Engine lugging down

[cpowell]

I guess I should have called myself "This Old Boat" instead of my real name....I posted this question in the props section but it was suggested that I move it over here so here I am again.

This old boat, Maxum 19 foot with Mercury 115 will often times lug getting started. Sometimes it will run just fine then suddenly there is an increase in RPM but a loss of power. It then slows from running 20-27 mph to around 9 mph and won't come back up to speed. This is at WOT.
Turn it off and let it set while you fish awhile then it will crank up and run good again for awhile.
The increase in RPM makes me think it is a prop problem along with everything else that is wrong with it.
No, I don't know what the RPM is yet. Am getting a tach tomorrow at Bass Pro in Houston....I hope....
Oh, I think the prop says 17 on it if that helps your guessing.
Since last night when I posted this I have gone to BPS and gotten a tach. Hope to get it installed tomorrow and report back on RPM Wednesday

 

[andy6374]

Re: Engine lugging down

Does it rev real high? If so could be a slightly spun prop hub.

 

[studlymandingo]

Re: Engine lugging down

Yep sounds like the hub is slipping in the prop.

 

[cpowell]

Re: Engine lugging down

So what do you do about that? New prop? Lower unit??? What's the next step?

thanks for all your help

 

[andy6374]

Re: Engine lugging down

Take your prop to a prop shop to get fixed.

 

[studlymandingo]

Re: Engine lugging down

What is the brand of prop? Some props have an integrated hub, while others use a drop in hub that is replaceable. The integrated hubs are best fixed by a prop shop, the replaceables are well, replaceable. You can buy one here on iboats, or at a boating store near you.

 

[cpowell]

Re: Engine lugging down

I just checked while in for supper.
There is no brand name on the prop just the numbers 2036 17

 

[cpowell]

Re: Engine lugging down

I pulled the prop off today and checked again and no, there is no brand name on it just those numbers. I looked at the splines on the inside and on the shaft from the lower unit and they all look fine. There is a brass insert that comes out I am guessing that is the replacable part you refer to (?). Tomorrow I will take it in to a prop shop somewhere, if I can find one, and see what they think.
Man, this boat stuff is hard! and expensive....ha ha

 

[andy6374]

Re: Engine lugging down

If you are taking about the brass "thing" behind the prop on the propshaft, that's the thrust washer and it isn't what we were refering to. The hub is "glued" between the prop and the splines and if the hub comes loose (spun hub)... when the propshaft turns it will turn the splines but since the hub is spun it won't turn the prop, so it will rev high because there is no load on it.

 

[cpowell]

Re: Engine lugging down

No, I see the "thrust washer" behind the prop and I am talking about something else. The prop rides (?) on a brass insert that slips onto the splines of the shaft. When I took the prop off this part fell out of the prop when I turned it over to look for a brand name.
Someone said there was supposed to be some kind of rubber thing inside and you refer to "glued". There is no rubber or plastic anything anywhere there and since you refer to "glued" I am guessing that it isn't supposed to just fall out like it did.
Is the washer supposed to turn freely or is that something else that is wrong?
Oh, inside the brass insert there are some other locks but they look fine as well but then what do I know. ....
Making a quick trip to the "prop doc" with it this morning to see what he says. May have to get a whole new prop as this one is pretty chewed up on the edges. I don't know.....but I sure do appreciate the help here! Thanks guys!

 

[cpowell]

Re: Engine lugging down

Just got back from the prop shop, went to two places and both told me the prop wasn't spun but that the blades were bent so bad it probably wouldn't go anywhere, so I left it at the second shop because they said they could get to it today. Projected cost of the repair was $55 that is IF the blades don't break then it would be $5 extra for each weld. I thought it a reasonable price. At least I can be sure that the prop will fit when I get it back on.
Honey will be back in this afternoon to go fishing, he said he should have it finished by 5:30 and I will let you know how it does tomorrow.

 

[cpowell]

Re: Engine lugging down

Well, he didn't get the prop done today, said it would be more like sometime Saturday so I brought it home and put it on the boat again. I am taking it out tomorrow morning so I can get a reading on the RPMs so that if I have to buy a new prop I will at least know that much.
I am pretty sure that I have the tach hooked up right since the schematics that I have seen indicate a gray wire is the tach sending wire and I know that it went to zero when I turned on the ignition. Here is hoping for the best tomorrow.
I will keep you posted still.

 

[cpowell]

Re: Engine lugging down

Well, the tach didn't work out. I had it connected to a gray wire but it did not register at all when it started. While honey fished I looked around for another prospective wire and found the purple one and hooked it up. It worked as long as it was cranking but when it started the tach shut down again to zero. I guess the purple wire is the starter circuit. I will try again later.