Missing Bleed Screw on T-Stat

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johank
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Missing Bleed Screw on T-Stat

Post by johank » Mon Jul 02, 2007 9:07 pm

Hi all,

I recently tried to change my coolant, and noticed that the bleed valve described in the owner's manual isn't there. There's a smooth hole in the top cover of the thermostat valve, with large diameter going to smaller diameter (presumably for the threads of the screw that's supposed to be there - no threads cut, though) and then a plug at the bottom. I took the cover off, and the plug looks like it is part of the cover casting, not simply a broken-off bleed screw.

Is this normal or maybe some sort of revision? If there's no bleeder there, where the heck do I bleed the cooling circuit? I'm tempted to just drill out the plug, tap the hole, and put a bolt in, but I figured I'd consult the experts :wink: before taking drastic action.

Thanks a lot guys! Appreciate the help...

-Johan
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Mats
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Post by Mats » Mon Jul 02, 2007 9:55 pm

I have honestly never seen a bleed screw on a 116 car, 105 cars have them on the housing though.
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johank
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Post by johank » Tue Jul 03, 2007 2:10 am

Hmm... interesting. So I guess it doesn't need it? I know there's some air pockets in there right now, and I have a hard time seeing how those are going to get out of there. I'll run it and see what happens.

Thanks for your help, Mats!
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Post by Maurizio » Tue Jul 03, 2007 2:43 am

Mats take a look at a V6 for a change :lol:

I recently bought a thermostat for my QV. And at the alfa parts store they had a 164 thermost laying around. This didn't have the bleed screw and was a bit cheaper.
I ordered one with a bleed screw, to be sure.
My guess is that the water routing is different on the fwd V6's but didn't check this.
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Post by Mats » Tue Jul 03, 2007 3:38 am

Hmmm, Vat is dis vee-sechs?? :)

ok, ignore my first reply then. :roll:
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Post by johank » Tue Jul 03, 2007 3:52 am

This makes me wonder if some yahoo put a 164 thermostat on mine... :?

It looks like the cover's the same as with the bleed screw, just minus threads and opening at the bottom of the hole... I may try my luck with opening it up and putting a bolt in there. We'll see how that goes...
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Post by Alfettish » Wed Sep 26, 2007 2:39 am

I've got the same issue. There is a smoothed hole out the top and no other way (that I can see) of opening the thermostat up.
What do I do? I'm scared of airlock but can't find out how to bleed it.
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Post by Alfettish » Wed Sep 26, 2007 3:42 am

Here is a pic of my thermostat and a pic of one with a bleed screw.
There is no hole in mine, it's completely tight.
Image

Image

Thanks to Greg for the photo from his site hiperformancestore.com
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Post by ar4me » Wed Sep 26, 2007 6:35 am

I suspect some aftermarket thermostats did not have the bleed screw. Personally, I wouldn't be too concerned. On the Milano/75 V6 you can "upset" the coolant by pressing the upper radiator hose forcefully with your hand. This tends to move things around enough to get large air pockets to rise to the overflow bottle.
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Post by Alfettish » Wed Sep 26, 2007 3:18 pm

Thanks AR4me.
I talked to my mechanic and he thinks that if you can get all of the capactity of fluid in there then there should be no problems.
I put 8 litres in there, he thinks that you would only be able to put about 4 litres in if there was serious air in the system.
I did squeeze all of the hoses and it did clear some air.
Thanks all, I hope this helps some people.
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Post by x-rad » Wed Sep 26, 2007 4:16 pm

Johank:

New to me....looks like it's not tapped (obviously...otherwise major leak)

tap it and put in a bleed screw...will help when filling system

I'm in Plymouth...let me know when you are in the area!!


if you need parts there is a guy with lots of new and used on Ann Arbor trail just east of garden city.....
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Post by MR2 Zig » Fri Sep 28, 2007 8:33 pm

I've recently had a bit of "fun" with the cooling system. I'd stay away from the drill on this one as its not really necessary to bleed it that way. if you top up the resivoir bottle then heat cycle the engine (bring it to operating temp then let it cool down) several times it will bleed itself. just check the coolant level each night for a week after you get home from work and keep the resivoir topped up. You will see some usage initially and then you won't be adding to the system anymore. at that point you're finished. realize also that as the coolant expands when heated you may have some coolant go out the overflow. What you will see is that once bled the resivoir will always have coolant in it.

HTH,
Scott
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Post by johank » Thu Aug 07, 2008 12:27 pm

For anyone still reading this (better late than never):

I ended up initially doing what Scott said last year and it probably was o.k., but I didn't like that the car was dumping coolant every time the engine was turned off after being hot. It did seem like it was getting less each time, but I just was not happy with it.

So I got a new bleed screw from IAP ($13! but I guess it's fancy enough to merit that price) this summer and drilled and tapped the cover. That seems to have done the trick.

X-rad - actually moved out of AA, but I'll let you know if I'm ever back in town. Would love to check out your Alfa!

Thanks again for the help...
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