Will a different size prop cause overheating ?

[Grassman619]

I have an 1983 Johnson 35 hp motor

ok so the pitch orignaly was 10x13 a guy said a 10 1/2 x11 would work fine so I put it on ran it five minutes later when I get to the spot where we were gonna fish and I looked back to see no water was spitting out tha talltail and the hole motor is steaming hot so I shut it off and used my troling motor back in

could a different size prop caused this or just a bad water pump/ impeller?? Thanks for the help

what can I do to fix my problem

 

[ezeke]

Re: Will a different size prop cause overheating ?

If anything the motor would run cooler because the 11 pitch prop would be less likely to lug the engine.

Troubleshoot the cooling system. You have three possible areas of concern: the waterpump, the thermostat, and the water passage deflectors. Also, make sure that the water intake screen is in good repair.

 

[F_R]

Re: Will a different size prop cause overheating ?

The water "sees" the tell tale before going through the rest of the powerhead, so no water there pretty much narrows it down to the water pump. Or a blockage or breakage between the pump and tell tale, which is possible but pretty rare.

In any case, you can't blame it on the propeller. Stuff just happens.

 

[Al-53]

Re: Will a different size prop cause overheating ?

I have the same engine....changing the prop wont cause over heat...I just did my pump this year..very easy job...get a OMC kit

one thing I want to ask you..what was your RPM with the 10x13 prop...reason I ask is I have a SS 10x13 and when I put it on rpm and speed dropped bad...I had a 11x9 on there and ran great...I went back to that prop..the 10x13 just did not work well on my engine...so I am sticking to the 11x9 for my boat...

also how did the 10.5x11 work ..just curious is all...

but get a OMC kit..no others....also when you do the pump and if the impellar is bad as in broke up in there...take the hose off the tell tale fitting when you start it..let it run a little like that so if any small pieces of rubber is in the motor it may pass out the hose and not block the tell tale...then reconnect it....

Al

 

[Grassman619]

Re: Will a different size prop cause overheating ?

Well it seem to run good with the newer prop but I've hade a lot of bad luck with my motor lately so haven't had much times to see all she can do it seems like every time I fix one thing another goes bad

Well how can I tell the rpm and speed I don't have a tackomoter on it maybe u can tell me

But over all I like the performance the 10.5x11 gave I was thinking it gave to good performance to where it messed up the water pump or something

thanks for all the help

 

[mikesea]

Re: Will a different size prop cause overheating ?

An interesting story for ya.back in the &0's I had an awesome Formula ,18ft.inboard outboard.It had an overheat problem from the day I bought it.Only overheated at high speed.I changed every component in the cooling system other than the eng and the manifolds.I was given a newr prop by a guy that sold his boat.It was a different size.My overhea went away.I used the boat for a couple seasons ,with the problem,just basically didnt run it hard.What I CONCLUDED ,not being a prop expert was.My old prop caused cavitation ,which ment my lower unit was often sucking air at top speed(RPM was high,dont recall)something to think about.You may be over rev ing the eng,causing an air pocket by the water pick up

 

[Grassman619]

Re: Will a different size prop cause overheating ?

Oh ok yeah that can be right and a dude told me it might be a good thing to put a fin on it but I guess for now Im just gonna replace the water pump and the impeller with the kit I'm guessing every thing is included right

Might there be anything ealse I need to change while I'm in there?? Thanks ounce again

 

[tedious]

Re: Will a different size prop cause overheating ?

a dude told me it might be a good thing to put a fin on it

If this dude thinks a fin will help your overheating problem, I'd think carefully about taking any of his advice in the future, because he clearly doesn't know what he's talking about.

A fin will help you get planing and stay planing, but if you don't have a problem with that then it will only slow you down.


Tim

 

[ondarvr]

Re: Will a different size prop cause overheating ?

Lots of stuff here.

Grassman
A fin will not help with overheating, nor will it slow you down if used correctly.

You didn't give any information about the boat and how it performed, so its impossible to say if an improvement was possible with a different prop. Was there a reason you thought the 13P prop wasn't right? A prop with an 11P will allow the motor to reach much higher RPM's, this may be good or bad, it just depends. Going from a 13 to an 11 would be like downshifting one gear in your car/truck and cruising on the highway, it might be the right thing to do if pulling a heavy load up hill, but not correct when unloaded and driving on flat ground.

The different prop probably didn't cause the overheating, but if the increase in RPM was well beyond what the recommended range is, then it is possible for it to have some effect.

You need to know what RPM?s the motor is turning at WOT to determine if you have the correct prop.



Mikesea
The water pickup on the motor should not be affected by cavitation, which you probably didn't have. Most likely it was a different pitch and allowed the motor to run cooler.

 

[Grassman619]

Re: Will a different size prop cause overheating ?

Thanks for all that addvice so how can I determin rpms on it?

When I push it to wot it takes a second then just takes off it's like the cables to the shifter are to long it has g gap it's eather slow or fast with no real middle speed idk is that normal to be like that

I know my motor has quite a bit of problems I really just wanted this motor to last a few months befor I could save for a brand new one

oh yeah and it an 18' gregor alum with a steering wheel it's like an 1985 but is in perfict condition only problem is my cursed motor