My two month old Honda has just covered 800 enjoyable dry miles.
On carrying out the normal cleaning after today’s run I noticed dry green crystallised discolouration under the water pump.
I made cursory checks around all the hoses to the pump and the pump seal area itself and all looked good.
I decided to clean it up and in doing so I found a small weep hole right under the pump. It’s very small. Clearly a small amount of coolant has found its way the wrong side of the bearing.
This was always a problem or should I say issue with my Vespa 300’s when I owned them.
I guess Honda will say a small amount of leakage is expected. I must admit since leaving Vespa for Yamaha and other Hondas I’ve not noticed this issue before. Before you ask the bike has used less than an egg cup full of coolant from new.
Has anyone else noticed a similar issue with an ADV or Forsa before I make myself a nuisance with the dealer..
Bugsy.
Honda ADV350 water pump weep hole.
- bugsy
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Re: Honda ADV350 water pump weep hole.
During the running in period this may be acceptable because the ceramic part of the seal will possibly work better when the working surfaces bed in. So I would be inclined to clean it up then check after another couple of hundred miles. Also keep an eye on the colour of the engine oil. If there is the slightest trace of water in the oil that would be a much more serious issue.
Located on UK South Coast
Honda Supercub SYM Joymax 125 and Honda CB300R. Previously Silence S01, Kymco AK550, Triumph Tiger 850, Triumph Street Twin etc...
Honda Supercub SYM Joymax 125 and Honda CB300R. Previously Silence S01, Kymco AK550, Triumph Tiger 850, Triumph Street Twin etc...
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Re: Honda ADV350 water pump weep hole.
I had this on my CRF300 Rally, from brand new. It leaked seemingly at that spot from the first ride, and eventually lost all it's coolant. If you Google "Honda 300 Coolant Loss" you will see it is a common problem. I think it is actually leaking from the flange of the metal pipe just above the water pump. ( I'm assuming the "350" and the "300" are similar basic engine). The dealers seem to know about it. I had to trailer my bike back to the dealer, but the warranty repair was approved immediately and I had the bike back in a week. I've done about 600 miles on single track roads all over Scotland since and it is fine. There was I understand a bad batch of flanges. Talk to your dealer and make sure they know about this issue.....
Honda NC750X, Honda ADV350
- bugsy
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Re: Honda ADV350 water pump weep hole.
Thank you both for your valuable insight into this issue.
I have emailed the dealer, who is closed on Mondays and await a reply. Unless there have been other reports I suspect I will be told they will note my issue and I will be asked to watch it for the next two or three hundred miles.
In case others are having similar issues I will keep you updated with their advice and how things progress down the line.
I have emailed the dealer, who is closed on Mondays and await a reply. Unless there have been other reports I suspect I will be told they will note my issue and I will be asked to watch it for the next two or three hundred miles.
In case others are having similar issues I will keep you updated with their advice and how things progress down the line.
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Re: Honda ADV350 water pump weep hole.
I have had an email from the dealer who has asked me to monitor the issue.
They have told me quote. ’ it has been common to have a little coolant coming out of the drain hole especially from new and the running in service. We do get some brand new bikes from the crates which expel a small amount of coolant from there even before they have been run.. ‘
I haven’t used the bike since but will monitor the problem over the coming weeks and will report back…
They have told me quote. ’ it has been common to have a little coolant coming out of the drain hole especially from new and the running in service. We do get some brand new bikes from the crates which expel a small amount of coolant from there even before they have been run.. ‘
I haven’t used the bike since but will monitor the problem over the coming weeks and will report back…
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Re: Honda ADV350 water pump weep hole.
Since being advised to just pay attention to the coolant level for a while I have now covered 1400 miles. I have carefully watched the area around the weep hole on cleaning after ride outs. Some times there is no evidence of any leak and others there has clearly been a loss with staining below the water pump housing.
The level was just over half way between low and full. I have topped it up to the line to watch it more accurately.
I really don’t know if this is acceptable or not.
Any other ADV owners out there had to top up at all?
Thanks
Steve.
The level was just over half way between low and full. I have topped it up to the line to watch it more accurately.
I really don’t know if this is acceptable or not.
Any other ADV owners out there had to top up at all?
Thanks
Steve.
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Re: Honda ADV350 water pump weep hole.
Mine hasn't needed a top up after 11 months and 4600 miles.
2023 Honda ADV350 & 2020 Honda Super Cub 125
- bugsy
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Re: Honda ADV350 water pump weep hole.
Mottza
Thank you, noted. I will try another longer day out having topped it and if there’s any trace I will give the dealer notice to sort it.
It’s the only black mark about a bike I am so-is so pleased with. Yes I’ve enjoyed all the Yamahas and Hondas I’ve owned of which the NC was great but heavy with all the kit attached.
Now age is gradually catching up with me this bike ticks all the boxes. It’s price, handling comfort and power for a 350cc is extraordinary. With the back box it delivers a great package.
Bugsy.
Thank you, noted. I will try another longer day out having topped it and if there’s any trace I will give the dealer notice to sort it.
It’s the only black mark about a bike I am so-is so pleased with. Yes I’ve enjoyed all the Yamahas and Hondas I’ve owned of which the NC was great but heavy with all the kit attached.
Now age is gradually catching up with me this bike ticks all the boxes. It’s price, handling comfort and power for a 350cc is extraordinary. With the back box it delivers a great package.
Bugsy.
- Data
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Re: Honda ADV350 water pump weep hole.
bugsy, congrats on getting the new bike. Regarding the water pump weep, with my ex-tech hat on, I can tell you it probably isn't ever going to stop weeping. If it was it would have done so by now with 1400 miles on the clock. If you do a much longer than usual run it's my guess you will see a nice weep after the bike cools down. The system runs at 13psi & it'll find it's way out but will only be visible when cold after a good trip. Definitely time to tell your dealer I'd say. Not normal to use that amount of coolant.
Probably not ugly enough for the 'Ugly Bunch'! 
Been riding for 55 years & owned too many bikes to list here...

Been riding for 55 years & owned too many bikes to list here...
- bugsy
- Posts: 98
- Joined: Wed May 07, 2014 9:18 pm
- Current Ride: ADV 350
Re: Honda ADV350 water pump weep hole.
Thanks Data,
Weirdly enough it’s never leaked after a ride. Even giving the weep hole a good wipe with tissue during the cooling period doesn’t show any coolant. It’s clearly evaporated off the warm transmission.
I will definitely speak to the dealer….
Weirdly enough it’s never leaked after a ride. Even giving the weep hole a good wipe with tissue during the cooling period doesn’t show any coolant. It’s clearly evaporated off the warm transmission.
I will definitely speak to the dealer….