Stripping out the threading on water pump

[Phildor]

I'm trying to reattach the thermostat housing to the water pump on my 84. Each time I try to thread the bolts that run through the housing into the pump, they begin to tighten before snapping into free rotation and, as I can see upon removing them, taking the threading of the water pump with them.

I don't understand what has caused the aluminum to weaken or what I should do about this. I didn't remove the water pump as part of my original project, doing the cylinder heads. Any advice or input would be helpful. Thanks.
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'84 Vanagon GL 4-speed

[IdahoDoug]

I don't know what others will suggest, but I would personally take the bolt to a machine shop and come home with a thread cleaning tool. Some call it a thread chaser and there are other names. It's intended to clean existing threads, not cut new ones so it's fairly easy to use.

DougM
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Two fully locked 80 Series LandCruisers. 2013 Subaru Impreza boxer. 1990 Audi 90 Quattro 20V

[rubbachicken]

if you have enough aluminum to tap the thread deeper into, then do it that way, other than that you will need to use a thread insert like a helicoil, or if you can find someone to do it, a wurth, timesert, they are the best i've used
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lucy our westy

lucy's BIG adventure

lucy is 1985, with 2.1 Digifant, 4 speed manual

nesting in socal

[Phildor]

I'm going to run a tap through both spots.

Thanks for the input, guys.
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'84 Vanagon GL 4-speed

[70coupyel]

Get a bottom tap. Or grind off some of the lead on a standard tap to get full threads deeper into the hole.
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