Inspection and maintenance
Starting at the engine end, it may not be absolutely clear which is the last part of the engine proper and the first part of the exhaust system. So the best thing is to start with the water injection elbow and the pipe, usually rubber, bringing water from somewhere on the engine cylinder head. This must be rated for hot water. Car heater hose is quite suitable in this case. Check for perishing and general condition, and look for leaks, particularly at both ends.

The hose clamps should be of stainless steel, free from significant corrosion and gripping the pipe tightly, but not so tightly that the pipe is reduced in diameter by more than a millimetre or two. Over-tightening of hose clamps is a common mistake that leads to premature failure, as the edges will actually cut into the hose in extreme circumstances.

Then work your way back along the exhaust system, looking for damage and deterioration to components and checking the tightness of the exhaust clamps. Signs of blow-by due to loose joints are evident by staining of the pipe next to the hose. But again, be wary of over-tightening tee-bolt type clamps.

When inspecting an exhaust system you aren't familiar with, do check that all the components are of the right quality -particularly the hose. Replace anything that doesn't come up to scratch. A common fault is lack of support, which can be dangerous and will certainly shorten the life of the system as stress is applied in places it shouldn't be. If you have any doubts about the quality~ design or the way your system is assembled, your exhaust supplier will be happy to advise.

Draining silencers
Waterlift silencers always have some water in the bottom of them and should be supplied with a drain tap or plug. Freezing can cause damage to the silencer as the water expands, so it's wise to drain them off if the temperature is likely to fall to +5 deg C for fresh water and 0 deg C for salt. This leaves a bit in hand for the weathermen to get it wrong!

You should also drain all silencers before you lift the boat if there is any danger of the crane, lorry or ship putting the boat in a steep enough bow down angle to allow water to run forward out of the silencer. Take particular care if the pipe entering the silencer is anywhere near the minimum 1 in 8 gradient. Draining silencers for transport might seem unnecessary, but imagine what happens to the water in the silencers when the transporter has to make an emergency stop. On ships, boats are often carried as deck cargo, strapped down laterally. One good roll in rough weather and bingo -you may have a hydraulically locked engine and a very large bill.

Maintenance Guide