Hello everyone,
I'm trying to determine the cause of an intermittent gearbox slippage.

To save on the cost of a haul out,
Is it possible to draw the gearbox oil out of the saildrive with a suction pump, via the filler point at the top?

Also, the manual states to use ATF type A.
Is Castrol ATF Dex lll a suitable equivalent?

Hurth Saildrive mated to a 27hp nanni diesel.

Thanks in advance.

Cheers Chris.

Chris, certainly possible to change oil on Yanmar SD40/50 Saildrive leg. There is a filler hole in the top cover and another filler plug at the flange level. The flange filler is a seperate gallery to the bottom of the leg. Can purchase but I made a couple of fittings from a brass hose barb with an M10 thread cut in place of the NPT thread. The oil is blown out using low pressure air in the top filler hole. It is unlikely that the top filler hole has a gallery and therefore will not be possible to suck oil from there.
Does yours have such a lower fill point?

A note about the oils, VP recommended ATF OILS, but have changed recommendations to non friction modified engine oil.
this is due to clutch slip and plate swell. So a good quality wet clutch compatible motor cycle oil could be adavantageous!
cheers Richard

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frant said..
Chris, certainly possible to change oil on Yanmar SD40/50 Saildrive leg. There is a filler hole in the top cover and another filler plug at the flange level. The flange filler is a seperate gallery to the bottom of the leg. Can purchase but I made a couple of fittings from a brass hose barb with an M10 thread cut in place of the NPT thread. The oil is blown out using low pressure air in the top filler hole. It is unlikely that the top filler hole has a gallery and therefore will not be possible to suck oil from there.
Does yours have such a lower fill point?

Thanks for your reply Frant.

I'll head out to the boat tomorrow & check for a lower filler point.

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Stockie said..
A note about the oils, VP recommended ATF OILS, but have changed recommendations to non friction modified engine oil.
this is due to clutch slip and plate swell. So a good quality wet clutch compatible motor cycle oil could be adavantageous!
cheers Richard

Thanks Stockie.

Does this mean use a JASO wet clutch motorbike oil instead of the ATF?

The oil currently in the saildrive smells like a gear oil.
The slippping became noticable after the last slip/antifoul/oil change.

This could be coincidental, but I thought it might be worth changing it to ATF, to see if that improves it.

My mate just went through a problem with his NorthShore 340, Nanni and sail drive that was slipping in forward. Worked for a while in reverse, so he just reversed out to the start line and reversed back onto his mooring. Until the whole lot stopped working.

No replacement sail drive available, and required parts to fix the problem are not in Australia. Some parts were brought in from Europe, some manufactured in Australia I believe. Big dollars overall, not much less than replacing the whole shebang in the end.

I know nothing about this gearbox. If it has a cone like the Volvo units the cone may benefit from a rough up.

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EC31 said..
My mate just went through a problem with his NorthShore 340, Nanni and sail drive that was slipping in forward. Worked for a while in reverse, so he just reversed out to the start line and reversed back onto his mooring. Until the whole lot stopped working.

No replacement sail drive available, and required parts to fix the problem are not in Australia. Some parts were brought in from Europe, some manufactured in Australia I believe. Big dollars overall, not much less than replacing the whole shebang in the end.

Hi EC31,

My slippping gearbox is still only intermittent at this stage.
It's usually just 3 or 4 1/2second blips in the first minute of motoring off the mooring.
I've been told by a mechanic to keep on using it, until it becomes worse.

Did your mate have to remove the entire leg for the rebuild, or did he leave the boat in the water & just remove the top box?

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Ramona said..
I know nothing about this gearbox. If it has a cone like the Volvo units the cone may benefit from a rough up.

Hi Ramona,

My uneducated guess is that it might have a cone clutch.
If a simple oil change does'nt improve it, then I'll send it to the marina for repairs.

Maybe re lap, or shim the cone. Maybe clutch plates.
Hopefully not the whole leg.

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chris340 said..

My slippping gearbox is still only intermittent at this stage.
It's usually just 3 or 4 1/2second blips in the first minute of motoring off the mooring.
I've been told by a mechanic to keep on using it, until it becomes worse.

Did your mate have to remove the entire leg for the rebuild, or did he leave the boat in the water & just remove the top box?

The boat was on a mooring near RPAYC / Sirsi for a while, but I was away when the repairs were completed. I wont see him again until the 12th of next month, but will get some more information for you and the place who fixed it and pass them on.

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EC31 said..

chris340 said..

My slippping gearbox is still only intermittent at this stage.
It's usually just 3 or 4 1/2second blips in the first minute of motoring off the mooring.
I've been told by a mechanic to keep on using it, until it becomes worse.

Did your mate have to remove the entire leg for the rebuild, or did he leave the boat in the water & just remove the top box?

The boat was on a mooring near RPAYC / Sirsi for a while, but I was away when the repairs were completed. I wont see him again until the 12th of next month, but will get some more information for you and the place who fixed it and pass them on.

Thank you very much.
That would be helpful.

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chris340 said..


Hi Ramona,

My uneducated guess is that it might have a cone clutch.
If a simple oil change does'nt improve it, then I'll send it to the marina for repairs.

Maybe re lap, or shim the cone. Maybe clutch plates.
Hopefully not the whole leg.

If this is a cone clutch and it is delaying going into gear or slipping it could be just the wrong oil or the cone has gotten polished up. I had a Volvo stern drive years ago that did this, The Volvo dealer repaired it in the water, just lifted the leg clear and pulled out the cone. They used a fine wet and dry paper and just touched it up. I think there was a fair bit of this happening at the time and the dealer, Fenquin Marine just got straight onto it.

Chris, I'm not sure, but you said that the saildrive smells like gear oil. Does that mean you think it smells like it came out of an old Holden?
I'd call the workshop who supposedly serviced it and ask them what they put in it. Or check your invoice, as it may say what they used. If they used a plain gearbox oil (remember a lot of the simple stuff is left to apprentices, who don't always ask what is the correct oil to use).

It's rare for a manufacturer to change the specs greatly from what was originally specified. So if it was specified to use Type A fluid, then that's what you should use.

Here's some info about it from Penrite. www.penriteoil.com.au/products/classic-atf-mineral#/ here it says Dexron III is not the equivalent, but Dexron II is.

Disclaimer, I'm a motorcycle mechanic, not a saildrive mechanic, but the principles remain the same. I'm only offering additional information, and I don't have an affiliation with Penrite either.....

We always have a principle in the workshop. Take it back to specifications, check all the basics and then assess whether the problem is still there. In your case, first thing I'd do is make sure the oil is correct before doing anything else.

Good luck with it!

Chris,
im still suggesting changing your oil to a non friction modified engine oil. I use Penrite MC I THINK IT IS 40 weight. I've got old Triumph bikes and the clutch runs in oil from the engine, wrong oil equals clutch slip and drag, when the fibres swell up. Google Volvo Penta sail drive oil recommendations, Volvo issued a guide sheet about their switch from recommending ATF types to wet clutch engine oils.

chhers Richard

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chris340 said..

frant said..
Chris, certainly possible to change oil on Yanmar SD40/50 Saildrive leg. There is a filler hole in the top cover and another filler plug at the flange level. The flange filler is a seperate gallery to the bottom of the leg. Can purchase but I made a couple of fittings from a brass hose barb with an M10 thread cut in place of the NPT thread. The oil is blown out using low pressure air in the top filler hole. It is unlikely that the top filler hole has a gallery and therefore will not be possible to suck oil from there.
Does yours have such a lower fill point?

Thanks for your reply Frant.

I'll head out to the boat tomorrow & check for a lower filler point.

Select to expand quote

chris340 said..

frant said..
Chris, certainly possible to change oil on Yanmar SD40/50 Saildrive leg. There is a filler hole in the top cover and another filler plug at the flange level. The flange filler is a seperate gallery to the bottom of the leg. Can purchase but I made a couple of fittings from a brass hose barb with an M10 thread cut in place of the NPT thread. The oil is blown out using low pressure air in the top filler hole. It is unlikely that the top filler hole has a gallery and therefore will not be possible to suck oil from there.
Does yours have such a lower fill point?

Thanks for your reply Frant.

I'll head out to the boat tomorrow & check for a lower filler point.

Yes Frant, there is a second capped opening on the Hurth gearbox. It is on the top at the same level as the filler point.
The filler cap is the dipstick, the second cap is stamped with an arrow showing 'up'.

I'll source, or make some fittings to blow some air down the filler hole to extract the oil via the second port.

Extracting the oil through either hole with a suction tube is not possible.

Thanks for your help.

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Ramona said..

chris340 said..


Hi Ramona,

My uneducated guess is that it might have a cone clutch.
If a simple oil change does'nt improve it, then I'll send it to the marina for repairs.

Maybe re lap, or shim the cone. Maybe clutch plates.
Hopefully not the whole leg.

If this is a cone clutch and it is delaying going into gear or slipping it could be just the wrong oil or the cone has gotten polished up. I had a Volvo stern drive years ago that did this, The Volvo dealer repaired it in the water, just lifted the leg clear and pulled out the cone. They used a fine wet and dry paper and just touched it up. I think there was a fair bit of this happening at the time and the dealer, Fenquin Marine just got straight onto it.

It very well could be a bit of glazing, Ramona.
But I will try a change of oil before digging any deeper.

It shifts into gear perfectly, as I just had the gear selector cable replaced & properly adjusted.
I've been for a swim to check the prop. It's a 2 blade folding prop. It seem to be opening freely.

I drove the boat for one & a half hours yesterday.
Again, it slipped 3 times whilst motoring off the mooring.
Then it grabbed and ran faultlessly.

I switched the engine off after one hour and floated for 10 minutes.
Then restarted it.
It slipped twice, then ran perfectly for the remaining half hour back to the mooring.



It is'nt a big problem yet, but I'd prefer to sort it in case (before) it becomes worse.

Michael R &
Stockiie,

The gearbox is definately running with a gear oil at the moment.
I'm usure what type of oil, but it smells like the old fashion mineral stuff.

The nannni manual, clearly states, to use ATF type A.
But
Oil recommendations have changed.

Thank you both.
I will try both of your suggestions (if necessary) before undertaking any mechanical work on the gearbox.

Select to expand quote

Stockie said..
Chris,
im still suggesting changing your oil to a non friction modified engine oil. I use Penrite MC I THINK IT IS 40 weight. I've got old Triumph bikes and the clutch runs in oil from the engine, wrong oil equals clutch slip and drag, when the fibres swell up. Google Volvo Penta sail drive oil recommendations, Volvo issued a guide sheet about their switch from recommending ATF types to wet clutch engine oils.

chhers Richard

I would suggest the oil change first as well and go with Stockie's suggestion re non friction modified oil. I had an incident recently with the gearbox in my race car. Blasted all the oil out the breather. Apparently the friction modified oil was not compatable with the gearbox type. Buying better oil is not always the answer and in this case I would stick with what ever the manufacturer recommends.

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chris340 said..
Michael R &
Stockiie,

The gearbox is definately running with a gear oil at the moment.
I'm usure what type of oil, but it smells like the old fashion mineral stuff.

The nannni manual, clearly states, to use ATF type A.
But
Oil recommendations have changed.

Thank you both.
I will try both of your suggestions (if necessary) before undertaking any mechanical work on the gearbox.

Hi Chris
just a thought.
Might be worth running the motor/gear box to heat the oil up prior changing as it will flow better and may carry any grit/dirt with it. Close inspection may give a hit to any problems.
Flush with a bit of clean oil may be wise, also a tip a mate told me when changing diff oil in a car was to pre heat in a microwave (think he was squeezing from a plastic bottle.

The one question no one has yet asked, is what is the model number of the gearbox? Low powered earlier model ZF boxes used engine oil, but as the horsepower went up they then switched to ATF fluids, it is definitely not ok to switch oils which is why a specific oil was specified in the first place. Type A was for GM xmissions and type F was for Ford xmissions. With the information you have given it would seem that a Dexron type3 oil is what your gearbox craves. Check this ...
www.penriteoil.com.au/applications/car-4wd/automatic-transmission/atf-dx-iii-mineral#/

TYPE A & TYPE A Suffix A: The original fluids. They came out in 1949 & 1957 respectively and are obsolete.

DEXRON?-IID: Now obsolete, it was the closest to an industry specification. Indeed, it formed the basis of many other OEM (Original Equipment Manufacturer) ATFs Specifications. It is still used by GM Europe up until recently and by other European and some Japanese OEMs.

DEXRON?-IIE: A development that had better low temperature properties than IID. Now superseded.

DEXRON?-III: For many years it was in "F" & "G" specifications, which had the same low temperature characteristics as the -IIE version, but with modifications to antioxidancy and friction material. The 2003 -IIIH specification was for 160,000km drain intervals and extended durability and superceded "G". This specification became obsolete at the end of 2006 and was replaced by DEXRON?-VI.

DEXRON?-VI: Initially released in 2005, this is a special low viscosity fluid which replaced DEXRON?-III in all GM manufactured Automatic Transmissions. It has a very long oil drain capability of up to 400,000km.

Hi LooseChange.
This is the ATF that I purchased and intended to use.
But the more I researched it, the more confusing things became.
Hence the purpose of this thread.

I am still getting differing opinions, from several marine mechanics, as to whether or not the boat has to be slipped to drain the current gearbox oil.

Hi Chris,

Spoke to my mate with a 340 last weekend about his Nanni gearbox issue. He suggests you talk to Jason at Marine Gearbox Services, 2/3 Marina Close Mt Kuring-Gai NSW. Number is 0409 962 366 and web is www.marinegearbox.com.au/

They lifted the boat out at RPAYC, took out the gearbox, fitted a plate and put the boat back in the water. Some parts came from France, the rest were reconditioned in Oz.

Thanks very much EC31,

I'll definately give Jason a call.

Hi Chris & your story sounds very familiar. I had transmission problems with a ZF 150 Hurth (not saildrive) but same same. Initially tried gear change & like you found the classifications & recommendations by mechanics confusing. I also chose the ATF Dex III. My issue was possibly a bit clearer - only slipped in forward.
So changed oils, but this only seamed to fix in short run. Final solution was a total gearbox recondition. A kit is available (from Italy? & cost around $600 via ZF Services in Sydney). Have to admit that I was **** scared at getting this wrong - I.e. comprised 100+ parts & all bolts require torsion etc & lots of shims/ tolerances to deal with. I took it on & it now works perfectly & incredibly satisfying to do yourself.
PS - check out the shifter in the attached photo - My old man (mechanic) would call it the Gorilla Approach!