Whats the purpose of the spring loaded metal disc on the bottom of the thermostat , What happens if you install a thermostat that dose not have that feature on it ??

 

If you don't have the spring on there you will have coolant flowing through the engine wide open, not allowing the engine to ever get up to temp except in extreme heat conditions.

Ask me how I know. And, no, I didn't install a thermostat without a spring, before any one asks.

 

The metal disc is holding the coolant in the block this would open when the engine was hot then close again if it cools down too much. Did you break the disc off or was there a reason you dont have it. I cut mine off when I did my engine flush so I could run it with the cleaner in it.

 

I bought a stant 195 thermostat and noticed it was shorter than the one I took out of the car, also I checked the one I took out and measured it, Is the disc suppose to acuallly make contact with the inside port on the intake ?? heres two different stlyes of thermostatsthat are supposed to be correct for a 98 Blazer but they have a different design

STANT Part # 14119 {Regular Thermostat - 195 Degree Bottom By-Pass (2 5/16" x 25/32" x 1 13/32" x 1 3/16") w/Seal}
195 Degree; Original Equipment Temperature; Seal included
http://info.rockauto.com/Stant/Detail.html?14119.jpg

GATES Part # 33019S {Premium 195º Superstat (2 5/16" x 25/32" x 1 29/64" x 1 13/64") w/Seal}
195 Degree; Original Equipment Temperature; Seal included
http://info.rockauto.com/Gates/Detai...at-Cutaway.jpg

 

It is all about the design of the thermostat. Almost every aftermarket manufacturer has their own design. They all work on the same basic premise.

In this case, you are comparing pictures only which may not be of the actual product, especially the Gates one.

The Stant tstat shown is for a bypass type system which allows coolant to recirculate back to the pump to keep coolant flowing while the tstat is closed. Once the tstat begins to open, it will close off the recirculation port to the pump in relation to the opening of the port to the radiator. This style of system keeps hot spots to a minimum as coolant is continuously flowing through the system.

The other style is for a non-bypass setup.

I honestly cannot remember which one is used on the 4.3L... ACDelco.com shows the one for a bypass style system.

 

Yah the disc should make contact if it was only close you would still get radiator mixing when the engine was below 195. The stant part number is correct for the regular one the gates seems wrong if the dimensions are correct on both. The regular and premium should both be able to touch the block to seal off the coolant. Is the thermostat fully seated into its hole the gasket becomes close to flush along the top of its opening when its in. I used a stat premium 45119 just because it was a few more bucks, that supposedly controls engine temp better.