beta 28

[Gav]

Hi, i have a Beta 28, kabota 3 cylinder diesel engine. Under load at about 1500 rpm with the temp at about 155F there is steam coming out of the exhaust and less water than when idling. This is while still tide to the dock. The engine is mounted just below the waterline. Has a highrise manifold. I have replaced the impella and there appears to no obstruction with water passing thu the strainer. Thanks.

[freshalaska]

The obstruction can be after the strainer. 90 degree elbows can collect trash.
Take the hose off the engine side of the strainer and put it into a bucket of water with a garden hose suppling additional water and see if this corrects the problem.
I think you still have an obstruction. See if you can figure out where.

[Compass790]

As fresh alaska says, also any blades missing off the impeller you replaced?
Don't know your Kubota/Beta but has the heat exchanger ever been cleaned/ descaled?
Definitely should have more water coming out at 1500rpm than idle.
Also not unknown for rubber part of impeller to spin around the boss, looks ok but doesn't pump much.

[freshalaska]

One of the impeller blades could have broken off before and is stuck somewhere downstream.

[sailah]

I'll second the impeller blade. I have found them in my heat exchanger which seems fairly obvious and I check that often. However I found 3 blades jammed in the 90 degree brass elbow right at the RW pump outlet recently. I would never have seen them had I not removed the pump for a rebuild. Anyways, check any area that could potentially cause an obstruction.

[FPNC]

It is really hard to maker a judgement call on water flow by looking at exhaust output. You literally have to measure it in a bag or a bucket.

Your engine temp is not high at all. The engines thermostat does not begin to open until about 165 F. If you are seeing white smoke this time of year it can very likely be the cooler air temps and you are seeing steam. Particularly up north.

If you are concerned with water flow check impeller, check heat exchanger core ends for blockage or buildup and go ahead and remove and clean the heat exchanger core if you have not done so in the last 3-4 years.