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Can't I just RTV-it and fill the system with an vacuum airlift?!



Really?! A bleeder...that's held in with a Jesus clip and sealed with an O-ring? That's what phantom I've been chasin'!

(just repl'd the T-stat per PM and R&R'd the housing gasket- figured it that anoying little weepage is gotta be one or the other-)

Pressurized the system and it held at <13psi; starts spittin' at 14-16- can't see it with soapy water... and and then holds at 17psi!!!

I put an airlift on the system figuring maybe I can see where the soapy water's gettin drawn IN!!! WTF! Put 1/2 gal of H20 ('Cause I'm not gonna WASTE coolant, right?!)..then pressure test to 15 with a mirror I'm starin' at: 'WTF is that for?!' NOTHING!
 

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Subscribed for future reference...
 

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It's out of the thermostat housing...let's see if I can get some better pics up.



That's a top shot of the thermo housing, it's underneath towards the front of the housing...



The above pic is of the hole where the plug goes and housing...if you need some more shots just yell! [:D]

Rockauto had the whole housing with upper hose neck and thermostat all in one unit for like $40. Just unbolt the old and bolt in the new, its all assembled in one unit!
 

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Am I right in thinking the thermostats housing comes in 2 part's and seals the tstat inside, what is used to seel both part's? Any one got dissected pic's? And this washer/plug that every one had prob's with is it at the front on the under side of the pipes? Schematics would help thanks
 

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SO i have a leak also.... However based on this thread i am more confused at the end than i was at the beginning

I see this question raise a few time with no affirmative answer " Does only the SVT version have the Plug with a O-ring that fails?"

May i have an answer to this please :D

I have a 2003 Focus ZX5 premium, i replaced a hose with about a 3/4 inch diameter tot he t-stat house already , but have a leak under the t-stat houseing it seems as thats the only place i see coolant leak and hit the ground.

Do i need to :

A) look for a plug with o-ring ?
B) replace the front part of the houseing with the 3 screws and gasket
c) or change the who damn thing because i can't figure out where the coolant is coming from
d) go suck a lemon and complain about it? lol :p
 

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" Does only the SVT version have the Plug with a O-ring that fails?"

May i have an answer to this please :D
The SVT model is the only Zetec engined version that has the coolant temperature sensor in the thermostat housing that senses the fluid temperature directly. It uses an O-ring to seal the sensor in the thermostat body as shown in the pics.

The "normal" Zetec (i.e your ZX5) uses a cylinder head temperature (CHT) sensor that measures engine coolant temperature indirectly; it measures the temperature of the metal of the cylinder head near the coolant passages. The CHT sensor is located by the alternator (rear passenger side of the motor). There is no sensor fitting near the thermostat housing for your car and thus no O-ring.

Two different methods of doing the same thing - measuring engine temp.

Therefore, only the SVT has the O-ring that fails. However, the normal Zetec fails in its own way - the much larger sealing O-ring between thermostat housing and cylinder head fails or the housing cracks and leaks or a combination of both. It is theorised this is usually due to the valve cover gasket leaking and seeping oil down the side of the head by the housing. It's a common problem whatever the cause.

Do i need to :

A) look for a plug with o-ring ?
B) replace the front part of the houseing with the 3 screws and gasket
c) or change the who damn thing because i can't figure out where the coolant is coming from
d) go suck a lemon and complain about it? lol :p
a) No.
b) No.
c) Yes. Leak is likely between thermo housing and head.
d) Umm...No comment.
 

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just replaced my non-svt housing and stat, and was very careful not to torque down the screws to the cover and bolts to head per the warnings of cracking plastic. Although it did say 15ft lbs or something to the head ( dont quote me ) on engine torque specs someone posted on FF.

I also put a little tiny bit of RTV in the corroded pit marks left in the head around where the housing o-ring mates.

Leaked out about less than a half quart, at that rear spot of the trans pan. not 100% sure its the housing area, maybe hose, HOPEFULLY not head gasket. happened after a day driving and then sitting on ramps for 8 days.
 

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Just thought I'd put in my 2 cents. I used a zip tie and pliers to get the wire out since there wasn't enough clearance to get the wire out of the plug. FYI someone here suggested a mastercarr one, but there was a gap in the aluminum indent and the o ring with it. It still fit and I drove it 60 miles w/out leak from there. Time will tell. Perhaps the Danco one on the first page is more filling or over filling.
 

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Necro bump. Just did mine, haven't had a chance to drive it yet or refill (Thanksgiving day job...). Quick question: Does the plug have some play in it it/wiggle after the new ring? Forgot to check before for reference before the swap. Ran the car briefly (with admittedly low coolant) and didn't se a gush of coolant, but seems to be holding when running/coolant is pumping... Used the metric 7mm ID, 13mm OD 3mm viton ring. Went in easy, tried jamming it in there as I put the clip on. It's in there, but still seems to have some play. IDK. New to the SVT world, so maybe that is normal and if it holds, seems like no prob.

Side note, I have 5 extra rings if you need one.
 
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