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Discussion Starter · #1 ·
hey everyone. im getting ready to change my thermostats. in the winter my truck will only get to 160 degrees while driving and at idle it drops to 130. my heat is not so great. so I figure its time to replace the thermostats.
now being a mechanic I usually replace every o ring and seal that gets disturbed, that said. from looking at the lay of out of the thermostats. im thinking I need the two thermostats.
now here is the question. is there a seal that seals the housing down? and do I have to remove the tube that is bolted into the back of the thermostat housing? and if I do, is that o ring separate from the pipe?
thanks for all your help!
 

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Discussion Starter · #2 ·
no one? no one can give me some help??
 

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Been a while since I done t-stats but IIRC the t-stats have a seal on them, the small hose is just a clamp on, but if you remove the large pipe from the housing I would replace that o-ring. You shouldn't have a problem bleeding the system, some say crack the fitting on top but they actually have a small bleed hole built in, not a big project to do.
 

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Discussion Starter · #4 ·
thanks! i didnt know if the housing had a seal or an o ring around it. i wish i could pull up a parks expoded view somewhere.
i like when i get parts at work or even online for Polaris it shows the parts and what is attached to them
 

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I need to change mine too I think. Is it a one way fit or is it possible to put them in the wrong way?


Sent from AutoGuide.com Free App
 

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Discussion Starter · #7 ·
dont think so, but i have seen people do stupid stuff before.
ive tried to do a search on here of a "how to" but didnt find any. anyone know of one?
 

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there is no gasket on the housing, just the two seals around the t stats.

I'm not sure what pipe you're talking about? the big radiator hose? it runs behind the A/c compressor? that has an o-ring.

I'm not totally sure, but I believe if you unbolted that hard rad hose from the driver valve cover, you might be able to unbolt the 4 t stat housing bolts and just lift up enough to change the stats. But my truck has been too far from stock for me to remember what 100% stock is like.
 

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Discussion Starter · #9 ·

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Removal Procedure
1. Remove the water outlet.
2. Remove the bolt for the fuel line bracket.
3. Remove the fuel line bracket.
4. Remove the thermostat housing cover bolts.
5. Remove the thermostat housing cover.
6. Remove the thermostats and seals.

Inspection Procedure
1. Inspect the thermostats for sticking, cracks, and/or leakage of wax.
2. Replace the thermostats if damage is found.
3. Clean the thermostat housing and thermostat housing cover sealing surfaces.

Installation Procedure
1. Install the thermostats and seals to the thermostat housing . The rear thermostat (4) has 2 vent valves. Install with the vent valves towards the rear of engine.

2. Install the thermostat housing cover.

Notice: Refer to Fastener Notice in Service Precautions.

3. Install the thermostat housing cover bolts.
^ Tighten the bolts to 21 Nm (15 ft. lbs.).
4. Install the fuel line bracket.
5. Install the fuel line bracket bolt.
^ Tighten the bolt to 21 Nm (15 ft. lbs.).
6. Install the water outlet tube.
from alldata
 

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I have an 05 LLY and my truck would only get to 170 in the middle of the day after running it fairly hard.

I changed both thermostats yesterday and now it's running 180-190 degrees. The t-stats that I bought from the GMC parts at my local dealer were 180 & 185 I think, so it's now functioning correctly.

I know your truck is different so I'm posting mainly to say it made a definite difference.
 

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The thermostats have a seal-- there is no gasket. The pipe that connects into the rear of the thermostat has a large o-ring.
 

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