The last few weeks have been iritating, seized an oil pump but caught it before any engine damage & while the T gauge didn't show any overheating the car pissed a lot of coolant out the overflow tube from the expansion tank. While replacing the oil pump and inspecting everything I put in a new 195F t-stat.

Got the car back on the road last Saturday, which was a cool day, so I dialed the temp control to H and got a strong antifreeze smell and steam coming in thru the defroster vent and drips in passenger floor. Quick guess is the heater core is shot and maybe the bypass valve (if I have one sense I haven't seen it yet) too. Interestingly when I dialed the control back to C it kept leaking and steaming into the cockpit. I boiled the old Tstat last night and it never opened which gave me confidence that this was my original cooling problem and age got the heater core. Today I bypassed the heater core with a simple loop to get a quick driver fix and went for a short drive after topping off the coolant. Everything seemed to work fine until I got home....pulled in the garage and shut down but within a minute there is coolant coming out of the radiator from near the drivers side upper hose neck and going all over the floor. The upper radiator hose was steamed swelled as it was before I replaced the Tstat.

Is my new Tstat bad too? I'll pull it and boil it tomorrow.

Is 195 too high? It is the factory recommended T.

Is the cap on the expansion tank bad or wrong pressure rating? It was on the car when I got it but not factory 15 LB rated, this one is rated at 12-18 lb.

System leak taking the system to atmospheric thus lowing the boiling point of coolant (I'm running 60/40 mix)?

Water pump issue?

Cracked head/blown head gasket? There no water in the oil or vice versa.

I have a feeling I'll be visiting Tom DeWitt this winter during storage time, but I hate to spend a K buck if it doesn't fix the real problem.

I've got 2 weeks of driving weather left at best case and would like to get a few more miles on before winter storage & project time. Thanks in advance for the suggestions you guys are so good at!

 

Since it's summer, try it with no T-stat installed and then try a lower temp stat like 1 80 with a 1/8" hole drilled through it to relieve some pressure prior to it opening.

With the system cold and the radiator cap of, make sure there is about four to five inches of air to the water lever. You should be able to see it just fine with a flash light.

Have you used a secondary, mechanical, or even an IR gun to check temperatures of the heads, intake, and rad when the gauge says it's hot?

 

First of all,you need a 15 lb or 16 lb pressure cap on your expansion tank.(I use a 16 lb)..second,I'd replace that upper rad hose...third, a Robert Shaw 180 stat is a good choice,as they fail open...

Here are pics of my heater core by-pass....



I just used a 90 fitting...



Good luck...doubt you cooked your engine..fingers crossed..check your oil dip stick just in case...

Rich

 

Thanks for the tips guys.

The engine itself never overheated so I'm not concerned about engine damage. I pulled the newest 195 Tstat and boiled it today, and either it's off or my wife's candy thermometer is. Didn't open until near 205+. Replaced it with a 180 (yes I boiled it before installation and it came open at the right temp) and the car runs better than previously. No balloned hose or boil out from the radiator. I'm starting to feel better that it was still a Tstat issue and possibly a little too much coolant in the system. I am going to order a 15 lb cap just for insurance.

Weather is supposed to be nice again tomorrow so I plan to make another outting to say it's done.

Thanks again.