Marinette Boat Forum

I was doing some testing on my engines. The starboard engine is not as strong as the port. I will save details for a different topic. I was letting one engine idle while throttling the other to compare the difference and listening to the engine. After a few full throttle tests, the starboard engine would "slip" and the RPM would jump. I have noticed sometime before when throttling to full speed the starboard engine did a quick RPM jump or slip. I originally thought is was a cavitation. I don't run very often at high throttle. I think is a problem has been there awhile but have not stressed the transmission that hard.

Shifting it at idle is smooth but makes a different sound in reverse. More of a rumble than a wine.

I checked and smelled the fluid. It has less than 50hr and does not look or smell bad.

I am going to check the pressures next.

Has anyone had problems with their Velvet Drive?

Might check the cable linkage back at the tranny. Mine slipped out of the bracket (was hard to notice) but I lost reverse.

Sounds like clutch plates are worn and slipping. Might want to try Lucas tranny additive to see if it helps, but more than likely looking at a rebuild.

It is not a good idea to have one engine idle and running the other at full throttle. Puts tremendous strain on the engine and transmission.
Running WOT on one engine I am not surprised it slipped.

Imagine running with one engine in reverse and the other full forward!

I do run at times on a single to save some fuel and am in absolutely in no rush. I never run above 1,700 rpms on one.

Now do you save 50 percent fuel? NO!!! with the drag about 25 percent.

I would change the fluid make sure it is Dextron not the Ford ATF.

It brings up another question. Is it hard on the transmission to "drag" it by running on other ONE. I am concerned about the planetary gears not getting lubed.

The lube I have in it is Chrysler Spec ATF. I am going to drain it and also remove the strainer to look for debris.

I just finished rebuilding the transmission. It wasn't a terrible job. It will be a lot easer now that I have done one. The forward clutches were toast. It was caused by an internal leak and not holding enough pressure on the forward clutches. There were light rust marks on the piston seal area just enough to rough up the seal. (from former water getting into it when I bought the boat it was a repo and the rear plug was not pulled and water was over the transmissions) The rust marks were not that bad but enough to rough up the seal areas.

The trans has good pressure and shifts great now. One indication it did is the shaft turned slowly in neutral when the clutches toasted and warped. Now no movement in neutral.

Looking at the design I would be a little concerned running a long distance on one engine and letting the shaft turn. May cause problem with the reverse planetary gears not getting enough lube????

Great topic... Running one engine at low rpm dragging a prop. I will start a new thread.

A Velvet Drive will slip if it's a tiny bit low on oil--as little as a quarter of a cup! So check the oil level before doing anything else.

Jeff

PS: There's only two freeakin' quarts of oil in the entire transmission! The one in my car has 7 to 8 quarts--and it's an ordinary economobile. (The average pick me up trans takes 8 to 10 quarts or more.) Why they didn't enlarge the sump and double that capacity baffles me.