40 Plus: Century "minus", maybe leaky block?

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Bergie
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Joined: Fri Aug 07, 2009 9:03 am
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40 Plus: Century "minus", maybe leaky block?

Post by Bergie »

I have a 40Plus from my uncle that was not pumping water, in fact the faster the motor run, the less water came out. Its now fixed and its pumping a thick stream right down to sputter speed. I'm sure the impeller was the wrong way around, but struggled so much getting the water pump off I can't confirm. There was no blockage as far as I can make out.

The Century is now officially a minus! :wink: I swopped the gearboxes of the 40 and the Century, (you have to swop them at the water pumps though, and it fits perfectly) and then the century runs with a lot more power. That is the final nail in the gearbox coffin. The weak power is still a problem though. The 40 I need to really force a rag unto the flywheel to make it stop, but the century takes a little bit of effort to kill. I even swopped carbs (Villiers) to make sure its not carb related. Ignition is fine and honed to perfection. (The 40's points is set to 0.4mm, but I left it there since it does not seem to mind.) I've even been so daft as to try the 0,4mm gap on the century, but it does not like it at all. I think the the rusted through block has killed it, although it was/is only to the outside. Maybe there is a crack or hole from the water jacket to the the carb intake that I can't see.

For those who may want to know. The water jacket corroded away to the outside of the carb side. It was fixed by welding a plate on the outside of the block, it curbed the water leakage, but I now have reason to believe there may be an air/water leak to the carb intake as well. There is no obvious signs of it, at least it does not suck water into the crank! Any idea how I can test for a carb/water jacket leak or maybe crank outlet to cylinder? The cylinder wall is definately 100% intact. Maybe I will start a new thread on the topic in future.
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Waggles
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Joined: Wed Mar 05, 2008 10:27 am
Location: Essex, UK

Re: 40 Plus: Century "minus", maybe leaky block?

Post by Waggles »

To be perfectly honest with you I think I would be looking for a replacement block. There is a strong possibility the motor will have overheated at some time and could have distorted the block, even welding it could have done so too.

If the motor is down on power and everything else seems ok, have you checked the compression?

If you want to proceed to check for a water leak the only way I can think of would be to place said block upside down so water inlet and outlet are at the top, put some flexible tubing on the block input and connect a column of water ( in a clear glass / plastic tube or container ) once the water is coming out of the outlet so you know block is full put a well fitting bung in the outlet. Leave that for a while and see if water level falls and look for leaks. If all OK try heating the bore as the leak may only 'open' when hot.
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