Overheating Volvo shaft seal

N

nmelton

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Has any one had any experience of an overheating Volvo shaft seal? Quick search through past posts did not reveal any reported problems. The old-fashioned stuffing box was replaced professionally by a Volvo seal last winter (- on general recommendation and the advice of my marine engineer).

The problem started immediately after launch. After about an hours running under power the shaft was too hot to touch for more than a few seconds. The seal was vented after launch and several times subsequently. Adequate grease has been inserted. I have tried venting before each trip and I do seem to get a little air out every time. The heat appears to be generated around the area of the three internal lip seals but the design is so simple that, with adequate grease in this area, I think this is unlikely.

My engineer who installed the seal has been out on the boat and checked it all out. He, quite frankly, is mystified and suggested I contact Volvo who came up with little apart from suggesting that I re-vent the seal.

Any useful advice would be appreciated. The boat is kept on a deep water mooring by the way.

Nigel /forums/images/graemlins/frown.gif /forums/images/graemlins/confused.gif
 
Is it the correct shaft seal? I wanted to fit one to my boat, however I have a one inch shaft, and the Volvo specialist I spoke to said fitting the 25mm one would result in it overheating, and that I'd need to have my shaft turned down in order to use it. The Volvo seals are only made for metric shafts. Is this perhaps your problem?
 
On my last boat the shaft and seal would get hot after a long motor but never leaked or appear to get damaged. Although I checked and greased it each season and vented it often, it seemed to pull in air in regularly. I had replaced the shaft with one bought from Volvo so there should not be any oversize problem. The through-hull tube was not aligned particularly well (had been replaced by the previous owner after a failure) so I put it all down to that. The seal is meant to be sea water cooled; maybe you have something in the through-hull?
 
We've just fitted one, and forgot to burp it on launch. A five min (or less) motor out to our mooring resulted in a very hot shaft around the seal.

When I vented it I had to do it seven or eight times - with a little fart each time - until a trickle of water came out. Are you getting water out round it when you vent it?

I don't really understand how they work anyway . . . there is such a small volume of water in the stern tube that I do not understand how it can take all the heat away - it;s not actually circulating anywhere after all.

Does anyone know how hot they would have to get to fail?

We are taking the old stern gland with us on our trip just in case . . .

- Nick
 
Strange that your specialist told you a 25mm lipseal will not work on a 1" shaft. I use 25mm seals in the halyard sterngland on my boat with a 1" shaft and no problem - Changed after 5 years although not leaking - just part of "routine" maintenance and I did not fancy having to lift her again to change the seals.
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I used a 25mm gland for many years on a 1" shaft with no problems or overheating. Shaft speed could be a contributing factor but it is most likely to be air in the system - make sure you pull the gland up from the bottom to let the air out at the top!!
 
Rick I do have a one inch shaft on the Moody but if you look at the tolerances quoted by Volvo the 25mm seal should accomodate this. My engineer says he fits several Volvo seals a year to one inch shafts and has not had any overheating problems previously!

I have even dried out the boat and removed the seal to check the through hull clearance as Stellina has suggested. For info a new cutlass bearing was fitted and the engine/shaft aligned at the same time as the seal fitted.

Thanks Webcraft but yes I am getting water out after venting, up to a cupful or more to ensure all the air is expelled.

I just wonder if air is being trapped in the top of the seal and I am not sufficiently successful in venting this. Thanks to all for your suggestions

Rgds, Nigel


/forums/images/graemlins/smile.gif
 
I was told a Volvo 25mm seal would fit the 1" shaft on a Moody 336 but could not get the clearance on the hull to fit the Jubilee clip(s).

Sounds like there is air in there somewhere. You could try your question on the MOA website MOA
 
We had the same problem on the boat I did the last ARC and just re-bled the seal a couple of times a day. At times the water was hand hot at least.

At the time it did seem rather odd as the PSS gland on GoldenEye is normaly quite cold.
 
Never had a problem with a Volvo seal... think it's the only bit of kit that I would buy from Volvo, however, when fitting first one back in early 90's was told that must clear the stern tube of any grease leftover from the old sytem........otherwise, would prevent sufficient water getting in for cooling... HTH
 
In my experience lip type shaft seals only overheat from misalignment (in which case they usually leak as well and it is usually any associated bearing that over heats) or from a shortage of cooling water through blockage (or in the case of faster boats, venturi effect evacuating the stern tube).

If a yacht, I too as Mudplugger has, would suggest looking at the stern tube being clear of old grease or whatever. Also, if, as is the case on some boats, the outboard end of the stern tube has a close fitting bearing then that may also be inhibiting the amount of water available for cooling. Our own boat is like this so with our different make of lip seal type seal, which also has provision for water injection, we have to be sure of that injection or else it and its associated bearing overheats. Our seal has an integral bearing on the outboard side of the seal and overgreasing the bearing is sufficient to cause the seal to heat up due to the grease restricting the water passages.

John
 
Thanks mudplugger and shipscat! Removal of the seal about a fortnight ago did not reveal any left over grease. However there did not seem to be a huge clearance between the shaft and the outboard end of the stern tube, perhaps about 3mm all round from memory. I am sure I have seen references to other Moody 336's being fitted with the Volvo seal and having no reported problems.

Maybe I will have to think about water injection as I would like to stay with the Volvo seal - the lack of drips and no fiddling about with adjustments are a definite bonus. However that's assuming the heat build up is due to lack of cooling water. By feel, the heat build up seems to come from the forward end where the lip seals are lubricated with grease.

Rgds, Nigel
 
You mentioned that you burped it on re-launch and inserted grease. You did not mention the "cup" that fits on the exposed shaft to deflect water into the stern-tube, I guess that was fitted?
 
just curious but my bene has one of these but also has a 1/2 " hose running to the bit where it is clamped on from a sea cock. presume it is for a flow of cooling water but cannot understand how it gets a flow! does yours have this feature? all the benes ive seen are set up like this.
stu
 
Jim,

Please tell us more about the 'cup'. That's a new one on me, as is the water tube mentioned by Stu. Most Volvo seals in my experience are just the plain 'gaiter'.

Thanks.
 
How do you fit water injection to the Volvo seal?

The reason I ask is that we have a close-fitting stern bearing, and I am not 100% convinced that enough water will get to the seal to cool it sufficiently. I don;t know yet, but research in advance does no harm . . .

- Nick
 
Hi'

When I spoke to Volspec they quoted me for a 1" shaft seal part no 3819724 and the price(38.29 + VAT) was cheaper than the 25mm one. Volspec stated that was the price in the current volvo catalogue as opposed to about £80 for a 25mm. I'm looking at the invoice as I speak the list price was £43.76 + VAT which they discounted to £38.29.Everything came in the volvo box including grease, protective cup to insert shaft etc.
This was in April 2006. I'm just about finishing a complete engine and ancillary parts replacement. Hope my seals ok.
Please respond if you know something I need to know.
Best Wishes
Harry.
 
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