Water inlet/thermostat housing stud - broken casting

[Steve127]

Hello, everyone. This is my first post. My son has a 1986 Toyota Tercel SR5 wagon for which I am the chief (amateur) mechanic.

I'm currently renewing the cooling system (radiator, water pump, thermostat, hoses, fasteners) amid lots of rust and oil. While re-installing the water inlet housing and thermostat, I over-torqued one of the two nut-stud combinations that hold the housing to the engine. The aluminum casting around the stud cracked and broke (see photos).

What's the fix here? I can't tell if the aluminum casting into which the studs are mounted is part of the head, part of the engine block, or a separate removable part. I saw an older thread where a newbie like me did the same thing but I'm unclear on how to proceed.

ANY advice would be most appreciated. Thank you.

Steve

[dlb]

That is part of the water pump housing assembly so the whole thing can by removed fairly easily. You will need to remove the timing belt cover and the bolts fastening the water pump to the block. There is also a 12 mm (I think) bolt under the exhaust manifold toward the rear of the engine, this fastens the tube that runs coolant to the heater core. That bolt is a little tricky to find but if you feel under there for it, then take some pictures with your phone to give a clearer idea of things under there, you shouldn't have too much problem with it. That's what I did recently anyway. With some careful maneuvering you can remove the whole unit out the front but it's easier if the radiator is out. Oh I just noticed your car has AC, that might complicate getting it out of there but it should still be do-able. Then you just need to find a new water pump housing assembly. Try car-part.com or call a local wrecker. Remember to replace the o-ring that goes between the back of the water pump housing and the block.

It's possible that stud/casting on your car was already damaged but FYI (in case you don't know due to being an amateur mechanic), small nuts and bolts don't require much torque. Only use small wrenches and ratchets on them, it will help prevent over-torquing them. I made the same mistake early on and broke studs off a with a few 10 and 12 mm nuts. Save the big torquing for bigger bolts, like 17 mm and up.

[Steve127]

Thank you, dlb! This is exactly what I needed to know. I will look for that bolt under the manifold.

And thank you for the advice on torquing small bolts. Lesson definitely learned.

I'll post my progress.

[dlb]

No sweat, happy to help.

I just thought of another piece of advice. When I did the same job recently, I installed the thermostat and its housing while the whole assembly was out of the car. It's kind of tricky to get it in place normally so this was a way to avoid that. Good luck!