Ford 4000 pto slippage

[FarmerBlair]

I noticed the pto slipped on my 1968 Ford 4000 while rototilling. The slip clutch on the tiller itself was too tight, so the slippage occurred at the tractor pto, enough that it nearly stopped turning. There were some spots where I got into some heavy sod and clay soil. But I'm also tilling only 3-4 inches deep. I was at about 3/4 power. I noticed right away and stopped the pto. It did not bog down the engine when it happened and I would not have known it if I wasn't watching the whole time.
The tractor is an 8 speed with independent pto that uses hydraulic braking/engagement.

My question is, if the tractor pto is in good shape, should you be able to stall or nearly stall the engine if the pto gets bogged down? I'm wondering if I need to look into replacing the clutch pack in the pto. It works fine when mowing with flail or rotary mowers. The tiller works fine in looser soil.
New Holland said they could put it on a dyno, but would cost a few hundred dollars just to do the test.

The lever pulls up to activate the pto and is on the left side of the tractor.
The pto does not engage until the last inch or less of the lever travel. That probably doesn't matter since it actuates a valve, but seems like where 80% of the lever movement doesn't do anything has me wondering.

Thanks!

 

[sotxbill]

Yes, it should bog down the engine. The pto should have a pressure check first to see what the low pressure is in the off mode and on mode as it could be a worn out pump, or in the pto itself.

 

[Destroked 450]

First thing I would suspected low oil level, a leak in the pto supply line or a weak hydraulic pump
Not saying the clutch pack couldn t be worn but what caused it
The pto clutches on my 69 4000 are original and will choke the engine out before it slips, same for my 72 4000SU
One other point for pressure loss is the aluminum hub support, I did replace that on the 4000 23 years ago while we had the lift top, also replaced the pto brake pawl while we had it apart

 

[Bern]

Not only should should the PTO be able to bog the engine, a dyno should be able to kill it. Every time I dyno a tractor I bring it up to full load and RPM and then quickly lug it down almost to the point of stall, to make sure the PTO does not slip.

As for your local dealer wanting to charge you a few hundred to dyno, tell them to get real. It's a half-hour test at the most. Unless they're planning to charge you an hour just to dig the thing out of storage.

 

[FarmerBlair]

Thanks guys. Could someone point out where to connect the gauge to do the pressure test? In my manual, it is not obvious to me and the photos are almost useless. Is there an external port or do I have to remove the top cover? Thanks again.

 

[Ultradog MN]

It is clearly spelled out in the I&T FO-31
manual.
I have an NOS pto clutch pack that I would
like to sell if you need it.

 

[FarmerBlair]

(quoted from post at 17:50:26 05/01/23) It is clearly spelled out in the I&T FO-31
manual.
I have an NOS pto clutch pack that I would
like to sell if you need it.

Thanks Ultradog. Yes, I would reach out to you if it turns out I need a clutch pack. Thanks for the pic. Here's what I was looking at in a manual I got on the internet a few years ago. It's not an I&T manual and has poor rendering of images, and the organization is confusing while attempting to cover multiple tractors and no index. It says to remove the "service tapping plug", but couldn't clearly make out the location in the pics. I should just find the I&T manual.

Regarding the clutch pack: my tractor is dated April 19th, 1968. According to New Holland parts, the clutch pack changed after March 31st. But my tractor is one of the few still built with the 192 cuin engine, so I wonder if the clutch pack in the transmission might also be the older version (prior March 31st). Maybe a code on the trans case might be a clue? Anyway, the older version clutch pack has limited availability, which often means I can't get it. Which one do you have?