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Replacing J2 water pump seal


gbclive
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If I may, I’d like to resurrect this 2 year old thread in order to seek further advice. Long story short… the coolant pump body on my J2 was modified by a previous owner, reasons unknown. This has resulted in there being room for only 2 rings of 3/8” or 10mm  packing.

 

My previous experiment with a hydraulic seal + 1 ring of packing seemed to cause more aggressive wear to the chromed ram than conventional packing. So 2 years ago I reverted to using 2 rings of conventional packing. This gave 1 year, about 1000h, of acceptable leakage, but steady deterioration over the last season with about 100ml per hour in spite of regular nipping up of the gland.

 

So I’ve just replaced the packing again using the same product as last time, then carefully reassembled the pump as before, only to find that the max amount of gland thread that can engage into the pump body is a paltry 2/3 of a revolution before reaching the top packing ring. This is a bit less than I recall last time and is obviously unacceptable and results in significant weeping past the threads. So I’m back at square one and looking for reasons and solutions. The nominal 10mm sq packing seems a sensible size in relation to the cylinder and ram diameters. 9.9mm gap and about 10.6mm actual size of packing.

 

First question please. I’ve attached some photos including the top of the pump body and a quick sketch. Can anyone enlighten me as to the previous modification and why it may have been necessary?  I’m guessing that some bronze has been removed from around the  top of the cylinder?

 

Second question. Would using a lathe to removing say 1/4” or so from the lower surface of the gland be something to consider in order to allow more of its threaded upper portion to engage with the top of the cylinder thread?

To my mind it would be bad form to do this kind of irreversible mod to a Kelvin component, but I’m working with a pump that’s already been altered in some way.

 

Thanks everyone.

 

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Certainly,alter the gland to fit properly-...at least five turns of thread engagement.......there should not be any water in the threads,the packing should exclude all water from the OD,and only a few drops to lube the piston ...I can see where someone has ground out damaged threads,further reducing engagement...........if threads barely engaged are continually stripped ,youll end up with no thread left...........however ,its quite easy to build up bronze housings and re machine them,or to braze in an insert .......Do be careful with bronze tho,its got a very sudden melting point ,and flows like water..............I would have said at  one time to pack up the casting with wet asbestos ,just in case,.......but now I wont.

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Lovely photos, we see a lot of crap photos on this forum so its lovely to see some good ones.

We have a beta JD3 but I have been lucky enough to briefly drive two boats with Kelvins.

I realise this post is of no help 😀

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Looking back at this....the packing gland is also a crosshead bearing for the piston...and too short already..........the whole mechanism is a crap design........I used to get stuff like  this to modify so it works properly ,and it makes you wonder why the manufacturer didnt do this at the factory...............another product where the customers were the test engineers,and had to pay for the privilege.

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The top of the pump body has been chamfered, presumably because the top threads were damaged.  That means you have lost the equivalent number of threads engagement before you start.  

I think your idea of taking 6 mm or so off the gland follower is the way to go.  The other possibility is to fit a sleeve as suggested by john.k. That seems like a lot more work.  A new gland follower is fairly easy to make if you ever wanted to go back to original set up.  You need a fairly big chunk of brass though!⁸

 

I find that water pump packing either lasts about a year, or for about 5 years.  I can find neither rhyme nor reason to this.  I have never managed to get more than two turns of packing in.    That said, a litre a day is not a  terrible consumption rate for an open ram gland packed  pump.  I tend to think I need to do something when it gets to about 2 l a day.

 

For john.k.  The later, double acting water pump was a better design.  Unfortunately it has leather washers which are hard to come by.

 

N

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I was wondering from the pic if the pump may have originally had greased leather washers in the location,in the interests of economy...............as most will know ,the woven square section packing is not cheap,and leather would have appealed ............on ocassion ,Ive found square cut fur felt ,saturated in grease,also make a servicable seal for a waterpump.,and also the combination of felt and leather washers ,well greased.

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9 hours ago, john.k said:

Certainly,alter the gland to fit properly-...at least five turns of thread engagement.......there should not be any water in the threads,the packing should exclude all water from the OD,and only a few drops to lube the piston ...I can see where someone has ground out damaged threads,further reducing engagement...........if threads barely engaged are continually stripped ,youll end up with no thread left...........however ,its quite easy to build up bronze housings and re machine them,or to braze in an insert .......Do be careful with bronze tho,its got a very sudden melting point ,and flows like water..............I would have said at  one time to pack up the casting with wet asbestos ,just in case,.......but now I wont.


Thanks John. I usually find simple trumps complicated, so I’ll probably have the gland adjusted. 

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10 hours ago, john.k said:

Certainly,alter the gland to fit properly-...at least five turns of thread engagement.......there should not be any water in the threads,the packing should exclude all water from the OD,and only a few drops to lube the piston ...I can see where someone has ground out damaged threads,further reducing engagement...........if threads barely engaged are continually stripped ,youll end up with no thread left...........however ,its quite easy to build up bronze housings and re machine them,or to braze in an insert .......Do be careful with bronze tho,its got a very sudden melting point ,and flows like water..............I would have said at  one time to pack up the casting with wet asbestos ,just in case,.......but now 

Edited by gbclive
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10 hours ago, dmr said:

Lovely photos, we see a lot of crap photos on this forum so its lovely to see some good ones.

We have a beta JD3 but I have been lucky enough to briefly drive two boats with Kelvins.

I realise this post is of no help 😀

Thanks dmr. I did not have the required gizmo to transfer files from my camera to my iPad, so made do with using the iPad’s camera. The in situ one was lit by my head torch. The black backgrounds ones were taken on a spare micro fibre cloth to reduce reflections. Their usual purpose is to mop out the sump during oil changes😏

10 hours ago, john.k said:

Looking back at this....the packing gland is also a crosshead bearing for the piston...and too short already..........the whole mechanism is a crap design........I used to get stuff like  this to modify so it works properly ,and it makes you wonder why the manufacturer didnt do this at the factory...............another product where the customers were the test engineers,and had to pay for the privilege.


But I still love my J2🙂

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2 hours ago, BEngo said:

The top of the pump body has been chamfered, presumably because the top threads were damaged.  That means you have lost the equivalent number of threads engagement before you start.  

I think your idea of taking 6 mm or so off the gland follower is the way to go.  The other possibility is to fit a sleeve as suggested by john.k. That seems like a lot more work.  A new gland follower is fairly easy to make if you ever wanted to go back to original set up.  You need a fairly big chunk of brass though!⁸

 

I find that water pump packing either lasts about a year, or for about 5 years.  I can find neither rhyme nor reason to this.  I have never managed to get more than two turns of packing in.    That said, a litre a day is not a  terrible consumption rate for an open ram gland packed  pump.  I tend to think I need to do something when it gets to about 2 l a day.

 

For john.k.  The later, double acting water pump was a better design.  Unfortunately it has leather washers which are hard to come by.

 

N


Thanks BEngo.  I’ll phone Dick Goble to see if he would like to turn down the lower surface of the gland.

Your comments on leak rates and number of packing rings are reassuring - thanks.

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1 hour ago, john.k said:

I was wondering from the pic if the pump may have originally had greased leather washers in the location,in the interests of economy...............as most will know ,the woven square section packing is not cheap,and leather would have appealed ............on ocassion ,Ive found square cut fur felt ,saturated in grease,also make a servicable seal for a waterpump.,and also the combination of felt and leather washers ,well greased.


That interesting. Duke is not that old, built 1993 with a 1948 J2. When I purchased the boat, the engine was getting warmer than it should on rivers etc. Kelvin engineers RW Davis investigated and identified the large but very poorly designed skin tank under the floor as the culprit. They welded a much smaller but properly baffled one externally on the aft swim. It was subsequently discovered that the original skin tank was clogged up with three bucket loads of thick grease! 

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2 hours ago, gbclive said:


Thanks BEngo.  I’ll phone Dick Goble to see if he would like to turn down the lower surface of the gland.

Your comments on leak rates and number of packing rings are reassuring - thanks.

If Dick is too busy, send or bring  it to Somerset and I  will happily  turn the end off for you.

 

N

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23 minutes ago, BEngo said:
23 minutes ago, BEngo said:

If Dick is too busy, send or bring  it to Somerset and I  will happily  turn the end off for you.

 

N


Thanks, thats very kind of you.

I’ve left a message on Dick’s answer machine.

Edited by gbclive
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4 hours ago, gbclive said:

Thanks dmr. I did not have the required gizmo to transfer files from my camera to my iPad, so made do with using the iPad’s camera. The in situ one was lit by my head torch. The black backgrounds ones were taken on a spare micro fibre cloth to reduce reflections. Their usual purpose is to mop out the sump during oil changes😏


But I still love my J2🙂

 

The iPhone can take some good photos. Taking engineering type photos is quite a skill and many appear to fail. Where I used to work one of the machine shop staff also specialised in engineering photography. I like yours because they show the required detail but are also pleasing to look at. I have tried to take some photos of my injectors before and after cleaning but the soot is so black its really difficult to show the detail.

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