Replacing coolant thermostat housing
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Hooked
GTS250ie
Joined: 18 Feb 2016
Posts: 193
Location: Treasure Coast, FL
Mon Mar 14, 2016 2:43 pm quote
Im replacing the thermostat housing on a 2007 GTS 250.
I combed through the workshop manual PDF and it did not address this procedure at all, except the torque values for the bolts.
I was told by someone that this does not require a gasket.
Does someone know?
Does it use any kind of gasket or the liquid gasket maker stuff in the tube?
Molto Verboso
'95 Yamaha Riva 125- '05 Piaggio BV200-'05 Honda Reflex-'08 Honda Metropolitan
Joined: 22 Oct 2005
Posts: 1646
Location: Ohio
Mon Mar 14, 2016 3:22 pm quote
Good question as I'm about to replace mine. Looking forward to hearing some comments.

Bob
Addicted
Vespa GTS 300 Super
Joined: 13 Jun 2013
Posts: 913
Location: London, UK
Mon Mar 14, 2016 3:49 pm quote
If I'm right in assuming that the thermostat housing is the piece with the bleed nipple, then no - you won't need a gasket.

image.jpeg

Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: 21 Oct 2005
Posts: 7263
Location: The state of insanity, SoCal
Mon Mar 14, 2016 4:23 pm quote
the housing is sealed by the gasket on the thermostat itself and that smaller o-ring that is in the picture there. so, no you do not need a gasket to replace the housing-- unless either of those is damaged or somehow compromised.

when you remove the housing do so carefully, sometimes the gasket will stay in the head and sometimes it'll stick to the housing. what i'm saying is don't knock it off and down into the coolant passage.

-g
Hooked
GTS250ie
Joined: 18 Feb 2016
Posts: 193
Location: Treasure Coast, FL
Mon Mar 14, 2016 9:19 pm quote
That's right.
I replaced mine tonight and the oring on the thermostat seals the housing.
I made sure to apply the lightest of pressure on the bleeder when tightening.
All good.
Veni, Vidi, Posti
Lx 50 4T, S 150, GTS 250
Joined: 21 Feb 2011
Posts: 7201
Location: KS USA
Tue Mar 15, 2016 4:49 am quote
You will find the double o ring that wraps around the edges of the thermostat. If all goes well it will stay stuck around it.
Enthusiast
GTS
Joined: 19 Aug 2016
Posts: 88
Location: Edinburgh,Scotland
Wed Apr 11, 2018 3:17 am quote
Sorry folks, digging up an old thread as it the photo shows exactly the part I am trying to locate.
I've got a very slight coolant weep out of the thermostat housing.
Ive replaced the thermostat, given a smear of high temp silicon around the thermostats double o ring and the mating surfaces but no joy.
What does the smaller separate o ring do?. The one that is beside the thermostat
Can't find a part number for it to replace.
New housing?
Any help greatly appreciated
Molto Verboso
GTV300 (wife's)
Joined: 08 Nov 2014
Posts: 1077
Location: Central New York
Wed Apr 11, 2018 4:20 am quote
I believe that small oring is the one for the bleeder screw. The Vespa parts book is not too good in showing it but does give a part number of 297027 which is the same as the sku# in Scooterwest's page as shown below:

vespa oring.png

Enthusiast
GTS
Joined: 19 Aug 2016
Posts: 88
Location: Edinburgh,Scotland
Wed Apr 11, 2018 4:38 am quote
Many thanks for that, reckon you are right
I'd looked at that part on SIP , but convinced myself that it wasn't it.
Scooterwests description is way more helpful.

Out of curiosity , what do you reckon part 22 is on this drawing.
Didnt notice anything like that on the underside of the housing, and I thought the thermostat/ gasket was one item?

Regards from Edinburgh

[/url]https://www.fowlersparts.co.uk/parts/5708072/vespa-gts-125-vespa-gts-125-vespa-gts-125-4t-ie-super-e3-chassis-number-prefix-zapm45300-zapm45301-2007-2015-vespa-gts-125-4t-ie/head-unit-valve[/url]
Molto Verboso
GTV300 (wife's)
Joined: 08 Nov 2014
Posts: 1077
Location: Central New York
Wed Apr 11, 2018 7:01 am quote
stage2 wrote:
Many thanks for that, reckon you are right
I'd looked at that part on SIP , but convinced myself that it wasn't it.
Scooterwests description is way more helpful.

Out of curiosity , what do you reckon part 22 is on this drawing.
Didnt notice anything like that on the underside of the housing, and I thought the thermostat/ gasket was one item?

Regards from Edinburgh

[/url]https://www.fowlersparts.co.uk/parts/5708072/vespa-gts-125-vespa-gts-125-vespa-gts-125-4t-ie-super-e3-chassis-number-prefix-zapm45300-zapm45301-2007-2015-vespa-gts-125-4t-ie/head-unit-valve[/url]
I'm a little confused as the link you posted is for a parts break-down for a GTS 125 is that what you have or is it a GTS 250?

The original post here was for a GTS 250!
Enthusiast
GTS
Joined: 19 Aug 2016
Posts: 88
Location: Edinburgh,Scotland
Wed Apr 11, 2018 7:18 am quote
My bad, I thought the thermostat and housings were all the same through the range.
Its a 218 on a 125, however, the part I refer to wasn't there before the conversion.
I'm going to replace the small o ring anyway, so I'll investigate further when I open it up.
Much appreciated
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