do I have a bad prop?

[AlTn]

Re: do I have a bad prop?

you mention that you have a 15 hp. as well...does it plane the boat with just you in ti?

 

[wilde1j]

Re: do I have a bad prop?

... and what happened with the marks??? Still lined up???

 

[kfa4303]

Re: do I have a bad prop?

Hello again. It sounds like the motor may be "cavitating". It usually happens when the lower unit of the motor is too high and the prop can't "bite" into the water well enough and slips. You want the cavitation plate, which is found right above the prop, to be level, or even up to 1 1/2" above the bottom of the boat. However, if it's more than an inch, or so above the bottom, then the prop may slip. If that's not it, you may have a bad/worn clutch dog and/or the shift rod linkage may need to be adjusted. Check the line across the hub test, double check the height of the cavitation plate relative to the keel, the check the shift rod linkages, and finally open the gear case to check/inspect the clutch dog. some pics might help. Let us know what you find.

 

[7173george]

Re: do I have a bad prop?

The marks were lined up.I haven't tried the 15. The cavitation plate is about 2" above the bottom of the boat.when i am at the dock the cav. plate is under water.when i start moving and the boat wants to get up on plane the exhaust gets loud . i think it must be to high. I think it is cavitating. thats the right term for it. if the clutch were bad would it make a knocking sound or some type of noise. it throttles up very smooth. i really think it's cavitaion. the temp will hit 7 degrees this week end,not going to be able to test it.maybe till spring.

 

[7173george]

Re: do I have a bad prop?

Do you think i should hold off on the ext?

 

[nwcove]

Re: do I have a bad prop?

jmo, but i would hold off on the parts, its a costly modification. pics of the setup would be nice. ( and as mentioned earlier, cutting the transom down , if you are 100% sure thats the issue, is a much more cost effective solution)

 

[7173george]

Re: do I have a bad prop?

I don't want to cut the transom.the boat is brand new.if were an old boat i wouldn't hesitate, but this is the only boat i've bought new.

 

[nwcove]

Re: do I have a bad prop?

ahhh.....a brand new boat does change things!!! you may want to do a cost comparison to buy a bracket (or have one made) to set the motor back and down a couple of inches, as compared to buying the extension and associated parts.

 

[kfa4303]

Re: do I have a bad prop?

I agree. I think you might be cavitating. The plate 2" above the the keel, is a little too high. I would try to find a way to lower the motor. Perhaps an adjustable bracket would help. Pics would be good too.

 

[AlTn]

Re: do I have a bad prop?

I agree with kfa...I saw brackets in Bass Pro for the lower hp. motors...iboats may handle them as well....it would be less costly than converting to a long shaft and you would have some adjustment room as well

 

[7173george]

Re: do I have a bad prop?

I ordered the parts on sunday.they will be delivered today.when i do the conversion is there a way to know it is pumping water correctly?it's an old motor with no water shooter.i was thinking about putting one on it.I smoked a 1974 15 hp one time and i don't want to do that again.the 74 was n't pumping water and blew in about 5 min. ROOKIE MISTAKE!!!

 

[AlTn]

Re: do I have a bad prop?

remove the thermostat cover, start it, and you'll know if you have flow that far up....I used an ir temp. gun to check the flow on a 25 hp...look for 140 degs. or so on the top of the block and heads after warm up and running it a while...then check it after full throttle a few times until you become satisfied that it's working as it should

 

[7173george]

Re: do I have a bad prop?

thanks, i have an Ir temp. as well. how long can i let it run in a 55 gallon drum?

 

[AlTn]

Re: do I have a bad prop?

long as you want to?..in gear at much more than idle, it's gonna kick a lot of water out so don't let the hose get too far away...I ran this one maybe 20 minutes total in a barrel...kept the water level a few inches below the exhaust relief holes...biggest problem was the carb sucking exhaust fumes...a windy day or a fan would help..wot throttle test were done on the lake

 

[7173george]

Re: do I have a bad prop?

thanks , I'm going to do the leg ext. this evening. I am going to try to put up some pics.next project is remote steering.I have all parts here.if i run into trouble, pics. will be great for getting help so you guys can see whats going on.

 

[kfa4303]

Re: do I have a bad prop?

you won't have a nice constant "pee stream", or tell tale like modern motors. Instead the cooling water is expelled along with the exhaust gasses from the large hole in the midsection of the motor. It should come out as a nice strong spit/spray about the temperature of a cup of hot tea. As AlTn said, you don't want to run it in the barrel for too long and when you put it into gear it will cause the water to overflow out of the tank so keep the hose handy and the water lever sufficiently high (1-2" below the exhaust port). It will probably smoke quite a bit, but that's normal too. It will smoke much less on the open water. Good luck. Keep us posted. Holler if you get stuck.

 

[7173george]

Re: do I have a bad prop?

put the ext. on. now it doesn't shift right.goes into rev. & neutral ok.goes into farward sometimes,sometimes not.the shift rod couple seems right. the rod is up in the coupler far enough. the manual isn't give me alot of help on the adjustment.hope you guys can tell me how to adjust it right.I loosen the clamp nut and try to turn adjustment screw but i must be missing something. seems like it only needs a sixteenth and it would engage consistently. had a heck of a time getting the short water tube out and longer one in.

 

[nwcove]

Re: do I have a bad prop?

i personally cant offer any advice on a fix, but starting a new thread on your new issue should get some responses from the members that can help.

tim

 

[AlTn]

Re: do I have a bad prop?

did it shift ok before the ext. work?..with the brass coupler screw out, shifter in fwd, can you hold the coupler and force the lower shift rod further up into the coupler?....up at the shift lever to bias it towards fwd, you've done as necessary by loosening the shift handle clamp and loosening the adjustment screw so the handle can rotate on the shaft....to bias towards fwd move the handle backwards and vice versa making sure the handle is moving and not the shift shaft as well... a little yields alot in this adjustment and it may take several adjustments so you have f/n/r , the coupler and shift rod would be the beginning point I would look to first

 

[7173george]

Re: do I have a bad prop?

THANKS!! to all of you for your help,the motor is shifting much better now. old man winter has given us a major cold blast today.Won't get to try her out till maybe march. ran it in the barrel today seems to be pumping water good. hope this solves my problem.