Pressure check cooling system?

I have a Deere 1520 gas in the shop and when we changed oil it seemed like a little water came out first. I do not think it was anti-freeze but it drained before I could be sure. Today I hooked a pressure gauge to the radiator and pumped in 15 lbs of pressure. Three hours latter it has dropped maybe 1 lb in pressure. I am guessing this could be anything like not a perfect seal on the tester and that my engine water was condensation? Am I thinking correctly? First time ever doing this. I did think that Monday I would relieve the pressure then run the tractor with the gauge on to make sure it is not getting compression in the radiator. Any thoughts or experience? Thanks Tom

It's very common for the pressure to drop, in fact it's unusual that one will hold pressure, and it really doesn't prove anything if it does or doesn't.

Just FYI, I would never put that much pressure on one, especially if it had some years on the radiator, but it's done, and you got away with it...

But what I would look for is coolant in the oil by cracking the oil drain plug and see if anything drips out.

Then remove the spark plugs. Look at the ends of the plugs for evidence of water, and spin the engine through, see if any vapor blows out.

Typically if there is coolant getting in the crankcase it will show up as water condensing under the valve cover, underside of the oil cap, inside the dip stick tube, and coming out the cc vent tube or PCV system if equipped. If there is coolant getting into a cylinder, it will have mystery coolant loss, overheating, abnormal steam out the exhaust, misfire, even liquid locked cylinder as it progresses.

There can also be collection of moisture from the outside, not related to the cooling system if the engine has been operated intermittently, not brought up to operating temperature, or operated with no thermostat or a failed open thermostat. A clogged crank case vent system will contribute too.

I tried to do the drain plug check but spun it to far and got oil with something in it. I do not think it was antifreeze but it was to fast that I am not sure. The tractor has low hours on an overhaul and the cylinder head was replaced.Need to figure out if it has a problem and deal with it now rather than sell it and have a unhappy customer. Not sure how to proceed. My dyno is apart and needs fixed so I can't work it. Thanks for your ideas. Tom

I think you're ok, unless maybe it's only leaking hot or something. That little pressure loss is normal. I'd run it some if you have some jobs for it and crack the drain plug again. How long has it been since the last oil change? Some condensation may likely be normal

I would not worry about it unless you find that you are loosing coolant. As Steve said unless a machine is run long enough frequently enough it won't drive off the moisture from combustion.

If you are getting compression pressure in the radiator it would puke coolant out. Did you notice if the coolant was low when you put on your tester? If head was just off, maybe head needs to be retorqued. If you are getting coolant in the oil you will find a nasty looking coolant/oil deposit on inside of oil filler cap, inside of valve cover etc as mentioned. If you are getting coolant in the combustion chamber when running it will make a steam that smells kind of like coolant in the exhaust and exhaust will be very clean looking. If the only symptom was a little something that drained out of a cold engine that hasn?t been run in a while I would blame condensation and run it some to check for any other symptoms.

Tom, I am going to ask you a question that no one else mentioned, Does that tractor have a vent to crankase any place that rain with a violent rainstorm have gotten blown in to the engine. Even if vent is under hood a violent rain storm could possibly have blown enough rain to get in there. Not just a normal rain but like comes with a tornado or huricane? Compression leak it would be oil going to radiator and not the other way unless the leak was so bad engine would not want to run. And compression leak into radiator does not always mean blowing water out bot possibly putting a small film of burned oil onto top of water. And I would think it should have only 7-8# pressure put on with that tester.