thermostat refit issues , advice required

[soin]

hi all , spent all day today working on my 2000 gti 1.8t , firstly i changed the discs and pads , a first time for me but relatively simples . Next the thermostat , now i tried with various flexi drives and wobbly head ratchets but i could not get anything over that bottom bolt so i removed the alternator which gives plenty of room and only takes 10 mins . I bought a cheap stat from a motor factors for £6 odd but it looked identical to the one in there , however the rubber o ring supplied was smaller by far in circumference and there were a selection of gaskets in the box too   I decided to retain the original o ring seal as it cleaned up like new and not to use a gasket as there wasnt one on previousley.
All back together and refilled the g12 , straight up to 90 degrees within mins  ..perfect , start driving home and temperature alert comes on the dash , checked under the car and im leaking coolant . Topped up and got home , stripped it all back down and refitted the O ring and housing , built it back up drove round the block and its still leaking  . Gonna go at it again in the morning as i can pull the alternator and remove the housing in under 15 mins now ....
just wanna check if im going wrong somewhere

how tight should i cinch the housing bolts ?? i think i may be over-tightening them
if i were to use some grease to secure the o ring seal , what type ??
can an O ring seal be re used??

i built back up exactly as i stripped down , stat brace vertical , stat first then O ring ..
unsure as to why im not getting a water tight seal

any advice welcomed

[rio_gti]

You may have cracked the housing when over tightened so a new one will be in order.......

[soin]

hmmm i didnt think of that, i'll check for cracks tomorrow when i strip down.......again 

[rio_gti]

Can't believe that you have to take the alternator off every time thou 

[harlemex]

check the thermostat is in the correct way. If not it will deffo leak. 

[soin]

i cant believe people are getting at the bottom bolt without removing it (alt ) , i tried for about ten minutes with allen keys , small spanner , flexable drive shaft . .. god it beats me 

the thermostat went in visually identical to the one that came out , it fills the inlet perfectly , then the rubber seal and the place the housing in place , i guess maybe im knocking the seal out of place or overtightening , gonna try some grease tomorrow .. would vaseline work ?? 

[harlemex]

you can get to the bottom one using a universal joint, thats how I did it.

[harlemex]

come to think of it, I had the seal on in the wrong order if you get me, thats why mine leaked.

[soin]

yeah i guess that would cause issues , so you used a universal joint with a 10mm socket on the end ??
how tight were you torquing the bolts

[barrym381]

u sure the bottom bolt is tight thats what i had probs with