The temp gauge on my '93 940T is red lining. I observed coolant escaping through the joint between the top driver side corner of the radiator and the hose. I was hoping to find a rupture there to solve problem. But upon inspection, both that radiator section and hose look fine. I'm wondering if the boiling coolant just found that weakest point to escape? ​​​​Does the Volvo thermostat fail closed or open? Any other ideas? Water pump replacement was recent but not too recent. Thank you.

 

only time I've had a thermostat fail it created a boil over. Given the part is $15, I'd suggest you simply replace. I'd also do the engine coolant temp sensor, a system flush (since its quite possible your radiator has some clogging) and the coolant overflow reservoir cap (that's your "safety" and will pop if you boil over. This would also be a good time to replace any suspect hoses - particularly if they are original. Hoses should not be the weak link but you can do a system pressure test to see what the hot pressure is running.

 

Once the engine cooled down, I was able to do a more careful inspection. The radiator is indeed ruptured at this point. Ugh. A new radiator I guess. I'll also replace hoses, and thermostat, and cap, and do a proper flush.

 

been there :-( kind of a PITA but once done your cooling system will be good for many years to come (ok sure, now that I've said that, your heater core and/or O rings are next!). PS - when you do the flush just use regular water (demineralized etc can be found at Walmart for like $1 a gallon) then use a standard 50/50 "green" anti-freeze.

 

Thanks. I guess the Nissen is the only readily available radiator these days. I hope it holds out.

 

see if FCP or IPD sell a radiator kit (ie radiator, hoses, clamps, coolant etc) specific to your model.