Modern Vespa

Hi all! Greentings from Chile 🇨🇱!
I am proudly a new owner of a 2007 Vespa GTS 250 and I cannot love it more.

The Vespa was 9/10 when I purchased it and we made all fluid changes when done.
A strange thing I noticed was that it did not have the cap for the bleeding valve, but I didn't think about it very much.

After a few months of using it I was able to find the plastic cap and put it back on.
However after a 100km-trip I went back home and noticed that the cap gas gone, and a little drop of coolant was in the tip of the bleeder[/img]

I asked a person that loves Vespas and told me to screw the valve 90° tighter. Once I did it the coolant started pouring quite a lot for a couple of minutes and then it stopped.
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However, whenever I ride the bike, coolant starts to leak, slowly but steady, so I had to buy new coolant (same brand) and refilling some 50-100 ml after I use it.

Therefore, I'm not sure if I should replace the valve's o-ring or the full piece.
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Attached you can see the images. I took a look at the valve and the o-ring looks quite small, but not damaged.

Your support is very much appreciated!!

The oring may be bad but the plastic housing may have cracked which is very likely as people tend to over tighten the bleed screw

Oh no... do you mean this part? https://www.sip-scootershop.com/en/product/cover-thermostat-water-sip-performance-for-vespa-gts-gts-super-gtv-gt-60-250-300ccm-4t-lc_MV845604?q=845604[/url]
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I would first try replacing the o-ring with a new one from a hardware store.

That's clearly leaking out of the center, I think you're safe on the housing. There's an old thread here where someone tapped the hole and fit a small brass screw to stop the leak. Hopefully a new O-ring fixes it. Mine leaked from the thermostat gasket.

Thank you so much for your replies!
So I changed the o ring and the leaking is smaller, but persists.
Once I start the engine it starts pouring a bit more. As you guys mentioned, the leaking is from the middle hole, but it won't stop even if I screw strong.

Maybe I'll have to change the whole system, while refilling coolant in the meantime until the spare parts arrive?

Yo can see a video example here
?si=ogdVt-bdSiNEO1HS
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On the screw below the O ring is a cone saddle, it should seal the joint, it is a fingerprint or this is not a reason for leakage of liquid.

Seem not to leak from metal/plastic, like mine did, as they spoiled it in service tightening too much. But if end up change the whole, get the metallic option of theme.

Thank you for your replies.
I think I might have to change the whole set since the leaking persists.

I'm taking this video and the parts it mentions as a reference (the housing is metallic fortunately!)

https://www.youtube.com/watch?time_continue=567&v=tpYHZzezNac&embeds_referring_euri=https%3A%2F%2Fwww.scooterwest.com%2F&embeds_referring_origin=https%3A%2F%2Fwww.scooterwest.com&source_ve_path=Mjg2NjIsMjg2NjIsMjg2NjY

Just tap the hole M6 and screw in a short bolt.

The hole tapping + screw sounds a bit compromising.
I guess the hole is there for a reason, right? Maybe it ends up damaging the whole system.

I am 90% confident to purchase the new metallic bleeder + thermostat etc.

Thank you everyone for the support!

I think jimc was referring to a temporary repair to block off the leakage. The only time you need the bleed screw is when you change coolant every 2 years so unless you need to change fluid, you can buy the needed parts and do the jimc repair.

That is useful repair, temporal or not, but, the thing is: that has to be done with great care, as othervise the leak is next on metal/plastic border.