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Author Topic: Hydraulic Question  (Read 371 times)

RedandSilver

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Hydraulic Question
« on: August 14, 2017, 07:07:21 PM »
Is there any reason NOT to use Teflon tape on hydraulic fittings?

The bottom of my coach is pretty wet.
After looking around a lot I can't see any evidence of Teflon tape being used on the fittings going to the hydraulic fan.
And that is where I think most if not all leaking is coming from.

 
2002 Rexhall Rose Air  Cummins 8.3  350hp

Rene T

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Re: Hydraulic Question
« Reply #1 on: August 14, 2017, 08:03:57 PM »
If the threads are pipe threads, no problem. If the fittings are flared fittings, the threads are straight threads and the tape won't do anything. The flare is what seals.
Just make sure you don't wrap it around the 1st thread and looking at the end of the fitting, wrap it in a clockwise direction to prevent the tape from peeling off when you screw it in.
« Last Edit: August 14, 2017, 08:09:32 PM by Rene T »
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2011 Chevy Duramax 2500 HD 4X4
2011 Montana High Country 343RL
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& Florida Snowbird in Lakeland FL

RedandSilver

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Re: Hydraulic Question
« Reply #2 on: August 14, 2017, 10:15:33 PM »
So are you saying it SHOULD have tape on them?  I believe they are standard pipe threads.
2002 Rexhall Rose Air  Cummins 8.3  350hp

Tom

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Re: Hydraulic Question
« Reply #3 on: August 14, 2017, 11:52:59 PM »
Teflon tape isn't a sealant; As you tighten the fitting, the threads will cut through the tape. It (the tape) acts as a lubricant, allowing you to tighten the fitting further, which presumably tightens the seal between the two threads.
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Rene T

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Re: Hydraulic Question
« Reply #4 on: August 15, 2017, 04:04:29 AM »
So are you saying it SHOULD have tape on them?  I believe they are standard pipe threads.

Tom is !00% Correct. Yes you should use it.  Here's what the Wikipedia, the free encyclopedia says about tape:

The tape also works as a deformable filler and thread lubricant, helping to seal the joint without hardening or making it more difficult to tighten,[3] and instead making it easier to tighten.[2]

Typically the tape is wrapped around a pipe's thread three times before it is screwed into place. It is commonly used commercially in applications including pressurized water systems, central heating systems, and air compression equipment


« Last Edit: August 15, 2017, 04:08:22 AM by Rene T »
Rene & Lucille & co-pilot Buddy
AKA  Pep N Mem
2011 Chevy Duramax 2500 HD 4X4
2011 Montana High Country 343RL
From the Granite State of NH
& Florida Snowbird in Lakeland FL

RedandSilver

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Re: Hydraulic Question
« Reply #5 on: August 21, 2017, 08:27:03 AM »
Update.

I THINK I found the problem - or at least one of them.
I bought a 1.250" combo wrench and put it on the hydraulic fan fitting and couldn't move it.
Later I tried to move the TOP fitting (from the inside with the bed raised) and did get it to move some.
Because I had to reach quite far I didn't have good leverage on it -  I finally found a few pieces of metal tubing
that was big enough to go over the 1.250 combo wrench end and could tighten it a little more.  Then since I had
the cheater bars there I decided to try the lower fitting again and could move it.  Guessing I moved it about 1/2 revolution.

I started the coach up and moved it some and then rechecked and there was still a drop of oil on the lower fitting SO
I tried to tighten it some more and maybe moved it another 1/6 of a turn.  I don't think I can get it any tighter than what it is now.

I'm not sure if there is or was any Teflon tape on the fittings or not. 
What I'm NOT WANTING to do is undo the fitting and lose a lot of oil.

Here is my question:

Is there anything I could use to wrap around the fitting (to seal it) that would not come loose if hydraulic oil came into contact with it?

Pig-putty  or  Water Weld  or  Plumbers Putty  etc.

Any help is appreciated. 
« Last Edit: August 21, 2017, 05:18:09 PM by RedandSilver »
2002 Rexhall Rose Air  Cummins 8.3  350hp

Tom

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Re: Hydraulic Question
« Reply #6 on: August 21, 2017, 09:13:29 AM »
Tough to seal externally if it's coming out under pressure. If a light drip, self-amalgamating tape (aka as Tommy tape and rescue tape) might work.
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kdbgoat

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Re: Hydraulic Question
« Reply #7 on: August 21, 2017, 09:29:11 AM »
One thing that may help is ensure there is little to no pressure on the fitting when you tighten it. Is there a way to remove power from the pump motor and still keep power on the switches and solenoids? That way you can use the switches to operate the solenoids to relieve the pressure in the affected line.
I know you believe you understand what you think I said,
But I am not sure you realize what you heard is not what I meant


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Tom

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Re: Hydraulic Question
« Reply #9 on: August 21, 2017, 01:32:51 PM »
That might be too permanent.
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kdbgoat

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Re: Hydraulic Question
« Reply #10 on: August 21, 2017, 02:18:32 PM »
^agree^. The "miracle tape" Tom suggested will probably work well for a temporary solution. I have seen it in use on a drum pump that leaked badly when a trucker was trying to empty one of his fuel tanks into drums after gashing the bottom of it. The tape worked well on that pump even running diesel fuel through the pump. That was about two years ago, and I think the tape is still on the pump.
I know you believe you understand what you think I said,
But I am not sure you realize what you heard is not what I meant


2016 Leprechaun 319DS

RedandSilver

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Re: Hydraulic Question
« Reply #11 on: August 21, 2017, 05:47:16 PM »
One thing that may help is ensure there is little to no pressure on the fitting when you tighten it. Is there a way to remove power from the pump motor and still keep power on the switches and solenoids? That way you can use the switches to operate the solenoids to relieve the pressure in the affected line.

It is the fitting on the Hydraulic Fan which runs when the engine is on.
Don't think there is a way to remove any pressure (if there is any with the engine off) without removing the lines which I'm not going to do.

I like the tape Idea and if that didn't work or hold then the underwater Weld would be next.
The hose looks newer - don't know if the PO changed it out for some reason and then didn't get the fitting tight enough or not.
But because the hose looks newer I wouldn't be afraid to make it a permanent fix because in a closed system nothing but a leaking hose
would make me change that fitting (if it was THAT hose) so I may go straight to the Weld stuff.  Worse case is I would have to cut the hose off
and then MAYBE chisel away the weld but there is a 90 elbow that I could remove and then replace it too if the worse case happens,
although that would require the removal of the fan from the bracket.

Thanks for all the helps and ideas - I'll let you know how it works out after I do something.  ;D

All I know is I'm really tired of it being so wet down there and feel this has to be a big part of it.
If it's still wet later I'll be looking for even more leaks.  I've cleaned the underside pretty well (like with a toothbrush) so
I hope I will be able to tell if it's leaking someplace else too.  :o
 
2002 Rexhall Rose Air  Cummins 8.3  350hp

JSplaine

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Re: Hydraulic Question
« Reply #12 on: August 23, 2017, 03:28:31 PM »
Do Not Use Teflon Tape on hydraulics. I managed a marine hydraulics service business for ten years, so some experience with the sealing of hydraulic fitting. Any piece of that tape gets into the system it will find it way to the valves and pump. There it will gum up operations, in the pump it will melt and cause pressure and/or flow loss. Use a high quality thread sealant like Loctite 569.
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boatbuilder

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Re: Hydraulic Question
« Reply #13 on: August 23, 2017, 03:45:59 PM »
JSplaine hit the nail on the head.  Done very carefully you can get away with it for a while but one day you will slightly overwrap the end and the piece will break loose and gum up the works.  If they are brass fittings they should seal with maybe just a little lubricant to help tighten.  Pipe threads are tapered and get tighter as you thread them together.  If they have a flange then they may be straight threads and have a gasket of Oring to seal.
Charlie

 

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