrong. Nothing should be cracking or striping. If you already have the crank plate on, you can always pull the outer pump out then put the cover back on and see if it spins that way.So you can figure out witch pump it is locking up. It obvious you have one of the pumps locking up.

MX Quad Dad · #3 Post by **MX Quad Dad** » Mon Oct 24, 2011 12:53 am

Like 900 says and also you can pull the outer rotors out and reassemble and then if it turns freely install one at a time to find out which one is binding also if it is still binding with both outer rotors off pull off both inner rotors and if the shaft is bent or damaged it might not turn with anything on it.

I rebuild hydraulic hammer drills which have a rotation motor that looks simular to the dale pumps. and it only takes a very small bur or pice of grit to lock it up after torquing it together so if you can find which part is binding, it might make it easier to find by eliminating pieces one at a time. just my thoughts is it wold have to be something fairly large to hold the cover up enough that it would crack when torquing and I don't know how the shaft would get bent without doing a lot of other damage.

who_gives_a6 · #4 Post by **who_gives_a6** » Mon Oct 24, 2011 1:02 am

Turns out it was the cartridge plate. Once I took it off again it was noticeably bent. Switched out and went together like butter. Thanks guys.