Shaft seal LM27

[paulsailing]

Does anyone have experience of stripping one of these?
I have what I think is the original oil feed shaft seal? It has clearly been on the boat for some time. It does not leak water in to the boat but the pressure of water forces the oil up the tube and out of the top of the reservoir. Am I correct in assuming this means the seal at the aft end has failed and sea water pressure is now only being held by the front seal?
Hope someone can help....


Paul 

[duckie]

Hi Paul,

Yes it means that the sealing on the "water" end is letting in waterpressure - but, replacing the oil seals is easy and cheap. The oil seals are on my LM27 the size of following messurements: inner 25 outer 35 - thickness 7mm - I think the original ones comes from Bukh systems - the rubber seals are having a stainless steel spring inside the rubber - they can be taken out with a screwdriver (just flip it out) and replaced with moderate pressure on a plate or something to even the pressure on the seal when pressing the new ones in place. Remember to grease the lips before replacing new ones.
IF the boat is in the water, it can still be done - but You get some water inside - I had it done 12 years ago but since then I make the replacing the seals on land in early spring - I replace them every 3-4 years just in case.

Duckie

[paulsailing]

Thanks, I am going to take the boat out at the weekend and dismantle. Nice to know that I have the correct diagnosis.
Happy sailing
Paul

[jandane]

The best solution is to buy a new Volvo Penta Black Jack seal. Look here: www.marineudstyr.dk/volvo-penta-gummipakboks.html
and a picture here:
It is not a problem to change it when in the water. Loosen the old seal, loosen the propeller axel in the gearbox flange, slide axel and propeller 10 cm back until it it hits the rudder. Slide the old seal off the propeller bearing and prepare for water flood! Hold a cloth/rag firmly to the axel. Slide the new black jack on the axel. Secure it around the bearing...and fasten the axel in the gearbox.
The only difficult part is the moment when the water is coming in via the axel/bearing. Make sure the new one is well greased and filled with marine grease. It is a better seal than the one you have on now. It is maintenance free, the bearing is lubricated by the water and it will normally be tight for 10 years+. Only thing to remember: every time you have been on land with the boat and the bearing has dried out, you MUST massage the black jack a little to let out air and let in water.

[Sula]

Jul 8, 2019 6:25:56 GMT jandane said:

The best solution is to buy a new Volvo Penta Black Jack seal. . .

It is maintenance free, the bearing is lubricated by the water and it will normally be tight for 10 years+. Only thing to remember: every time you have been on land with the boat and the bearing has dried out, you MUST massage the black jack a little to let out air and let in water.

You should also lubricate the Volvo seal with waterproof grease:  'The seal shall be lubricated after every 200 operating hours or once a year. Press in about 1 cm3 grease on each occasion.'  (From the Volvo instructions, see No. 11 and the diagram at the end - www.generalpropeller.com/pdf/Volvo%20Penta%20Shaft%20Seal%20Installation%20Instructions.pdf )

The easy way to do this without risking damaging the seal, is to use a drinking straw.  Press the straw into some waterproof grease until you have about the 1 cubic cm, flatten the very end of the straw with the grease in it, gently lift the inboard edge of the edge of the seal and slip the straw under the first seal rib. Now squeeze the grease out of the straw as you withdraw it.

Various other techniques discussed here, together with an informative photo of a Volvo seal cut in half:  www.ybw.com/forums/showthread.php?195132-Volvo-dripless-seal-how-to-service   

[jandane]

Right Sula. Pardon. Grease in every year as well

[jandane]

Right Sula. Pardon. Grease in every year as well

[paulsailing]

Thanks All
I looked at the volvo option as a replacement then priced the seals at Solent Bearings.... The ones I found on dismantling appear to be the originals made by a company who went out of business in the 80s. I bought a set of new seals for £11 and replaced them with ease, although I did have the boat out of the water..(no cost to me as pull out is covered by my mooring fee at Hythe SC)
Ebbtide is ow back in the water and ready to go..
Paul