Campbell "VT" pump won't seal

[yossarian19]

It's a 3" bore twin cylinder pump from ~1987.

Issue is that I can't get the valve plate to seal to the cylinder bores. I've tried RTV, Anaerobic, and the correct gasket. I've lapped the valve plate flat with my drill press table & sandpaper. Still pours air out of the seam between valve plate & cylinder bores.

I think I may have the cylinder bores upside down? The bore block has little "ears" where the 6 head bolts pass through and thread into the crank case. Do those ears go up or down? I was only able to assemble it with the ears down though I can see how they would lend support to the valve plate, maybe keeping it from flexing as I tighten the bolts?

Anyone know for sure if the ears go up or down? If I've got it assembled correctly, I might be done with this pump. If not... one more round with it.

 

[yossarian19]

Nobody?

Sent from my XT1031 using Tapatalk

 

[redmondjp]

Have you checked the surfaces of both the cylinder and the head for warpage with a precision-ground straight edge?

 

[MacMcMacmac]

Are the cylinder bolts bottoming out in a blind hole before proper clamping force is achieved? Do you have the gasket between the block and crankcase installed?

 

[pop pop]

I've got that same unit with a bad valve plate. Will check it tomorrow.

 

[pop pop]

Well, looks like I don't have the same model. The twin cyls. on my unit have tapered cooling fins and the widest part goes to the top, so difficult to confuse. Sorry I could not help more.
You are using gaskets, right?

In looking back at your pic., I don't see a valve plate. Mine goes between the head, which I see on yours and it looks like mine, and the top of the cyls. Are your valves in the head? Or did you leave the plate out? Might explain bolts too long?

 

[yossarian19]

OK, a few things I found:
One, the "ears" go to the bottom. Confirmed this by a photo a parts seller put up on Ebay.
Two, I finally got it to seal like this: I held some sandpaper down on my drill press table (any *flat* surface will do) and slowly made figure eights, circles, etc with the parts on the sandpaper until they had a totally uniform surface on them. I was surprised how out of true everything was.
Once I trued all the mating surfaces as best I could, made a new gasket, used a little RTV for good luck - it pumps up as high as 110 (I shut off the compressor at this point) with no blow-out that I can tell. Before truing, a dry OEM gasket blew out badly at 80 psi.