Testing without Lower Unit?

[nathanhooper]

I know this may sound like a crazy question. Maybe it is, maybe not. But I can not seem to find where it has been asked before.

Is is ok to test the motor without the lower unit on?

I know, there is a big red flag with the fact you should NEVER run your engine without water flowing through it. Got that, but can you hook a hose up to it and provide water that way? There is more than enough pressure to move the water through the motor like a impeller would.

The only draw back is it over revving. But if you just wanted to start and let idle, would that be any different then starting and idling with the lower unit attached?

Why would I want to do this? Well its a generic question really, but I did get this funny little hose attachment with the boat I got, and wondered what it was for. I have not tried it yet, but it looks to be so you can hook a hose directly to the water inlet tube. However, you could only do that if the lower unit was off. So, hence the question.

Please feel free to give any and all advice concerning this. Thanks.

 

[Frank Acampora]

Re: Testing without Lower Unit?

Sure you could do it, but the idle most likely will not be correct because the lower unit gears and water pump absorb some horsepower. Kinda like in the old days when they would dino-test an engine and rate horsepower. The engine was mounted on the dynamometer with no water pump, no fan, no power steering, and no alternator. Of course the power to the rear wheels was significantly less than quoted.

 

[nathanhooper]

Re: Testing without Lower Unit?

So you do not think there would be a problem with it "running" away? Or am I correct in thinking they are just referring to the lower unit and the way the gears are set up in it? I would think that it would not be the same thing with the powerhead because there are no "gears" in it.

I am not concerned with calculating h.p., or with timing, or anything like that. Just curious to see it run, and I know the water pump is going to have to be rebuilt, the motor is really to big for any containers I have or want to mess with, so I figure I could rebuild the lower unit, test the powerhead, then take it to the lake for the final "tune" up. I really do not like the muff thing and all. I never feel as though I have a good connection on it. And besides all that, I was just curious about the hose adapter thing that came with the boat.

I just do not want to do something stupid, and was wondering if anyone had done it before with a bad outcome because of it.

 

[john from md]

Re: Testing without Lower Unit?

It will be very hard to keep the engine from overspeeding in any throttle settings except idle for some of the reasons Frank gave. It will serve no purpose to start just the powerhead without the lower attached.

Do yourself a favor, wait until you have everything else fixed and the engine back together before starting it up.

John