Tilt line leaks at VB connection

Arawak

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Aug 27, 2010
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Been fighting with a leaking connection on the bottom port of my Chrysler 105HP tilt trim valve body. The flare nut threads look fine and the end of the stainless steel line itself seems ok, so I replaced the VB but it still leaks under pressure right past the threads.

Any ideas on repair? Should I try to replace the line and if so is it the same thread as 3/16 brake lines?
 

jerryjerry05

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May 7, 2008
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Yes same as a 3/16 brake line.
​They are stainless and a regular brake line will rust.

​Does it have a cracked in the line?
​Is the head of the line/mating surface bent?

Maybe a bit of pipe tape?
 

Jiggz

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Oct 23, 2009
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If you can post a close up pic of the line with the fitting end and flared end it will help a lot in diagnosis.
 

pnwboat

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The seal is made between the cone shaped area around the hole in the valve body and the flare on the end of the line. This is how most hydraulic fittings seal.

If there is a leak, either the end of the line is cracked/deformed or the cone shaped area around the hole in the valve body is deformed and no longer mates to the flare on the end of the line correctly.

The threads are not intended to seal. All they do is to allow you to tighten the fitting to apply pressure to the flare on the end of the line to the cone shaped area around the hole in the valve body.

I've seen some connections repaired to fix the problem that you're experiencing by using a brass inverted flare fitting. The technical description is 1/8" Inverted Flare Tube Female x 1/8" Male NPT Pipe Adapter. I'm pretty sure the threads in the Valve Body are the same pitch as 1/8 pipe, but you need to verify that first. They're usually less than a dollar at a hardware store. The female part of the brass adapter has the cone shaped area around the hole for a flare fitting like what is on the end of your hydraulic line. The other end is a tapered pipe fitting which seals against the threads as you tighten it down. Not saying that this is a definite solution because the success of using this adapter is dependent on the conditions of the threads in the valve body, and there is no guarantee that it'll work in your situation but it might be worth a try.

Attached is a picture of the fitting.

Inverted Flare.jpg
 

Arawak

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Thanks guys... I'll post a photo as soon as I get a chance to take it off. It's actually the trim cylinder port (facing down) so I'd have to take the motor off to get at the other end if I replace it :(
 

Arawak

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OK, here I am 6 months later, finally got the motor off the boat (yesterday).

My mechanic buddy thought that the line of the line looked suspect, so I'm going to replace the line with 3/16" cunifer (Ez-bend) brake line. Never done this before, but I have a double flare tool and plan to make a wooden jig for the actual bending to match the line after I remove it.

I'm not 100% that the fittings on pre-made brake line fitting are the right thread, as per pnwboat's comments above. Do I just re-use the fittings from the existing line?

There are several conversations involving RRitt on this topic, but they never mention the fittings (at least as far as I have been able to find).
 

jerryjerry05

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They make a thread chaser for the pipe threads.
RRitt has passed.
The also can be tapped out to a bigger size.
​That doesn't always work.
​The manifold is aluminum and when it gets around salt water it get soft after a while.
 

pnwboat

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It all depends on where the damage is. Typically the lines and fittings are made of stainless. Pretty tough stuff. The valve body itself is made of some type of aluminum alloy. Usually the aluminum cone shaped seat where the stainless threaded fitting mates to gets damaged since it's softer, or the threads in the valve body get stripped so you can't tighten the fitting hard enough to get it to seal.

If however, the fitting itself is damaged and the seat and threads in the valve body is OK, then replacing the line should fix it.
 

Arawak

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RRitt has passed but his posts on the topic are about the best reference I have been able to find.

So I actually replaced the valve body last year with a new one and it leaks in the same place. The seat and threads on both VBs look fine. Seems it must be the line.

I was just trying to figure out if I can re-use the stainless fittings. Don't see why I can't. Hopefully can give it a try tonight.
 

pnwboat

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Well normally I would see no reason not to re-use the original fittings. They're pretty tough and I couldn't see the aluminum valve body damaging the fitting. Just to be sure though, I would switch the fittings if you can. That is, use the fitting that was originally screwed into the cylinder and install it into the valve body. Use the fitting that was originally in the valve body and install it in the cylinder. If the leak moves to the cylinder, then I would suspect a bad fitting. This is all dependent on the fittings being the same. I'm pretty sure they are, but you need to check and make sure.
 

Arawak

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Update... I had to go to the brake shop for my car, so I took the old line in and they made me up a replacement for $20. Cunifer line, new steel fittings.

Tonight I hooked it up, refilled to reservoir, and tilted her up. Still leaked but only a little. I tightened a bit and it started to leak heavily, so i backed off a 1/4 turn and it seems to have stopped. No idea how that's possible.

So i cleaned everything off, and left a sheet of paper under the connection. After 15 minutes there's one drop on the sheet. Will see in the morning if it has leaked down.
 

pnwboat

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It all depends on how the bell mouth opening on the fitting mates up to the "cone" around the hole in the valve body. That cone area is where the seal is actually made.
 

Arawak

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Well, this morning there were no more drops of oil and the motor had only dropped a little. The lake and my driveway are saved :)

Thanks guys for your help!
 
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