Cutlass Bearing/Stern Gland lubrication - what to use?

[richardsussex]

I am helping a friend with some maintenance on a shaft-drive internal-engined cruising boat approx 13m. The Cutlass bearing/stern gland is connected to a small header tank reservoir by a tube. The liquid in the reservoir is a red colour, similar to ATF, and does feel "oily". There is no indication as to what the fluid is.

Unfortunately the boat is a one-off aluminium craft from a now defunct French manufacturer so there is no information available.

There is no leak and all seems OK at the moment. All we want to do is to keep the tank topped up. I don't want to cause problems by putting in ATF it is expecting, say, Brake fluid or mineral oil, or some specialist hydraulic fluid.

I have only ever seen water-driven connections or a grease pump to this part of a boat so am a bit mystified.

Any ideas as to what I should top up with gratefully received

Thanks in anticipation

 

[charles_reed]

I've had oil reservoirs on both Bukh and Halyard shaft seals. Both recommended the use of conventional lubricating oil (not hydraulic fluid).
Perhaps. if you could find some makers mark on the seal (not the cutless) it would be easier to point you in the direction of the correct information.

 

[cliff]

A picture or two of the seal would help but if same as the Bukh/Halyard type seals then a light machine oil (low viscosity) is all that is required. As for the cutlass bearing - water lubrication is the "norm"

 

[Neil_Y]

We used to supply an oil lubricated stern gland/shaft system somewhere I have the spec of the oil, but like many companies they had their own branded bio degradeable oil. In the mean time give these guys a call http://www.rpmarinesurveys.co.uk/p/stern-gland-types

 

[Neil_Y]

A picture or two of the seal would help but if same as the Bukh/Halyard type seals then a light machine oil (low viscosity) is all that is required. As for the cutlass bearing - water lubrication is the "norm"

The shaft bearing could be oil lubricated white metal or composite, depends where the lip seals are, these are still available. The bearings are happy in a wide range of oils and even grease (at lower rpm or where there is good cooling)

 

[vyv_cox]

There are photos of many versions of oil lubricated seals on my website at http://coxengineering.sharepoint.com/Pages/Sternglands.aspx well down the page. A 10W/40 multigrade oil is commonly used but if yours is red it is ATF. It may be compatible with a multigrade but it is probably safer to stay with what is there now.

 

[theoldsalt]

This diagram probably explains the arrangement.

View attachment 40198

 

[rob2]

I also have a lip seal arrangement on the inbord seal/bearing. Mine seems to have been from Vire, although I can find no details about it, but I suspect it is only a seal, not a bearing. It is fed with ATF - red in colour and with a distinctive aroma - from a small metal reservoir, similar to a remote clutch or brake hydraulic reservoir on a car. As far as I can ascertain, the oil does tend to lubricate the seals, although if it were to start dropping in level it's time to haul the boat and fit new seals or even a new shaft if it has become scored.

The outboard end of the shaft runs in a cutless bearing which is water lubricated purely by being submerged in the stuff.

The beauty of such a set up is that there is no grease working its way down from the upper bearing and contaminating the otherwise water lubed lower one. Also, there is little friction in the seal to be transmitted to the hose so you are unlikely to ever wring the hose off/apart and sink. I doubt any of the lip seal types were ever manufactured incorporating locating dogs as seen on the better stuffing boxes to absorb the torque of the shaft.

Rob.

 

[richardsussex]

Hello all,

Many thanks for your very helpful replies. There wasn't a maker's name on the reservoir tank or anywhere else, and the engine make is a Lombardini which isn't that common.

The consensus seems to me that ATF was the likely bet and so we topped up with that and it hasn't had any ill effects.

Much appreciate all of your time in taking the trouble to help,

Best Regards