View Full Version : TR4/4A Hole at Bottom of Threaded Stud Hole in Block

06-23-2019, 02:06 PM
I've been prepping block to reinstall the cylinder head on my TR4A and noticed this hole at the bottom of the right front threaded stud hole that goes through to the threads in the block for one of the water pump bolts.

My main question:

Is it fixable?

It does not appear to be going further into the water passages just where the bottom of the stud hole and the bolt threads meet. I'll investigate that further, but would welding in new material and a helicoil be a reasonable approach?

The head has been off before. I don't think the rest of the engine has ever been touched. I was going to leave that for another day, but I'm thinking the engine needs to come out and do everything right, including fixing this hopefully or getting a new block, but I would like to hear if anyone has specifically dealt with this before.

Thanks in advance. I have not been on in a while so I appreciate everyone's consideration.


Frank Canale
06-24-2019, 12:37 AM
This is just a thought for consideration. you can make a headless slotted set screw. Get a bolt that is the correct thread. Grind the end of the bolt to match the drill bit angle so the end of the bolt matches the bottom of the hole.thread the bolt into a nut 2 -3 threads and cut the end of the bolt off. With a dremel, cut a slot on the cut end , then use a screwdriver to remove the set screw. Use a q tip to swab a small amount of red stud and bearing loc-tite to the bottom of the hole before installing the setscrew. no chance of damage from welding, no shavings from the helicoil installation. Frank

06-24-2019, 09:22 AM
Im having a difficult time viewing your pictures, but it almost looks like a helicoil has been installed in that hole. The bolt/stud at the bottom with the mark in the center is from where?

06-24-2019, 11:34 AM

Thank you for the replies. I've attached an explanation of the layout. I hope that helps. Another way to explain this is that if I spray WD40 into the cylinder stud hole, it comes out the water pump bolt hole. The hole is not supposed to be there, right?

I talked to the machinist and he thought sealant and the correct hardware would be okay for a fix if I did not want to go further with the engine.

Thanks again!

06-24-2019, 04:17 PM
Well that clears everything up! Clean out the holes and seal them with your favorite goop. I like Permatex Ultra Gray for applications like this. If you are using ARP cyl head studs you may have to clean them really well and install them a little more snug than finger tight. The hole for the water pump is actually for the water pump housing?

06-24-2019, 08:27 PM
Thanks, Rut!
Yes, the bolt hole is for the water pump. I do have the ARP studs and am working on my cleaning method.
All the best,

06-25-2019, 07:13 AM
Yes I do not see the hole being under much pressure, so yes seal it up that should do it. It would probably rust itself closed after time.