OP
UTC

Lurker
GTV 250ie
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Location: Melbourne Australia
 
Lurker
GTV 250ie
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Location: Melbourne Australia
UTC quote
Hi All,

After paying A$68 to learn how delicate the thermostat housing is I thought it would be interesting to section it to understand how it worked.

After changing out the water pump seal I followed the great YouTube instruction posted by ScooterWest on how to bleed the system. Unfortunately after buttoning up the bleed screw I had a very small leak coming out of the hole so I did my usual trick and turned it another 1/4 turn...bang goes $68 bucks.

Turns out the brass bleed screw will seat on a moulded (plastic) step in the thermostat housing. Over tighten it as I have and you destroy the seat and allow coolant to get into the hole just below the o-ring and it comes straight out the nipple. What looked like a very small leak could empty 500mm of coolant in about 4 hours.

The manual says tighten to 3nm. For those without a torque wrench that goes down that low, this is about finger tight + about 1/10th of a turn. This is not like a brake bleed screw that seals against an aluminium or steel seat, when I stuffed this one I got no real feel of resistance and I was using light two fingers of pressure on the spanner.

Hope this saves at least one person my fate. The good news is that it seems I wasn't the first one to make this mistake, when I rang the dealer he just laughed and fired back, "yeah mate, got plenty in stock"

Happy trails
Forum member supplied image with no explanatory text
@tor2ga avatar
UTC

Ossessionato
Looking for the next one, probably electric
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Location: Babcock Ranch, Florida
 
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@tor2ga avatar
Looking for the next one, probably electric
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UTC quote
Nice piece of analysis. Thanks.
@glasseye avatar
UTC

Ossessionato
GTS, LX, VSD, VSX, VNX, LD 125, Chucky, LI125
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@glasseye avatar
GTS, LX, VSD, VSX, VNX, LD 125, Chucky, LI125
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UTC quote
Been there, done that.

Its a rite of passage.

Clown emoticon

R
⬆️    About 1 year elapsed    ⬇️
@jimithesaint avatar
UTC

Member
Just bought myself a GTV250ie
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Location: Nicosia, Cyprus
 
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@jimithesaint avatar
Just bought myself a GTV250ie
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UTC quote
Re: Warning when bleeding the coolant system
Hooksta_V1 wrote:
Hi All,

After paying A$68 to learn how delicate the thermostat housing is I thought it would be interesting to section it to understand how it worked.

After changing out the water pump seal I followed the great YouTube instruction posted by ScooterWest on how to bleed the system. Unfortunately after buttoning up the bleed screw I had a very small leak coming out of the hole so I did my usual trick and turned it another 1/4 turn...bang goes $68 bucks.

Turns out the brass bleed screw will seat on a moulded (plastic) step in the thermostat housing. Over tighten it as I have and you destroy the seat and allow coolant to get into the hole just below the o-ring and it comes straight out the nipple. What looked like a very small leak could empty 500mm of coolant in about 4 hours.

The manual says tighten to 3nm. For those without a torque wrench that goes down that low, this is about finger tight + about 1/10th of a turn. This is not like a brake bleed screw that seals against an aluminum or steel seat, when I stuffed this one I got no real feel of resistance and I was using light two fingers of pressure on the spanner.

Hope this saves at least one person my fate. The good news is that it seems I wasn't the first one to make this mistake, when I rang the dealer he just laughed and fired back, "yeah mate, got plenty in stock"

Happy trails
Just did exactly the same thing too!

Thankyou for this visual explanation ... will i need to replace any gaskets or anything when changing this part?

Also, will I have to flush all the fresh coolant that I just put in, or will in not come gushing out when I remove the thermostat housing?
@miguel avatar
UTC

Veni, Vidi, Posti
2009 GTV250 (Gone), 2003 Inder trailer (also gone), 2001 BMW R1100RT
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@miguel avatar
2009 GTV250 (Gone), 2003 Inder trailer (also gone), 2001 BMW R1100RT
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UTC quote
Thx for that. You in all likelihood saved me from doing the same.
Best
Miguel
@harvey avatar
UTC

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2016 Honda NC750XD, 2007 GTS (sold),
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@harvey avatar
2016 Honda NC750XD, 2007 GTS (sold),
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UTC quote
The expansion tank is above the bleed screw. I think you will get draining if you remove the thermostat housing. If there's any chance there're bits of plastic in the cooling system, I would flush and replace. There's no coolant filter, and your water pump impeller is plastic (a water pump rebuild kit is $48 from SIP & I understand it's a difficult repair).
@alpard78 avatar
UTC

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2010 GTS300 Super
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@alpard78 avatar
2010 GTS300 Super
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@jimithesaint avatar
UTC

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Just bought myself a GTV250ie
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Location: Nicosia, Cyprus
 
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@jimithesaint avatar
Just bought myself a GTV250ie
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UTC quote
WOW! At $150 I'd rather buy the OEM part and 'be carful' tightening the bleed nipple next time.
@alpard78 avatar
UTC

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2010 GTS300 Super
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Location: Hillsboro, OR
 
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@alpard78 avatar
2010 GTS300 Super
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UTC quote
Well, after tinkering with this I decided to make a quick fix instead of buying the housing.

The bleeding hole is perfect for a 4-40 thread so I made a thread in there and I'm fitting a stainless steel 4-40 screw with a tiny o-ring. The o-ring is spec'd to resist ethylene glycol and up to 400F.

Even if the o-ring breaks over time I'll just put teflon tape on the small screw.

There. I fixed it.
$2 if you have the tapping tool.
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@jess avatar
UTC

Petty Tyrant
0:7 And counting
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@jess avatar
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UTC quote
alpard78 wrote:
There. I fixed it.
$2 if you have the tapping tool.
Nice work!
@italian_hog avatar
UTC

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S150
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Location: Temecula, CA
 
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@italian_hog avatar
S150
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Location: Temecula, CA
UTC quote
alpard78 wrote:
Well, after tinkering with this I decided to make a quick fix instead of buying the housing.

The bleeding hole is perfect for a 4-40 thread so I made a thread in there and I'm fitting a stainless steel 4-40 screw with a tiny o-ring. The o-ring is spec'd to resist ethylene glycol and up to 400F.

Even if the o-ring breaks over time I'll just put teflon tape on the small screw.

There. I fixed it.
$2 if you have the tapping tool.
Nice fix!!
@tazio avatar
UTC

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2007 Vespa GTS250ie 2007 Buddy 125 Series Italia 2012 Ural Gear-Up
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@tazio avatar
2007 Vespa GTS250ie 2007 Buddy 125 Series Italia 2012 Ural Gear-Up
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UTC quote
"That's what Ivan would do." as they say over on the Ural site.
⬆️    About 3 years elapsed    ⬇️
UTC

Enthusiast
2019 GTS300 Notte & 2012 GTS300 Mid Blue
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Posts: 93
Location: Los Angeles
 
Enthusiast
2019 GTS300 Notte & 2012 GTS300 Mid Blue
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Posts: 93
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UTC quote
Anyone know where to currently get one of these?
Seems like they are NLA everywhere that I have looked.
⬆️    About 1 month elapsed    ⬇️
UTC

Lurker
GTS 250 ie
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UTC quote
Going to try this, seems like one of the best solutions out there. Buying a new housing is only going to postpone trouble the next flush. Bought the tapping tool (EUR2.80) and got the bolt and the rubber ring free
⬆️    About 1 year elapsed    ⬇️
@anndee4444 avatar
UTC

Hooked
GTS 250
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@anndee4444 avatar
GTS 250
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UTC quote
Another method to solve the bleeder screw issue is to use a Stahlbus (or similar) brake bleeder screw/valve.

https://www.stahlbus-us.com/bleeding-brakes/bremse-entlueften-bleeder-valve/conical-sealing-standardtype/

External inline image provided by member with no explanatory text
@web-tech avatar
UTC

Veni, Vidi, Posti
2008 MP3 500, 2013 BV350, 2020 Vespa Sei Giorni, 2008 Vespa S150
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UTC quote
Dudematters wrote:
Going to try this, seems like one of the best solutions out there. Buying a new housing is only going to postpone trouble the next flush. Bought the tapping tool (EUR2.80) and got the bolt and the rubber ring free
Not if you don't over tighten the bleed screw. This doesn't seem to be a big problem that gets posted about regularly. Razz emoticon
@rajron avatar
UTC

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GTS 300
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UTC quote
Re: Warning when bleeding the coolant system
Hooksta_V1 wrote:
Hi All,



The manual says tighten to 3nm.

Happy trails
It can't be 3 Nm's it must be 3 Cnm.
@web-tech avatar
UTC

Veni, Vidi, Posti
2008 MP3 500, 2013 BV350, 2020 Vespa Sei Giorni, 2008 Vespa S150
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UTC quote
Re: Warning when bleeding the coolant system
rajron wrote:
Hooksta_V1 wrote:
Hi All,



The manual says tighten to 3nm.

Happy trails
It can't be 3 Nm's it must be 3 Cnm.
Hold the ratchet from the head with one hand and get it as tight as that lets you
@gene avatar
UTC

Hooked
GTS300 Super/Burgman 650/BV500/ B&W250/BMW R60/CL77 Scrambler/YDS1 Big Bear/CB160/Hayabusa
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@gene avatar
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UTC quote
Thanks for the tip and YES this will help many that just read this Scooter emoticon
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BV 350
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UTC quote
Re: Warning when bleeding the coolant system
WEB-Tech wrote:
Hold the ratchet from the head with one hand and get it as tight as that lets you
Sorry, have gorilla hands. I could probably get 20 ft.-lbs. using that technique.

Tapping and adding the screw may seem like a good idea, but you have just added another failure point to the machine. Fine to get you by until you actually fix it, I suppose.

Don't mean to be mean, but when you are screwing a metal piece into a plastic piece, should be pretty obvious to take it easy on the torque.

Or maybe that is the voice of experience talking, as I have, no doubt, made a similar mistake myself in the past.
UTC

Molto Verboso
Vespa GTS 250ie
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Location: San Francisco Bay Area
 
Molto Verboso
Vespa GTS 250ie
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UTC quote
The Vespa part is just plain cheesy. Why should we have to go through these efforts for something as simple as this item?
@madison_sully avatar
UTC

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@madison_sully avatar
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UTC quote
SCTLVR wrote:
The Vespa part is just plain cheesy. Why should we have to go through these efforts for something as simple as this item?
Actually the whole point is avoiding effort. Too much of that is what causes the damage.
@anndee4444 avatar
UTC

Hooked
GTS 250
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@anndee4444 avatar
GTS 250
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UTC quote
Looks like Piaggio has recognized that this is actually a problem. The new 2019 300 HPE motor has an aluminum thermostat housing.

https://photos.google.com/share/AF1QipMicX9f0_OBMkr19zIWyXZ2NVsFG8CkpDWITSXEwNBrZPZoJDbPK5zO2LTrM5qhNA/photo/AF1QipNFR_9IM0rim7KVKhck1b1KrHgY9-XVJjwI4UqZ?key=UzNDTHl3TnJZZjhHYVU2UGlfSFB5TjBUNGotaGpn
@etchkid avatar
UTC

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@etchkid avatar
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UTC quote
Oh nice! Thanks for he heads up! Just about to do mine.
⬆️    About 1 year elapsed    ⬇️
@anndee4444 avatar
UTC

Hooked
GTS 250
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GTS 250
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@guisaltini avatar
UTC

Member
Piaggio BV 250
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Location: Brazil
 
Member
@guisaltini avatar
Piaggio BV 250
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Location: Brazil
UTC quote
I still wonder why my BV 250 doesn't have the bleeder. And as far as I researched, is not possible to just change the thermostat housing. I have a blown head gasket and I've been researching how to bleed the coolant system without the bleeder.
@max6200 avatar
UTC

Banned
2006 GTS 250
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Location: KS USA
 
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@max6200 avatar
2006 GTS 250
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UTC quote
8)
@web-tech avatar
UTC

Veni, Vidi, Posti
2008 MP3 500, 2013 BV350, 2020 Vespa Sei Giorni, 2008 Vespa S150
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@web-tech avatar
2008 MP3 500, 2013 BV350, 2020 Vespa Sei Giorni, 2008 Vespa S150
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UTC quote
Change the thermostat too and bleed it from the thermostat housing. Just loosen the bolts a little.
@guisaltini avatar
UTC

Member
Piaggio BV 250
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Location: Brazil
 
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@guisaltini avatar
Piaggio BV 250
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Posts: 42
Location: Brazil
UTC quote
WEB-Tech wrote:
Change the thermostat too and bleed it from the thermostat housing. Just loosen the bolts a little.
Thanks for this! I'll give it a try. Just wondering if it will works since in the BV 250 the hose does go up after the housing. So most upward place for the bubbles to stay would be inside the hose. But piano piano it will work.
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