Rebuilt 1986 Velvet drive slipping in forward

[dmdmd]

I have a 1986 340 Express Cruiser. Port transmission overheated and blew dipstick and sensor plug resulting in a small flash fire. Only charred some wires.
Velvet model #10-18-004 1.52 was rebuilt and a damaged ring gear was replaced.
When it was started (after rebuild) it still had a significant "cluncking" sound in reverse. This was corrected when throttling up and finally by increasing the idle speed by a few hundred rpms. Still had a slight rotation when in forward (it has done since I've owned the boat..3yrs).
Test run seemed to go very well. Next day I was pulling out of dock and noticed port didn't seem to engage in forward, then seemed ok for a short time but then was definitely slipping around 2000-3000 rpm. Returned to dock to take a look....still pretty quiet in idle reverse, noted that there was no rotation when in neutral (for the first time ever). Without changing throttle the rotation speed in reverse was probably 2-3x the rotation speed in forward. Fluids were well monitored during the test the previous day (but didn't check day 2). No apparent leaks.
Does anyone have any ideas what could be happening if this is not a fluid problem?
Thanks for any help!

 

[fwebster]

Worn or damaged hydraulic pump not holding the clutch plates and iiiallowing them to slip.....?

When the transmission was rebuilt did you just replace the obviously worn parts or was the case vatted and cleaned and all new bearings, shims, thrust washers pump, etc. installed. All to often a rebuilder just replaces the clutch pack in order to keep the rebuild cost low. If a transmission has has a bearing or other parts failure, it is very difficult to get all the metal filings out of the transmission case and those filings can damage the pump when the rebuilt transmission is put into use.

I'm not pointing fingers or accusing anybody of anything......... just hoping to give you a direction to look.

 

[dmdmd]

Thank you, will check with him. He did say everything inside looked "extremely clean"

 

[LG111]

How about proper fluid level? The trany may have an air pocket giving a false full fluid reading after install. You ran the boat and the air releases and now the fluid is to low to do its job on the clutch plates. Hence slipping.

 

[dmdmd]

How about proper fluid level? The trany may have an air pocket giving a false full fluid reading after install. You ran the boat and the air releases and now the fluid is to low to do its job on the clutch plates. Hence slipping.

 

[dmdmd]

That would be the best possible news. Will check soon. Thank you

 

[ttmott]

Important also is to ensure the gear shift mechanism is being fully articulated to their engage positions when the shift levers on the helm are actuated. If they are not then full hydraulic pressure will not be available to the clutch packs.

 

[PlayDate]

What caused the transmission to overheat? Did the cooler fail?