Lift Kit for 641

mooboy

Member
I use the 641 to sickle mow. When it gets hot it sometimes does not want to lift the mower. This does not happen all the time, and I can usually get it to work again by moving the quadrant lever back and forth. Would a lift kit help and how hard is it to do?
 
Will a lift kit help?? - Maybe. Since it only does this hot, it is safe to assume you have a leak that gets worse as the oil thins out with heat.

How hard? - Not bad to do, but it a bit intimidating the first time. The lift cover is heavy, Two guys or one with an engine hoist. Plan on buying a lift cover gasket kit, a cam follower pin, and an I&T manual. I would definitely replace the piston o-ring and back up washer. Inspect the cam follower pin and replace if it shows any sign of wear.

Before you start, next time it won't lift, remove the round PTO cover on the left side and take a look inside with a flashlight. You can see the bottom of the cylinder. If you try to lift and oil is coming out of there, you have found the leak.

There are some adjustment to do. The I&T manual has the procedure (the Ford method requires special tools) or buy Zane's booklet (it includes a cam follower pin and gauge blocks)

We can help you when you are ready to go. Ask lots of questions.

BTW, the top cover overhaul is an afternoon job for someone with experience, but figure a long day or so the first time.
 
(quoted from post at 07:34:07 03/17/14) deffintely check for internal leaks before tearing the top cover off.

How do I check for internal leaks? Pull off round cover where lever for PTO is? What do I look for and how to fix?
 
(quoted from post at 21:40:28 03/17/14)
(quoted from post at 07:34:07 03/17/14) deffintely check for internal leaks before tearing the top cover off.

How do I check for internal leaks? Pull off round cover where lever for PTO is? What do I look for and how to fix?

Not to be a butthead, but you need to read or re-read Kurt's post. He describes it well...

After that, when you are ready...post here with further questions.
Chris
 
As you sitting in the seat, if you reach down under the seat on the left side there is a lever that engages the PTO. Under that lever is a round plate with 6 bolts. Remove the bottom bolt first and drain off any excess oil into a drain pan. Then remove the other 5 bolts. Pop the cover off, you may have to raise it slightly.

Use a small flashlight and look inside. You will see some of the linkage and the bottom of the hydraulic cylinder.

With something heavy on the lift, start the tractor and raise the weight. With the weight in the air, stop the tractor. If the load drops with the tractor off you have a leak. Usually the drop is slow. Take a look inside the round hole and you may be able to see where the leak is. Common places are the bottom of the cylinder and from above the cylinder.

One you know where the leak is, we can help you fix it. If you pop the cover without looking, then you may not fix the problem the first time. You cannot find the leak with the cover off.

Also, is your system showing any symptoms such as jerking, bobbing (hiccuping), bleed down with tractor off, or no lift when first started?
 
(quoted from post at 14:50:56 03/18/14) Yep, Kirk covered well, most common leaks are from top side

It may be a few days since till I get to check since I have the tractor torn down for a clutch replacement. Thanks for the replies.
 
Hello,
I have an 801 Diesel that has hydraulic lift issues such as hiccups,jerking and no lift when first starting. It is fairly stout however and will lift heavy weight. Can you give advice on what to do?
Thanks, Jeff.
 
Welcome to the forum Jeff.

A Jerky lift is a sign of air bubbles in the pressure side of the pump, usually due to a leaking seal in the pump.

Hiccups are due to a very small leak between the control valve and the cylinder. Usually an o-ring or the control valve itself.

No lift at start up that gets better as the tractor runs is a sign of a pump that is loosing its prime. Usually do to a leaking seal in the pump - see Jerky above.

The pump seal and o-ring are repairable, the control valve is more difficult

Does that help?
For what its worth, I had all three symptoms on my 660
 

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