johnson 150 prop question

[satman7475]

was having rpm problems, had a 14 1/4 pitch 24 prop on. was told to reduce pitch, went out and bought a 14 1/4 by 17 prop. with the 24 prop the problem was the boat had trouble getting up on plane would just drag along for a while and finaly get on plane. the 17 pitch is great it gets up on plane everytime just like that, but the 24 pitch only got to 3800 rpm and ran about 38-40 mph and the 17 pitch is getting too much rpm about 5800-6000 rpm and runs about 45 mph but the water gage im asuming the temp gage gets to hot too fast and the beeping nosie coms on. do i still have the wrong prop, can i ajust somthing. what should the right prop be for a john 150hp faststrike.i wold be happy with 5000 rpm and 45-50 mph, forgot to mention i had to run about 30 mph to keep the heat gage from going off and it was running about 4500 rpm at 3/4 troddle . something not wright. any help would really be appr. or any inputs thanks

 

[ob]

Re: johnson 150 prop question

If you were running the boat with a light load aboard ,I'd say your propping is just right.You may be able to swing a 19" prop depending on the load when current prop was tested and the X-demension or height that the engine is currently mounted to transom.You'd like to have the engine mounted as high as possible without excessive prop ventilation while executing tight turns at 1/2 to 2/3 throttle.Lower unit anti-ventilation plate (just above prop) running on an even plane with the boats bottom is a good starting point.Then move up from there until optimal placement is obtained.Only a water test can confirm the final placement.You may be just fine now with respect to engine height.Just wanted to offer some food for thought.<br /><br />Otherwise, from your description above ,it sounds like your engines cooling system needs attention.(ie replacement of waterpump and T/stat assys.)

 

[satman7475]

Re: johnson 150 prop question

OB thanks for the reply so soon the boat was just in shop and the waterpump and t/stats were just replaced. as far as the heat gage it runs accordingly with the 24 pich prop does not overhrat, thats why im confused. as far as eng height i didnt think of that. its in the second to last to the bottom. i can raise it up four more slots what do you think of that?

 

[ob]

Re: johnson 150 prop question

In your first post I see that you mentioned the "beeping noise.Is it rapid short tones or a constant tone?Post the year model of your engine so we can determine which alarm you are getting for sure.

 

[satman7475]

Re: johnson 150 prop question

sorry its a 94 jonhson faststrike 150hp v6 crossflow i do beleive and its a slow beep every 1-2 seconds

 

[ob]

Re: johnson 150 prop question

Rapid short tones is a no oil alarm from the vro.It could be due to a restriction in the oil flow from reservoir to vro,a failing vro pump,or a faulty alarm.In any case ,you don't want to second guess this alarm and should mix fuel and TCW3 oil at 50:1 in fuel tank unitl you can rectify the problem.A good starting point would be to clean/inspect the vro oil reservoir and pickup strainer.Insure that the vro cap vent is working properly and there are no kinks in the oil hose up to the vro inlet.This is all assuming that the vro is still in service and has not been bypassed,in which case the alarms should be disconnected.

 

[satman7475]

Re: johnson 150 prop question

thanks OB I WILL INSPECT THE VRO TANK AND PUMP AND HOSES TOMORROW . SO I GUESS A RAPID BEEP IS A NO LOW OIL WARN. AND A LONG STEADY BEEP IS A HEAT PROB? IS THERE ANY OTHER KIND OF BEEP PATTERN? ONE MORE YOU SAID SOMTHING ABOUT THE ENEGINE HEIGHT. WHAT WOULD RAISING THE HEIGHT OF THE ENGINE DO/ THANKS FOR THE HELP

 

[satman7475]

Re: johnson 150 prop question

sorry didnt realize i typed all in capital letters hope i didnt make anyone mad

 

[ob]

Re: johnson 150 prop question

Alarms as as follows :<br /><br />steady tone is overheat and rpms are elctronically limited to 2500 through the s.l.o.w. system.<br /><br />steady tone and engine will operate at any rpm indicates a fuel restriction alarm from vro<br /><br />rapid short tones is the no oil alarm from vro<br /><br />one short tone every 40 secs is the low oil in reservoir alarm.<br /><br />Your local dealer should sell some alarm I.D stickers to place near your controls for future identification.<br /><br />Running the engine at its optimal height setting reduces drag and exhaust back pressure and will allow you to get the most out of your set-up.

 

[satman7475]

Re: johnson 150 prop question

alright OB its been great talking to you have to run out for a while. thanks for the info, learned some new things i did not know still new the the boating world.thanks again for the great info.

 

[ob]

Re: johnson 150 prop question

Glad I could help some.Make sure and give us an update on your issue so we can all learn.

 

[walleyehed]

Re: johnson 150 prop question

oB has given good info as always, but may I add my 2 cents and suggest a double decarb on that engine....If your prop is only allowing 3800RPM, over a short period of time you will have some build-up that will need attention. This RPM would also generate much higher temps than being propped for 5800-6000, which is correct with a light to normal load...<br />As ob said, please keep us posted