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Welsh Plugs
https://ausmini.com/forums/viewtopic.php?f=5&t=29675		 Page 1 of 2
Author:  Sprite_Man [ Mon Mar 26, 2007 11:21 am ]
Post subject:  Welsh Plugs
I have just had my second welsh plug pop out. What is the reason for this? The car wasn't overheating, oil presure was normal, and not revving too hard. This is the second time the same plug has popped out. The block isn't damaged. What is the cause? Please help.
Author:  Lillee [ Mon Mar 26, 2007 12:15 pm ]
Post subject: 
Are you sure you have the right cap on the radiator?
Author:  drmini in aust [ Mon Mar 26, 2007 12:33 pm ]
Post subject: 
Lillee wrote:
Are you sure you have the right cap on the radiator?

.. common prob, as pristic found the other day.
There are 2 common Mini radiator necks, the Oz one and the shorter UK one. However, many other cars have a longer neck still and if you use too long a cap, the valve cannot open when it hits 13psi.
Then..
1. welch plugs can pop, and or
2. radiator hoses can pop.
Author:  peter1 [ Mon Mar 26, 2007 5:59 pm ]
Post subject: 
When I rebuilt the motor of the MGA it didn't take long to have 2 welch plugs depart the scene, the 2nd one at night on a lonely country road (but I was carrying a spare, having learnt my lesson the 1st time, and a local farmer had some loctite - all fixed in a few minutes!), and it turned out to be the size of the welch plug - metric sizes had been used in the imperial block, and they were ever so slightly undersize and hadn't seated properly when tapped in the middle. I later found out that this was a problem others had encountered too.
Don't know if anymore popped out later - it was fine for a few more months before the car was sold.
Anyway just a thought........
Peter :)
Author:  Wombat [ Tue Mar 27, 2007 8:45 am ]
Post subject: 
KC says in Mini Expert that the seats have to be completely free of rust and smooth and use a sealing compound in there as well.
Author:  gafmo [ Tue Mar 27, 2007 8:21 pm ]
Post subject: 
Must be the Problem for the week it seams...they are poppin out every where :?
Author:  matt van'74 [ Tue Mar 27, 2007 10:29 pm ]
Post subject: 
Use Stag as a sealant between the Welsh Plug and the block - It works really well but it is a bit messy.

Also everything else that has been said above :wink:

Matt
Author:  Drekkus [ Wed Mar 28, 2007 7:44 pm ]
Post subject: 
drmini in aust wrote:
Lillee wrote:
Are you sure you have the right cap on the radiator?

.. common prob, as pristic found the other day.
There are 2 common Mini radiator necks, the Oz one and the shorter UK one. However, many other cars have a longer neck still and if you use too long a cap, the valve cannot open when it hits 13psi.
Then..
1. welch plugs can pop, and or
2. radiator hoses can pop.


No 2 is what happened to me, though there seemed to be some leakage around one of the welch plugs as well.Cost me a head gasket and a tow.
Author:  Sprite_Man [ Thu Mar 29, 2007 8:11 am ]
Post subject:  thanks
Thanks for all the help with welsh (welsch) plugs. I thought it was a very un-common occurance for them it pop :oops: , so thanks for the help.
Should be back on the road real soon. :D
Author:  Besser [ Mon Apr 02, 2007 8:55 am ]
Post subject:  tap tap
When I was rebuilding engines (as a job), we always were critical of Welsh plugs.

1: Clean surface of seat (a wire brush on a die grinder works great)
2: Clean welsh plug edge (thinners)
3: Apply epoxy glue on seating surface (some glues soften with heat!)
4: a: On disc welsh plugs fit with the dome out and as it hits the seat step, use a socket (or better the end of a flat bar) 1/2 the diameter of the plug and a hammer to splay the plug out. I have seen plugs people have used a ballpean hammer to splay and they are the ones that fall out.
b: On bucket welsh plugs I would always lay them on a bench and tap the centre slightly flat. This splayed the OD slightly and made for a tight fit (dont tap to much or it wont go in). then use the biggest socket the fits into the plug to drive it in.
5: Wipe off excess glue.

PS: Do not stake the plug once in as it will be the last time you get a good seal if you do.

Problem solved
Author:  peter1 [ Wed Apr 04, 2007 11:37 am ]
Post subject: 
On the 1275 Cooper S are they cup or dome welch plugs? And what size? (Are all 4 the same?)
(I haven't got access to my motor at the moment to physically check, and need to order some, hence the silly question sorry).
Peter. :)
Author:  drmini in aust [ Wed Apr 04, 2007 7:18 pm ]
Post subject: 
Cooper S and 1100S are both cup type, but different sizes.
They give less trouble, IMO.
Author:  peter1 [ Wed Apr 04, 2007 7:40 pm ]
Post subject: 
Thanks Doc. Do you know what size they are?
Author:  drmini in aust [ Wed Apr 04, 2007 8:41 pm ]
Post subject: 
Cooper S 1.625", 1100S/LS1275 etc- 1.3125". :wink:
Author:  peter1 [ Wed Apr 04, 2007 9:10 pm ]
Post subject: 
Thanks mate, you're a legend 8)
Peter :)
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