I just installed a new thermostat from msa and a new cap... 160 degrees. It never did open when it was supposed to for the two weeks I have had it installed. On the freeway yesterday the temp gauge went almost to the red line :tapemouth before opening. So I pulled over and took it out... problem solved. So I keep thinking why is this happened... my question is: How many pound cap should I be running and if it is wrong can this prevent the thermostat from opening? I am running a 13 LB cap... Also the spring goes down right??? One more ?? which way does the water travel from the top radiator hose.. does it travel into the radiator or does it travel into the block from the top hose?? I know its possible I just got a bad thermostat... but before I put a new one in I wanted to cover my bases...thanks

Pretty easy to test 'em...put it in a pan of water on the stove with a meat thermometer. Watch till it opens.

I will see you in Fremont tomorrow, no? Do you have a car in the show? I will be there--proudly representing 'Modified 280z's"--VERY popular catagory here in CA (that was sarcasm, folks). Please come by and say hi.

steve77

In general:

Water flows from the bottom hose through the engine and back to the radiator through the top hose.

The actuator of the thermostat should point to the engine side of the housing because that side would heat up faster when the 'stat is closed and when the water in the engine gets hot you want it to open.

get a pot, put some water in it and put it on the stove. hang the thermostat in it from a bit of wire and heat the water to see of you thermostat is working.

Is should start to open at ___? degrees (someone with an enging manual fill in the blank). and be fully open at __? degrees. If the waters boiling and it hasn't opened its faulty.

The radiator cap shouldn't affect the thermostat.

You dont have electric fans do you?

Most thermostats are stamped with the temp at which they open. I think you will find that most 'standard' ones are 160-180 degrees.

If I remember correctly, changing the pressure of the tank will raise the boiling point of the coolant.

Yep, typical Z thermostats are either 160 or 180 degree units. Changing the pressure does change the boiling point, but that shouldn't affect the operation of the thermostat. Typical radiator cap is rated at 13 pounds, but even at atmospheric pressure the coolant should be liguid at either thermostat setting. A 240 thermostat only costs 6 or 8 bucks, so it wouldn't be a budget-buster to just get a new one and plug it in.