Trim and tilt Falls over 10mph

termz

Seaman Apprentice
Joined
May 4, 2011
Messages
37
Alright i have a 1992 force 120 hp 1208x92c. The tilt and trim holds the motor up just fine when im out of the water, i can leave it up all night and wont leak down at all. When i went to the lake today i took the boat off the trailor and everything seemed fine. tilt stayed up while idleing through channels. When i got to the main part of the lake i got on the throttle and once i hit 10mph the outboard just dropped and would not raise while going over 10mph. If i slowed the boat back down to under 10 i could raise and lower the motor and it would stay just fine. Any ideas on what could be happening and what i should do first?
 

johnbottsr

Petty Officer 2nd Class
Joined
Oct 6, 2012
Messages
104
Re: Trim and tilt Falls over 10mph

I would check the reservoir first.

I did read on here that past a certain RPM threshold the tilt would not work but I don't recall the number.
 

termz

Seaman Apprentice
Joined
May 4, 2011
Messages
37
Re: Trim and tilt Falls over 10mph

fluids are topped off. i can understand that your tilt wouldnt work at a certain rpm from force of the water but the motor shouldnt drop like a rock when i go over 10mph
 

johnbottsr

Petty Officer 2nd Class
Joined
Oct 6, 2012
Messages
104
Re: Trim and tilt Falls over 10mph

fluids are topped off. i can understand that your tilt wouldnt work at a certain rpm from force of the water but the motor shouldnt drop like a rock when i go over 10mph

Agree with you there.
If you're lucky, RRitt will drop in. He is the guru on these things.
 

RRitt

Captain
Joined
Mar 30, 2006
Messages
3,319
Re: Trim and tilt Falls over 10mph

post pic of system with engine fully raised from automotive passenger side and slightly behind boat.
 

termz

Seaman Apprentice
Joined
May 4, 2011
Messages
37
Re: Trim and tilt Falls over 10mph

Alright well i went out to take somes pics. i had the motor resting down to take weight off of trim unit and now the motor wont go up at all. i can hear the pump pushing fluid when i press the up button but nothing. if i have my wife press the up i can lift the motor but it falls instantly. if i dont press the trim up to lift it its stuck down!. Also if i lift the motor by hand and press the trim down once ive raised it the trim unit will pull the motor down. so seems like only up if messed up. could this be a bad o-ring under the pump? photo.JPGhmmm.jpgyes i know the bolt is not in on the trim motor(replaced gasket). the other pic is of the trim unit off the boat dont know if that will help any.
 

RRitt

Captain
Joined
Mar 30, 2006
Messages
3,319
Re: Trim and tilt Falls over 10mph

two most likely suspect in decreasing order

1) the trim piston is missing the strike plate on swivel bracket due to either bad trim shoe, bad bracket, bad transom, or bad mounting hardware.

2) the spring between manifold and gearcase is rusted. you need new spring, 1/8" precision BB, pair of bn90 orings (size 8? , maybe 7?, if not that then 9 or 10 for sure .... unless its a 6 ... well, it's a small one). and DO NOT split the gearcase. only take loose the one hex bolt that holds gearcase down. I'm not going to help you if you split the gearcase and get into trouble.
 

termz

Seaman Apprentice
Joined
May 4, 2011
Messages
37
Re: Trim and tilt Falls over 10mph

i have replaced the hydrolic cylinder so i dont think its that. i have 3 of the same units i will swap out the spring and see what happens. Are you talking about this spring?spring.JPG<- this is not the unit im working on just using an older one for refferance.

Dont worry i wont crack the case, i dont have a hydrolic shop near me to fix it! Also where can i purchase these 0-ring? i will buy 4 of each size u listed if i can find a place that sells them.
 

RRitt

Captain
Joined
Mar 30, 2006
Messages
3,319
Re: Trim and tilt Falls over 10mph

that looks like it. there should be a 1/8" precision ball on top of it. I haven't done one of those in 2 years but i think that is only spring in manifold. later models used a thinner, taller spring with 7/32" acetal ball and #8 oring.

idk where to buy single orings. maybe try a hydraulic repair shop. you don't want to use hardware store plumbing orings.

i would still bet on transom or strike plate trouble. holding tilt indicates about 900psi. Which should be much more than 10MPH.
 

termz

Seaman Apprentice
Joined
May 4, 2011
Messages
37
Re: Trim and tilt Falls over 10mph

alrigh ritt well found the problem. took the pump back off and the ball had fallen off spring. bought a new ball installed it and now the system works like new! thanks for the help and saving me allot of money.
 
Top