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1980 Evinrude 35hp only pees while on the muffs, not in a bucket

SaltyScot

Regular Contributor
I bought this motor and of course tested it before buying and it peed fine while on the muffs. So a month later, I put it on my boat and put a bucket of water under it up to the cavitation plate and it wouldn't pee at all. Put the muffs back on: pees great. So I changed out the whole water pump and it hasn't changed anything. I barely have the hose on so it's not putting out too much pressure. In searching forums, it's usually more likely to not the pump on the muffs, but yes in water. Anyway, IDK, i'm getting tired of these 31.8's. I had a 1976 25hp that I was never able to get pumping any water at all. Should I just take it out to the river and see if it pumps while in deeper water? I can't go any higher in my bucket. Any thoughts?

Stephen
 
Great. Thanks guys.

I'll note, it's on an 11' two seat hydroplane I just finished building over the summer. Should be fun.
 
Post #1 says you had it up to the cavitation plate. Think about it, that's way below the water pump. Besides that, as I've said many times, you cannot test a water pump by running on muffs anyway.
 
Make sure you get a suitable prop for high speed and a light load.-----Very easy to destroy a motor with too low a pitch !!
 
Agreed. Not enough water. Gotta put a deeper bucket on your "bucket list". As Racer pointed out....Gonna need a pretty bad prop too. You'll hatch the motor with the prop that came with it.
 
Agreed. Not enough water. Gotta put a deeper bucket on your "bucket list". As Racer pointed out....Gonna need a pretty bad prop too. You'll hatch the motor with the prop that came with it.

At least there’s more props available for this motor than the 25. On the 25 the water outlet tube was just dangling and I could not align it when reconnecting the LU. The 80+ have a better design.

Would I need like a 13 or 15? I’ll probably be too scared to run it full throttle for awhile.
 
There was nothing wrong with water tube from pump to powerhead design on OMC motors.----Maybe there was a problem with your motor that could have been fixed !
 
There was nothing wrong with water tube from pump to powerhead design on OMC motors.----Maybe there was a problem with your motor that could have been fixed !

Yeah, I'm pretty sure it was loose at the powerhead. By better design, I meant there is enough of a gap to actually see the tube enter the pump housing as you raise the LU. On the old ones, there wasn't enough of a gap to see. Just kind of eye-ball it and hope.
 
I worked on a lot of different OMC motors over the years.------Never encountered this " bad design " you speak of.
 
Well, we had some ugly weather in Portland today so I got a bigger bucket and it's pumping fine. Happy happy joy joy!

Thanks for setting me straight on that water level Racer.
 
So I made it out to the Willamette River today. Man, we need some more water out there. It's getting really low. I put the motor on a 14' Starcraft aluminum boat I just bought last weekend. First time out for the boat and the motor and everything went great. Motor was smooth and peed great. I didn't go to full throttle, only about 2/3 or so. Still was pushing it 22 mph. I also picked up a 1976 Johnson 35hp, instead of having to swap this one back and forth between my hydroplane and fishing boat. Now I'll have to make a thread about prop selection for these two boats. Fun stuff:)
 
Finally got it out. It was awesome! Even only at 27mph it seemed like 50. Very smooth ride and didn't turn too bad for a hydroplane. I didn't want to push it anymore. I ran out of light before I tried all the trim settings and gas tank locations. I want to get it trimmed better and with a 10x15 prop. I put a hydrofoil on my motor and there was ZERO cavitation. Of course my 240 lbs kind of helps in that department.:D Boat is called a Minimost XL and there's 5 different videos of them on youtube and only 1 or 2 didn't cavitate. Very pleased with the performance so far.
 
Agreed. Not enough water. Gotta put a deeper bucket on your "bucket list". As Racer pointed out....Gonna need a pretty bad prop too. You'll hatch the motor with the prop that came with it.

Well, it hatched! But not with the prop that came with it. I put a 10x15 on it. I was only pushing it about 4000 rpms and going 30 mph in my hydro. But it overheated and fried the powerhead. Now 60psi per hole. The impeller, housing, and housing spacer are all melted. I don't know what happened. I had it out six times since I replaced the water pump. Everything seemed fine as it peed fine every time. Apart from the water pump, the lower unit appears to be ok. I'll have to inspect that more closely though. Maybe I just cooked the head gasket?
 
They are pretty good. Could the intake have gotten plugged with something?

That's very possible. There was a lot of sticks and vegetation in the river yesterday from all the heavy rains. It seems like things went bad when I would decelerate for the turns. I didn't see anything stuck to the intake screens when I lifted the motor. I'm going to start opening this motor and check it out today.
 
Of course with less rpm, the suction is minimized, then as you continued with a melted impeller, there was NO suction.....and the debris washed off.....reasonable thinking?
 
Yes, but I'm wondering if I have the foot deep enough in the water. I've heard differing opinions on this type of craft. I have the cavitation plate level with the bottom of the boat. I have a keel down the middle of the boat, but it terminates 30" in front of the transom. There is no bow rise and very little draft. Some people run their motors higher for better performance and use a low point pickup. But that's with more bow rise than me. I don't know. I gotta figure this out before I put another motor on there. I will start a new thread about adding an overheat alarm to the 1976 Johnson 35 I will put on there(no telltale).
 
Agreed....might not be the correct motor for your watercraft.

which would beg the question... what would be the right motor? �� or the right depth? I know, much more data would be needed for that question, but i guess a couple inches deeper would be a starting point? Or a low point pickup? Or?
 
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