Another Velvet Drive Question Thread

Happy Thanksgiving to all and good morning. This may be a little rambling. Sorry.


I was going through my FL120s over the past few days installing all new hoses, coolers, filters, belts, lines, etc etc. (1979 49-ft MT RPH, original FL120s, one with 240 rebuilt hours, one with 2200 original hours, also original trannys) Upon completion, I noticed a rather steady drip of tranny fluid coming from my Stbd bell-housing. Yep, time for a new front seal.



This got me thinking. What is the correct amount of tranny fluid for a set of BW VDs with reduction gears AND the cooler? I see answers from 2 quarts to 5 quarts. I thought it was a straight 2.5 quarts, but does that include the cooler as well?


I previously had issues with fluid puking from my breather on the Port tranny. After extracting about 4 quarts, I believe it was simply over filled (like most of you said). It got that high because I was trying to match the Stbd trannys fluid level. Sounds like that one is high too.



So what is the official amount of fluid for 72C Reduction gear units (one is a drop center, I think - Stbd)? Can too much fluid force its way past the front seal and be causing my leakage issue, without going through the breather instead?


Sorry for the bad photo. This was from last year before any recent maintenance was done on it. Just to show you what I am dealing with.

Depends on your transmission cooler size and hose length. I fill my 71C to the high mark on the dipstick with engine off. Start the engine and shift F,N,R several times then shutdown again. Go have a cup of coffee then come back and top off to high mark on dipstick again. Done.

I have heard/read that at least some BW VDs should have their dip sticks checked immediately after shutdown.

Seems crazy as even a few seconds would result in major fluid drain back.

So as a pro or two have said through the years.you should be able to see fluid circulating with the dip stick out, but no where's near the neck bottom. Sounds iffy but helps with a too high or too low amount..

Is it possible the vent (breather) is plugged? This can sometimes cause a seal to leak.

Not sure if this link to a manual helps.

https://www.tadiesels.com/assets/do...ve_Marine_Transmission_Owners_Manual_0001.pdf

James

My 72Cs list 3 quarts I think. Spec is to check the fluid level with the trans warm, right after shutdown. Should be at the top mark on the stick. Once you get it there, let them sit overnight and check cold after any cooler drainback. That'll give you a reference for where the fluid should be on a cold check.

rslifkin said:

My 72Cs list 3 quarts I think. Spec is to check the fluid level with the trans warm, right after shutdown. Should be at the top mark on the stick. Once you get it there, let them sit overnight and check cold after any cooler drainback. That'll give you a reference for where the fluid should be on a cold check.

Click to expand...

That procedure is correct.
My 71 series held approx 2.7 qts

Redhook98 said:

Happy Thanksgiving to all and good morning. This may be a little rambling. Sorry.


I was going through my FL120s over the past few days installing all new hoses, coolers, filters, belts, lines, etc etc. (1979 49-ft MT RPH, original FL120s, one with 240 rebuilt hours, one with 2200 original hours, also original trannys) Upon completion, I noticed a rather steady drip of tranny fluid coming from my Stbd bell-housing. Yep, time for a new front seal.



This got me thinking. What is the correct amount of tranny fluid for a set of BW VDs with reduction gears AND the cooler? I see answers from 2 quarts to 5 quarts. I thought it was a straight 2.5 quarts, but does that include the cooler as well?


I previously had issues with fluid puking from my breather on the Port tranny. After extracting about 4 quarts, I believe it was simply over filled (like most of you said). It got that high because I was trying to match the Stbd trannys fluid level. Sounds like that one is high too.



So what is the official amount of fluid for 72C Reduction gear units (one is a drop center, I think - Stbd)? Can too much fluid force its way past the front seal and be causing my leakage issue, without going through the breather instead?


Sorry for the bad photo. This was from last year before any recent maintenance was done on it. Just to show you what I am dealing with.

Click to expand...

Looking at your picture I can see that you have CR2 transmissions (there is distinctive ribbing on the reduction section of CR2s). If you get the number off the small brass plate I can tell you exactly which ones you have. (There are 24 different models of CR2)

The manual says 2 1/2 quarts and then whatever the oil cooler and lines require. But like I said, it’s impossible to get more than about half the oil out. Even poking around with a 1/4” suction line barely helped. Part of the problem is that one cannot drain the drop section reduction gear at all.

Filling them correctly is tricky and is exacerbated by the fact that it’s impossible to even remotely drain all the oil out. The manual I have is clear that with a cooler there is some drain back and they want the level to be correct “when running”. I have tried it and there is a significant rise in dipstick readings when checking immediately after shutdown and then a couple of minutes later.

According to the manual, the right way to check is immediately after shutdown. Once the level can be confirmed to be correct immediately after shutdown, the trick (also in my manual) is to let it settle overnight. Recheck the next day and MARK the dipstick with the new level. That level will be correct anytime the engine hasn’t been run for a while. This makes it really easy to get the level right. If I remember correctly, mine ended up about 1/2” above the full mark.

They will most definitely spit oil out of the vent if they’re overfilled even a fairly small amount.

Ken

CR2 typically takes around 3 quarts. Seals usually leak due to wear, but a pitted shaft will shorten the life considerably. The control valve should route excess pressure to the sump. Very unlikely it would blow a seal unless valve is gummed up with sludge. 30 min and a new gasket and you can pull control valve to check it's condition.

If you replace seal on the high hour engine replace the pressure plate as well. All the work is in removal of the transmission and the plate is not that expensive.

That's good advice.

So the transmissions are 10-13-000-005 and -006 units. 2.5:1. I pulled the control valve from the one in question with front seal leaks. Valve looks brand new, no build up. Guess I am pulling it.



Seal is being replaced on the low hour setup. It had a new dampener plate when it was rebuild, but I will still check it.



Great advice you guys, thank you!