Modern Vespa

Went out for a ride on my gt and coolant spewed from the resevoir.

The temperature was perfect and the coolant was filled to the proper level before the ride.

Any ideas would be great.

Might the thermostat be bad, even though I just changed it?

Maybe the cap was loose???? or you have a stoppage somewhere?

Cap was tight.

Stoppage somewhere sounds fun though.

Did u check part for function in hot pot, if so u may have trapped air in system, check service notes for purge procedure. Good luck.

You have a leak. If the cap is tight, either the cap seal is bad, or the hose clamp at the reservoir tube is loose. The reservoir is under pressure when the engine is at operating temp.

i just replaced a coolant resevoir on a relatively low mileage bike this week. i couldn't seem to figure it out untill i pulled the g'box off, and then i found the hairline crack down the side next to the cap.

get it up to operating temp and then see if you can figure where it's spewing from.

best,
-greasy

The thermostat is operating just fine according to a hot pot test.

Obviously when it spewed the first time I was unable to see where from due to the cover. The funny thing is though, I had it perfectly filled to right below the max line when I left after reinstalling the engine and even after the spew of say a half litre it was still at the right below max line.

?

This GT is driving me mad Thanks for the input thus far. I hope to get to the bottom of this and your ongoing help is appreciated and needed.

Trade you for my LX.
I have never had radiator problems since I bought the scoot..

i hate to ask the obivious, but are you sure that the t-stat is installed the right way around?

i'm just sayin'...

best,
-greasy

I have never touched a stat on a GT....so this may be pure BS....but here goes.

There is no bleeder for trapped air on the GT, you have to 'burp' the air from the system at a hose connection. I remember being told to bleed out the air at the highest point at the motor, which should be at the stat housing.

On a GTS project I had one heck of a time getting all the air out of the system, even with a bleeder built into the housing.

The 'max' line at the reservoir is where you want the coolant level when the motor is warmed up, the level will be below that when the motor is cool, but this detail is not a problem that could cause the reservoir to overflow.

You can always pull the new stat and test it per instructions in the service manual to eliminate it as a fault.

Why did you change the stat? Were you overheating?

If the stat checks okay, work on getting the air out. Once that is done if you still have a problem you might need to pull the waterpump cover and check the pins driving the pump impeller, but this would cause noticeable overheating. Bad head gasget can cause air to be pumped into the system causing the problems you describe(worst case).

A stat won't work right with air trapped below it.

The entire cooling system only holds about 2 liters.....

Hope this helps.

R



8)

I wish it was that it was mounted the wrong way greasy, although the thermostat housing only allows it to be installed one way. but thanks for just saying.....some times it is the simple things.

Also the head gasket along with the top end is brand new as I just rebuilt it after a major overheat.

This GT is driving me nuts.

Did you change out the cylinder along with the head?

Crack in cylinder can act like bad head gasget....

Malossi kit?

Horror stories about cracks in Malossi kits for the GT....

Best of luck to you

R

8)

No I did not change out the piston, damn it!

I changed the rings and the cylinder head to no avail and now I must change out the piston and the piston housing to the malossi 210 kit since it is the same cost.

I hate my GT at this point and I have no one to blame but myself for letting it overheat.

Mine did that ...


... when the water pump failed.