1973 rude 50 hp spun prop question

[Andy in NY]

okay, after asking a few questions, i THINK the problem i have is a spun prop hub.

i just got the boat, and the previous owner said they were out in the water and all of the sudden the boat would barely move, but the prop was spinning still. i asked a local marine mechanic, and here on iboats and that seems to be the general thought is a spun prop hub. i would like to diagnose this myself if possible.

can troubleshooting be done in the garage with a garbage can of water instead of on the drink?

if i need to replace the prop and hub, how do i know what pitch i need?

how difficult of a job would this be (i have some mechanical knowledge)?

once replaced, how would i be able to verify that it is working correctly and will move the boat?



if i could do this myself, it would surely save me a bunch, but if it is difficult for a beginner then i would just assume bring it to a pro.

 

[F_R]

Re: 1973 rude 50 hp spun prop question

You can verify if it is spinning by making a mark on the prop nut and another on the prop itself, aligned with the first one. Then run the motor (on the lake) till the suspected slippage occurs. Then stop as see if your marks are still aligned. If they are not, then it slipped. But if they are, try agian. There is a slim chance they stopped spinning in the same position.

Of course you can replace the prop yourself. Just remove the cotter pin and nut and washer and then pull the prop off. Clean up and grease the shaft with some good marine grease before putting the new prop on. Use a NEW Stainless Steel cotter pin. WARNING: there is a large thrust washer between the prop and gearcase. That absolutely must be in there before you slip the new prop on. It may have stuck to the old prop when you pulled it off.

Most props are marked with the diameter and pitch near the hub.

To verify that the new one works, go for a ride. No, you can't tell in a bucket.

 

[Andy in NY]

Re: 1973 rude 50 hp spun prop question

damn, that means waiting till spring just to troubleshoot.

 

[tashasdaddy]

Re: 1973 rude 50 hp spun prop question

like this

 

[Andy in NY]

Re: 1973 rude 50 hp spun prop question

what else can i check for if that is NOT the problem?

 

[F_R]

Re: 1973 rude 50 hp spun prop question

If that is not the problem, then you have a major grade A serious problem. But fear not, that is probably the problem, just going by your description.

 

[TerryMSU]

Re: 1973 rude 50 hp spun prop question

I would agree with the spun prop. My prop was dinged up as well as spun and I got it fixed for $27 including reshaping the prop and getting a new hub placed. So cheap that I would just do it over the winter to avoid a big wait at the start of boating season. The only other thing that comes to mind is that your prop might be cavitating or sucking air if it is at the wrong height. Cavitation is not likely to totally stop thrust, but sucking air might.

TerryMSU

 

[Andy in NY]

Re: 1973 rude 50 hp spun prop question

I would agree with the spun prop. My prop was dinged up as well as spun and I got it fixed for $27 including reshaping the prop and getting a new hub placed. So cheap that I would just do it over the winter to avoid a big wait at the start of boating season. The only other thing that comes to mind is that your prop might be cavitating or sucking air if it is at the wrong height. Cavitation is not likely to totally stop thrust, but sucking air might.

TerryMSU

terry, in my limited experience and waht the previous owner told me, i dont believe cavitation is the issue... he ran it all summer long, and one day just stopped being able to push the boat. he said it would spin, but the boat barely moved.

would it be an okay idea to just replace the whole prop/hub assembly? i see i can get one for $90.

there arent any marine mechanics/shops for almost 70 miles...

 

[HighTrim]

Re: 1973 rude 50 hp spun prop question

Of course it would be ok, your time may be worth more than the extra expense of buying new.

 

[Andy in NY]

Re: 1973 rude 50 hp spun prop question

what is involved with just changing out the hub and keeping the current prop?

( i have ordered a manual, just havent got it yet)

 

[tashasdaddy]

Re: 1973 rude 50 hp spun prop question

as terryMSU said he had his done for $27.00 which is really cheap. they take your existing prop and recondition it.
i googled this Duquette's Welding & Propeller
32 South St
Champlain, NY 12919
(518) 298-2166

http://www.google.com/search?ie=UTF-8&oe=UTF-8&sourceid=navclient&gfns=1&q=propeller,chateaugay,+ny

 

[F_R]

Re: 1973 rude 50 hp spun prop question

Yeah, I sort of wonder about that $27 figure. But I haven't had one done for many moons. Rehubbing is not a do-it-yourself job. Has to be done at a specialized prop shop.

 

[tashasdaddy]

Re: 1973 rude 50 hp spun prop question

we have a company here Ellis Propeller they do all props, even the huge ship props, you should see their yard. here's their site. "http://www.custom-ps.com/index.htm"

 

[TerryMSU]

Re: 1973 rude 50 hp spun prop question

$27 was correct. The initial quote was about twice that but the actual bill was only $27. That was in the middle of summer (2007). If I understand correctly, the shop that I used in Grand Rapids, Mich sent it to another shop across town and I had it back within 5 days. Dropped it off on Monday and picked it up on Friday after work.

Terry

 

[Andy in NY]

Re: 1973 rude 50 hp spun prop question

i will definatly check them out, its only about an hour from here. i am going to be removing the motor from the boat tomorrow, and the prop will come off shortly after. thanks for all the help. you guys are the best.

 

[Andy in NY]

Re: 1973 rude 50 hp spun prop question

okay, i just called to find out about getting my prop into them, and the guy was asking me a few questions. first he asked me if it was SS, and when i said it was aluminium he was surprised that it wasnt dinged up... he said usually dont see a spun hub in aluminium unless something has been hit.


any thoughts?

 

[Andy in NY]

Re: 1973 rude 50 hp spun prop question

Okay, I dropped my prop off the other day to have them check it out. They called me yesterday and said that they didn't think that it had a spun hub, but they could do a prick test but that could risk actually spinning it if it isnt then it would defanatly need to be re hubbed. He said the prop didnt look in that bad of shape and that he would be surprised if it was spun. I told him to go ahead and do the prick test and work from there. They quoted me $60 for a complete recondition of the prop.

So, if it is NOT the prop, what should be the next thing to look at?

 

[Andy in NY]

Re: 1973 rude 50 hp spun prop question

Anyone have any suggestions? I really don't want to pay $75 an hour to someome to trouble shoot it...

 

[Xcusme]

Re: 1973 rude 50 hp spun prop question

Andy,
If the hub is in question, have them recondition it, then you know it's not the problem. Install and test on the water. If you still have a problem, we can go from there.
As a side note, I'd drop the lower unit and replace the water pump impeller, and change the lower unit lube too. Since this is a "new to you" motor, you can only guess when the impeller was last replaced. When you have the lower unit down, you can inspect and grease the drive shaft splines too.

 

[Andy in NY]

Re: 1973 rude 50 hp spun prop question

Andy,
If the hub is in question, have them recondition it, then you know it's not the problem. Install and test on the water. If you still have a problem, we can go from there.
As a side note, I'd drop the lower unit and replace the water pump impeller, and change the lower unit lube too. Since this is a "new to you" motor, you can only guess when the impeller was last replaced. When you have the lower unit down, you can inspect and grease the drive shaft splines too.

Yes, I am going to have them recondition it while they have it.

How hard is the lower unit to drop? I have some mechanical experience, but not a whole lot. I have a repair manual, but from a realistic standpoint how hard is it?

With the problem I have, what are some other options that could cause the boat to have this problem (motor runs fine, boat barely moves)