Winterizing Yanmar 2GM

[chuck yahrling]

I tried flushing my Yanmar by removing the lid on the Perko raw water strainer and filling with fresh water from a garden hose, with the engine running (seacock closed, of course). I observed the water in the strainer occasionally dropping, it would happen 4-6 times then stop, resume after a few minutes, then stop. No more than a trickle came out the exhaust pipe at any time, but the mixing elbow was only lukewarm to the touch.

I replaced the lid on the strainer, opened the seacock, and started the engine; this time a lot of water came immediately gushing out the transom pipe, then it settled down to a normal, bursty flow.

I'm puzzled; the strainer body is well above the water pump, and I was careful to keep it full of fresh water. Shouldn't the flow out the exhaust be the same when flushing this way when compared to raw water intake? Or do I have to close the strainer and pressurize with the garden hose?



yahrling@cybertours.com

[Stephen Sousa]

I tried flushing my Yanmar by removing the lid on the Perko raw water strainer and filling with fresh water from a garden hose, with the engine running (seacock closed, of course). I observed the water in the strainer occasionally dropping, it would happen 4-6 times then stop, resume after a few minutes, then stop. No more than a trickle came out the exhaust pipe at any time, but the mixing elbow was only lukewarm to the touch.

I replaced the lid on the strainer, opened the seacock, and started the engine; this time a lot of water came immediately gushing out the transom pipe, then it settled down to a normal, bursty flow.

I'm puzzled; the strainer body is well above the water pump, and I was careful to keep it full of fresh water. Shouldn't the flow out the exhaust be the same when flushing this way when compared to raw water intake? Or do I have to close the strainer and pressurize with the garden hose?

Chuck,

The method I use is to fill a bucket with fresh water and maintain a constant flow rate while running the engine with the hose from the water pump in the bucket, then switch to antifreeze which protects the system for the winter. The impeller will create a suction in the bucket and flush the system. "DO NOT PRESSURIZE THE SYSTEM, IT IS NOT RECOMMENDED" When filling the sea water filter and closing the seacock a vacuum is created which will not let the water flow into the motor. The motor will run and not overheat without water running into the heat exhanger for a short time, the impeller shouldn't be installed in the water pump during this time. The oil and filter should be changed due to the acids within the oil from running.

Stephen




jsss@net1plus.com

[chuck yahrling]

I tried flushing my Yanmar by removing the lid on the Perko raw water strainer and filling with fresh water from a garden hose, with the engine running (seacock closed, of course). I observed the water in the strainer occasionally dropping, it would happen 4-6 times then stop, resume after a few minutes, then stop. No more than a trickle came out the exhaust pipe at any time, but the mixing elbow was only lukewarm to the touch.

I replaced the lid on the strainer, opened the seacock, and started the engine; this time a lot of water came immediately gushing out the transom pipe, then it settled down to a normal, bursty flow.

I'm puzzled; the strainer body is well above the water pump, and I was careful to keep it full of fresh water. Shouldn't the flow out the exhaust be the same when flushing this way when compared to raw water intake? Or do I have to close the strainer and pressurize with the garden hose?

Chuck,

The method I use is to fill a bucket with fresh water and maintain a constant flow rate while running the engine with the hose from the water pump in the bucket, then switch to antifreeze which protects the system for the winter. The impeller will create a suction in the bucket and flush the system. "DO NOT PRESSURIZE THE SYSTEM, IT IS NOT RECOMMENDED" When filling the sea water filter and closing the seacock a vacuum is created which will not let the water flow into the motor. The motor will run and not overheat without water running into the heat exhanger for a short time, the impeller shouldn't be installed in the water pump during this time. The oil and filter should be changed due to the acids within the oil from running.

Stephen

Thanks for the comments, but I'm not sure they apply:

I don't have a heat exchanger, just raw water into the water pump.

I don't follow how any vacuum would be created, as in my method I'm just substituting the raw water strainer reservoir for the bucket you suggest. That is, the garden hose goes right into the top of the strainer body (with the lid off) and overflows into the bilge. As long as I keep the reservoir filled, there should be no starvation to the water pump.

The only thing I can figure is that the pump needs a closed loop in the supply end to develop enough head to push water into the mixing elbow. But....I put my hand over the strainer opening to test that theory and it didn't help.

Also, it seems water actually was getting to the muffler but not out the transom, as I saw a lot more than normal come out at first when I put the system back to normal.

Maybe my impeller is marginal......