How much does the thermostat jiggle pin matter? Replaced aftermarket thermostat without it with OE

[slacktide_bitog]

Just replaced the thermostat on a 2001 Firebird 3800 V6, which is actually very easy on these cars! Depending on the job, the 4th gen Firebird/Camaro is either very easy and simple or almost impossible to replace something on!

The OE thermostat is Stant and the gasket is already installed on the thermostat. The OEM thermostat also includes a jiggle pin.

The aftermarket thermostat that came out did not have that pin.

P0125 code kept popping up even after replacing the coolant temperature sensor, which was broken. It was replaced with an OEM ECT sensor, but the code came back! The coolant was also a few quarts low, though this particular cooling system on the F-body takes almost 3 gallons. I refilled with Peak 10x then used the Lisle coolant funnel to bleed.

The temperature gauge also behaved oddly, staying at cold until almost at operating temp, when it popped right to the middle. Now, it behaves in a more normal manner.

 

[tasch72]

The jiggle valve helps alleviate air pockets.

It sounds like you may have had a pocket trapped around your thermostat that got pushed out when the thermostat opened and the engine came up to temp.

If it continues to be a problem, I would switch to a different thermostat with a jiggle valve. It looks like your Stant 13849 just isn't equipped with one

 

[Chris142]

The aftermarket stat will have small grooves around the piston that is supposed to do the same thing.they do...kinda. definitely makes it take longer to warm up.

The oe stat is no longer available for my Jeep so I'm stuck with longer warm up times.

 

[Tman220]

The way the jiggle pin is designed is that when the engine is off and the water pump isn't creating any water pressure the pin will fall and provide a pathway to vent air. This helps purging air from the cooling system on the initial fill.

once the engine is running and water pump is trying to move coolant the water pressure should push the jiggle pin back up and seal off the coolant/air leak the jiggle pin allows.

As a general rule on cooling systems like yours it's probably not a requirement to have a jiggle pin. on systems where the thermostat is at the outlet to the radiator high on the engine I like to fill the engine with coolant through the thermostat housing, really helps getting rid of excess air pockets compared to filling from the radiator.

 

[slacktide_bitog]

The jiggle valve helps alleviate air pockets.

It sounds like you may have had a pocket trapped around your thermostat that got pushed out when the thermostat opened and the engine came up to temp.

If it continues to be a problem, I would switch to a different thermostat with a jiggle valve. It looks like your Stant 13849 just isn't equipped with one

I installed an OEM thermostat. ACDelco GM Original Equipment 131-120. It does have the pin:

 

[slacktide_bitog]

The aftermarket stat will have small grooves around the piston that is supposed to do the same thing.they do...kinda. definitely makes it take longer to warm up.

The oe stat is no longer available for my Jeep so I'm stuck with longer warm up times.

Is it the 2002 Wrangler in your sig? If so, there is an OE Mopar thermostat listed for a 2002 Wrangler on Rock Auto, though it is $30

 

[tasch72]

I installed an OEM thermostat. ACDelco GM Original Equipment 131-120. It does have the pin:

Ohhh I misread then I apologize.

So the coolant temp was acting up with the aftermarket tstat that didn't have the pin, but is acting normally now with the OE replacement with the pin?

 

[bdcardinal]

So I noticed after I did the t-stat in the Mustang that the FSM states to put the jiggle valve at the 12 o'clock position. I honestly wasn't paying attention, but it still bled out ok.

 

[Chris142]

Is it the 2002 Wrangler in your sig? If so, there is an OE Mopar thermostat listed for a 2002 Wrangler on Rock Auto, though it is $30

Ya. It's a motorad piece of junk in the jeep box! Already been down that road

 

[Lubener]

Jiggle pin eliminates the trapped air pocket behind the stat. I even have drilled a very small hole - 1/16 inch in the thermostat's flange when there was no jiggle pin or notch on my new thermostat.

 

[HankHill]

F-Body guys used to drill a very small hole in the stat, just like where the jiggle valve goes.

 

[ripcord]

Dad always wedged the thermostat open with an aspirin tablet when installing a thermostat to help bleed the system.

 

[wpod]

Dad always wedged the thermostat open with an aspirin tablet when installing a thermostat to help bleed the system.

interesting !!!

 

[slacktide_bitog]

Ohhh I misread then I apologize.

So the coolant temp was acting up with the aftermarket tstat that didn't have the pin, but is acting normally now with the OE replacement with the pin?

correct

So I noticed after I did the t-stat in the Mustang that the FSM states to put the jiggle valve at the 12 o'clock position. I honestly wasn't paying attention, but it still bled out ok.

every thermostat with a jiggle pin is supposed to have it installed at the top like that

Ya. It's a motorad piece of junk in the jeep box! Already been down that road

I HATE when they do this

Do you know who the OE supplier was for your Jeep?

Dad always wedged the thermostat open with an aspirin tablet when installing a thermostat to help bleed the system.

Bleeding can be a headache, so I can see why the aspirin helped

 

[BlueOvalFitter]

The jiggle valve helps alleviate air pockets.

It sounds like you may have had a pocket trapped around your thermostat that got pushed out when the thermostat opened and the engine came up to temp.

If it continues to be a problem, I would switch to a different thermostat with a jiggle valve. It looks like your Stant 13849 just isn't equipped with one

^^^^^^^^^^This^^^^^^^^^^

 

[Chris142]

I HATE when they do this

Do you know who the OE supplier was for your Jeep?

Nope. Looks different than a stant or motorad.

 

[oldhp]

I've always drilled a 1/8" hole in all the thermostats that didn't have one or a small vent. Always install the stat with vent hole at 12 o'clock if mounted sideways.

 

[Chris142]

I've always drilled a 1/8" hole in all the thermostats that didn't have one or a small vent. Always install the stat with vent hole at 12 o'clock if mounted sideways.

1/8 is way too big. Will take forever to warm up

 

[slacktide_bitog]

I've always drilled a 1/8" hole in all the thermostats that didn't have one or a small vent. Always install the stat with vent hole at 12 o'clock if mounted sideways.

1/8 is way too big. Will take forever to warm up

The hole in the OE thermostat I installed is about 1mm or maybe 1/32

 

[ripcord]

I can confirm that a 1/8 hole will slow down the warm up... made that mistake before.