Filling the Tilt/Trim System

MikeyB3649

Seaman Apprentice
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Jun 3, 2010
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44
So I finally got the tilt/trim system rebuilt and today I went to fill it. I raised the system to the full up position and filled the reservoir up to the bottom of the fill hole. I cycled the system up and down a few times but the only thing is does is make a God awful screeching sound and then sounds smooth. I go the other direction, it screeches then gets smooth. I keep filling the system and it keeps making the noise. Right now, the reservoir is full in every position and the fluid appears to be very milky. I'm think from the air being forced through it. It won't lift unless I help it along and when I lower it, it drops instantly. Any suggestions? What am I missing?
 

my1stboat1

Petty Officer 1st Class
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May 31, 2010
Messages
307
Re: Filling the Tilt/Trim System

consult or message RRITT hes the guy to talk to about these systems... I bought my valve body from him and my system has worked great since...
 

RRitt

Captain
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Mar 30, 2006
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3,319
Re: Filling the Tilt/Trim System

not enough info and too many possibilities. are the rams known good? if air bubbles make the fluid milky then you are using the wrong fluid. if the right fluid is being used then where did the water come from? too many questions and too little meaningful descriptions.
 

MikeyB3649

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Re: Filling the Tilt/Trim System

not enough info and too many possibilities. are the rams known good? if air bubbles make the fluid milky then you are using the wrong fluid. if the right fluid is being used then where did the water come from? too many questions and too little meaningful descriptions.

I apologize for the vagueness of my previous post. I was in a hurry to get to work.

I took the system apart because it had started to take on water during my last trip to the river. Prior to that it had been working fine. I rebuilt the system using the kit that I bought from your eBay store. When doing the rebuild, I followed your instructions to the letter and checked every o-ring for proper size as I put them on. I flushed the lines out using the ram to suck up mineral spirits before disassembly as you suggested in a previous post and then blew the lines out using compressed air until no fluid came out. I also replaced the pump with one purchased from DB Electrical, since the old one was getting very corroded anyways. It came with 3 drive shafts. I checked each one to ensure it would engage the valve body. One was too long, one was too short, and so I selected the middle size. When I put the system back together, I put everything back exactly as it came off. The fluid that I am using is ISO 32 hydraulic fluid, as you had previously suggested.

Thank you for your response and I apologize again for the vagueness of my previous post.
 

my1stboat1

Petty Officer 1st Class
Joined
May 31, 2010
Messages
307
Re: Filling the Tilt/Trim System

for some reason i think i used sae 30 motor oil in mine... 1 season on the system and its been good.. Where you able to get the trim cylinder off of yours to get the oring out from under neith it.. I couldnt frozen solid...
 

MikeyB3649

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Jun 3, 2010
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Re: Filling the Tilt/Trim System

Well RRitt had told me in a previous post that due to the detergents in the oil, it would decrease the overall life span and that it'd best to use ISO 32 hydraulic fluid.
 

RRitt

Captain
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Messages
3,319
Re: Filling the Tilt/Trim System

I apologize for the vagueness of my previous post. I was in a hurry to get to work.

I took the system apart because it had started to take on water during my last trip to the river. Prior to that it had been working fine. I rebuilt the system using the kit that I bought from your eBay store. When doing the rebuild, I followed your instructions to the letter and checked every o-ring for proper size as I put them on. I flushed the lines out using the ram to suck up mineral spirits before disassembly as you suggested in a previous post and then blew the lines out using compressed air until no fluid came out. I also replaced the pump with one purchased from DB Electrical, since the old one was getting very corroded anyways. It came with 3 drive shafts. I checked each one to ensure it would engage the valve body. One was too long, one was too short, and so I selected the middle size. When I put the system back together, I put everything back exactly as it came off. The fluid that I am using is ISO 32 hydraulic fluid, as you had previously suggested.

Thank you for your response and I apologize again for the vagueness of my previous post.

iso32 is designed to release air bubbles quickly and absorb transient moisture as might happen with condensation on a cool night. So the milky color means there is still water somewhere.

My kits on ebay only go up through 1991. I finally found a place that carries a debris wiper to fir 1992-1995 but they are still on backorder. This matters because force trim systems did not use drive shafts prior to 1992. If you used a 1991 seal kit on a 1992 tilt ram and forced the cover to fit then it is not any good and has to be redone. I have the body seal but the debvris wiper is going into its second month of backorder.

So let's assume that you have a 1992. That yould be the tall skinny motor with a square base and four ports pointing directly down towards the ground. Great pump. But it has zero tolerance for debris. having to help the system up as you describe is common with 120-150HP 1992-1995 force. mercury used cheap atf fluid and the big engines generate enough backpressure to impregnate the rubber and the trim piston ring splits. If you fixed the trim piston ring then your lift problem is probably debris in the pump. The pump you have is not like the prestolite. It is a very easy pump to work on and fairly DIY friendly. All you need to do is take it apart and find the little flake of debris that is jamming one of your valves. Just make sure to work in a clean area and hold things inside of a large tub when disassembling. The aluminum cylinder is your pump and it is held down by the single black bolt. the three little hex bolts hold the top aluminum to the bottom. When lifting aluminum of black base springs will pop out. Do it slowly without tipping over so that you can put it back together in correct order.

The grinding could possibly have been you gears. if the lubricating film gets washed away by water then they can burn and score. Probably not the noise you hear. But tread with caution to avoid this. It is fatal to your pump.

regarding fluid - ISO32 is best but 1988-1992 engines have a tendency to buck if the fluid is too thin. For those engines, ND30 is the safe fluid since it doesn't buck. Most other years hydraulic oil is best choice because of longer rubber life, absorption of moisture, and ability to release trapped air.
 

MikeyB3649

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Re: Filling the Tilt/Trim System

My kits on ebay only go up through 1991. I finally found a place that carries a debris wiper to fir 1992-1995 but they are still on backorder. This matters because force trim systems did not use drive shafts prior to 1992. If you used a 1991 seal kit on a 1992 tilt ram and forced the cover to fit then it is not any good and has to be redone. I have the body seal but the debvris wiper is going into its second month of backorder.

You included a pair of 2x35mm body to cover seals in my kit since I informed you I was working on a 1992. I didn't change the wiper seals, since you had already told me that there was no replacement for this. My rebuild should still be ok, correct?

I'll drain the system, clean the pump, ensure I get all the water out, and then try using a different fluid.
 

RRitt

Captain
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Mar 30, 2006
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3,319
Re: Filling the Tilt/Trim System

iso32 is best for 1992. the pump with square base works best with thin fluid. ATF will impregnate your trim ring and cause failure in 10-15years. So ISO32 is as good as it gets.

double check your trim cylinder. The 92-95 had tendency to blow out trim piston rings due to ATF and sometimes the piston would jam or score the cylinder sleeve. leave a little piston hanging out and make sure it moves freely as you tighten the cover bolts. also inspect the centering ring and retainer to make sure they are both square and solidly seated. If your sleeve got jammed or scored then it should be replaced with part# F449010
http://www.boats.net/parts/detail/merc/M-F449010.html

It is extremely rare for the tilt piston to get crooked and make scraping noise. Possible? yes, it is possible. Is it common? No, not at all.

another hot-spot on 1992-1995 rebuild is the tilt piston ring. If you are not careful you can knick the oring and get blow by. It would be
hard to get enough internal leaking to match your description though. It is unlikely that you could have knicked the tilt piston ring without having that little voice go off saying "that didn't seem right". You won't knick the ring if you used a little vaseline or grease during assembly and did not force it.

Assuming that the trim piston/sleeve/ring is okay then the #1 suspect remains debris in the pump body. It is a user friendly pump. Be slow and meticulous. Lift everything off very slowly over a tub so that none of the small parts get lost. It is a very intuitive assembly. the bypass valve in bottom goes back into base spring then seat then 1/8" ball.
 

MikeyB3649

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Jun 3, 2010
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Re: Filling the Tilt/Trim System

Ok. I took the system apart again and inspected everything. The trim cylinder has no issues and the tilt cylinder has no issues. I took the pump apart and found where the water was coming from. I didn't find any debris though. I cleaned everything up with mineral spirits, lubed all the orings and put it back together. Very easy process. Thank you RRitt for the assistance with the pump! You're description was dead on. So in light of the fact that all orings are fine, the pump had no debris, and both cylinders are fine, I starting to wonder if I might have had the lines swapped. I checked my Clymer's manual but couldn't find anything on the proper connection of the lines.

Can anyone help me out? I have the 1992 pump with the square base and the 4 ports pointing straight down.

Thank you in advance.
 

MikeyB3649

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Jun 3, 2010
Messages
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Re: Filling the Tilt/Trim System

Can anyone help me out? I have the 1992 pump with the square base and the 4 ports pointing straight down.

Disregard, I found a picture of one on sale on eBay and used that as a reference. I got it all hooked up and everything works like a charm. I'd had them hooked up correctly after all. Guess it was something in the pump like you suggested RRitt, even though I didn't see anything!

Thanks a lot for the help with the kit and with the troubleshooting! You are the best!
 

RRitt

Captain
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Mar 30, 2006
Messages
3,319
Re: Filling the Tilt/Trim System

glad it works. Yeah, it was probably that little tiny speck of black stuff you found near the gears. It always seems to happen sooner or later whenever you have ATF in a 120-150HP force.
 
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