CAMBELT AND BRACES
Rick Channon’s Beneteau needs a cambelt change but things aren’t as simple as they seem
y boat Greyfin is now 5 years old and due for a cambelt replacement – or at least I think it is! To be honest I’m finding it difficult to ascertain exactly when it needs to be changed. The manufacturer, dealers and service agents are all telling me different things.
I’m certainly no expert in marine engines but I do like to maintain things by the book and appreciate that a cambelt failure can cause catastrophic engine damage. However if I replace it too early I am simply wasting money, and with the sums being quoted it is worth getting the balance right between over caution and excessive risk.
My engine is a Nanni T4 200, which is a marinised version of Toyota’s 3-litre diesel engine from the Land Cruiser. It has done 250 hours and has been professionally winterised each year. According to the manufacturer, and my owner’s handbook, the belt should be changed every two years or 1,000hrs. Thinking that this was perhaps excessively cautious I sought further expert advice. According to Nanni’s UK agent it should be changed every four years but two local Nanni engineers told me every five years would be fine. Interestingly Toyota recommend a cambelt change every 10 years on the Land Cruiser!
Just to add to the confusion, changing the fresh water cooling pump while I was at it was also thrown into the mix and since this is what I do on my car it did not seem unreasonable.
However with a potential bill of over £1,500 looming I was keen to understand what was really necessary.
I quizzed a couple of experienced marine engineers who explained that firstly there is no connection between the cambelt and the water pump. The cambelt does not drive the water pump or block access to it. Therefore there is no benefit in doing both jobs at the same time as you would in a car. It seems that the water pump should be replaced on its own merit, with the first indicators of an issue being a leak from the seal or slight play in the bearing which can be ascertained by hand.
They then went on to explain that the cambelt and associated pulley and tensioner in a marine engine is prone to more wear in spite of the substantially lower hours of use. This is apparently due to the engine sitting idle in the winter which causes strain in one spot, particularly on the bearings. However, they still felt that a five-year replacement cycle would be frequent enough to avoid problems given that warranty obligations have lapsed.
Now that I was feeling more informed, I decided to change the belt set and to just monitor the water pump for signs of wear.
This still cost me £900 – twice that charged by Toyota, but as galling as it is, I did not have the nerve to buy non-nanni parts.