Water leaking from heater vent when pump on

Hello again! 

Just wondering if anyone has ever come across this problem - when I turn on the water pump in my van water starts pouring out of the side of the water heater vent (not sure of the technical term) on the outside of the van. 

The guy I bought the van from reckons a seal has gone, but is now not replying to me..so no real idea on what that would be called or if he's just trying to make it sound like a simple fix when it's not. 

I will get it checked by a professional, but thought I'd post here in the meantime to see if anyone has come across this to shed any more light on it for me! 

My van is a 1995 Peugeot Boxer Harmony. 

Thanks in advance, 
Katie 

I guess it's fair to assume that you have a Carver Cascade water heater? Exactly what part of the vent is the water coming from? The degree of seriousness depends on whether it's coming from the lower drain plug (which can split), the upper air bleed valve (which may not be present on earlier models) or the central combustion gas vent.

I would suspect that if he has suddenly stopped talking to you, he was probably aware that the problem existed when he sold the van to you.

Yes, I suspect that too! 

That's right, sorry I should have said it was the Carver Cascade water heater. It's coming from the lower right side of the heater vent. 

Thanks for taking the time to reply 

So, from the central flue and not either of the other two? That suggests that it was left with water in it over winter and has sustained internal damage. Assuming parts are available, I think it is fixable, but it's a lot harder (from what I can recall) than the typical split inlet/outlet spigots.

It's probably worth making contact with Arcsystems (arcsystems.biz will find an email address for them) to see what they suggest.

That's right, the central vent. Let's hope it is fixable! Thanks @roopert.

Need to take the vent cover off to see where the leak is coming from. Many causes possible.

Mine was a complete failure - tie rod broke but just had a leak due to hose coming off a spigot which was easily fixed (relatively due to location being awkward.

Or the gas burner was lit without venting the heater first and the fusible plug melted?