Trobleshooting/repairing trim cylinders on mercruiser 470 outdrive

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Nov 3, 2006
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I have an 79 Mercruiser 470. Driving up the boat ramp as I was taking it out of the water, the trailer winch cable snapped and the boat rolled stern first off the boat trailer and onto the boat ramp. The outdrive took alot of the force of hitting the ground and the pivot end (by the prop) of the two trim cylinders sheared off of the outdrive at prop end of the sterndrive. I need to (at least) replace the pivot end cap on the two trim cylinders. The trim cylinders appear otherwise to be OK. Is there a manual or troubleshooting guide that I can use to test the trim cylinders and hydralic pump system to see if hitting the boat ramp caused additional damage beyond shearing the pivot end caps off?

Thanks

David
 

Haut Medoc

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Re: Trobleshooting/repairing trim cylinders on mercruiser 470 outdrive

Welcome to iboats...:)
You need Mercruiser Manual #6....
There is a free online link, but I don't have it....
Stick around, someone will post it up.....
You could try the archives, Don S has posted that one many times...........JK
 

Don S

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Re: Trobleshooting/repairing trim cylinders on mercruiser 470 outdrive

I'm afraid that links not going to help him guys. It doesn't cover back that far. Only back to 83.
His cylinders are completely different, inside and out.
Need manual #4, Mercruiser pn 90-86137.

There are also 2 different types of cylinders. Ones with internal lines and those with external lines.

Here is a parts breakdown for your model.
http://216.37.204.206/Shorts/mercruiser_OEM/Mercruiser.asp?Type=12&SubType=113&A=37
 

Bondo

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Re: Trobleshooting/repairing trim cylinders on mercruiser 470 outdrive

The outdrive took alot of the force of hitting the ground and the pivot end (by the prop) of the two trim cylinders sheared off of the outdrive at prop end of the sterndrive. I need to (at least) replace the pivot end cap on the two trim cylinders.
I don't quite understand,.......
It Sounds to me like you Need New Trim Rams,.......
The Ends are Welded onto the Ram........
Or,.....
Did you Shear Off the rear Anchor Pin,..??..??.....

A Picture should would Help......
 

Don S

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Re: Trobleshooting/repairing trim cylinders on mercruiser 470 outdrive

He must have the internal line cylinders bondo, they had replaceable ends on the cylinders, not welded like most are.
 

Bondo

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Re: Trobleshooting/repairing trim cylinders on mercruiser 470 outdrive

Luckily,..........

That's 1 of the Alpha Changes I Haven't run in to,.................... Yet............:love:
 

Don S

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Re: Trobleshooting/repairing trim cylinders on mercruiser 470 outdrive

You keep futzing with them things long enough, you will.
Probably thought you would never run into a Dana drive either, did you :)
 

Bondo

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Re: Trobleshooting/repairing trim cylinders on mercruiser 470 outdrive

Didn't Think there Was such athing a few months ago.............d:)

"Mom's Paycheck" comes Out of the Water tomorrow,...... At Daylight.......

Probably otta Go to Bed,.......:/
 
Joined
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Re: Trobleshooting/repairing trim cylinders on mercruiser 470 outdrive

bond-o said:
The outdrive took alot of the force of hitting the ground and the pivot end (by the prop) of the two trim cylinders sheared off of the outdrive at prop end of the sterndrive. I need to (at least) replace the pivot end cap on the two trim cylinders.
I don't quite understand,.......
It Sounds to me like you Need New Trim Rams,.......
The Ends are Welded onto the Ram........
Or,.....
Did you Shear Off the rear Anchor Pin,..??..??.....

A Picture should would Help......
 
Joined
Nov 3, 2006
Messages
8
Re: Trobleshooting/repairing trim cylinders on mercruiser 470 outdrive

Hi Thank you for all your mails.

I have an older outdrive. Using

http://www.sterndrive.info/sterndriveparts/identify_my_outdrive.html

It is listed simply as a Mercruiser outdrive (1972-1983).

Pictures of trim cylinders showing broken cap and also a pict of outdrive sans trim cylinders are attached.

Thanks for your help. I want to go thru a testing methodology to figure out if i only need to replace caps or whether the damage extends into the cylinders or pump systems. I would like to diagnose problem(s) before startingto throw parts at it.

Thanks again for your interest and assistance.

David
 

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Joined
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Re: Trobleshooting/repairing trim cylinders on mercruiser 470 outdrive

well, first, the older 470,s came with borg warner transmissions and TRS outdrives.

does your boat still have the seperate transmission / outdrive system or is it a bravo set up?

i love the TRS outdrives, they are as tough as nails.

second, if the trim cylinders wer broken off as a result of the outdrive being pushed past their limitations, im thinking the pistons are the least of your problems

testing the pistons is easy. just disconnect them from the drive, remove the anodes, and have someone activate them while you watch to see of the shaft is bent, or if any fluid leaks from around the seals while going in or out.

if its leaking fluid, the shaft is probably bent even of you cant see it. replacing the seals wont help, but im pretty sure you can rebuild the entire assembly and replace the shaft.

second. if the drive was pushed beyond the limits of the actuators, you need to remove the drives.

you need to check the gimble for damage with the drive off, the transome around the gimble for stress cracks, and you probably need to realign the drive shaft as well.

third, if it hit the skeg, your probably ok, if it hit the props however, you should also check to see of the prop shaft is bent. easy enough to do, just remove the prop and start the engine. put it in gear adn look for wobbeling or fuild leakage around the shaft seal.

i smacked my twin TRS drives against something submerged in the water hard enough to lift both of them out of the water and take the boat off a plane. a 9000 lb donzi going about 45 mph.

after removing and checking everything, it cost me about 400 bucks to have a new skeg welded back on one of the drives and 150 to streighten a prop. tough as nails i tell you. my brovo three would have cost me thousands to fix under the same circumstances.

good luck. if its a TRS, you probably stand a better chance of destroying your gimble and transome than the drive.,
 

Don S

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Re: Trobleshooting/repairing trim cylinders on mercruiser 470 outdrive

well, first, the older 470,s came with borg warner transmissions and TRS outdrives.

Never heard of that before, never seen it before either.
Not sure where you got that info from, but it's not true at all. They all had the Alpha STYLE drives.

merc470, your pictures didn't show up. You can't post pictures using that method. Not even sure why they show that option, no one has ever made it work.
You need to have your pic on the web, then use the image icon above that looks like this
image.gif
to insert your pictures URL into.
 
Joined
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Re: Trobleshooting/repairing trim cylinders on mercruiser 470 outdrive

Hi Rosco, I believe I have an old borg warner transmissions and TRS outdrive. See photo. Can you tell?

Thanks David
 

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Don S

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Re: Trobleshooting/repairing trim cylinders on mercruiser 470 outdrive

David,
Like I said before, you DO NOT have a TRS drive and borg tranny, the 470's NEVER came out with them. Not sure where rosco got that info, but it's all wrong.
Up at the top of the page I gave you information for a service manual and a parts breakdown.
After looking at your pictures, you have the trim cylinders with internal lines, and you can order the ends for the rods. They are less than 20 bucks each. but I couldn't imagine those ends breaking without bending the trim rods. If they are bent even a little, they will bind and leak. Here is the parts breakdown. Kind of a poor picture, but it has the PN's.

http://216.37.204.206/Shorts/mercruiser_OEM/Mercruiser.asp?Type=13&SubType=113&A=37&B=14
 
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Re: Trobleshooting/repairing trim cylinders on mercruiser 470 outdrive

Ok Thanks on part ID and the url . If cylinder is bent, am i correct in needing to overhaul kit since I do not see separate part for cylinder itself? Do you think the damage could have impacted hydralic pump? After the damage I tried to run trim down using switch at cockpit. Noise from pump but no mostion on trim cylinder. Afer I took cylinder off, I was able to push cylinder in to housing as the fluid was squited out from opening where kline would be attached? Is there a troubleshooting wat to check ouot the pump and trim cylinder system?

Thanks david
 
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Re: Trobleshooting/repairing trim cylinders on mercruiser 470 outdrive

SORRY FOR TYPOS ABOVE MY MAIL WAS SENT BEFORE I FINISHED>

Ok Thanks on part ID and the url . If cylinder is bent, am i correct in thinking that I need overhaul kit since I do not see separate part for cylinder itself? Do you think the damage could have impacted hydralic pump inside boat? After the damage I tried to run trim down using switch at cockpit. Noise from pump but no motion on trim cylinder. Afer I took cylinder off, I was able to push cylinder into its housing as the fluid was squirted out from opening where line would be attached? Is there a troubleshooting way to sytamatically check out the pump and trim cylinder system?

Thanks david
 

Don S

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Re: Trobleshooting/repairing trim cylinders on mercruiser 470 outdrive

All of that troubleshooting info is in the manual. There is a complete section dealing with the trim pumps and a seperate one on the rams.
But if the rod itself is bent or damaged, you replace the whole trim cylinder. There is no seperate part for that rod. You can get a seperate tube, they have had problems in the past with them corroding thru.
The internal parts of that cylinder includes a shock piston and valve assembly that may be stuck open due to the impact.

One other thing on forum use. If you look at the box under your name that says -interact-, if you click the little gray button to the right of it, there is a dropdown menu where you can click "Edit Post" . Click it and your post will come up so you can edit any spelling, links, etc.
 

Bondo

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Re: Trobleshooting/repairing trim cylinders on mercruiser 470 outdrive

Don said:
but it's all wrong.

Just a Crazy Thought,............

I wonder if Trog has moved to south Florida,..??............d:)
 
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