MG T-ABC

One of my 3 TC XPAG engines has a problem with the water tap fitting on the block. The tap thread in the block has rusted stopping the tap fitting tightly, so it would leak.
My question is to what would you do? The block as we know is very casting and difficult to re-thread, even if new helical coils where to be fitted. The problem is that the thread is 1/8" bsp so hard to find ... so again, what would you do ... or even have done yourself to get a decent solution to this? cheers Chris (TC1472, TC2686 & TC4245 + D0407)

You should be able to get a good seal with a fiber washer. If the surface of the casting is too rough, a bit of sealer under the washer should do the trick. Since there is no pressure in the cooling system, it shouldn't take much to keep the water in.

ah, not a bad call Steve but there are few threads in the block to keep the tap in when i attempt to fasten, not even tight!

I wonder if you cleaned the threads well and fill with something like JB Weld and then tap threads into that. I would think it might be strong enough. Of maybe there's a better product. I remember seeing an aluminum-based product once that could be used that way. Maybe someone else has a better idea. Otherwise you could go this route:

https://www.threadtoolsupply.com/18-28- ... r-kit.html

or in the UK...

https://www.recoilshop.net/shop-recoil/ ... 8-kit.html

I've bought BSP Helicoil-brand thread inserts, which would really be your best long-term solution.

For the short term you could try some Teflon tape to seal what threads are left.

Tom Lange
MGT Repair

Clean the threads as best you can, degrease and use good amount of JB Weld as sealant on the threads, let dry for a day or two and refill cooling system, but that seals it up.

Cast iron is easy to thread just don't use any cutting fluid as it is self lubricating. Always use high speed steel taps (HSS) never the cheaper carbon steel (or snap-on) as they are just not sharp enough. See if you can get a bsp heli-coil for the best repair.