Bitin' My Tounge

I've got this "Red Mech" who to my mind is just an absolute 'monster' IH mechanic. Been at it all of his 70 years.

Okay, I watch him test the rear hydraulic pump on my 966. He tells me that it is just so-so and a little weak, 'cause it is only putting out 1800 psi at idle and he says it should be 2250psi.

I stood there and watched him test it.

So, I'm readin' in my IT manual this morning and according to it, he was actually doing a flow and pump pressure test instead of the "system relief pressure" test.

IT manual says it should run 1800psi & 10gpm @ 2400rpm and should be taken at one of the remote ports (which is exactly where he was at).

The manual goes further to say that the relief pressure test should measure 2000psi on the 966 (2250psi on the larger tractors), but is taken at the port right on the face of the pump body itself and that the hitch lever should be set past 'full up' to insure a "full and constant system pressure".

He obviously read the manual wrong.

Just keep my mouth shut? I don't wanna "correct" this guy, 'cause he really is good.

Allan

1- Run the engine at about 1500 RPM, tie the remote on demand, and turn the knob to restrict the pressure until it shows about 1200 psi, and at the same time, make sure that the flow guage shows flow. The pressure builds heat to warm the oil, but you don't want too much pressure right now, or you won't get enough circulation to get the system good and warm. Once the oil gets to 120 degrees, back out the restriction knob to 0 psi, run the engine up to rated speed, which would be 2600 RPM on your Black Stripe 966.

2- Check the flow guage- it should show around 12 gpm, mabey a little more, but not much less. This is called "free flow"

3- Now crank that restriction knob down and get as much pressure as you can. This could be anywhere from 1800-2500, because there are about four different relief valves that will fit your 9. At this point, you will have zero GPM flow.

4- Now back your pressure off about 250 psi from your maximum reading and check the flow guage. It should read at least 80% of your free flow.

If all of this checks out, you're good to go. If the max. pressure is low, the relief valve needs attention. If you don't have 80% of free flow at 250psi below max psi, the pump is shot. Hydraulic testing should never be done at low idle, since you've got a positive displacment pump, its output will be greatly effected by speed.

Yes, that's kinda how it went down and how we left it, so far anyway (just to let it go). But then, I also left them instructions that if they should find anything at all wrong with the tractor, don't bother calling, just repair it.

Reading this manual now has me wondering if maybe I'd better stop in there and have a little visit. :>)

By the way, saw your friend Scotty on Saturday night while I was working an anniversary dance. Had him up and he did a few; he does a pretty darned good job. Known him all these years and I had never heard him before. He says to tell you hi.

Allan

I notice he rubs his hands together and has a wicked gleam in his eye when I walk thru his door. :>)

Allan

Never thought of that.

This one is the authentic IH "Blue Ribbon Service Manual".

I sure don't know; I'm about two thirds retarded as it is. :>)

Allan

Wrong is wrong and I would try to find a way to approach him about it. I would probably start by just asking him some subtle questions, like, “Is there a test that would show if I had a faulty relief valve?” That might spur enough interest that he would check the manual again. That might lead him to discover that he misread the manual, and he would do the test and be an even better mechanic in the future! You don’t come off as a smart aleck, and still accomplish your goal. My belief is that everybody, including life long mechanics, should be willing to both accept their errors and learn from them. That is what makes a good mechanic (or any other professional) what he is. You don’t need to be rude, crude, or anything other than maybe just inquisitive.

Just my thoughts…

Yes, it has already cost me a new Relief valve, 'cause we were trying to "fix it". Now he wants to pull that rear pump and "inspect the body".

Sounds to me like the pump is above the spec the way it is because it is pumping the 1800psi at idle instead of the called for 2400rpm. :>)

The only reason I hesitate saying anything is because he is such a nice man and he and his boys are so very through in their work otherwise. Just this one little mistake..... ..

Heck, I make a dozen mistakes before I pull my socks on in the morning. :>)

Allan

LOL Have a good one!

I would lightly bring it to his attention and play dumb. Its what I do and it easy and works well.

The advice to ask him to interpret the manual is the best and he will explain it, even if it is his error.