Hydraulic reservoir tank access leaking, replaced gasket twice...

[George Mason]

The access hole to the hydraulic reservoir tank on my Ford/New Holland 555E is slowly leaking/dripping. I have soaked the cap in diesel fuel and hit it with the air compressor to make sure it was not clogged and causing a ventilation issue, that did not help. The tank has no damage, dings, pits, and the gasket has been replaced twice now, making it the third one on there to leak, none of them were dry rotted or damaged and two were brand new from New Holland. I figured I'd come here for some help before racking up the big cost of having the dealer come out and investigate what is not such an obvious fix - until one of you mentions it. I appreciate the help.

RW

 

[Ed of all trades]

Did you try a very thin layer of silicone gasket on each side of the gasket? I would just smear it on, like thick paint, it sometimes helps.

 

[pmsmechanic]

Two things come to mind. Check to make sure the vent on the cap isn't plugged. When the oil warms up it expands and the pressure might be pushing the oil out. Also the next time you replace the gasket lay the cover on a level surface to check if it is bent. Someone in the past might have tightened the bolts too much and bent the cover. It shouldn't be too hard to bend straight with a hammer on a solid piece of wood. And as Ed of all trades mentioned a little silicone can go a long way.

 

[Rocky Hoffler]

Did you try a very thin layer of silicone gasket on each side of the gasket? I would just smear it on, like thick paint, it sometimes helps.

good advice but let silicon tack up before install to keep excess from squeezing into tank.

 

[puckgrinder85]

If the holes aren't blind you need to seal the threads.


Ps- its actually looks like its starting out on the bolt in the 2-3 o-clock position and running down the cover from there, if the gasket were leaking Id think you might get more around the edge of the cover, not down the face of it.

 

[skyhook]

Use a silicone thats oil/gas resistant,
ensure both surfaces that you are applying the silicone to are clean and free of rust.
Torque all the bolts "equally.

 

[George Mason]

All good thoughts, so this apparently happens more to many pieces of equipment and more often than we'd like?

I have tried permatex brand oil resistant silicone on the gasket, and then another brush on type of oil resistant sealer that was real stringy and appeared to be like liquid fiberglass or spider web, that's the red colored stuff you can see the remnants of around the tank. They worked for a while and then sure enough the oil seeped out and once it starts it keeps on coming. I don't know much about the sealing the threads, what exactly does that mean? I've seen where others had mentioned sealing bolts or something of that nature in similar threads/posts.

Do you think there is a need to get another gasket to try again, is it shot once the leak takes place? I am thinking of taking it off and cleaning it with dish detergent to get the oil off, let it dry nice and flat, and then try again. Those gaskets are running $25 or so.

 

[puckgrinder85]

When you take the bolts out does that bolt go clear through and into the tank? If so you must seal those threads with a pipe compound or something. Fluid can weep through the threads as they are not perfect by any means. We use "the right stuff" from permatex on all of our automotive gasket making areas, works very well and can tolerate a little oil being on the sealing surface.

 

[ruffdog]

Puck...you beat me to it !

 

[aczlan]

When you take the bolts out does that bolt go clear through and into the tank? If so you must seal those threads with a pipe compound or something. Fluid can weep through the threads as they are not perfect by any means.

Exactly. If replacing the gasket, you might look for an anaerobic sealant (Permatex makes one). That is what Dodge uses on the transmission pan iit only cures in the absence of air. That is supposed to prevent any extra that might squeeze out on the inside from plugging up valves and such inside the transmission.
If you don't want to take the seal off again, you might back the bolts almost all of the way out (one at a time) and put something like Oatey Great White Pipe Joint Compound with Ptfe on the threads, then run them back in. If its leaking around the threads that should fix it.

Aaron Z

 

[Coyote machine]

All surfaces you want to mate must be absolutely clean and dry prior to trying to make your seals. Brakleen or similar cleaner is good for surface prep. You should verify the flatness of both mating surfaces, on the tank, AND your cover. Since you have several new gaskets you might try putting one on the tank and one on the cover and use a grease film between the two, AFTER each is sealed to it's surface with 'the right stuff' or similar. Try torquing the nuts at 12/6, 3/9, etc. to effect an even pressure on the gaskets surfaces.
Another possibility is to use a piece of Bituthane, (Grace ice/water shield) over the bolts, then install the nuts and tighten them down. This might keep any seepage from bolt threads from escaping.
Also, don't rule out the tank's cap as a source of building pressure and forcing the leak over time during use. Is there an in tank screen or something else that might be clogged or need replacement? Filter or fluid change due on the machine?