Trans, oil change

I pumped out all the transmission oil today in my boat. I don't know when it was changed last, could of been many years ago. It looked kind of purplish and creamy and not the red color of new ATF. I took out about 1 1/2 quarts and hope that is what should be in there. Replaced it with Castrol Dextron III/ Mercron ATF.

I'm thinking maybe I should change it again after running it a few times to get out any remaining contaminated oil.

Does this sound right for a trans. oil change ? It's a 71c Velvet Drive.

Eric
Are you saying to overfill the transmission to the top of the fill hole and then run it?

I'm gonna change my fluid this pre season, should i go with a synthetic fluid? I was thinking about going with this.... Royal Purple

P.S.-Eric, we have been getting a medium loud tranny noise when the tranny is cold. Sounds like rocks in a dryer, and it loud enough to hear over the exhaust. Goes away when it is warm. any ideas?

Chris,
Our transmissions are not the same as automotive trans's which are basically a pump and turbine where a: " low co-efficient of friction and high film strength help to dramatically reduce heat and wear." is beneficial. Marines are a pump that applies pressure to the clutch plates engaging the engine to the prop shaft. A low coefficient of friction is not what you want between the clutch plates. If they slip, they heat and the plates warp then you'll be sending you trans to Eric!! Instead of looking at what I would call "bling" fluids, take some time to look through the trans manuals in our ref. section. Some show the internals so you may get the idea on how they work.

Stick with regular Dexron/Mercon

Concerning the noise, how's your dampner plate?

Eric, Anything to add?

BTW, it does sound if you did need a damper plate also

you may have a slight miss with the engine when cold and will smooth out as it warms, dont get me wrong that the damper springs have weakened but also it could be an engine problem aggrivating the damper. a half a degree of timing will cause a damper noise, a bad plug also...when you hear a damper noise think of it as a jack hammer, it is causing premature wear and needs to be addressed

Eric,
Speaking of damper plates, I think I'm about due on the BFN. Motor runs like a top after new DUI dizzy, carb rebuild and full tune up. It produces a big clunk apon engageing in forward gear. Never does it it in reverse gear, just forward but does it every time warm or cold. Am I thinking right? It's only got 400 hrs. and new been apart.
What do you recomend?

Steve

Pete,
I talked to my dad this morning. He has no doubt he can do it, just he would like to call Eric and ask a few questions first. Its got 1600 hours, and never been apart.

Stev,e it is a Chevy and tend to be a little harder on the damper plates because of torque lol, its probably due, Ive seen them go bad as early as 300 hours...it wont hurt
and, 74 with 1600 hours I would probably do more than a damper, thats from thinking while its out....just hate pulling them twice, and you do know about alignment I presume?

8122pbrainard wrote: You have a Velvet drive so it takes a 26 tooth spline. The best out there is the Sachs plate. sachs plate Eric uses them and he should have one too. Trimming the OD on some of the smaller flywheels may be needed. My 302 needed it trimmed.

Yes, I got the Borg Warner 1:1 71c Velvet drive. We might use it as is this season, and then in the fall, pull it out. Maybe rebuild the whole thing, or trade for a remanufactured one. Could it be a broken spring? If it is, that adds more load on the other 5. What makes the noise exactly?

74Ski - I'm all thumbs & I was able to replace my damper plate in 1 afternoon. I wouldn't put if off if I were you. It's not a big job.

There are some threads here that will explain the procedure.

Just make sure & get it aligned to the trans shaft (tighten after assembly recommended).

Pete, FYI, they do offer a dampner, damper with the edge's already shaved off, i accidentlly ordered one and it showed up with the edges trimmed already, i believe it is a da-106a, no trimming necessary, i found this out late in the season...

We didnt think anything of it, Because the oil still looks brand new, but its not like engine oil where it changes color from combustion. How often should it be changed? We change the Engine oil every fall.

okay, Yea well put. So five years is too long then...

i keep this rule: motor oil every 50 hours or 6 months, tranny fluid 100 hours or 1 year...
Getting that fluid is a pita with a manual pump...
Is there a more efficient non expensive tool to do the job?
Kapla