Jump to content
Strawberry Orange Banana Lime Leaf Slate Sky Blueberry Grape Watermelon Chocolate Marble
Strawberry Orange Banana Lime Leaf Slate Sky Blueberry Grape Watermelon Chocolate Marble
gbclive

Replacing J2 water pump seal

Featured Posts

The gland of my J2 water pump has for some reason previously been modified, resulting in insufficient space to fit enough packing. This, combined with a worn piston, had resulted in excess leakage.

 

So a few years ago the piston was turned down to remove the wear groove, then chrome plated back to the correct size and a hydraulic seal used in place of packing.

Initially this worked quite well, but over the last 1000 hours or so of use, the leakage has gradually returned.

So now It’s time for me to replace the hydraulic seal in the hope that it and not chromed piston degradation is causing the excessive leakage🤔

 

I’m not an engineer, so I’d be very grateful for any advise on extracting the piston from the cylinder to enable inspection and replacement of the hydraulic seal, of which I have several spares.

My best guess is to wind the locking nut fully down, then screw the pump rod lower end into the upper end as far as it will go, in the hope that this is enough for the piston to clear the gland.

If not, then I guess I’ll need to remove the top bearing bolts.

 

Any advise, including potential pitfalls, hints and tips would be much appreciated.

In particular, is it safe to rely on the top bearing to resist the torque when dealing with the lock nut?

 

Thanks.

P1060567.jpg

P1060572.jpg

P1060573.jpg

Edited by gbclive

Share this post


Link to post
Share on other sites

Turn off the water to the pump if you can.  If not drain down or it will nearly all run out anyway when you take the piston out.

Slacken the gland follower a couple of turns.  Undo the locking nut and wind it down as far as it will go.  I have never had any trouble with the top bearing whilst doing this.  Then  unscrew the piston rod from the top end until it runs out of thread.  You should be OK doing this by hand but if not a spanner on the locking nut or a grip on the plain part of the rod is the answer.   Then push the piston down into the cylinder so the top of the rod, which originally had a short plain section, will clear the big end  piece.  A bit of a lever with an open ended spanner may help, but I think with a lip seal pushing the piston down should be easier than with packing.  Undo the gland follower and slide it out up the piston rod. Pull the piston up and out. Remove packing/lip seal. 

 

Reassemble in reverse order!

 

N

Share this post


Link to post
Share on other sites

As always, thank you Nigel for the detailed instructions.

I will sit down and transfer them to a sketched diagram as my mind works best with pictures and that should highlight any confusion on my part😏

Hope to escape back to the boat next week for a few days😊

Share this post


Link to post
Share on other sites

One other thing.  Start by setting the water pump big end to top dead centre.  That gives you the maximum space to move the piston etc downwards.

N

Share this post


Link to post
Share on other sites
20 minutes ago, BEngo said:

One other thing.  Start by setting the water pump big end to top dead centre.  That gives you the maximum space to move the piston etc downwards.

N

Ta. That makes good sense .

Share this post


Link to post
Share on other sites

Hydraulic seals are generally polyurethane.....I would suggest you change to a material which can use water as a lubricant........natural rubber is one,and I have no doubt a seal specialist could recommend others more modern.....Although some seals using teflon sinters and the like are kinda spendy.

  • Greenie 1

Share this post


Link to post
Share on other sites
7 hours ago, john.k said:

Hydraulic seals are generally polyurethane.....I would suggest you change to a material which can use water as a lubricant........natural rubber is one,and I have no doubt a seal specialist could recommend others more modern.....Although some seals using teflon sinters and the like are kinda spendy.

Thanks, that’s very helpful to know.

I guess it ties in with the advise from the respected Kelvin engineer who did the work a few years ago, to squirt a little oil around the piston before each use. I have done that, but as the leak rate increased, I would think it got flushed out rather quickly.

I’ll do some detective work.

Share this post


Link to post
Share on other sites

I would guess the solution lies in a teflon filled polymer seal,as the teflon deposits on the metal surface and provides a run dry lubrication........For an economical teflon seal,Ive found the ones made of thin (002/003) teflon sheet cut into "washers" and stacked into a seal the required thickness.Needs to be clamped in the housing tho,something like a gland nut,but not further adjustable after being set tight.

Share this post


Link to post
Share on other sites
19 minutes ago, john.k said:

I would guess the solution lies in a teflon filled polymer seal,as the teflon deposits on the metal surface and provides a run dry lubrication........For an economical teflon seal,Ive found the ones made of thin (002/003) teflon sheet cut into "washers" and stacked into a seal the required thickness.Needs to be clamped in the housing tho,something like a gland nut,but not further adjustable after being set tight.

Thanks for the suggestion - definitely thinking outside the box😏

Unfortunately, my practical skills would probably stretched a tad too far.

Once I manage to get the pump dismantled I’ll have a better idea of the problem.

I guess It’s possible that the chrome plating may have played a part in the deterioration?

I’ll update the post with what I find.

Share this post


Link to post
Share on other sites

Hardchrome is a good surface for a seal,your problem is probably the seal starting dry ,then running wet.......Natural rubber likes water as a lubricant, even one dry stroke will tear it, oil will ruin it........this is why some suitable polymer is needed,to provide that initial lubrication when dry....Another idea might be MoS2 filled plastic,but I would look at the thin sheet idea..........I fitted these to piston valves used to controll the flow of yucky stuff in a dog food factory.......the liquid was very corrosive and erosive,and despite the hard stainless of the valve failing,the seal stack was still working without leakage,or apparent wear...........Another idea is to modify the gland to include a lubricant sump,use UHMWPE as a seal,and silicone seal lube from Graco .A I litre bottle should last years.

Share this post


Link to post
Share on other sites

I also see that your hydraulic seal has a quad ring packing in the section......this is to provide sufficient force to seal oil at pressure.......this is contributing to the wear.......the ring should just come out of the seal,its normally a loose piece,with maybe a dab of sticky to keep it in.

Share this post


Link to post
Share on other sites
5 hours ago, john.k said:

Hardchrome is a good surface for a seal,your problem is probably the seal starting dry ,then running wet.......Natural rubber likes water as a lubricant, even one dry stroke will tear it, oil will ruin it........this is why some suitable polymer is needed,to provide that initial lubrication when dry....Another idea might be MoS2 filled plastic,but I would look at the thin sheet idea..........I fitted these to piston valves used to controll the flow of yucky stuff in a dog food factory.......the liquid was very corrosive and erosive,and despite the hard stainless of the valve failing,the seal stack was still working without leakage,or apparent wear...........Another idea is to modify the gland to include a lubricant sump,use UHMWPE as a seal,and silicone seal lube from Graco .A I litre bottle should last years.

Thanks again, you have certainly given me some ideas to think about.

Incidentally, when I googled Graco here in the UK I initially found a company that manufactures baby strollers😏

Persevering I found https://www.graco.com/gb/en.html - I’m guessing that’s the company you are referring to?

 

 

5 hours ago, john.k said:

I also see that your hydraulic seal has a quad ring packing in the section......this is to provide sufficient force to seal oil at pressure.......this is contributing to the wear.......the ring should just come out of the seal,its normally a loose piece,with maybe a dab of sticky to keep it in.

My spare seals are on the boat - I’ll take a closer look at them on my next visit, perhaps next week.

Share this post


Link to post
Share on other sites
On 04/11/2019 at 20:42, BEngo said:

Turn off the water to the pump if you can.  If not drain down or it will nearly all run out anyway when you take the piston out.

Slacken the gland follower a ........................

Update:

By following BEngo’s advice carefully, the dismantling was straight forward once the ram was persuaded downwards a few more mm by reappropriating my bamboo fuel measuring stick😏

 

It turned out that the hyd seal has been supplemented by a single ring of packing above it.

As previously mentioned, a mod prior to my ownership has restricted the number of rings of packing that can be fitted whilst still leaving enough thread for the gland to engage with the pump body. 

 

Visually, there seems to be significant wear to the chromed ram, with two distinct areas seen.

The coarser lower 1/3 being swept by just by the lower lip of the hyd seal and the more polished upper 2/3 swept by ether both seals or just the packing.

Surprisingly, the deepest measurable wear depth is just below the top line at about 0.1mm (0.2 off the diameter) compared to the nominal 44mm diameter just above this line.

The wear is somewhat less in the lowest segments, so it seems that the lip of the hyd seal has caused the most scratching and the packing has caused the highest wear. Of course, this ignores the depth of the scratches and lateral forces from the pump rod.

Three slight ridges can be felt; however the wear has not exceeded the thickness of the chrome plating.

 

If necessary, I’m now happy to service the pump each year, so I’m considering ditching the hyd. seal and reverting to the previous option of two packing rings.

 

I’d be grateful for any suggestions or observations; however I would prefer to avoid an alternative type of pump.


 

Thanks.

 

2_ram.jpg

3_wear.jpg

4_ram with seals.jpg

5_hyd_seal_top.jpg

6_hyd_seal_bottom.jpg

7_gland.jpg

Edited by gbclive

Share this post


Link to post
Share on other sites

Theoretically at lest you should be able to use an O-ring seal  but that would mean a different follower.  Practically, I did try one,  with good results for about 12 months, but once it failed it was pissing out water, where a packed item fails gracefully.

Two woven packing rings is all there now is in mine.  Forget exactly what, but I bought a 50 m box from Walkers and expect it to see me out! Last time I changed it was ages ago.

 

If you wanted space for another ring of packing you would need to modify the pump, not the follower.  Not something I would contemplate.

 

Might be worth considering a grease nipple on the follower with an outlet hole positioned to lubricate the packing? Bet the nipple would end up where grease gun access was impossible.  I would also worry about grease getting in the coolant.

 

N

 

 

Share this post


Link to post
Share on other sites
13 hours ago, BEngo said:

Theoretically at lest you should be able to use an O-ring seal  but that would mean a different follower.  Practically, I did try one,  with good results for about 12 months, but once it failed it was pissing out water, where a packed item fails gracefully.

Two woven packing rings is all there now is in mine.  Forget exactly what, but I bought a 50 m box from Walkers and expect it to see me out! Last time I changed it was ages ago.

 

If you wanted space for another ring of packing you would need to modify the pump, not the follower.  Not something I would contemplate.

 

Might be worth considering a grease nipple on the follower with an outlet hole positioned to lubricate the packing? Bet the nipple would end up where grease gun access was impossible.  I would also worry about grease getting in the coolant.

 

N

 

 

Thanks Nigel, I’ve decided to keep things simple and revert to two rings of 3/8 or 10mm packing, renewing them as required.

You mentioned woven packing rings, but looking at the Walkers website, I was a bit overwhelmed by the huge and varied range on offer.

After some further googling, I believe Graphite is best avoided as It may cause galvanic corrosion?

 

So that seems to leave PTFE, glass fibre, cotton or flax for the basic thread.

And then a choice of PTFE, or PTFE and mineral oil for the lubrication.

 

Any thoughts on what would be best, or indeed which, if any, to avoid.

Sorry if I’m over thinking this😏

Share this post


Link to post
Share on other sites

Certainly would not go for graphite.  Filthy stuff!  Nor glass fibre.  Too hard and may cause rapid wear if/when not well lubricated.  Cotton probably  is softer than flax, but with a chrome finish on the ram that will probably not make much difference. PTFE will self lubricate  but is probably more costly. 

 

PTFE for lubrication.

 

The important thing is to check the chosen packing is OK with a  sliding seal - some packings  are designed only for rotating seals  and then  have to be fitted the right way.

I am sure Walkers will make a reccomend if you give them the details of the application. Remember to tell them it will be in intermittent use with longish idle spells.

N

Share this post


Link to post
Share on other sites
1 hour ago, BEngo said:

Certainly would not go for graphite.  Filthy stuff!  Nor glass fibre.  Too hard and may cause rapid wear if/when not well lubricated.  Cotton probably  is softer than flax, but with a chrome finish on the ram that will probably not make much difference. PTFE will self lubricate  but is probably more costly. 

 

PTFE for lubrication.

 

The important thing is to check the chosen packing is OK with a  sliding seal - some packings  are designed only for rotating seals  and then  have to be fitted the right way.

I am sure Walkers will make a reccomend if you give them the details of the application. Remember to tell them it will be in intermittent use with longish idle spells.

N

Great information - thank you.

So probably go for cotton with PTFE.

Re contacting Walker, they will probably need the materials of the body, gland and ram - bronze or brass (in addition to the chrome)?

Also pressure involved - low, but care to hazard a guess😏?

Sorry for so many questions!

 

 

Edited by gbclive
Max ram velocity now sorted - 0.75mph

Share this post


Link to post
Share on other sites

Bronze ram as built,  I think.  Bronze body.

Max static head will be the vertical distance from the base of the pump housing to the top of your header tank. Max dynamic head is not going to be a lot more- I would guess about 10ft or so.  You might be able to measure it with a (BIG) manometer🙂

N

Share this post


Link to post
Share on other sites
4 hours ago, BEngo said:

Bronze ram as built,  I think.  Bronze body.

Max static head will be the vertical distance from the base of the pump housing to the top of your header tank. Max dynamic head is not going to be a lot more- I would guess about 10ft or so.  You might be able to measure it with a (BIG) manometer🙂

N

Thanks, the static is about 7’ so about 17’ total should be OK.

I’m going to mention that minimising further wear is a priority.

I’ll report back with their recommendation.

Share this post


Link to post
Share on other sites

Update.

Unfortunately, James Walker could not spare the resources to give me any advise (which I sort of get), but referred me to their online compression packing charts and a couple of their dealers, however 8m was the minimum order.

So I bought a meter of cotton flax packing with Teflon (PTFE) lubricant off eBay for £12.

Two 10mm rings skive cut and fitted (all there is room for).

So a further questions please:

Is it best to add some stern gland grease to help ease the ram into place and also to minimise initial wear?

Thanks.

 

Share this post


Link to post
Share on other sites

Yes provided it is not going to attack the ptfe.  I usually use grease or tallow but I don't have ptfe lubricated packing.   Rub some grease into a short spare bit of packing  and leave overnight.  If nowt has happened I expect all will be well.  The coolant will soon dissolve stern tube grease when in action.

 

  Getting the ram into the packing can be quite   difficult.  I usually put the ram into one ring then remove the ram, leaving the packing in place and add the second ring  ( joint opposite the first) then put the ram in again and fit the follower and adjust.  

N

Share this post


Link to post
Share on other sites

Thanks Nigel.

The packing is actually sold as stern gland packing, so I reasoned it would normally have to cope with grease.

I also searched on line for any mention of either cotton flax or PTFE being incompatible with grease, but found none.

But I like a belt and braces approach to these things, so I’ll test an off cut over night as you suggest.

 

Incidentally, I proceeded as you have suggested and found that with just one ring, quite a lot of pressure and gentle wriggling was needed to ease the ram past that ring. The PTFE feels very slightly tacky rather than slippery, which surprised me.

Based on that I held back from installing the ram a second time past both rings, as I thought it needed some grease, but wanted to check first.

Cheers.


 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.