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gbclive

J2 water pump top bearing

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Whilst planning my next job of replacing the modified water pump hydraulic seal on our J2, I photographed the whole water pump assembly, including the difficult to see components and discovered something odd about the top bearing of the water pump rod upper end.

 

My parts list shows the rod cap with its thimble mini reservoir, should be secured with two bolts inserted from below, with two nuts above secured with locking wire.

I discovered that mine only has two bolts inserted from above - that’s it, with the threaded end of the bolts visible protruding below and no obvious indication that nuts have ever been fitted.

I tried a socket on the two bolts and thankfully they seem tight.

 

The engine is a 1948 build and had a professional partial rebuild about 4 years ago and this included removal of the water pump for modification of the ram and seal. It’s done about 1,500 hours since then.

 

What am I missing?

Is this normal on some engines?

 

I’ll attach some photos and would really appreciate your thoughts or explanations.

Thanks.

96C66255-0E9E-4175-89E2-5BE7ADE02CA7.jpeg

D12BE38A-13C0-486F-AB2F-607B0A049648.jpeg

9EEDCB31-018A-4155-8C89-9B001800BE2C.jpeg

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The drawing refers to a bolt - If the term has been used correctly then the con-rod would not have threads in it.

What you have is a machine screw and for whatever reason the nuts and locking wire are not there.

The face on the con-rod has not been machined to allow the washers under the nuts to sit sit correctly.

Also is there enough clearance between the curved part of the rod and the M.screw to clear the flanks of the nut so it sits without cutting into the rod.

From your photo there does not appear to be the locking wire holes in the machine screws.

 

 

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1 hour ago, barry adams said:

The drawing refers to a bolt - If the term has been used correctly then the con-rod would not have threads in it.

What you have is a machine screw and for whatever reason the nuts and locking wire are not there.

The face on the con-rod has not been machined to allow the washers under the nuts to sit sit correctly.

Also is there enough clearance between the curved part of the rod and the M.screw to clear the flanks of the nut so it sits without cutting into the rod.

From your photo there does not appear to be the locking wire holes in the machine screws.

 

 

Thanks Barry, that all makes sense.

 

Re your question concerning sufficient clearance between the curved part of the rod and the M.screw to clear the flanks of the nut so it sits without cutting into the rod - I’m not certain, but perhaps not?

 

Hopefully, comparison with other J engines.will shed some light on this. 

Edited by gbclive
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Probably the angle (and no self respecting engineer would do it) but those look like they could be different threads.  If you are stripping it, make a note of their place, until you can compare.

 

 

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10 minutes ago, NB Esk said:

Probably the angle (and no self respecting engineer would do it) but those look like they could be different threads.  If you are stripping it, make a note of their place, until you can compare.

 

 

Thanks John, when you say “different threads”, do you mean that the threads of the two machine screws might be different from each other?

If so, the photos are close up wide angle views, so unfortunately there is quite a bit of visual distortion.

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1 minute ago, gbclive said:

Thanks John, when you say “different threads”, do you mean that the threads of the two machine screws might be different from each other?

If so, the photos are close up wide angle views, so unfortunately there is quite a bit of visual distortion.

 

Yes, most likely not but the furthest one looks coarser than the nearer one.  When you have them out, just hold the threaded parts against each other.  Good luck with the repairs...

 

 

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30 minutes ago, NB Esk said:

 

Yes, most likely not but the furthest one looks coarser than the nearer one.  When you have them out, just hold the threaded parts against each other.  Good luck with the repairs...

 

 

Thanks John, will do.

  • Greenie 1

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I agree with Barry, your water pump can never have been built in accordance with that engineering drawing as there are no flats machined onto the con rod to mate with the bolt heads as shown on the drawing. 

 

Therefore the holes must have been tapped and threaded from new. The might have had studs fitted as per many engine con rods originally, or the bolt-from-the-top arrangement might have just been the factory shop floor staff doing it their quicker way as often happens, and ignoring the drawing. Possibly they ran out of cross-drilled studs the day they built yours....

 

 

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31 minutes ago, Mike the Boilerman said:

I agree with Barry, your water pump can never have been built in accordance with that engineering drawing as there are no flats machined onto the con rod to mate with the bolt heads as shown on the drawing. 

 

Therefore the holes must have been tapped and threaded from new. The might have had studs fitted as per many engine con rods originally, or the bolt-from-the-top arrangement might have just been the factory shop floor staff doing it their quicker way as often happens, and ignoring the drawing. Possibly they ran out of cross-drilled studs the day they built yours....

Thanks Mike, I can see what you mean - so probably a non-problem except for the slight chance of the machine screws working loose?

I like non-problems😏

 

So now I can get on with my next post which will concern replacing the water pump hydraulic seal as the existing one is leaking progressively worse, after about four years use since the ram was machined, then chrome plated back to size and the packing replaced with a hydraulic seal.

A tiddly job for the engineers here, but I am only just above “rank amateur” level, so appreciate some hand holding😏

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My 1946 J2 water pump rod end is the pretty much the same as yours.  I have seen others like this.  The vertical space available on a J is less than on a K, so it is a much easier arrangement than nuts and bolts and washers etc.

 

The drawings in the model J spares list were "borrowed" from the model K spares list (saved a lot of time/money in depressed 1932) so do not always show the exact item on the J.

 

N

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31 minutes ago, BEngo said:

My 1946 J2 water pump rod end is the pretty much the same as yours.  I have seen others like this.  The vertical space available on a J is less than on a K, so it is a much easier arrangement than nuts and bolts and washers etc.

 

The drawings in the model J spares list were "borrowed" from the model K spares list (saved a lot of time/money in depressed 1932) so do not always show the exact item on the J.

 

N

Thanks Nigel - my angst level has dropped considerably.

I’ll bear that in mind in future - interesting historical context.

 

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You could always put some Loctite or similar on the screws when you reassemble, though mine have not yet come loose in 30 years use.

(Famous last words maybe!).

 

N

 

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19 minutes ago, BEngo said:

You could always put some Loctite or similar on the screws when you reassemble, though mine have not yet come loose in 30 years use.

(Famous last words maybe!).

 

N

 

Thanks Nigel - I’ve just happen to have recently bought some Loctite 243 which is Medium Strength and oil tolerant, which I guess should suffice.

 

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27 minutes ago, BEngo said:

You could always put some Loctite or similar on the screws when you reassemble, though mine have not yet come loose in 30 years use.

(Famous last words maybe!).

 

N

 

 

I was wondering about that. Did they have Locketite back in the days when Kelvin made that water pump con rod?

 

I can't say I ever have problems with bolts ever coming loose once done up suitably tight though. Studs however tend to be loose in the thread when not under tension.

 

 

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28 minutes ago, Mike the Boilerman said:

 

I was wondering about that. Did they have Locketite back in the days when Kelvin made that water pump con rod?

 

I can't say I ever have problems with bolts ever coming loose once done up suitably tight though. Studs however tend to be loose in the thread when not under tension.

 

 

 Split pins, lock nuts, locking wire, locking tabs and a few other techniques, but no anaerobic stuff AFAIK.

No namby -pamby torque wrenches either. "The cylinder head bolts should be dead tight" and a reliance on a skilled man to know how many white knuckles were needed.

N

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5 minutes ago, BEngo said:

 Split pins, lock nuts, locking wire, locking tabs and a few other techniques, but no anaerobic stuff AFAIK.

No namby -pamby torque wrenches either. "The cylinder head bolts should be dead tight" and a reliance on a skilled man to know how many white knuckles were needed.

N

 

I remember as a teenager discussing how tight to tighten cylinder head bolts on our cars, none of us being rich enough to afford a torque wrench. 

 

General opinion was the correct amount was tighten them until the thread strips, then back off 1/8 of a turn. 

 

 

Edited by Mike the Boilerman

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During my days as an apprentice there were three commonly used torque settings : half a grunt, a grunt and a grunt and a half.  

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