60hp Mariner WOT 3200RPMs need help

Author Message   Alan Heath New member Username: buford Post Number: 1 Registered: 06-2009 Posted on Tuesday, June 09, 2009 - 02:03 pm:    I bought the boat around the first week of May; it’s a pontoon boat with a 60 hp Mariner motor. I didn’t water test the boat before buying so it’s my fault that I have these problems. The motor started and ran fine on the water ears etc. it would start at the turn of the key. We ran a compression test on the motor while there; it had 115, 115, and 120 good numbers for a 1994 60hp Mariner. When I got it home I went ahead and changed the plugs, drain the gas tank, changed the water/fuel separator, changed fuel filter and checked the hoses and fuel bulb. Then we loaded it up and took it to the river, motor started and run but at WOT tac was only showing 3200RPM and it didn’t sound like it was screaming to the 5500RPM that the manual says this motor should turn at WOT. I took the boat to a local boat mechanic (in his mind anyways) he cleaned the carb, and adjusted all the cables and greased this and that for a three hours labor charge @ $75.00 an hour. I took the boat back out and it still only turned 3200RPM when I called the guy back he said the tac was wrong, the motor runs fine. Also while out on the river after a few stops and starts the motor got where it would not start in N – I would have to disable the prop, (via the button on the throttle control ) start the motor pull back into neutral and then forward, sometime it would stall even when I did this. So I decided not to take it back to him, since the motor seem to run/start worst then before taking to him. I took it to another boat mechanic (in his mind anyways) he checked a few things and said the throttle cable wasn’t adjusted right, I explained to him another guy just cleaned carbs, adjusted all the cables, throttle etc. He said he must have done it wrong,, I left the boat after explaining the first problem was that the motor would not operate at 5500RPM at WOT. I guess he must have done the same thing as the first guy and with no better results; I was charged three hours labor @ 60.00 an hour. He claimed to adjust carbs, adjust cables, check stator, (low and high speed checked OK) check ign boxes/coil drain and cleaned oil injection box, cleaned check valve for oil control etc. I took the boat out on the water again, same result 3200RPM at WOT. I had purchased a prop and decided to change the prop to see if any difference. I went from a 14 pitch prop to a 10 pitch prop. And that did as it should, picked up 800RPMs, so now the motor runs 4000RPM at WOT. So I’m looking for suggestions,,,,, the carburetors should be cleaned since they were done twice, the cables should be adjusted since they were done twice (Which the motor is still hard to start for the first time in the morning and after a few hours of stop and starting it has to be started in gear so to speak, with the throttle in the run position instead of N. So any suggests (other then dirty carbs, fuel lines, stator, these things I hope was checked by the two so call mechanics). Thanks,   Fastjeff Senior Member Username: fastjeff Post Number: 5978 Registered: 09-2003 Posted on Tuesday, June 09, 2009 - 04:46 pm:    You need an 8 pitch prop. A good prop shop could repitch yours and all will be well. Jeff   Alan Heath New member Username: buford Post Number: 2 Registered: 06-2009 Posted on Wednesday, June 10, 2009 - 08:15 am:    Thanks Jeff, a 8 pitch prop will give me 400 more RPM that would put WOT at 4400RPM, this motor should operate at 5500RPM at WOT so I would still be 1100RPM short.   Fastjeff Senior Member Username: fastjeff Post Number: 5988 Registered: 09-2003 Posted on Wednesday, June 10, 2009 - 10:01 am:    You might get far more than 400 rpms, for you're not into the power band yet at this time. Example: I "trailer test" my outboards, with the boat secured to the trailer, before 'blessing them' for use. A very fine pitch prop is required for the motors to get anywhere near the intended rpm range. But--and here's where it gets interesting--a slight, further decrease in pitch has often allowed the motor to jump up into the power band and start reving like mad. Jeff   Graham Lamb Senior Member Username: galamb Post Number: 5322 Registered: 05-2007 Posted on Wednesday, June 10, 2009 - 11:56 am:    What exactly are you pushing with this? Pushing a pontoon with too small an outboard is like trying to tow that boat with a Dodge Neon - ya, you may be able to get it rolling but definately not the best combo. Normally you would use a "bigfoot" model (with lower gears) for the heavier load to also help get the rpms up there and help the motor out. You may just have to go with the lowest practical pitch to prolong the life of the engine or repower if you are looking for better performance. It might be the case where there is nothing you can do with this particular motor/boat combination to get it work "properly".   Alan Heath New member Username: buford Post Number: 3 Registered: 06-2009 Posted on Wednesday, June 10, 2009 - 02:27 pm:    Jeff, interesting - I was hoping going from a 14 pitch to a 10 pitch would have put it somewhere near the factory WOT specs of 5500RPM. I will check with a shop about re-pitching the prop. The shop I bought the 10 pitch prop, said that an 11 pitch prop. should get the motor in operating range so I went with one pitch less. I hope you are right that another 2" of pitch will give me that extra 1500RPM I need for this motor. Graham; The boat is a Spectrum 18' fish pontoon boat. The sticker for motor size for this boat states 60hp as the MAX for this boat. I know of other boat (pontoons) that have an even smaller motor via 40hp/50hp those motor get to their normal operating RPM which are the same as mine @5500RPM. Now of course these boats do not MPH nor will mine, but if factory specs claim these motors should operate at 5500RPM I wouldn't see where it would matter if it was on a 500lb boat or a 2000lb boat it should get to 5500RPM. Now of course the 500lb boat will be going a lot more MPH then the 2000lb boat, but the motor should operate at 5500RPM. wouldn't you think?   Graham Lamb Senior Member Username: galamb Post Number: 5338 Registered: 05-2007 Posted on Thursday, June 11, 2009 - 01:06 pm:    The max horsepower rating has everything to do with the safe operation of the vessel and nothing to do with "performance" expectations. Of the 3 basic hull designs on powered boats (planing, semi-displacement and displacement) pontoons don't fit very well into any of those catagories. A "toon" is just a floating raft that was not initially intended to pull tubes or even move quickly through the water. It was meant to kinda putter around at low speed. It has taken a few years for outboard designers to build a motor that is better equipped to serve a pontoon and give it a little better performance. It's not just the weight that's the issue, it's the whole dynamics of the boat which is like trying to get a rock to plane out. A more traditional 60 horse has 1.64:1 gears while the newer 4 stroke bigfoots (60 horse) have 2.3:1 gears. That is a massive difference when you are trying to push a big dock across a lake with relatively low horsepower. So if the 40's or 50's you note are bigfoot models or have the lower gears, then yes, they will absolutely get into their operating rpm's - which will be high relative to their "forward motion" when compared against other rigs. Your 60 just wasn't meant to push a pontoon when it was built...   Alan Heath Member Username: buford Post Number: 4 Registered: 06-2009 Posted on Friday, June 12, 2009 - 09:55 am:    Thanks for all the information, looks like I'm going to have to re-power if I want a motor to operate to the factory specs of any given motor. But the toons with the 40/50 are just plain old 2 strokes. I guess I have been mis-informed, the 2.3 gears in a bigfoot was explained to me as torque. Like the gears in a car, If you have 4.11 gears in your car it will get to 5500RPM a lot faster then a car that has 3.00 gears. BUT both motors will turn 5500RPM no matter what. Which now I might can put a bigger motor on the boat, I believe this motor weight close to 300lbs, and I was looking at a 75/4stroke and it was only a few pounds heaver.   Graham Lamb Senior Member Username: galamb Post Number: 5343 Registered: 05-2007 Posted on Friday, June 12, 2009 - 11:24 am:    You have the gear part correct - just like a car, but have to include the weight equasion. I have very low gears in my truck because it's rigged to tow. So when I step on the gas, the engine roars (rpms shoot up), the truck "thinks" about it for a minute then starts to "slowly" edge forward and gets the load moving by putting gobs of torque to the rear end. If I had high gears and the load was light enough, then yes it would move faster but if I had a heavy load on, the motor would either gag out trying to turn the gears or more likely simply twist the universals to the point of destruction. Same with the outboard - it has gears meant for a sports car and you have it mounted on a 1 ton "dually" trying to tow a 5000 pound trailer (best analogy I can think of). So yes, you want to get your outboard to optimal rpms while turning the prop "slower", because it just doesn't have the "guts" (torque) required to turn the prop correctly. The only way to accomplish that is use a lower pitch/lower diameter prop or replace the gears. Before the days of "bigfoots" that would be considered a "high altitude" retro-fit (running above 5000 ft has the same effect on a motor).   Benjamin Jones Advanced Member Username: benjamin_jones Post Number: 246 Registered: 04-2008 Posted on Saturday, June 13, 2009 - 07:57 am:    Hi, Are the tubes 100% sealed? I'm with Graham here, but you could be carrying extra load without knowing it...   Alan Heath Member Username: buford Post Number: 5 Registered: 06-2009 Posted on Saturday, June 13, 2009 - 05:45 pm:    Benjamin, after each outting I pulls the plugs from both toons. I hear a whoose/air noise when I pulls these plugs out, no water just air escapes once plugs are pulled. So I don't think there is any water in the toons. I think the problem is more of a motor problem. I took the boat to a prop. shop and they said I had more then enough pitch on the prop. (10 pitch) to get that motor (60HP) into operating RPMs on the pontoon boat. They suggested the motor be checked out before a prop swith. I have had the motor to a couple different people and still have not fixed the problem. I now have it at a Mercury dealer, they have assured me that it would be water tested and fixed. So I'm just waiting to see what the problem is.   Alan Heath Member Username: buford Post Number: 6 Registered: 06-2009 Posted on Thursday, June 25, 2009 - 03:21 pm:    This is amazing to me!!! I've had my boat at a certified Mercury dealer for two weeks. This place has it own boat dock right in the yard that loads in the river. They checked the motor out, they took the boat out and adjusted the carbs. on the water. (Same results 4000rpm WOT) they changed the prop twice going down to a 8 pitch prop (which brought the RPM up to 4400@WOT)Still not the 5500RPM Mercury claims this motor should turn. They took the shop tac on the water, then they came back and got a salesroom tac. same results 4400 via 8 pitch, put the 10 pitch back on 4000 via 10 pitch. Now the certified mercury mechanic is telling me that the motor runs perfect, idles perfect, nothing wrong with the motor, it just operates at 4000RPM. Now, I'm now sure about ya'll but if the motor was running perfect and it had the correct prop. (which I guess would need to be a 5 pitch, which they don't make)then the motor would be turning in the 5500RPM range.... I guess Graham is right, it matters what kind of boat the motor is put on for it to run at factory RPM range. I'm going to throw my manual away, because no where in the manual does it say that if this motor is on a pontoon boat that it should only operate at 4000 RPMs.... Which if you know anything about boats a 10 pitch prop. should have this 60hp motor screeming no matter what boat it is on. This just amazes me... I guess I will have to re-power as suggested... I don't expect any comments, I'm just amazed... I guess I will have to look at one of those jap-crap motors they seem to work on pontoons just fine at factory RPM range.   Benjamin Jones Advanced Member Username: benjamin_jones Post Number: 258 Registered: 04-2008 Posted on Friday, June 26, 2009 - 09:51 am:    If you have a spare prop, why not trim the circumference to get a lower pitch? Do it quater inch at a time and make sure you trim same amount & profile across all the blades. Maybe this will help?   Benjamin Jones Advanced Member Username: benjamin_jones Post Number: 259 Registered: 04-2008 Posted on Friday, June 26, 2009 - 09:54 am:    Just occurred to me, do you have another boat to test the motor on? I know it's a truck load of work, but if you know someone with a similarly-rigged kit, it could be worth a try? Then you'll know if it's right.   Fastjeff Senior Member Username: fastjeff Post Number: 6133 Registered: 09-2003 Posted on Friday, June 26, 2009 - 07:12 pm:    Alan: I test my motors in a pond with the boat secured to the trailer. With this setup, a low pitch prop won't begin to let the motor rev up. Sooooo...I took an old 2 blade aluminum junker prop with minimal pitch and whacked an inch off the diameter. Better, but still not good enough. Another inch came off, and the motor reved up as I wanted it to. (One weird looking prop, thou!) You might try this, as Benjamin suggested, on a spare aluminum prop. Just make the blades all the same length and rough shape them as they were (only shorter). What have you got to loose, and you won't charge yourself marina wages doing it! Jeff   Benjamin Jones Advanced Member Username: benjamin_jones Post Number: 260 Registered: 04-2008 Posted on Saturday, June 27, 2009 - 02:29 am:    Imagine trailer testing with a 300hp Verado!!! You'd find the tub otherside the tow van! If you're trailer testing, make sure everything is tethered and safe. Personally, if I had to test as such, it'd be with small motors. Keep us posted as to your solution, we need the info for the other land lubbers...   Fastjeff Senior Member Username: fastjeff Post Number: 6137 Registered: 09-2003 Posted on Saturday, June 27, 2009 - 05:26 am:    How do you trailer test an OB without a boat? Mine is 90 miles away, so... Jeff PS: With higher hp motors I add a come-a-long to the setup.   Benjamin Jones Advanced Member Username: benjamin_jones Post Number: 266 Registered: 04-2008 Posted on Saturday, June 27, 2009 - 05:50 am:    Just hope you don't have a few wetties during the test and attempt launching Woody... You'd need some serious HP to keep her chugging along nicely! Nice toy hauler in the background... Assuming she's not the come-a-long...

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