i have to do a modification in my Toyota diesel forklift

when the steering hose got damaged or catted. is it possible to stop the engine at the same time??

Great! Thanks.

No need to take the counterweight off. Take the cylinder out by removing the 4 mount bolts, 2 steering linkage pins, and the 2 hoses. Put it on the bench and disassemble.

I know this is old but did you have to take the counter weight off to access the seals in the cylinder? I'm working on a 6FGCU25 that I need to replace the seals out of in the steering cylinder.

Today this forklift ran all day without any problems.
Thank you all for your input.

I did put new seals in the steering cylinder, and now waiting on tires. When I get it all together I will reply back and let you know how it turned out.

if the steering is comming and going intermittantly i'd bet you the priority valve is sticking but i'd still take the relief valve out and check the springs.

I ran this truck trying to get it not to react. after awhile I did notice a little wondering as pointed out (thanks). At that time I took loose the hose at the cylinder and did get some fluid coming out.
So at this time I will order a kit to rebuild the cylinder.
I must also say I have never seen the steering react so slow.
Thanks for all your replies. It has helped.

will do.
I will run it untill the I encounter the problem again, then test is.

In all the years I have been familiar with these Toyota 7F and 8F GCU20s & 25s, I have never encountered a steering issue similar to yours that was anything other than a worn and bypassing steering cylinder. The typical operator complaint that we get (when there is a steering problem) is that the truck wants to drift to the left or right without any input from the steering wheel whenever the truck is doing a long straight run of the dock.
I admit that your description of having to turn the steering wheel 10 full turns to get the steering to react fully is a bit more than I have ever dealt with.
You said the problem was not present when you checked it "cold", that too is a detail to consider. Hot oil will bypass much more than cold oil.
I don't see your reply about whether or not you actually did the test (suggested by snowmonkey) of loosening one of the hoses on the steering cylinder to determine if oil is flowing out of the fitting on the cylinder when the opposite side of the cylinder is pressurized by turning the steering wheel. Note that the cylinder must be positioned so that the steering ram is completely extended on one side of the truck and completely retracted on the opposite side of truck before loosening a hose on the cylinder.
Note which way you turn the steering wheel to move one side of the cylinder to full extension, you will turn the wheel in the same direction after you loosen a hose on the cylinder for the test. The hose you will have to watch for bypassing oil flow out of the cylinder is the hose on the side of cylinder that is EXTENDED. After the hose is loosened from the fitting, start the engine and turn the steering wheel only in the same direction as you turned it to position the cylinder for the test.
If you see any oil run out of the fitting the cylinder is bypassing oil.

might be wright. I'm puzzled.
From the steering valve must have some kind of problem.
Two hoses in and two out. And like I say at this time all is well, but not right.
I would like to get it to fail again before buying parts.

It seems to me that if the steering pressure was low due the relief valve it would be hard to steer and the steering wheel wouldn't want to spin around 10 times before it turned.

I got a price today for the steering relief valve pressure and priority valve. They run about 200.00 each. I am now looking to see what a rebuild steering valve assembly will cost.
I drove this like a few times today and everything was well. But something is wrong and now I'm rolling dice.
I hope to hear some other suggestion.

I did see the location of these to valves in our service book.
After sitting though the weekend I took the lift for a drive and the steering operated correctly.
Of course it is not going in service knowing this truck has a problem.
I hope I do not have to take a shot in the dark to fix this lift.

if you do have the service book on this truck then yes the setting pressures and locations where to check should be in there.

usually the steering pressure operates off the secondary circuit in the hydraulic system which is also the auxiliary pressure for the hydraulic system. They use a priority valve to regulate how the pressure is distributed to each of the systems (aux functions and steering).
At least in most of the newer designed lift trucks I've seen it done this way. Some older trucks did have a separate steering pump but they eventually got away from this design to eliminate the extra pump driven off the motor to reduce drag on the motor. If by chance this has the steer pump then the pressure would be set directly on the pump via a relief valve.

But i think you'll find this unit has the steering relief pressure controlled by the hydraulic auxiliary circuit.