Blakes - replace or can it be saved

DennisF

DennisF

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Hi all, just been carrying out the service on the Blakes seacocks on my 1979 Westerly Berwick. Most were fine, but the outlet seacock from the heads had quite a lot of pitting on one side (See photo). There is also some putting in the body itself in the position where the taper corrosion would be in the closed position. Age of the seacock is unknown - may be original 1979 as the bolts appear to be glassed in.

I’ve never tried lapping by grinding them, but my inexpert feeling was that as the pits are easily felt with a finger and be up to a mm deep it may be too severe to lap in - am I right? Also, the new Blake’s seacocks.now appear to have a different spacing on the bolts and feature an external plate so suspect replacement may not be trivial....

IMG_0129.jpg
 
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Pitting often occurs opposite the inlet/outlet pipe of the seacock. As long as you can get smooth all round concentric circles above and below this area the seacock will do the business.
 
DennisF said:
Yes, I always use Blakes seacock grease. However, can this one be saved?
Click to expand...

Almost certainly. Clean the cone and body, lap in with grinding paste and make sure you have a seal all the way round. A few random pits will not prevent a seal. It will become obvious as you start lapping in.
 
Tranona said:
Almost certainly. Clean the cone and body, lap in with grinding paste and make sure you have a seal all the way round. A few random pits will not prevent a seal. It will become obvious as you start lapping in.
Click to expand...

Thank you Tranona. For clarity, were you able to see the image? I put up 2 links but it appears photobucket is no longer worth using!
 
Can't see image - but can imagine the pitting as it is common on old valves. When you have the cone coated with paste and turn it through 360 you will see whether it is sealing all the way round - even clearer when you apply the grease.
 
Right - have managed to shrink it down to upload directly. Tranona - would this picture alter your opinion?

IMG_0129.jpg
 
DennisF said:
Thank you Tranona. For clarity, were you able to see the image? I put up 2 links but it appears photobucket is no longer worth using!
Click to expand...


I had a glimse before it objected to my ad blocker. I am pretty sure it will be ok, with a fettle.
I think Photobucket is a basket case, Flickr is still ok for me.

Hooray, all is now revealed.
 
I've not tried it myself but, if badly pitted and after a good degreasing I would probably look to an epoxy filler (? metal filler) to fill the pits and improve the cone form. There is hardly any stress on the cone if corectly greased.
 
I rescued one that looked like that, and one not so bad. I my case the cone sat quite high in the body, so I took the whole thing home, took a light skim off the cone in the lathe (awkward setup), then ground the cone into the body really well. I probably only took off 0.2mm, but that removed most of the pitting.
In another case where the pit wasn't so deep, just grinding it fixed it. Start with coarse grinding paste (valve lapping paste), then move to fine to finish. Thorough washing in between.
It was easier doing this will total removal to enable it to worked on at a bench.
 
Thanks all. The consensus seems to be that it worth trying some grinding paste before springing for a new seacock so I will give that a go. To be fair the seacock hasn’t leaked, but it did worry me when I saw the state of it!
 
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