# antifreeze keeps leaking out of thermostat housing



## swilliams27 (Feb 20, 2010)

after running for a while antifreeze starts to leak out of the thermostat housing what would cause this


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## tryin2vw (Dec 30, 2006)

*Re: antifreeze keeps leaking out of thermostat housing (swilliams27)*

Worn housing or bad seal. Waws the timing belt/WP/Thermostat just changed?


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## swilliams27 (Feb 20, 2010)

*Re: antifreeze keeps leaking out of thermostat housing (tryin2vw)*

it never did it until i took the thermostat out to see if it was good and after i put it all back together i let it run for a little and then it started to spray everywhere like thre was alot of pressure building up for some reason


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## Slimjimmn (Apr 8, 2006)

*Re: antifreeze keeps leaking out of thermostat housing (swilliams27)*

You always need a new o-ring when the old one is removed. Anywho I struggled with a leaky t-stat after I replaced mine only to find out the plastic flange warped. It was about 82.00 for a new plastic t-stat flange and o-ring. And you should replace the tstat with a new one, there is an updated one with higher opening temp to help the carbon buildup on the 2.8


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## swilliams27 (Feb 20, 2010)

*Re: antifreeze keeps leaking out of thermostat housing (Slimjimmn)*

i did replace the o ring before i put it back together
could the bleeders have anything to do with it i know theres two of them



_Modified by swilliams27 at 10:52 AM 2-22-2010_


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## Slimjimmn (Apr 8, 2006)

*Re: antifreeze keeps leaking out of thermostat housing (swilliams27)*

only one bleeder I know of, the one on the coolant crossover pipe by the belts on the driver side head front


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## swilliams27 (Feb 20, 2010)

*Re: antifreeze keeps leaking out of thermostat housing (Slimjimmn)*

no there is a front and rear bleeder do you need to bleed them both ??


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## Mopar Guy (Mar 21, 2008)

*Re: antifreeze keeps leaking out of thermostat housing (swilliams27)*

What's weird is the car did not leak right after we changed the thermostat. It took a couple of days to blow out of the thermostat gasket. It almost seems like it might be getting to much pressure in the cooling system. Where does the cooling system release pressure? Could it be a bad expansion tank cap?
The rear bleeder can be located underneath the expansion tank on the coolant pipe going to the head and can be seen in the top right of this picture: (not my picture) 
http://i2.photobucket.com/albu...2.jpg
We only bled the front cause the rear bleeder was stuck on and striped. The hoses were all hot telling me it is circulating somewhat. Maybe if you don't bleed the rear bleeder an air pocket forms on the engine and heats the engine up and blows out the weakest link (thermostat gasket)? 
If the system gets to much pressure with the correct circulation it should blow out the expansion tank cap first right?

_Modified by Mopar Guy at 7:49 AM 2-24-2010_


_Modified by Mopar Guy at 7:59 AM 2-24-2010_


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## O_o (Nov 12, 2009)

*Re: antifreeze keeps leaking out of thermostat housing (swilliams27)*


_Quote, originally posted by *swilliams27* »_no there is a front and rear bleeder do you need to bleed them both ??

There is a bleed port on the outlet hose from the heater core.

_Quote, originally posted by *Mopar Guy* »_Where does the cooling system release pressure? Could it be a bad expansion tank cap?

Yes, it vents through the expansion tank cap. I think it's supposed to pop at 7psi.


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## Mopar Guy (Mar 21, 2008)

*Re: antifreeze keeps leaking out of thermostat housing ()*

There is a bleeder port on the heater hose on the 1.8T but there is not one on his 2.8. However considering that the rear bleeder is stuck on and he never gets heat in the car maybe we should put one on it?


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## O_o (Nov 12, 2009)

*Re: antifreeze keeps leaking out of thermostat housing (Mopar Guy)*


_Quote, originally posted by *Mopar Guy* »_Maybe if you don't bleed the rear bleeder an air pocket forms on the engine and heats the engine up and blows out the weakest link (thermostat gasket)?

If there is an air pocket, it will be at the same pressure as the coolant, so it shouldn't do anything like that. Also, if there is an air pocket, it will bubble to the top of the circuit, and the cabin heat won't work well.


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## O_o (Nov 12, 2009)

*Re: antifreeze keeps leaking out of thermostat housing (Mopar Guy)*


_Quote, originally posted by *Mopar Guy* »_There is a bleeder port on the heater hose on the 1.8T but there is not one on his 2.8. However considering that the rear bleeder is stuck on and he never gets heat in the car maybe we should put one on it?

Definitely bleed the top then. On my 2.8 the heater core bleed was just a small hole through the wall of the hose so that when it was on all the way, it was over the nipple, but you could pull it off part way to expose it. If you don't have that, then you can just pull the hose off almost all the way, and then crack it open at an angle, if that makes any sense...


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## Slimjimmn (Apr 8, 2006)

*Re: antifreeze keeps leaking out of thermostat housing ()*

air pockets have nothing to do with coolant leaking. I am pretty sure the thermostat flange is bad causing the leak. http://****************.com/smile/emthup.gif


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## swilliams27 (Feb 20, 2010)

*Re: antifreeze keeps leaking out of thermostat housing (Slimjimmn)*

what and there is the flange


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## O_o (Nov 12, 2009)

*Re: antifreeze keeps leaking out of thermostat housing (swilliams27)*


_Quote, originally posted by *swilliams27* »_what and there is the flange

The disk-y part of the thermostat. They sometimes warp.
You should still burp the core to get the cabin heat back, but there's no point in doing so until you've replaced the t-stat.


_Modified by  at 10:50 AM 2/25/2010_


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## Mopar Guy (Mar 21, 2008)

*Re: antifreeze keeps leaking out of thermostat housing ()*

There is a bleeder port on the heater hose on the 1.8T but there is not one on his 2.8. However considering that the rear bleeder is stuck on and he never gets heat in the car maybe we should put one on it?


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## O_o (Nov 12, 2009)

*Re: antifreeze keeps leaking out of thermostat housing (Mopar Guy)*


_Quote, originally posted by *Mopar Guy* »_There is a bleeder port on the heater hose on the 1.8T but there is not one on his 2.8. However considering that the rear bleeder is stuck on and he never gets heat in the car maybe we should put one on it?

Can't hurt.


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## swilliams27 (Feb 20, 2010)

*Re: antifreeze keeps leaking out of thermostat housing (Slimjimmn)*

what and where is the flange


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## Slimjimmn (Apr 8, 2006)

*Re: antifreeze keeps leaking out of thermostat housing (swilliams27)*

the flange is the part that bolts onto the block that you have to remove to remove the t-stat. look at my DIY on here... b5.5 its plastic b5 its aluminum. 
http://forums.vwvortex.com/zer...88319


_Modified by Slimjimmn at 3:23 PM 2-27-2010_


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