Housing Stripped for Bolt Holding Thermostat

[Duffman]

Noticed a coolant leak from the thermostat area and thought the bolt closest to the engine holding the thermostat was loose from vibration, etc, so I tried to tighten it. The bolt "slipped" past the point of tightness and became loose. So, figured the bolt might be stripped, pulled it out looked fine. Replaced it with a new bolt, same thing happened: got to a certain point of tightness then loosened up. Now I am figuring that the housing for the bolt is stripped. Was looking at going to the next size bolt, rebore and rethread the housing.

Anything I should or should not do before I proceed? What is the best way to rethread?

Thanks!

[Bruce Palmer]

Heli-coil

[Arne]

Brand new thermostat housings for '70-72 240Zs (part #11061-P0300) are $22.47 from nissanparts.cc, and list for $29.48 from your local dealer before club discounts (if any).

[Duffman]

Bruce - thanks for the tip. Is there a good source for Heli-coil? Should I go with the repair kit, and rebore and rethread, or is there another kit I should look at?

Arne - the thermostat housing is fine, it is the seat that the bolt holds the housing down that appears to be stripped. Am thinking that I will need to rethread a larger bolt to hold.

[Arne]

Arne - the thermostat housing is fine, it is the seat that the bolt holds the housing down that appears to be stripped. Am thinking that I will need to rethread a larger bolt to hold.

If I'm understanding the problem correctly, the housing is not fine, the housing is the lower part that the t-stat sits in, and it is also the part where the stripped threads reside. (#38 in the attached picture.) Considering the dire consequences of failure in this area, and the low cost of the proper replacement part, I'd replace it rather than attempt to drill it out to a larger size.

[7277]

is it the lower half of the thermostat shell?. the female threads? whatever the case, call danny's datsuns (541-430-1180) for a used one...he'll probably charge you $20 for the thing. as for heli coil...take it to a welder (he'll probably charge you $25) to fill the hole, then redrill/rethread.

[Duffman]

Arne, you are correct, it would be easier and better to have a replacement thermostat housing unit, rather than redrill and rethread.

Thanks!