Cooling system

[Peter Arnold]

The coolant seemed to be requiring to be topped up rather more often than usual and I just assumed it was caused by the hotter weather as summer here is on the way. So I noticed the drain out cock looked a bit grotty and it’s hard to clean and service it while the radiator is in place, so I pulled the radiator out and found that there was nothing wrong with the cock and no radiator leaks. Reinstalled the radiator and refilled with coolant and then noticed a green flood heading towards the garage door. Turns out the thread in the block for the smaller bolt for the coolant inlet had failed so there was only one bolt holding the outlet on. There is enough metal to thread the hole out to 3/8 whitworth but questionable as to how long it might last. My question is how any member who has had this problem has carried out a repair and whether anyone has used the Metalock process as a solution?

[Brian Gibbons]

Hi Peter. Your solution may depend on the condition of the block casting, where your bolt has failed. If the casting around the hole is sound then taking it out to a 3/8 thread is quite successful (and has, in my observation, been done many times). A stainless steel bolt is often used. Exercise care to prevent accidental drilling or tapping into the bore ( I have put a plate behind the hole in past as a precaution). If you block casting is cracked at the hole, then a drilled plate can be purchased from Cherished suppliers to expedite this issue. There is generally not a lot of casting for the metalock process (though others may have another experience). I’m not an expert (just an owner for over 40 years).

[Peter Arnold]

Thank you Brian, I’ll certainly investigate the drilled (and tapped?) plate. That was a solution that had not occurred to me.

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Just checked out the plate on A7c and it looks like an excellent way to go. Thanks again.

[WILLIAM MCKENZIE]

Hi Peter
Austin repro tel 01202 625242 can supply new repair kit to sort out your side water issue
regards
Willie

[Robert Leigh]

Depending how bad the corrosion is you may be able to use a standard 5/16" BSF stud by fitting a suitable helicoil.  It is best to Loctite it in place. I prefer to use a stud than a bolt to keep future disturbance of your thread repair to a minimum. I always use a stainless steel stud and a stainless or brass dome headed nut with a fibre washer. This should eliminate any leakage along the thread.

[Graham Barker]

Hi Peter. Your solution may depend on the condition of the block casting, where your bolt has failed. If the casting around the hole is sound then taking it out to a 3/8 thread is quite successful (and has, in my observation, been done many times). A stainless steel bolt is often used. Exercise care to prevent accidental drilling or tapping into the bore ( I have put a plate behind the hole in past as a precaution). If you block casting is cracked at the hole, then a drilled plate can be purchased from Cherished suppliers to expedite this issue. There is generally not a lot of casting for the metalock process (though others may have another experience). I’m not an expert (just an owner for over 40 years).

My Ruby had a hole in the cylinder wall immediately adjacent to the water intake stud. So accidental drilling into the bore really does happen. 
Fortunately the hole was smaller than stud diameter. I suspect it was caused by drilling into a broken stud to insert an "easy-out" to remove the stud. Amazingly there was a similar size hole in the piston ring adjacent to the hole in the cylinder wall.
The engine was still able to run quite well because the guilty mechanic had filled the hole in the cylinder wall with plastic metal! The hole was sufficiently down in the bore to avoid being subject to full combustion pressure. 
Of course, when I overhauled the engine, I scrapped that block.