Order of operations: coolant temp issues

[spmls]

@Dirtman, the new t-stat does apparently have a jiggle valve, it's a Motorad 2000195 for anyone looking at this for reference. It isn't located on the flange like the old one though, it's under the frame closer to the piston.

 

[spmls]

Glad to hear that your problem seems to be solved now! Of course, some road-test results would be even more interesting (hint, hint).It's been a few years since I last replaced a stuck-open thermostat, but I don't recall any signs that the old thermostat had been stuck open upon visual inspection after I'd replaced it. But the replacement solved the problem ever since then. And the graph of ECT with the new thermostat shows a drop when it opens, whereas the old thermostat didn't.

Thanks for the update!

I finally got around to refilling the coolant this afternoon, let it warm up and took it for a drive. Now the ECT graph gets up to about 82° C, and then kicks down a couple degrees. The temp, gauge indicates just below halfway, perfect. @RonD was spot on with their prediction. I think that the old 165° t-stat was actually working fine, now that I know that the ECT temps are typically lower than the t-stat ratings...But hopefully running it a little warmer is better for MPG's and emissions in the long run.

Thanks all for your suggestions. Now on to the blend door

 

[RonD]

@Dirtman, the new t-stat does apparently have a jiggle valve, it's a Motorad 2000195 for anyone looking at this for reference. It isn't located on the flange like the old one though, it's under the frame closer to the piston.

That would defeat the purpose of a "jiggle valve", it needs to be on the flange, closer to the edge the better, and then when installed its put at the 12:00 position
Jiggle valve is there to let AIR out from behind thermostat when its closed

When you refill the system take one heater hose off at the firewall, that will let air out when there is no jiggle valve

 

[spmls]

I guess I'm a bit confused as to which part is the jiggle valve. Is this actually the bypass valve?

 

[RonD]

That's a jiggle valve
But for a thermostat that would sit facing down, like in a 4.0l SOHC, not good for sideways mounting

The distance from the jiggle valve(mounted at 12:00) to the top of intakes water passage is the amount of air that can be trapped behind the thermostat when its closed
So you could have 1.5"-2" of air trapped behind thermostat

The above jiggle valve wouldn't be any better that waiting for the thermostat to open, lol, BUT........it would let out enough air to at least keep thermostat covered with warm coolant so it COULD open and let more air out

Just giving you a hard time
But jiggle valves do belong at the edge of thermostat plate when its mounted sideways, or anytime really, not sure of the thinking of MotoRad on that one

 

[Dirtman]

Jiggle Jiggle!

 

[RonD]

Hooters

I love owls

 

[MikeG]

Would it hurt anything to drill an itty-bitty hole on the flange that would sit at 12 o'clock? Say less than 1/16" or so. Should serve the same purpose, right?

 

[RonD]

Yes, that's fine, I do an 1/8th inch hole when I get one that doesn't have the jiggle valve