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Re: Velvet Drive fluid level check 3697 Mariner
Posted: September 12th, 2023, 10:12 pm
by ron54
Finished the drain and refill, had to meet some friends this evening, just got home, here are the results.
Removed return line from bottom of trans after pumping out from fill opening. Let it drain for over an hour, also disconnected upper line at trans which connects to bottom of cooler, several more ounces from there. Used my wife’s Pyrex 3 quart to measure all fluid removed (she does not know, but it’s glass no harm). A total of about 72 ounces so 2 1/4 quarts. Spec is 2 quarts in trans plus what is in cooler and lines so seems about right, accounting for residual fluid in trans.
Filled with about 66 ounces and dipstick check was well above the scribe mark. Started motor, ran for five minutes or so while checking for leaks (none) and shifted into reverse and forward a few times. Moved my rear as fast as I could to check “hot” and it was about halfway between scribe mark and bottom of dipstick. Let it sit about 20 minutes and was about 1/4 inch below scribe mark.
I will check in morning, but feeling pretty confident that the dipstick scribe mark is for cold fill. Maybe when this was made that is how they did it, but some documentation would have been nice. Makes sense as a lot easier to check cold fill. Does this seem right?
Thanks again guys.
Re: Velvet Drive fluid level check 3697 Mariner
Posted: September 13th, 2023, 11:17 am
by bud37
Consider how the manufacturer would make sure the oil level was correct in the reservoir while the unit was running in any installation.....long lines, different angles etc/etc, all those things would change the amount of fluid in the system.
The only way as I see it and the instructions lay that out is, the factory scribe mark on the stick is the warm mark immediately after shutdown. If someone were to mark the cold mark there would be two marks, like it suggests to do. I actually think the terms cold fill and hot/warm fill are a bit misleading. I think if you check cold after sitting for a while is also misleading because of cooler line / coolers etc holding varying amounts of fluid.....but would represent/reflect your specific installation .
FWIW....the expansion between cold and hot fluid in that amount is really negligible....the difference coming from drain back as you have already noted.
That drain back amount could not be predetermined by the maker due to all the different installation parameters ( line sizes/lengths/coolers etc) hence the mark you see now to be checked immediately after shutdown warm thus guaranteeing the running fluid amount in the reservoir.
That is what I take away from the manual anyway....perhaps someone else can chime in with their opinion....I think KM already has.
Also FWIW.....I believe this is not an exact measurement here, so close on the stick would probably be passable as you have found over the last while. It is ultimately up to you as to how to proceed.
Good luck with your boat, keep up with the maintenance....good stuff....

Re: Velvet Drive fluid level check 3697 Mariner
Posted: September 13th, 2023, 9:53 pm
by ron54
Thanks, and after some more thought and calculations I am sure you are both right, that has to be the “hot” mark. Found info on cooling lines, the cooling lines are about 91 inches total and 1/2 inch inside diameter. Actually found a calculator for fluid volume in pipes and should be right at 10 ounces in the lines, plus whatever the cooler holds, I would guess at least 6 ounces. So if the pan holds 64 ounces the total fill for this should be about 80 ounces if my math is right. Going to add a few ounces at a time tomorrow and keep checking “hot”. I would guess since I refilled with 66 ounces there is close to 70 in there from some residual that did not drain. When I see it hit the scribe mark checking hot betting that will be close to 80 ounces total.
Re: Velvet Drive fluid level check 3697 Mariner
Posted: September 14th, 2023, 3:27 pm
by ron54
Thanks very much for the sound advice gents, that is definitely the so called hot scribe mark. Ended up adding 16 ounces plus the 66 so total fill is now 82 ounces and it hits right at the scribe mark “hot”so an additional 18 ounces over the two quart pan fill to account for cooler and lines. Seems right. Had my wife at the helm to shut off motor so I could check level immediately.
This begs the question, do you think there could be damage from running over a pint low? I suspect it has been that way for a long time but boat was not likely run hard by PO who owned it six years. I took a sample and sending to blackstone labs for an analysis.
Now draining the starboard engine to get it right.
Re: Velvet Drive fluid level check 3697 Mariner
Posted: September 14th, 2023, 4:13 pm
by km1125
I'll bet you're just fine. Because you don't have reduction gears bolted to the back of that case, the actual level would be a bit less critical. The rear bearing probably got plenty of lube because of the angle of the trans. Without the reduction gear on the back there's also less heat generated there too.
Re: Velvet Drive fluid level check 3697 Mariner
Posted: September 14th, 2023, 4:26 pm
by bud37
My guess also you will be ok.....you can never tell what previous owners have done but because you are only a couple months in and checked properly......you did say there was oil showing on the stick that way. I don't actually think it is an amount issue, more a level check for assurance of fluid as it is running.
The lab test should be a tell.....and you said it was nice and clear pink.
Sometimes the install angle etc causes those trans to leak when over full so it may find its own level......always good to put down some of the absorbent white pads under and keep an eye. Just one of the steps, no sweat, the joys of a new to you boat , we have all done it.
To add....i'll be honest, I don't think I have ever had one of the trans that didn't leak.......
Re: Velvet Drive fluid level check 3697 Mariner
Posted: September 14th, 2023, 7:59 pm
by ron54
Finished the starboard drain and refill, almost exactly the same numbers as the port. Can’t thank you both enough for the advice. Fluid on this also still pink and no burnt smell, so hopefully all well with the old girl.
Also on this side, I used my mercruiser gear lube pump and it actually fits perfectly on the fill/dipstick fitting and dip tube bottomed in pan, made things easy. Still removed cooler lines to drain them. Now I have a baseline for the transmissions.
Next change is the Walter RV40 vdrives, questions about oil, would it be best to start a new thread for future reference?
Again, thanks, what a great forum.
Ron
Re: Velvet Drive fluid level check 3697 Mariner
Posted: September 15th, 2023, 9:04 am
by km1125
ron54 wrote:QR_BBPOST
Next change is the Walter RV40 vdrives, questions about oil, would it be best to start a new thread for future reference?
Yes, definitely start a new threat on those because future readers could get the two discussions confused.
Great that you got the VelvetDrive fluid issue nailed down!!