1975 merc200 20hp wont plane...doesn't seem to be the engine

[ruff price]

i have a merc200 long shaft on a 1455 lowe high transom that wont plane just about when it gets to plane it sounds like it cavitates, the engine revs high.

first thought. prop is out. bought a new one.

has a broken anti cavitation plate and i installed a plane assist that should fix it.

third thought maybe transom is too high. so i put it on a 15 in transom boat still same thing

tricky getting it into reverse but not impossible even without force (linkage?)

cranks good and there is no power loss at the engine. it seems to be a strong running motor. clean carb

 

[ruff price]

Re: 1975 merc200 20hp wont plane...doesn't seem to be the engine

bump

 

[ruff price]

Re: 1975 merc200 20hp wont plane...doesn't seem to be the engine

bump

 

[tashasdaddy]

Re: 1975 merc200 20hp wont plane...doesn't seem to be the engine

tilt lower unit closer to transom.

 

[toocanshan]

Re: 1975 merc200 20hp wont plane...doesn't seem to be the engine

you should get a service manual for that motor, the reverse thing could be far more important than you think. it may lead to further or even worse conditions. the SM has a step by step section that tells you all the adjustments for the throttle and shift linkage. you will be surprised at the number of steps that is involved. and i will bet that if your off on one cable than you prob. off on the other, not to mention spark, timing and god knows what else!! TOOCAN

 

[ruff price]

Re: 1975 merc200 20hp wont plane...doesn't seem to be the engine

you should get a service manual for that motor, the reverse thing could be far more important than you think. it may lead to further or even worse conditions. the SM has a step by step section that tells you all the adjustments for the throttle and shift linkage. yothat if your off on one cable than you prob. off on the other, not to mention u will be surprised at the number of steps that is involved. and i will bet spark, timing and god knows what else!! TOOCAN

what service manual do you recomend?

as far as timing and are concerned...the engine runs strong...i haven't worked on many outboards in my day but i have worked on cars trucks and equipment and consider myself somewhat mechanically inclined.....it feels like a clutch slipping in a transmission (i.e. clutch weak on a truck, that drives fine except when under a load). Are there clutches in the transmission? it would seem to me like there would have to be.... thanks

 

[crem1]

Re: 1975 merc200 20hp wont plane...doesn't seem to be the engine

The MERC Manual is a good place to start

 

[Tig]

Re: 1975 merc200 20hp wont plane...doesn't seem to be the engine

Change the oil in the lower end. Look for metal filings. Water is not good either.
What you are describing could be the lower end gears skipping under load.
How did the anti cavitation plate get damaged? Is the lower end damaged also?

 

[toocanshan]

Re: 1975 merc200 20hp wont plane...doesn't seem to be the engine

i mean the service manual not the seloc!! and i would deff. check lower unit for any grit what so ever. the manual will give you all the specs that the seloc will tell you to see a "pro" for. whats a "pro" anyway?? the manual is around 100.00 but will pay for it's self the first time you use it. mine paid for itself the first time i read threw it. there are no clutches in that motor, just gears. the gears usually slip before they go out. TOOCAN

 

[ruff price]

Re: 1975 merc200 20hp wont plane...doesn't seem to be the engine

i changed the oil no grit a little milky tho, so i guess i got a seal out. anti cavitation plate looks like it was droped, or rolled around in the bed of a pickup...

 

[toocanshan]

Re: 1975 merc200 20hp wont plane...doesn't seem to be the engine

it's been a couple days, any sign of progress?? find the seal?? find the SM?? and by the way ive had a few outboards roll around in the bed of my truck. but mine always seemed to need some work by the time i got them home. how do you transport one??? TOOCAN

 

[ruff price]

Re: 1975 merc200 20hp wont plane...doesn't seem to be the engine

it's been a couple days, any sign of progress?? find the seal?? find the SM?? and by the way ive had a few outboards roll around in the bed of my truck. but mine always seemed to need some work by the time i got them home. how do you transport one??? TOOCAN

a little sign of progress,,,i found a complete lower unit in a outboard salvage pile for 150...but i bought a yamaha made mariner 40 in a package deal (fish finder, foot operated trolling motor, 40hp outboard, brand new cushion seats with swivels on two and two pedistal seats with poles and mounting hole for $700) and i have it on my big boat and i plan to put the 20 on my 1432 boat i use to run through the woods.......i got the 20 and the cavitation plate was already broken... the pickup theory is just what i guess happen the anticavitation plate. i thank you for all your help....this is a great site with a lot of helpful knowlege among its users...i will definately refer this site to any one because of people like you willing to help out a complete stranger