trim getting up on pad

[b-man]

Hi,
have a 16ft charger with a 125hp force and having a time getting boat up on pad. When I go to give it throttle the nose of boat seems to take longer to break over getting up on pad. Just put a new trim motor on it works okay, but seems like once it water motor don't raise up like it should. Could I have a wrong size prop on or could even make a difference? Motor does not seem to bogg down, just getting to break over to get up on surface any one have any ideals? Thanks

 

[RRitt]

Re: trim getting up on pad

Did you change motor type? Is your new motor an exact match to the one you took out? 125HP included both 3w and 2w trim designs. It is quite possible that if you did not put back exactly same motor then it may lift/lower faster or slower than before. Additionally, the internal gearing was different and it is quite possible for a system to lug down if a low torque motor is hooked up to a high torque valve body.

With all that said --- check your battery connections. Even a small voltage drop in the wiring can cause a big drop in power at the motor.

 

[b-man]

Re: trim getting up on pad

far as can tell same type of motor 2 wire it was a ARCO 6216 looks the same as old one. look into voltage drop thanks

 

[Frank Acampora]

Re: trim getting up on pad

You have a short hull with a relatively heavy engine. You probably have the battery and fuel tank in the back too. On a hole shot, she is going to raise the bow until sufficient speed is attained to "break over" onto plane. You will need to tuck the trim all the way in to get it up on plane faster. Then trim out for maximum speed.

This effect can be demonstrated (exaggerated) by my 10 foot tunnel hull. With no trim and a 25 HP engine, I must lean way forward over the steering wheel and bounce to bring down the bow and get it on plane. If I do not do this, she will wallow, with the bow pointing at the sky, all day, at full throttle without breaking over onto plane.

Additionally, understand that trim out will be slower than trim in because of the load on it and will be way slower than tilt function with no load.

In addition to battery connections, check the oil level. If it is low or if you are foaming it due to running the motor after it reaches its limits, then trim out will either be slow or non existant.

Since you replaced the motor, it stands to reason that you had trim/tilt problems. It might also be an idea to check the trim cylinder (center cylinder) to see if it is actually moving. If the piston has jammed at partial or full trim out, then getting the boat to plane will take longer. Even with a jammed trim cylinder, the tilt function will still work normally.

As to prop, a 16 footer with a 125 would normally use either a 19 or 21 pitch prop. I would expect a 17 pitch to be too low for the load and RPM would be too high at WOT. Lower pitch will help with quicker acceleration and quicker planing but if your wide open throttle RPM is within the 4500-5500 range, preferably 5000-5500, then the pitch of your prop is correct. If you are running right around 4500, then a step down in pitch would probably help some.

 

[jerryjerry05]

Re: trim getting up on pad

Frank covered it.Get a tach and do WOT readings.You should operate at 5300-5500 rpm at WOT. Jerry

 

[b-man]

Re: trim getting up on pad

Thanks Frank,
Will try that method of tucking motor and see if that helps, in meantime can you explain what might be happening when I am running down lake dosen't have to be fast but up on water and I hit button to raise motor is seems to me like it don't raise up or if it does don't notice it, say like I trying to raise it out of water. When I am not using motor like when I am in shallow water to raise it to keep from getting stuck or at idle it seems to come up far enough any thoughts?

 

[Frank Acampora]

Re: trim getting up on pad

If I understand correctly, you are saying that when you are up on plane and running, When you activate the up trim you don't see anything happening.

Also, as I understand you, while running the engine, it will not tilt up yet it does when the engine is not running.

First, the trim and tilt are separate functions; the trim is the center cylinder with the pentagon shaped cap and the tilt is the hydraulic cylinder right next to the starboard clamp. The other cylinder has no lines and is just a shock absorber. Even though the trim and tilt cylinders are fed from the same valve, because of the greater hydraulic advantage, the trim cylinder will move out first. Then when it reaches the limit of its travel, the tilt cylinder will move. Tilting DOWN, it is just the opposite.

Second: On some engines even though there is a much higher mechanical (hydraulic) advantage to the trim cylinder they still function slowly. Note that because of the much greater advantage of the trim, it will always function much slower than the tilt cylinder. Because of this slowness, it may seem as if the engine is not moving when you activate the switch. The trim cylinder only has about a two inch travel and if you are not paying attention, you may not notice the different engine position.

Third: because of the much lower hydraulic advantage of the tilt cylinder, it will never tilt while you are running the boat at almost any speed. It just is not strong enough. Additionally, there are relief valves in it. Once the trim cylinder has reached it full travel, at any speed much over 3-5 MPH, the tilt cylinder will not work no matter how long you hold the switch on. More next.

Fourth: You can never operate the tilt at anything much over 1000 engine RPM. It just will not rise. This number varies from unit to unit. Some good ones will operate at up around 1500 RPM. You can operate it at engine speeds around 1000 RPM but if you increase the engine speed again with it tilted, the relief valves will open and the engine will rapidly tilt down (or slam down) until it contacts the trim cylinder plunger.

 

[RRitt]

Re: trim getting up on pad

I thought he was saying one of two things ... either

A) His boat isn't getting up on plane. Could it be trim? I thought your first response was perfect for this possibility. (maybe he just has a ton of weight sitting on his stern and it makes him plow no matter what)

- or -

B) He bought new trim motor and it doesn't seem to lift as fast as it used to.
Which is either due to undervoltage or using a motor that isn't same as original. Because of geometry it takes more pump pressure to tilt than trim. Since he didn't mention bleed down then it is a fairly safe assumption that pump is okay.

 

[Gamblerman]

Re: trim getting up on pad

Ok This is the same thing I had going on with my 16ft bayliner
This boat had a 85hp on her.The motor was bad so I had a nice 125hp force in the garage so I put this outboard on and well I had a very hard time with this set up.The nose was up all the time and this is because it just to big of a motor for a 16ft boat and I had the same problem with my trim tilt (It was a leak) Now to get this boat to plan out I had to move the gas take and bat to the front. 1 2 3 she is up on her pad. Super fast now but I try not to go to fast Im over powered

 

[b-man]

Re: trim getting up on pad

Thanks for the help guys, Frank you seem to know what I am asking sorry if did not make it clear to you, but sounds like what is going on and the explaination you gave seem to help, thanks!
Rhitt: you mentioned about bleed down are you refering to when you motor is up and it drops down just sitting either fast or slow? I have a slight drop in motor when it raise up and it sets for a little bit it will drop. Guy that put motor on said it might still have some air trapped in lines, should work it self out, sound right? Fluid level is full at this point, keep checking it though.

Now for another question for either one of you, how is the best to check your tach, rpm guage works ? mine currently does not move, but have not checked it out enough to see if it is a electric issue or guage itself? How is the best or easiest way to tell? Thanks alot for all the help

 

[Frank Acampora]

Re: trim getting up on pad

When you turn on the ignition key to run position without starting the engine, the tach should zero the pointer. When the engine is running the tach should read steady, not bounce or fluctuate. If either it fluctuates or does not zero, then you need to check wiring before concluding the tach is broken. If it does not move at all, then again, before concluding it is broken, it is time to check both power to it and signal to it.

Signal is the purple wire. Power should be a wire coming off the "I" terminal of the ignition switch. The purple wire should connect to the purple terminal at the engine and the purple in the wire loom should connect to one A/C terminal of the rectifier mounted near the starter.
A black GROUND wire also should connect to the ground terminal on the tach.

Note that IF the rectifier at the engine either is bad or is starting to go bad, it can affect the tach. This is one thing you normally would not suspect, but usually it causes erratic readings or incorrect readings of RPM. Unless completely trashed and delivering no voltage to the battery, I would not expect the rectifier to cause no signal to the tach.

 

[RRitt]

Re: trim getting up on pad

......
Rhitt: you mentioned about bleed down are you refering to when you motor is up and it drops down just sitting either fast or slow? I have a slight drop in motor when it raise up and it sets for a little bit it will drop. Guy that put motor on said it might still have some air trapped in lines, should work it self out, sound right? Fluid level is full at this point, keep checking it though.
......

Pressure equalizes and trapped air stays trapped. Not related to bleed down in the slightest way. If fluid is low then system raises until reservoir runs dry. Gears aren't designed to pump air so system just stops lifting. Air bubbles in trim system are of no consequence no matter how you look at it. If a mechanic ever mentions air bubbles as a possible cause of problem then don't let him work on your trim system.

If system bleeds down then there are only three possible causes:

1) there is a leak and fluid is dripping off of engine and onto the ground below.

2) one of the rams is going bad. a leaky piston in either trim or tilt will casue both cylinders to bleed down. It has to be piston. If wall is scored then bleed down stops as soon as piston clears the damage.

3) valve body no longer holds pressure. 99 times out of a hundred it is the valve body. Buying a used valve body isn't going to fix it. Thje youngest one you ca buy is 20 years old. That's like playing russian roulette with only one empty chamber. Rebuilding or replacing valve body is the only legitimate fix.

 

[b-man]

Re: trim getting up on pad

Thanks once again gentlemen,
Tach needle does not move at all, no matter if just sitting or running down lake, that one reason for the question as the prop answer was stated, hard to tell rpms if you can't tell what you are running at?
Bleed down answer also helps me, appericate it.
Looking for a repair manual any suggestions?