5 - PROBLEMS AND OPTIONS

Do not use cast pot metal or unrated brass fittings from the local hardware store! Of course, I had to learn this the hard way. I see these fittings being used on hydraulic systems all the time, so I used an unrated street elbow for the custom fitting made to connect the supply hose to my 8N test port. The fitting lasted several years, but when it broke, hot oil went everywhere. It seemed like at least a quart ended up in my boot. That was uncomfortable.

This is the fitting that broke. As you can see, there's a big difference in this fitting and the correct hydraulic fitting.

Priming the pump - The new pump should prime itself almost immediately (Maybe not if you have 90 weight in the sump - See previous section). This is assuming the hoses are connected correctly, the belt is tight, and there are no leaks. It's much easier to suck air than hydraulic fluid, so any leaks on the suction side will result in no flow. There is very little lift between the level in the sump and the pump location. Most of the suction hose should begin to fill by gravity when you put fluid in the sump. The hydraulic pump should not be run very long without oil in it, so it is a good idea to verify rotation and prime the system by turning the pump by hand. The system should pump fluid into a bucket turning the pump by hand. Make sure you are turning the same direction the belt will be turning the pump.

Lift Operation - With the PTO disengaged, the lift should operate as it originally did when running off the internal pump. The difference is that now the lift operates whenever the engine is running. With the PTO engaged, there is a small problem. Both pumps are now supplying fluid to the hydraulic system. This can flow more volume than the system was designed for. With both pumps operating, and no implement mounted, the lift arms will rise up on their own even with the touch control lever in teh full down position. That's no big deal since moderate hand pressure should override this when hooking up an implement. In truth, the PTO shouldn't be engaged while hooking up implements, so this shouldn't be a problem. Once an implement is attached, you may notice the lift raises faster than it drops when both pumps are running. This is much more noticable with light-weight implements. If this difference in speed is undesirable, and you don't need the PTO, just disengage the PTO, and let the system run with only the front pump operating.

ADDITIONAL OPTIONS

FILTRATION - Most modern hydraulic systems have some sort of filtration on the hydraulic system. Adding filtration to the N-Tractor hydraulic system is a good idea. Keeping fluid cleaner saves wear and tear. Filtration may be able to extend fluid changes a bit. I have tried several different in-line suction-line strainers. All of them proved to be too restrictive. Even using full-synthetic fluid and the least-restrictive filter available, Winter temperatures created enough restriction on the suction side of the system to cause the high pitched squeal of pump cavitation. There was no was to miss that sound. Pump cavitation will ruin the pump. Cavitation problems can be avoided if filtration is moved to the high-pressure side of the system, but filters rated for 2500 PSI and 2 GPM are way too expensive for me to justify.
The best idea I've come up with so far is to make a custom suction line fitting using a replacement drain plug for the engine oil sump. The engine drain plug has a mesh screen around it. Modify the drain plug to accept a fitting for the suction hose. Cut the screen down until the plug will fit in the drain hole under the hydraulic pump. There is not a lot of room in there, but it is possible to cut the screen so any big chunks will be stopped before they get to the suction hose. The screen is not much of a filter, but better than nothing.

QUICK DISCONNECT FITTINGS - These hydraulic fittings have an internal ball seal that allows them to be taken apart with very little fluid loss. The disconnected fittings are sealed on both sides. This is very handy whenever a line needs to be disconnected for any reason. These fittings can also be used to re-route hoses to run an external implement like a log splitter.