V Drive

Sep 3, 2017
88
Boat Info
1987 Sea Ray Sundancer 340
Engines
Dual 454 Mercruisers
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One of my V Drives looks like it may be a little low. The manual calls for 10 wt. tractor hydronic fluid. Pictures below are what they gave me at the auto parts store. Any info/clarification appreciated.
 

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There's a good chance a previous owner has changed to standard ATF. You should be using Dexron III (not IV or V or newer). Napa Dex/Merc ATF (Dex III) is what I use. If your fluid is red, I think that means it's not that 10W oil.
 
Y'all be careful..........

My recollection is that Sundancers with Borg Warner v-drives require AFT, but the Velvet Drive straight inboards require Mobil 424, which is a tractor hydraulic dluid and probably isn't suitable for transmissions requiring ATF.
 
Y'all be careful..........

My recollection is that Sundancers with Borg Warner v-drives require AFT, but the Velvet Drive straight inboards require Mobil 424, which is a tractor hydraulic dluid and probably isn't suitable for transmissions requiring ATF.

Good catch, but it's actually the other way around. Mobil 424 was the spec for 71C and 72C V-drive BW, but can be changed to Dexron III, and most of these older boats have been changed by previous owners. I know mine was. To change it from 424 to DexIII, it must be flushed and refilled at least twice, including the lines and cooler, to get the 424 out. That means, pump out old fluid, refill with DexIII, briefly run in neutral, pump out 1st time, refill with DexIII, briefly run in neutral, pump out 2nd time, refill with DexIII to proper level and you're good to go. That's roughly 10.5qt for each V-drive, but really makes sure that things are ready to go. Napa DexIII is about $4-5 per qt, so you're looking at $100 in fluid for both drives, but cheap insurance.

The spec for the BW 71/72C straight drive was Dexron II or Type F. Both can be changed to Dexron III ATF. The oil he posted is within this spec, but would need to replace similar fluid (unlikely it's still old SAE). Since he has V-drives and probably has Dexron III, he should not be using the hydraulic oil. Since it's a new-to-him boat, the best way to proceed would be to flush and refill them twice with Dexron III. It's the only way to be certain things are correct.
 
Y'all be careful..........

My recollection is that Sundancers with Borg Warner v-drives require AFT, but the Velvet Drive straight inboards require Mobil 424, which is a tractor hydraulic dluid and probably isn't suitable for transmissions requiring ATF.
Glad to see some newer posts about Transmission fluid change
I’m new to this forum and recently bought a1990 Sea Ray express 310 inboard and I can’t find any info on my model B-W 63? Or Hurst? I’m experiencing some extra end play on the output shaft but no noise and would like rebuild my starboard side just to be safe.
 

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