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cshimek
07-19-2007, 10:59 AM
Hi my name is Cameron here is the problem I have, Iíve got an 81 mastrcraft with a velvet drive #10-17-006 1.52:1 and the other day on the lake it just stopped. No forward or reverse, the tranny was warm but lines were not like it was not pumping oil. Level was about a ľ inch from top line and looked redish brown with no water. Filled and tried again nothing happened. I removed a line started engine to see if fluid was coming out but nothing. So, I removed transmission checked damper plate and its not perfect but is turning trans. I started to disassemble the trans at the pump but Iím not sure how to tell if pump is bad or not. It seems to me just by looking at is like its not a very tight tolerance pump with the gears compressing oil? There is some scoring on the back side of the inner gear and the inside of pump housing from gear spinning, not sue if there is supposed to be a washer or something there but did not see one in any diagrams. There is also a scratch between the two ports on the inside where the pump bolts up against. It seems to me with the rubber seal this would leave a gap anyway but again not sure. The thing I am wondering in all this is if there is a pressure valve that could have blown or something to stop the trans and not allow the pump to build pressure with No previous warning or slippage. Also there is no signs of serious leaking from any gaskets or seals. I have read througt alot of posts and have not seen anthing like this. I would really appreciate any help.

ski_king
07-19-2007, 11:07 AM
I don'y have an answer for you, but....
Here is a link (http://www.correctcraftfan.com/Downloads/PCMsvcmanual.pdf) to the Service Manual. Look around page 251.

Bruce Carr
07-19-2007, 11:15 AM
My '83 velvet drive tranny pump went out in much the same way as yours. The pump had some scoring as well. I replaced the pump assembly which fixed the problem. I was told that the clearances between the pump gears and the housing are designed to be very close and the scoring allows the oil to bleed off from the pump resulting in a significant decrease in oil pressure to the cluth plates. While you have the tranny out and apart, it would be a good idea to replace the damper plate and the clutch plates.

cshimek
07-19-2007, 02:24 PM
Thanks for the replys; I talked to a MC dealer Mech today and he said the pumps can be pritty shaby and still pump oil but maybe he was wrong... Did you have to replace or machine the case cover that the pump mates to? I can understand if pump is bad cause there is just no oil moving.

Bruce Carr
07-19-2007, 03:16 PM
I was told the opposite, that it doesn't take much scoring to render the pump inoperable. Mine did not look too bad when I took it apart but it centainly wasn't putting out enough pressure to hold the clutch pack closed under load. Replacing the pump assembly fixed it right up. The pump assembly comes with the new gears and the case cover so machining should not be required. Call the guys at SkIDIM, they can give you more info.

cshimek
07-19-2007, 03:33 PM
I'll take your word for it, I can get the pump locally here so I'll pick one up today. Oh, also when it quit I went to pull the dipstick out and it was pressurized. Poped out like a cork, this mean anything to you other than malfunctioning vent? Thanks again.

TMCNo1
07-19-2007, 04:06 PM
I'll take your word for it, I can get the pump locally here so I'll pick one up today. Oh, also when it quit I went to pull the dipstick out and it was pressurized. Poped out like a cork, this mean anything to you other than malfunctioning vent? Thanks again.
Mine always does the pop thing when I check it hot, yet when I check it cold it doesn't. Must be due to the expanison of the oil and air from the heat. I don't think there is a vent as such on these transmissions, ICBW.

Bruce Carr
07-19-2007, 04:50 PM
There is a vent. It's a cylindrical fitting on top of the tranny case. The top of the vent fitting should move up and down a little.

cshimek
07-20-2007, 09:53 AM
So heres the deal, pump was definitaly bad got new one and compared inside under inner gear. The gear rides on the pump case and wears outwards (toward engine) and allows a larger gap to the front surface of the adapter plate. Re-assembled everthing else and tranny is pumping and turning now. Lake test tonight. Thanks again for all the replys, this is a great site.