burping

[scoty]

Volvo propellor shaft seal, I have recently purchased a motor boat with two of this type of sealing fitted and would be interested to know if the so called ·burping· needs doing monthly/yearly or what ever,,,,plus what is the life span or recommended replacement time.

Thanks in advance

 

[Tranona]

Burping is only necessary if the boat has been out of the water. The purpose is to expel trapped air in the stern tube. Just squeeze the tapered end until a bead of water escapes. However, you may find your installation has a vent or a water feed to the stern tube which makes burping unnecessary - but no harm in doing it just in case. If the bearing does run dry you soon know about it from the noise!

You need to lubricate the seals annually with a special grease you can get from Volvo dealers or Keyparts. The easiest way is to put some grease in the end of a drinking straw, flatten the end and push it along the shaft to get to the seals, then squeeze the grease in. Takes longer to explain than do! Volvo suggest 5 years life, but people report 10 years or more. Provided they don't leak (indicating worn lip seals), no reason to change them.

 

[Nautibusiness]

Hi Scoty

I am not familiar with them specifically as "Volvo".
I know them has stern glands and this type (assuming we are thinking of the same thing) are generally fitted to the small to mid sized shaft sized diesels.
My old Merry Fisher 695 with a 175Hp Nanni had one for example.

You need to bleed or burp the stern gland each and everytime the boat is relaunched after being lifted from the water.
grasp around the gland where the shaft emerges and squeeze firmly. You will feel a trickle of water on your fingers - job done.
When you let go the stern gland will reseal and the dripping will stop. When underway, expect to see a slow
drip

drip

drip of water. If you see a drip drip drip drip then it is time to change it.

All you are doing is allowing water all the way up the shaft from the outside to the stern gland itself. The water is simply doing a cooling / lubricating function.
If you fail to bleed it then the lip of the stern gland is liable to get very hot and make the rubber seal go hard. If this happens it will not seal properly and will need replacing much sooner.

Does that make any sense at all?
Are we thinking of the exact same thing?

Tom

 

[PCUK]

Sounds like you are talking about Deep Sea Seals which are totally different. Even so these should be totally dry. The only seals needing to drip are traditional packed stern glands.

 

[scoty]

All my previous sailing boats had traditional packing glands, now having in my senior years changed to motoring I·m told my boat is fitted with volvo type seals,,,,to me they are a rubber tube secured at one end with two jubilee clips, about six inches long tapering down to the propellor shaft, there·s no bleed or water tubes, hope this helps to identify them, did·nt think to take a photo before leaving the boat,
thanks for your replies.

Sounds like you are talking about Deep Sea Seals which are totally different. Even so these should be totally dry. The only seals needing to drip are traditional packed stern glands.

 

[Tranona]

Definitely Volvo. Good choice. No leaks, minimal maintenance, cheap to replace if needed (materials anyway!)

 

[peterandjeanette]

Had the Volvo seal replaced recently. The engineer burped the seal on relaunch. Then the seal got very hot when running. ???? Shaft distorted?

Burped the seal twice when under way. Hot water came out. Eventually resealed.
Just hope no permanent damage done.