Need some advice on welsh plugs please.

[Luigi_S]

Just recently rebuilt the engine in my daily, an Opel Kadett 200iS.

Replaced the welsh plugs with shellac as a sealant as a matter of course and they were leaking quite badly. Turns out the welsh plugs I bought were slightly under the 34mm required. I have now bought welsh plugs from another supplier and they are a little over the size, which I am led to believe they should be.

The main issue I have now is that the surface where the welsh plugs go is badly scored on all of them, which I am sure also assisted in the leaking.

What would be the best way to sort this out without stripping the engine again and sending it to the engineers?

I have some Isopon P38 metallic filler which I could use to fill the deep scores, then flat sand the surface smooth and then put the plug in with some shellac again.

I look forward to hearing from you guys.

 

[Gordvisr]

Just recently rebuilt the engine in my daily, an Opel Kadett 200iS.

Replaced the welsh plugs with shellac as a sealant as a matter of course and they were leaking quite badly. Turns out the welsh plugs I bought were slightly under the 34mm required. I have now bought welsh plugs from another supplier and they are a little over the size, which I am led to believe they should be.

The main issue I have now is that the surface where the welsh plugs go is badly scored on all of them, which I am sure also assisted in the leaking.

What would be the best way to sort this out without stripping the engine again and sending it to the engineers?

I have some Isopon P38 metallic filler which I could use to fill the deep scores, then flat sand the surface smooth and then put the plug in with some shellac again.

I look forward to hearing from you guys.

it could work yes but flush the block good after the flat sand before inserting the plugs. but the use of shellac for me is a new one, wont know if it will work.



Here are some links :

http://jeep-xj.info/HowtoWelshPlugs1.htm

http://www.howacarworks.com/cooling-systems/replacing-core-plugs

 

[Luigi_S]

Shellac is old school. It acts as a lubricant when you push them in and then once cured dries hard forming a good solid seal.

 

[Luis Malhou]

When I have encountered this problem, I have used a bit of sandpaper to to clean up the holes, even using a small honing tool used on master cylinders to get them round again. Then apply a thin film of black silicon to the hole and a small amount to the welsh plugs. The welsh plugs must be a very snug fit. If they are slightly oversize you can throw them into a freezer, here I am talking of a slight oversize!

Always use a socket that fits inside the welsh plug to hit them in. The silicon will fill any imperfections and seal the plug, the edges of the plug must end up flush with the block all the way around. Done many welsh plugs and never had them leak again. Shelac is also good, although many people use silicones instead of shelac now. When the silicon is dry use a toothbrush to clean up any silicon, always looks neater than leaving the remnants of the silicon on any work.

 

[Luigi_S]

Sweet, thanks for the input.

I have always done it the way you say, with cleaning it up with a little wet and dry, but have always used shellac. I saw the ones I took out had been done with silicone. Think I might just try that, although I only have grey 999 silicone gasket maker. Should be ok as it's good for up to 343 degrees.

I have never seen a block scored this badly where the plugs are. Then again, the corrosion on this block was something else.