Hydraulic leak

[Geochurchi]

Hi All, we have an in-line Donaldson filter base p561131, and can’t get the filter to stop seeping oil, we have tried 3 different filters with the same results, the vendor states that we must use a P551551 filter which we have ordered, just curious that if this doesn’t work what other option we should pursue, thinking possibly to much pressure, what types of gauge would we use to check that, there are tappings on the base to install a gauge.
Thanks

[Greg_Lewis]

If it leaks after three filters I'd be looking for a defect in the head.

[warmstrong1955]

If you over-pressure it, the filter will fail, not the head. They split vertically and horizontally on the can, up by the threaded end, when pressured over 375 psi. I know, because Donaldson made a bunch of them, that failed below the max working pressure some years ago. To prove their filters were defective, we blew up about a dozen on a test bench.

Easy enough to check pressure, and you should. They are rated for 150 max working pressure. Install a gage, and see what you got, cold, op-temp, and while cycling whatever it runs at full flow. I doubt that is your problem.

That particular head has NPT ports. Bad news, and born leakers. It is not difficult for someone to over-tighten the adapters when they are installed, which can distort and/or crack the filter head. This is especially true, if 90 or 45 degree adapters are used. Sometimes that extra turn to get the adapter to the desired angle will do it. Other times an adapter may be weeping a bit, and someone will 'snug it up' to stop the leak.
I would replace that head with one with SAE straight o-ring ports. Part number is P563280. Same 25 psi bypass, and (2) 1/8" NPT gage ports as what you have, You would need to buy a couple new adapters for the -12 ports.

Any name brand filter element should work fine, like Baldwin, Luberfiner, Fleetguard etc. I've used them all with no problems with any. (I can't say that about the genuine Donaldson) All those filter guys make filters that 'meet or exceed' the OEM's standards. They also stand behind that statement as well.

I have seen bad castings in filter heads before. One, on a larger Donaldson model, had small cavities which were visible where the flat was machined for the o-ring to contact. I've also seen casting flaws inside the ports where the threads were tapped. Some......are not so obvious.

Other Bill

[Bill Shields]

Take it off. Put a new filter on it .plug all the holes with fittings.

Put it in a tub of water with an air hose attached and find the leak

If you are really in a jam..you can circulate some solvent into the head and out the weepy area using mild air pressure to cause it to flow and hopefully create a clean path.

Next pull a vacuum on it and suck some loctite into the weepy area...now that you know where the leak is.

Did this out in the desert 40+ years ago where the nearest filter head replacement was weeks away and a case of 'gotta make it run NOW'. A British fitter showed me how to do it using what we had handy.

Probably easier to just trash it and start over...but then the question was not 'what is easy'

[Geochurchi]

We have the Donaldson P567933 breather on the tank, is it supposed to be saturated with oil?

[warmstrong1955]

That's pretty normal, and I would expect it to be. Oil sloshing around and using anything hydraulic will do that.
If you have a lot of oil slobbering or spraying out of the breather, then there may be a problem. Several simple reasons for that.

Other Bill

[Geochurchi]

Does the P563280 base have a machined mating surface? I appears that the P561131 surface is cast, we are thinking that may be the source of the leaking.

[warmstrong1955]

All of them should be faced where the o-ring contacts the head, but I can only tell you they were. They are now manufactured in Italy, and I haven’t dealt with any made there, so all bets are off.

The filters use a square cut o-ring, which would not seal well on a rough surface.

Other Bill

[warmstrong1955]

You should contact the supplier you bought it from. A picture of the questionable surface would be a good idea.
Or, you can ask the question to Donaldson. I'd give you a phone number, but all the folks I knew there have retired like me!

https://www.donaldson.com/en-us/contact/
I have no idea how responsive these guys are these days, but may be worth a shot.

Other Bill

[Geochurchi]

Hi, just got done texting with Donaldson, and as expected they had no knowledge of leaking problems with that base, as for contacting the vendor of the locomotive his response was, use the correct filter P551551, not any equivalent, he said the the “O” ring had to fit precisely into a groove, I think we will order the base suggested and see how that goes, I have called 4 mobile service co’s to have a look in case we are missing something, and no one has returned the call.
All these “O” rings were square cut.

[warmstrong1955]

It's just a flat, not a groove.

If you send Donaldson a picture, with a specific question, ie; 'Is this surface supposed to be so rough, because it leaks by the o-ring?', instead of a generalized question, you may stand a chance of getting some information from them. I don't know your location, but you may try a hydraulic's dealer, rather than a service company, like Applied, or Motion Industries etc. They may have a filter head in stock they can take a look at, as it is a pretty common one.

And, if it was mine, I'd face the seal land. Easily doable on a lathe or a mill.

Other Bill

[Geochurchi]

Update, I replaced the base and filter, nothing leaking so far, the old base has what I believe may be a check valve which I just noticed, it seems like it may be out of place.