Guests - If You want access to member only forums on FM. You will gain access only when you Sign-in or Sign-Up on Fishing Minnesota.

It's easy - LOOK UPPER right menu.

Sign in to follow this  
Followers 0
Troublehook

Another o/b motor question

17 posts in this topic

Well I am having a little problem with my 4 horse mercury o/b. When I am driving it at or near its highest speed, it will sometimes make a louder than usual noise that sounds like the rmps are going way faster. The boat doesnt though, so I know its not just accelerating or anything. It kinda sounds like it is going into nuetral. All I know is that its not a good/normal noise, and it has prevented me from going full speed because I dont want to break it. Any thoughts on what the problem might be? I am thinking about having it tuned up if it is not too expensive. Do you know how much a tune up might cost? Any help is appreciated cool.gif, and I am sorry if I am not providing enough information. I will try to answer any questions that would help troubleshoot for answers on the problem.

Thank you. TH cool.gif

Share this post


Link to post
Share on other sites

It sounds like it might not be trimmed to where it needs to be. I don't know the specific term, but it gets into an "air pocket" and basically free spins the prop. Another thing might be weeds. If you get a heavy or even a little amount of weeds on the motor it can create this same affect. I would first try and trim the motor down as far as it will let you go (if it has a pin to trim it) and try that out first. I had similar issues with my motor when i first got it.

Share this post


Link to post
Share on other sites

Fishin, you meant "cavitation". Doubt it on a 4 horse.

Share this post


Link to post
Share on other sites

Yup thats what I meant. Yeah probably not, but its worth a shot before he takes it in.

Share this post


Link to post
Share on other sites

The prop could be spinning on the rubber mount.

To check this, first pull the spark plug wires so it doesn't start. Then put it in gear and use a rag as a cushion and try and turn the prop with your hands. If it moves that's the problem and the rubber mount is bad.

Share this post


Link to post
Share on other sites

Well Im going to take it out very soon tonight so I wond be able to check the rubber mount yet, but I will lower the trim because that does seem possible, and also I will check for weeds when it happens. thanks for those tips, and I will go out and see what happens tonight. smirk.gif

Share this post


Link to post
Share on other sites

I have a feeling you have a short shaft motor on a 20" transom. You are probably getting up to X speed and your prop is starting to come out of the water.

If it is a newer motor and it could be a spun hub(prop), or a slight chance its a shear pin if its an older motor. Sometime the broken pin can bind and hold the prop until there is too much torque and it will slip. I dont think either of these are the case because your boat isnt losing speed(prop is still spinning).

I think I was right in my 1st comment.. your lower unit is too short.

Share this post


Link to post
Share on other sites

To test for a spun prop use a magic marker and draw a line on the prop to the prop nut. When the motor surges again look at the line you drew on the prop. If it is not straight the hub is spun and you will need a new prop or have to get yours fixed.

Share this post


Link to post
Share on other sites

heres a pic of his boat from a previous post. I think the motor is long enough for the boat.

IMG_0294.jpg

Share this post


Link to post
Share on other sites

I agree with Fishin4Life, drop your trim.... go all the way down with it, then gradually experiment with higher and higher.

Share this post


Link to post
Share on other sites

Well I dropped the trim down, but only by one setting. Had I gone any further the prop would be at a very odd and badd angle. I want it to be able to plane out so I cant have the angle of the prop be where it would completly keep the bow down. maybe this drawing will help explain what I mean.

prop.jpg

Even at the angle I set it at tonight it wouldnt plane. But the good news is that it didnt make that noise tonight. Hopefully that was the problem, but I will have to take it out another time to really be sure.

Share this post


Link to post
Share on other sites

I seriously doubt you will get your boat on a plane with a 4hp.... grin.gif

Keep your motor down will help a lot, as I said you can study the right angle with time.

As other mentioned watch for weeds, if they get tangled in motor when you are going forward they will slow down your propulsion, put motor in reverse for a few seconds then forward again, it will clean it up.

Share this post


Link to post
Share on other sites

That boat is not going to plane with a 4 hp with a person in it. I have a raft here(zodiac) that will plane with a 5 hp, but I have to hit full throttle on the motor, then shift all my body weight forward and it will plane out on calm water.. the raft is only 9 1/2' long and floats high.

The lower unit looks to be the proper length for your boat. If you get 5 or 6 mph from a 4 hp motor, you are doing good.

Share this post


Link to post
Share on other sites

I go way faster than that on it, and I think it does plane, at least the bow gets out of the water and thats planing isnt it? It goes at least 10mph but I am pretty sure it actually goes fifteen. well it made that noise again tonight when my mom was in it as well. I think I will try looking at those other tips that were mentioned before.

Share this post


Link to post
Share on other sites

Its not a bad rubber mount because I put it into gear and it spun just a tiny bit and then it did stop. I may be going boating again today so I will check the spun prop idea. The nut on it is one that I havnt seen. Its a lot different than the one on my I/O(stern drive) boat's prop.

Share this post


Link to post
Share on other sites

Quote:

Its not a bad rubber mount because I put it into gear and it spun just a tiny bit and then it did stop. I may be going boating again today so I will check the spun prop idea. The nut on it is one that I havnt seen. Its a lot different than the one on my I/O(stern drive) boat's prop.


The nuts will be much different you I/O is a much bigger motor so it will have a bigger prop than you 4 horse. On a small boat and motor I would put it on the bottom or second to bottom hole. Start there. I have a 9.5 that I have on the bottom hole all the time.

Share this post


Link to post
Share on other sites

Quote:

To test for a spun prop use a magic marker and draw a line on the prop to the prop nut. When the motor surges again look at the line you drew on the prop. If it is not straight the hub is spun and you will need a new prop or have to get yours fixed.


I think that is the problem. I tested it yesterday and they were not allingened after it happened. I will take the motor to a marine mechanic and tell them the deal and see what they can do for me. thanks eurolarva, and everyone else for the information.

TH cool.gif

Share this post


Link to post
Share on other sites
Guest
This topic is now closed to further replies.
Sign in to follow this  
Followers 0

  • Posts

    • jigginjim

      Posted

      I have put my guide clients on lots of pike this summer. So far largest bass is 21"- 5lbs  Pike 36" Approx. 8-9lbs, Walleye is 23 inches 3lbs. The walleyes will get better as the water cools. Time to start jigging, everything you got. I'm even started using my crankbaits.

    • bassbouncer

      Posted

      I'm a local and yes we boycott the place. Friends have been told that they aren't wanted there that they only want the tourist business. Wife and I boat to Wolf Bay when we go out. We live 2 miles from the landing and wish it was still run by Jack.

    • RoosterMan

      Posted

      Well I made a decision to put the trolling rods away and go do some jigging.   It seemed to be a good one.  I concentrated on rocky transition areas.  I had three slot fish in an hour.  Went back in for some VC pizza and picked my kids up and went back out for a evening trolling run and that produced as well.  You have to love this lake.  

      image.jpeg

      image.jpeg

      image.jpeg

      image.jpeg

      1 person likes this
    • CigarGuy

      Posted

      We have friends up and they wanted to take us out for dinner, via the boat.  With the wind, the only place was the landing, I tried vetoing It, but lost out.  Had $12.00 burger and fries.  Very good and the service was fast-only 8 others in the dinning area and a few at the bar.  I checked the prices on the wings-$16.00 for 1-1/2lbs.  Del, they had a pretty good burger menu.  I asked about the 20% off deal and the waiter blew me off and said he didn't know anything about it.  I asked who I should talk to, he said the manager or the owner.  We paid the bill and left without asking.  I liked it a few winters ago when they had ,25 wings and 2.00 beers.

    • knoppers

      Posted

      seen enough grouse to keep me interested, lots of turkeys, seems they and the deer are everywhere this fall. did not here much shooting from the duck hunters though.

    • ANYFISH2

      Posted

      First off I am not a waterfowl hunter, so this info is second hand.

      Here in the Morrison/E.Todd cty area, the hunt really seemed slow considering the weather conditions.  Although a few birds were shot early in morning the day seemed slow by most accounts around here.

      Good luck to all.

    • she's getting big

    • delcecchi

      Posted

      Crescent and south switch have good burgers too, and I wouldn't have to drive so far. 

    • monstermoose78

      Posted

      No internet in the field today. Had a group sky busting keeping birds out of anyone's range. Riverrat and I got buzzed by teal a few time and a pair of woodies scooted through. Should have had a shoveler and some woodies. The bugs were so bad I lost 4 pints of blood. 

      Now to the fun parts Finn was jumping woodcock son the fields on our way out. Finn did good but does not like no action. After leaving the refuge I checked my dads pond. O yeah there was a woodie sitting on the log bang!! No finn needs to do his job.

      IMG_0607.JPG

      IMG_0610.JPG

      IMG_0612.JPG

      Finn did good he got it and brought it back to me!! Way to go Finn. 

      1 person likes this
    • Lindy came along on our trip to Western MN for duck opener. The guys that came out Thursday to start scouting had a field lined up with alot of geese but they got busted off the roost early in a huge flock and didn't commit. We ended up with only 2 birds today.  She had to stay back in her crate during the hunt but got to play with a wing afterwards. 

       

       

      IMG_20160924_110720925.jpg

      IMG_20160924_104852333_HDR.jpg

      1 person likes this


  • Posts

    • jigginjim
      I have put my guide clients on lots of pike this summer. So far largest bass is 21"- 5lbs  Pike 36" Approx. 8-9lbs, Walleye is 23 inches 3lbs. The walleyes will get better as the water cools. Time to start jigging, everything you got. I'm even started using my crankbaits.
    • bassbouncer
      I'm a local and yes we boycott the place. Friends have been told that they aren't wanted there that they only want the tourist business. Wife and I boat to Wolf Bay when we go out. We live 2 miles from the landing and wish it was still run by Jack.
    • RoosterMan
      Well I made a decision to put the trolling rods away and go do some jigging.   It seemed to be a good one.  I concentrated on rocky transition areas.  I had three slot fish in an hour.  Went back in for some VC pizza and picked my kids up and went back out for a evening trolling run and that produced as well.  You have to love this lake.  
    • CigarGuy
      We have friends up and they wanted to take us out for dinner, via the boat.  With the wind, the only place was the landing, I tried vetoing It, but lost out.  Had $12.00 burger and fries.  Very good and the service was fast-only 8 others in the dinning area and a few at the bar.  I checked the prices on the wings-$16.00 for 1-1/2lbs.  Del, they had a pretty good burger menu.  I asked about the 20% off deal and the waiter blew me off and said he didn't know anything about it.  I asked who I should talk to, he said the manager or the owner.  We paid the bill and left without asking.  I liked it a few winters ago when they had ,25 wings and 2.00 beers.
    • knoppers
      seen enough grouse to keep me interested, lots of turkeys, seems they and the deer are everywhere this fall. did not here much shooting from the duck hunters though.