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MG MGA - Stripped water pump bolt thread

One of the bolts securing the water pump on the engine in my car is stripped. It is the thread in the block that stripped. It is the one under the pump. Close examination reveals a small pin hole allowing water from the pump chamber to penetrate the bolt hole and over time has corroded the thread.
I will clean the thread up with a 5/16 unf tap tomorrow and apply some thread sealant but I fear that I may have to drill it out and instal,a thread insert. It is not something I relish doing as there is only about 1/8 of an inch of metal to work with. If the casting was to crack then I imagine the engine is toast

Has anyone ever confronted this in the past? Iam open to good ideas.
Thread inserts are not cheap as you usually have to buy a whole kit with way more than you need. I happen to have some 5/16 coarse thread inserts and could use one of them. Does anyone know if a fine thread insert would make a significant difference.

Brendan Sullivan

I would try to re-thread the block with the next size tap of ANY system and install the pump with one odd-ball bolt. Installing a threaded insert will work, but you'll still be threading the block to accept it. Either way, you're threading it.

Go slow and remember the pump has 3 other fasteners and we have lots of gasket goop, so.....

If you are short of metal, can you drill and re-tap the hole for 3/8 UNF? Helicoils need more room I believe
Art Pearse

Mandrus - you beat me by 11 sec!
Art Pearse

Remember, you're not mooring the Queen Mary on that thing. 3 other fasteners can take the lion's share. A nice fluffy gasket with some sealant will do the rest.

Install a Heli-Coil to get back to original thread size. Use thread sealant on the bolt threads for reassembly to assure it does not leak through the threads in the future. Easy-Peasy

I would not use a helicoil. I would use a solid insert like a time sert. The open coil of a helicoil does not seal as well as the timesert.
A larger bolt would not be my first choice.
A broken flange can be repaired. There are those that can weld the cast iron. Fairly common repair in engines from a wrecking yard. Crash damage can break a bolt hole. They won't throw away a good engine for just a broken hole. They will have it repaired.
R J Brown

This thread was discussed between 17/03/2017 and 18/03/2017

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