Velvet Drive puking oil out breather cap?

Redhook98 · Sep 27, 2020

I have a 1979 49-ft MT RPH with twin Lehman 120s. Standard 2.10 ratio (oil return at bottom of trans) Velvet Drive trans. My Port transmission will start puking oil out the breather cap after about 5-10 minutes of operation in gear. It comes and goes at that point. Temp has never been over 130-140 since I bought the boat. Usually runs at 130 using a temp gun. Fluid is bright red, no sign of burning. New cooler (old one checked out perfect though). Trans shifts and operates perfect besides the oil puking issue. Trans has about 2400 hours on it.

Have a new breather cap, but haven't figured out how to get the old pressed-in assembly out without mangling something.

Any ideas? I have see a few mods with overflow tanks. But would rather it be "right".

O C Diver · Sep 27, 2020

A dumb question, but is the fluid level correct? Some transmissions require checking the level with the engine at idle, warmed up. Don't know the requirement on a Velvet drive. The other thought is if the dipstick is original for the transmission and correctly marked. Is the transmission level or a significant up angle? How does the dipstick on the other engine compare to the one puking?

Ted

SoWhat · Sep 27, 2020

Breather cap is a simple press fit. Vise grips should pull it right out. Surround the new cap with ice for 1/2 hour. It should then drop right in. I think I found a small wrench to fit over the body of the cap and rest on top of the hex. I then just tapped it to final position with a screwdriver.

But Ted raises the question on fill level. Either you have a very efficient oil pump, or it's overfilled. If you don't refill, does it keep coming out the vent?

kchace · Sep 27, 2020

130-150 is a good temp for Velvet Drive. It’s really unlikely that the breather is at fault it’s an extremely simple device. A Velvet drive will definitely puke oil out of the breather if it is overfilled and it doesn’t have to be too much. Even slightly overfilled can cause fluid to come out. Velvet drives have a very specific fill process, make sure to follow it.

Ken

Redhook98 · Sep 28, 2020

Thanks all for the input. One other tidbit I forgot to mention. When I would push on the breather cap, fluid would pour out as well.

I swapped breather caps yesterday. Just the caps. I pried the old cap off the assembly by bending back the tabs and putting the new one on. Won't have a chance to test until next outing.

Also read about a baffle in the return line inside the trans and possibly a plugged screen causing a potential build up in pressure. Installation manual says to ensure the return line is the highest point , or air could be trapped in system, causing cavitation, loss of fluid thru breather, etc.

What is the the "correct" way to fill these transmissions? I have replaced fluid in perhaps a dozen of them, but never in a specific way. Fluid out, fluid back in. Is there something special about these when connected to a Lehman and the cooler orientation?

I changed the fluid on the other trans the same way. No issues there.

timb · Sep 28, 2020

my surveyor noted mine doing the same thing it's right there in his report . i don't think I have ever seen any evidence of it doing it .

but i ran the boat easily on the 250 mile trip to it's new home and changed the trans heat exchanger when I winterized it right when I got it home. I never have ran my engine over 2000 rpm they took it to 2700 on the sea trial.

Redhook98 · Sep 28, 2020

timb said:
my surveyor noted mine doing the same thing it's right there in his report . i don't think I have ever seen any evidence of it doing it .

but i ran the boat easily on the 250 mile trip to it's new home and changed the trans heat exchanger when I winterized it right when I got it home. I never have ran my engine over 2000 rpm they took it to 2700 on the sea trial.

Out of curiosity, if you have FL120s, how are your trans coolers orientated? In other words, how are your in/out connections positioned? Out pointing up, middle or down towards tranny?

kchace · Sep 28, 2020

Redhook98 said:
Thanks all for the input. One other tidbit I forgot to mention. When I would push on the breather cap, fluid would pour out as well.

I swapped breather caps yesterday. Just the caps. I pried the old cap off the assembly by bending back the tabs and putting the new one on. Won't have a chance to test until next outing.

Also read about a baffle in the return line inside the trans and possibly a plugged screen causing a potential build up in pressure. Installation manual says to ensure the return line is the highest point , or air could be trapped in system, causing cavitation, loss of fluid thru breather, etc.

What is the the "correct" way to fill these transmissions? I have replaced fluid in perhaps a dozen of them, but never in a specific way. Fluid out, fluid back in. Is there something special about these when connected to a Lehman and the cooler orientation?

I changed the fluid on the other trans the same way. No issues there.

It certainly sounds too full to me. Are you using a dipstick? The level should actually be something like a few inches below the fill port (Where the dipstick goes) and the fill port is lower than the vent. The proper way to check the level is immediately after shutdown (within 60 seconds) since many configurations with coolers will drain back.

Ken

jleonard · Sep 28, 2020

Redhook98 said:
Out of curiosity, if you have FL120s, how are your trans coolers orientated? In other words, how are your in/out connections positioned? Out pointing up, middle or down towards tranny?

Originally mine were pointing in the middle (horizontal).
When I rebuilt the tranny and was having it bench tested, the very experienced mechanic who tested it suggested I orient the connections facing up to get more fluid in the system thus allowing to stay cooler.
I bought a couple of fittings to do that.
Did it really do much for me? It made me feel good anyway.

Redhook98 · Sep 28, 2020

kchace,
Yep, that is what I am doing. Before I filled yesterday, I looked in and saw barely any fluid at all. Not good when compared to the other trans. I started it up with the lower level of fluid and saw maybe a few flecks of fluid coming out of the pump. Definitely way low. Added fluid so I could see normal pump activity (again, comparing to the other unit operating next to me). Had to add almost a quart before it looked right and was comparable to the other side. Upon shut off, the fluid levels were the same for both trans.

Done this before and fluid will still spill out of breather. Only difference now is I replaced the breather. I'll idle it in gear at the dock today and see what happens after 15 minutes or so. That should be long enough to tell me something. Planning on removing the filter screen and making sure that is clean as well. I have no temp alarm on these, so those will be added next.

timb · Sep 28, 2020

Redhook98 said:
Out of curiosity, if you have FL120s, how are your trans coolers orientated? In other words, how are your in/out connections positioned? Out pointing up, middle or down towards tranny?

mine is a sn 136 American diesel . it's like an fl 135 with different manifolds . i found a video of it running and got this screen shot.

Redhook98 · Sep 28, 2020

timb said:
mine is a sn 136 American diesel . it's like an fl 135 with different manifolds . i found a video of it running and got this screen shot.

I was thinking of doing the same when I replaced my oil lines. They are original. Not leaking, but should be replaced sometime in the future. Maybe I can just get them to put the elbow in the assembly for me.

timb · Sep 28, 2020

Redhook98 said:
I was thinking of doing the same when I replaced my oil lines. They are original. Not leaking, but should be replaced sometime in the future. Maybe I can just get them to put the elbow in the assembly for me.

i would call American diesel if your lines are original .they should be able to get you everything . I bought new lines and have them for spares(mine don't look very original) . I actually bought all new hoses for the whole engine .and have changed all in the raw water system . I still need to do the freshwater cooling some of them are rough and may be original .

Redhook98 · Sep 28, 2020

timb said:
i would call American diesel if your lines are original .they should be able to get you everything . I bought new lines and have them for spares(mine don't look very original) . I actually bought all new hoses for the whole engine .and have changed all in the raw water system . I still need to do the freshwater cooling some of them are rough and may be original .

American Diesel is only 45 minutes from my house. I know Brian quite well. He has helped me out quite a bit over the past year. I have all new coolers, raw water hoses, pumps, etc to install during this down season. Along with block heaters. That is when I plan on tearing into the tranny as well.

timb · Sep 28, 2020

Redhook98 said:
American Diesel is only 45 minutes from my house. I know Brian quite well. He has helped me out quite a bit over the past year. I have all new coolers, raw water hoses, pumps, etc to install during this down season. Along with block heaters. That is when I plan on tearing into the tranny as well.

what type of block heaters are you using? you are lucky to have AD close .I i emailed him when I bought my boat couldn't find out why it wasn't matching up any other pictures on the web. so i sent him some pictures and the serial number .he emailed me back and said it was his company's version . he explained the differences and sent me a spare parts list .

Velvet Drive puking oil out breather cap?

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