The Honda PCX / Forza / ADV150 / SH Forums

So while riding, the bike kinda started to lose acceleration, felt it a lot when going though steep roads. Decided to stop half way through and the moment I stoped the bike, coolant started to poor out not sure if it was a hose leak/crack or was it just extra coolant overflow.(Will check and update) but the main concern is at that moment when I checked the temperature the bar was in the red area. Not sure where to start troubleshooting because can accretion response reduce when the a bike is overheating?

I think yes, and the engine will blow up subsequently... ! well , joking aside , it will cease eventually...

I had that happen to me once on a car 35 years ago, fell in a deep pothole at night that could not see, cracked the oil pan at the bottom, oil leaked out so quickly it was game over in 5 minute..., by the time the temperature gauge went to red and engine light came on it already ceased... - and it was my uncle's car, he still remember it and tell me I owe him an engine...! lol

I had that happen going up the very steep, very fast Coquihalla Highway in BC, Canada.

I had to open the radiator cap to add water from a bathroom. I got a cup out of the garbage can.

I had recently bought the used 2014 Honda Forza 300. I think it had an airlock in the cooling system. There is a proper way of getting the air out. I just kept adding water in the parking lot.

That bathroom water is still in my Forza after 140,000 km of riding. No problems.

Ok sorry for my noob questions as this my 1st scooter and its quite different compared to my usual dualsport bikes.

So few updates.
1. I just check for leaks and couldn't find a visible spot, so I drained the existing coolant which had around around 500ml of coolant when drained.
2. Poured in new coolant and let the engine idle for a minute with the radiator cap out and the coolant level had drop had toup about 200ml. Im used to this as trapped air leaks out the level drops.
3.Let it idle 2 twice for few minutes with the radiator lid on, and I had to topup 200ml each time.
4.Let it idle for the 3rd time and the coolant dropped again.

So now where is all the coolant going?
Overflow tank? No its still in the same level

This is definitely not right, these Forza are just like cars, I have no idea where your coolant is going, quite a few possibilities...! But if no leak to outside , God forbid it could leak in the engine...

3 years ago we had this on a car that I shared with friend, as coolant would go down and engine got hot we topped up, but no leak. Eventually white stuff appeared on engine oil cap and we suspected leak into the engine oil , we suspected head gasket , but mechanic opened, it was fine, then opened it further and found cylinder had cracked, total engine write off - but new engine was so cheap for that 20 years old Toyota, we just replaced the whole thing... (damn , so I had two engine failures in my time so far... lol)

I'm hope yours is something simple...

I also did about 3 fill ups when I had my problem. It took way more than I expected.

The Forza take 1.5 liters to fill up completely, radiator and coolant overflow tank.

Thanks for the tips.


Question:

Where does the excess pressure and heat overflow if the coolant level is low?

Can the pressure push the radiator cap spring up or
does it need to have coolant to the tip to push the spring up?

Its a sealed system there isn't an overflow.
The water pump shaft is a possible source of leaks, there's a weep hole under the water pump, if the water side seal fails coolant will drip from the weep hole.
PCX expansion tanks are known to crack due to faulty manufacturing, how is yours looking, is the cap on properly?

Can the pressure push the radiator cap spring up or
does it need to have coolant to the tip to push the spring up?

1) Doesn't matter if it's steam pressure or liquid coolant pressure. Any pressure in the coolant system which is over the radiator cap's rating will force past it into the overflow tank, no matter whether it's coolant or steam. Notice that the tube goes from the base of the radiator cap to the BOTTOM of the overflow tank.

2) Likewise, when the engine is turned off and the coolant system pressure drops to a negative, the coolant that was previously forced into the overflow tank will be sucked back into the coolant system .... thru that same tube which leads from the BOTTOM of the overflow tank to the base of the radiator cap.

This 1) & 2) cycle repeats itself every time the engine gets hot and then cools.

Put some coolant in the overflow tank and see what happens to it. Does it leak out because the tank has a crack or hole in it? ..... Or does the tube that connects it to the radiator have a leak?

Also when you fill the radiator / coolant system, be sure to also 1/2 fill the overflow tank as well. That way, when the engine cools after the scooter is run and the coolant system / radiator hadn't been filled completely (and it was steam / that was forced out), it will have coolant in the overflow to suck back in instead of air.

OP says he already checked for leaks and could not find a visible spot with any leaking...!

Well...

I just realized something on that day when stopped I heard a hissing sound thought it was the fan and I dont think the little smoke was off the boiling coolant leak. F$CK!!!!!!!!!
And the best part is this is my 1st scooter. Gave the bike to the mechanic to service it on the day of purchase and this happened on my way back when bringing her home for the 1st time.

So in the process of troubleshooting this happened...
Not very sure if this is normal please check the video. Btw as you may see the coolant didn't even boil up to a evaporating state.

https://vimeo.com/469860930