Trim problem diagnosis/advice

[gene8084]

I have a 1974 Formula 180, I/O Mercruiser 888, Merc I outdrive with the original trim pump/system.

Background.​

1. I have rebuilt the trim rams in an attempt to solve a sag problem​
2. I now understand that I need to replace the valve in the bottom of the pump due to actually solve the sag problem.​
3. Pump motor has a single solenoid and the original Mercrusier switch.​
4. Trim limit switch is long gone and no replacement parts are available.​
5. Replaced the trim gauge (esthetics only, so kicking myself for touching it) and haven't had much luck getting the new gauge calibrated.​

Symptoms​

1. Trims up/out at a reasonable rate across the full range from vertical (in) to up & out (trailerable).​
2. Trims down/in at a reasonable rate from out to 10-15% from vertical. ​
3. Last10-15% seems to take a long time to get to vertical. As this is the operating range it?s really a nuisance. Add to it the guage issue and I'm basically running on feel only (ok with normal trim operation), ..but does not work for my kids and wife, It seems like I'm running the pump excessfully to ensure the drive is IN.​

Q's ​

1. What are the likely causes of # 3?​
2. Where should I look first?​
3. Removal and replacement of the pump to replace the valve will not be easy (very hard to get at), so I hate to go through that to solve the sag problem if this other problem warrants something more extreme (full replacement of pump and motor) - big $$. ​

For now the reverse lockout works fine for trailering so I?m saving the value replacement for the off-season.

Thank you.

Gene​

 

[erikgreen]

Re: Trim problem diagnosis/advice

Usually when mine is taking a long time in that last 10 percent it's because the oil in the pump is low... at that point most of the oil has been pumped out into the cylinders, and the pump is sucking what it can to try and push more out and get the motor up.

Limit switches for the 888 (which is a pre-alpha or MC-1 drive) can still be purchased from a lot of places. I'll be buying a new trim indicator myself soon, which comes in a pair with the limit switch.

Erik

 

[gene8084]

Re: Trim problem diagnosis/advice

Thanks Eric. I'll crawl back there and double check the oil. I checked it early in the season and it was fine, but I'd love it to be that straight forward.

On the trim limit, I had not found one. Someone cuts the wires before I came along. I didn;t know they were still available. Tough location to replace, but I'll plan it for the next bellow job.​

 

[gene8084]

Re: Trim problem diagnosis/advice

Well, the oil level was fine. I timed it, it takes twice as long to trim all the way in.​

Next iidea?​

BTW, I have a 1974 MC1. This does not have the side mount trim limit and trim sender. The trim limit is up inside the bell housing. Still looking for one.​

I reinstalled the old gauge and didn't have any trouble calibrating. I'm pretty disappointed in the Teleflex gauges I bought. The speedometer isn't as accurate as my old one at low speed and the fuel gauge isn't much better. They just don't make them like they used to.​