T90 Exhaust problem

[chas]

I hope someone might be able to help me with a T90 exhaust repair. I have a system where the dry exhaust goes, via about 4 foot of flexible steel pipe, to a cast iron swan neck behind the panelling in the aft cabin, which is above the waterline. A separate pipe takes the cooling water from the exhaust manifold to this swan neck. There is a wet exhaust outlet which takes both from the swan neck to the exhaust outlet. I imagine this arrangement is there because otherwise the whole exhaust system would be below the waterline - even the outlet, which is below the counter.

What I think has happened is that 30 years of sea water has rusted the inside of said cast iron and the water is now getting down the dry exhaust pipe. It has rusted this and now, when I start the engine, most of the cooling water is being pumped straight into the bilge through a porous pipe.

I am having a bit of difficulty finding a replacement swan neck. Vetus do not seem to do one (I thought I had found one but it turns out to be an anti syphon device for water) Does anyone recognise my system and can advise on where I can find a replacement?

 

[Steve Clayton]

Chas,

from what I recall this is quite common. Moodyowners would be a good source of info regarding replacement.

Steve

 

[chas]

Thanks, Steve, I will try them

 

[NFCN]

Chas

This happened to my Moody 33 just as I was buying her. The previous owner was good enough to get the corroded exhaust elbow replaced. I think he went through Thornycroft itself:

http://www.thornycroftengines.co.uk/partsenquiry.htm

It's a common problem - they say they need replacing every few years. Cost I think was £70-80, plus fitting if you pay for it.

Good luck

Nick

 

[Danny]

[ QUOTE ]
I think he went through Thornycroft itself:

[/ QUOTE ]I did indeed, Nick. And, if memory serves, you've got the price about right. But from Chas's description I'm not sure he has the usual M33 arrangement. The normal arrangement is that the water injection elbow is bolted onto a 90 degree bend up from the exhaust manifold whereas Chas describes a 4' long flexible metal dry exhaust pipe before the water injection 'swan neck'. Sounds totally different to me. Maybe Thornycroft parts dept or the MOA forum can help identify it, though.

 

[chas]

Thanks, Danny & Nick. It would appear that I have an older system - dry exhaust and cooling water outlet going separately to the cast iron swan neck in the aft cabin and wet from there to the exhaust outlet. The swan neck is about 9 1/2 in wide, 9 1/2 in high and 5 in deep and weighs a ton. All the bolts holding it together are rusted solid so I cannot have a look inside without destroying it. It has 'YCGB' on it but I have never heard of them. I think the MOA might be the answer and I have registered so I can ask my question!

 

[Danny]

Chas, if you're stuck because you can't source the part then it may be worth thinking about changing to the usual arrangement of a right angled bend bolted to the exhaust manifold followed by an injection elbow followed by a long hose carrying the 'wet' exhaust to the stern. A good look at this arrangement on another M33 should show you how it's all installed. If you need part numbers these are available in the Thornycroft T90 manual which you can find a copy of on the MOA site.