Modern Vespa

Hi all,
I have a 2008 Piaggio BV250ie with the Quasar engine. It's suddenly started leaking coolant — a lot — especially when I start the engine. The leak seems to come from underneath, around the middle of the engine, near the oil filter area.
When the engine is off, barely any drips out. But when I start it, it flushes coolant fast.

I suspect it's the water pump. I'm looking at the RMS repair kit. Before I tear into it, I'll post a short video of the leak to confirm.

Anyone seen something similar or done this job before? Do I need anything beyond the pump kit?

And one more question: Do I need to rebuild the whole water pump, or is it possible to just replace one part (like the seal or bearing) if that's the only issue?


Appreciate any advice.

Here is actual video if u can see:

https://jmp.sh/s/t3Kvq5QlIGFw9hVVTz91

That's not a very helpful video. Is it coming out of the nipple on the water pump housing? If you replace the water pump, they sell the complete unit, no seals to press.

Thing is that the whole unit seems more expensive than the rebuild kit.
I wanted to know if I can order only some parts OEM not RMS Rebuild KIT. As I trust more OEM ones but getting full list of OEM is again expensive.

You can replace the ball bearings of the pump shaft. The ball bearings are 638. You will need 2. You have to buy the mechanical seal , oil seal and the gasket of the cover from piaggio.

Remove the stator from the cover and heat up the cover on an electrical plate for about 5 minutes it will help with removing and installing the shaft of the pump. Be very carefull when instaling the meachanical seal.

I rechecked again and filled fluid but it leaks after filling nonstop untill there is almost no coolant. Even that engine is off it drops coolant nonstop.

Idk if it helps but i got a new video so screenshoted this: in red circle seems that leak is comming from there somewhere. Can it be something else rather than water pump

Have you removed the seat bucket access panel and looked from above?

Yes I checked from there but I cant find any visible leak near thermostat or somewhere else visible. Only thing i see is this water source in image. Looks like water is comming from there. I dont know for sure where is the weep hole but I don't think that coolant is comming from the hole.

The leaking hole of the pump is under the stator cover. If there is no leaking from the hoses connections , freeze plug or the thermostat cover and the water is coming from the base gasket of the cylinder then the head gasket is leaking and water passing through the orings at the cylinder studs. What is the condition of the oil? Is there water in the oil?

I made another video of leaking. This is all i can see without removing plastic covers. But it doesent seem to come from under strator hole at all

Oil is in good condition I rechecked it seems normal without water.

What do you think ? Thanks in advance

https://streamable.com/0p69jq

I am sorry but it is very dificult to see from the video from where it is leaking . I have read that you already checked but remove the carburattor cover inside the helmet compartment and try to see if you can point the leakage. It could be a hose connection.

Have you checked all the(18 year old) hoses?
I would use some engine degreaser on it. Then use some coolant dye to see where it's leaking from.

You should start removing body panels down to and including the seat bucket. You're going to end up doing it anyway. Get down to the frame, so you can find the source. I suspect, as others have said, you'll find a compromised clamp.

I have a BV250 2006 so it has a carb. It was leaking from the thermostat housing so I replaced that, which helped but it was still leaking, just less. It turned out that there is a carb bowl heater that takes coolant from before the thermostat and runs it under the bowl and than back to the system after the thermostat and it was leaking under the carb. I just short circuited the tubing. I live in California where the temperature rarely goes below 45 or above 75, so it wasn't really necessary anyway. You don't have a carb so that shouldn't be an issue.

Taking off the plastic is a pain, but it's really impossible to solve this without doing the whole job, including the underseat storage.

A failed coolant hose will spray coolant a significant distance from its source totally mis directing you. As others have said , in order I would
1) Remove as much plastic as possible
2) Gunk / engine clean the motor to within an inch of its life, so all surfaces are clean and oil free. Then let the engine DRY.

3) Add a dye , food dyes will be the easiest, to clean water and add to your coolant
4) Get some good lighting below and at the side of the scoot.
5) Start the engine, THEN immediately stop it and look for weeps / coloured fluid.
6) Wipe it down , and restart the engine for a few seconds more until the source is revealed.

Good luck with your quest

His bike is fuel injected. No carb heater on it. If you take it to the frame and start it up, as quickly as it drains the coolant, I'm pretty sure the source will be obvious.

UPDATE:I finally had some time today to remove the plastic covers and properly inspect everything. Turns out the coolant leak is coming from the cylinder base gasket 😞 I was really hoping it would just be the water pump, that would've been much easier for me to handle on my own.

What should I order to fix this properly? Do I just need a top-end gasket set, or are there other parts I should replace while I'm in there?

I want to take only OEM parts from piaggio.

You will need
831174 head gasket
BO17342 sealing ring 4 pcs
828146 cylinder base gasket 0.4 mm
480853 exhaust pipe gasket
829536 head cover gasket
830249 damper drift 5 pcs
847928 cam chain tensioner gasket
If the thermostat was not ever replaced it would be wise to replace it
82831R5 thermostat
297027 o ring

Let me add that I've dealt with scooterpartsco.com for genuine Piaggio parts and been satisfied. Their prices are better than dealers. Search their site with the part number, which you were just given.

You don't *need* all those, although it might be wise to consider replacing them anyway. Done carefully, all you actually need is the head gasket itself.

Im giving update. I bought those all without termostat.

Today i talked with mechanic and he said that he couldn't notice any damage in cylinder or somewhere else. He said maybe O rings have allowed water to pass to cylinder base and leak. Also he jave checked again for coolant and oil mix , everything seems fine.
Mechanic suggested to do a head resurfacing then putting back all with new gaskets.

Im hopping this fix to work!
What do you thing , should it work ? And why it can happen

Thanks in advance

Head gasket failure is common problem in that engine. Mine was blown at 60000 kms and my friend s scarabeo 300 had the same failure at about 70000 kms. There is no need to machine the head surface if it is not worn, corroded or distorted.

Im not well informed and not so much into parts. Mechanic said for future is better to machine head surface. Maybe mine is not worn or something but he just wanted to be sure.
Also does resurfacing it does something bad to speed or anything else ?

If you haven't overheated it, there's little to no warpage expected.