Step away from the silicone on hydros -a Rant

[pfrederi 17,147]

A brief rant. If you are working on a sundstrand hydro and have a tube if silicone gasket maker...put it down and back away. If you are too lazy and or cheap to make or buy a proper gasket at least don't screw up the hydro for the next owner. If you are using silicone it will not last long and you will be selling it or parting it out. Silicone has no place in a hydro. i have been trying to make a working system out of 2 pumps and 3-4 motors. Most of them show evidence of silicone and it is stuck ion the darnedest place.

From now on for me if a hydro unit shows any external signs of silicone it is a parts value only unit. No professional would use silicone and if the person doing the work did use it I question the overall quality of his work.

Rant over!!.

[AMC RULES 36,945]

Good advise, thank you Paul. :thanks:

[can whlvr 991]

these hydros are not as easy to work on as some may think,and good advice on the sealant

[Hodge71 663]

Boy Paul, we share this sore spot don't we my friend. You and I know very well from just the experience with my 18 auto and what we went though due to the cobb job that was done before I had it. When I took the original pump and motor to Northeast Hydro, the older gent's exact words were "I hope you werent the one stupid enufft to use blue goo as a gasket, silicone don't belong in hydraulics."

When we used to rebuild pumps and cylinders at work for our presses, my senior mechanic taught me dont even use teflon tape on fittings. For some reason everytime we had one go down, we always found teflon tape in the filters. He showed me a sealant called Leak Lok by Highside chemicals. We used it on pnuematics, hydraulics, steam, water, oil, and natural gas. Pretty much any line we had with excellent results and no harm to the hydraulic pumps or anything else.

[kpinnc 10,741]

Good points. Silicone and hydraulics don't mix.

I have to ask though- what is a good gasket dressing, if we use a local supplier for such things like NAPA or similar? I've always used some kind of dressing on transmissions with a new gasket, because a gasket alone tends to leak.

Of course I only use a tiny amount. I think one mistake many people make is to use so much it squishes out into the case on reassembly. I use a very tiny amount- just enough to "wet" the gasket. NEVER enough to make a bead.

[SousaKerry 500]

In our hydraulics classes at work (we have 17 plants worldwide) it is right in the coarse material not to uses Teflon tape or any kind of silicone in any hydraulic system. We use Loctite pipe sealant with very good results, can't remember the number off the top of my head but it comes in a white tube. The best part about it is if it does get in the oil it breaks up into small enough particles that it flushes right through.

They do sell gasket glues that are in a spray can but I have never used it myself.

[wheeledhorseman 573]

Sound advice Paul and noted.

I don't think I'd have been tempted to use silicone but came close to using teflon tape (known as PTFE tape over here).

I can't see that it would serve much purpose for the standard hydraulic fittings but I needed to blank off two of the ports on the motor to run my D-200 without the damper valve assembly that's mounted under the rear fender.

It was very tempting to use cut down bolts to do the blanking off and I might have ended up using tape to get a good seal but something in my head told me to do it properly so I waited till I'd got a couple of blanking plugs from my local hydro place. They don't cost much and have the correct sealing washers called 'doughty washers' over here, Stat-O-seals in the US?)

Obviously I'm glad that I did now having noted what's been said here.

Andy

[meadowfield 2,545]

Andy, yes doughty washers are the right parts - tho' my cut down bolts just used o rings. The correct pipes actually use o rings anyway - so not too much of a bodge.

Re: teflon tape - there are two rules: never used teflon tape in a hydraulic system - and never ever use teflon tape...

Re: sealant, because my C-101 tranny leaks like a *$%^$ and had a new gasket, I wiped the surfaces with universal blue. It doesn't leak and I hope to god it doesn't cause any damage - if it does then lesson learned the hard way. Though I didn't use it as a bodge, it really was just belt and braces making sure it didn't leak on my new shop floor !

[pfrederi 17,147]

Permatex makes an aerosol gasket sealant (Hi-Tack maybe..I will have to look at my can tomorrow.

Andy... are the plugs you need ORB 6 (O Ring Boss) ?? I may have some.

[TT-(Moderator) 1,127]

Permatex Indian Head gasket shellac is great for holding/sealing paper gaskets. Never used it in hydro/hydraulic applications though. :confusion-shrug:

[wallfish 15,930]

OH $**T

I used teflon tape to seal all of the NPT connections on my backhoe. This was recommended in the instructions.

There hasn't been a problem that I know of yet so maybe it should be left alone, or should I remove it all ????????

What exactly is the problem with using teflon tape to seal the threads?

[can whlvr 991]

if the tape is pushed into the stream of fluid it wont breal down therfore it becomes a foriegn object running through the system till it gets caught in small openings,filters,valves,etc,for what you were doing you would be better to use pipe dope and use it carefully,dont put it all the way down the threads,leave 2 or 3 threads bare,and you dont need much,but as stated allready its not good in hydro situations,if you were careful and didnt over do it on the tape you may be lucky

[wheeledhorseman 573]

Permatex makes an aerosol gasket sealant (Hi-Tack maybe..I will have to look at my can tomorrow. Andy... are the plugs you need ORB 6 (O Ring Boss) ?? I may have some.

Thanks for the offer Paul but I did manage to get some plugs to do the job properly over here.

No leaks and no Teflon / PTFE tape. However, look carefully and something appears to have been used in the past on the little threaded plug at the very bottom. (Not my doing and its too tough to be Teflon thread tape. You can see where I tried to pull a bit off)

Andy

[otrelwood 32]

A lot of fittings have a sealent on them new that could be what is on yours there andy. Why did you not use the damper valve mine has it the replacement did not so i reinstalled it havent run yet but am wondering why some had it and some dont

[wheeledhorseman 573]

Lonny

The dampers have been mentioned I think in a couple of our D family's threads.

I gather they weren't fitted to early or late models and as long as you're not heavy handed with the forward-reverse motion control the they aren't exactly essential.

The reason I removed the dampers on mine was to check beyond any doubt that a faulty damper valve was not the cause of my tractor refusing to go backwards. Initially I just swapped the two valve units over but as I haven't come across a diagram of exactly what's inside these I thought I'd double check by removing them from the circuit completely.

Now that I know they're ok I will put them back but not until I get some new hoses made up as they'd obviously been weeping a bit from the swivel joints on the fittings.

I came to much the same conclusion about that stuff being some kind of sealant or locking compound.

Andy