New to me Cat 973 - is it working correctly?

[ippielb]

The filter that is in the metal housing is a mesh screen. It is for large particulate. You only have to clean it. I went through and changed all the filters on my machine so I replaced that one to have an hour number on it.

 

[Cmark]

Unfortunately I ran out of time to test fuel pressure. I did see a plug on the head of the spin on filter mount, is that the location you were referring to, Cmark? What should the pressure be?

Spec will be around 35psi but in reality these engines will happily run on maybe as little as 5psi.

As far as draining the tank, I can’t find access to the bottom of the tank except for through a very large plate on the bottom of the machine. The manual says it weighs about 200lbs, so I didn’t try to remove it since the machine is in a field. Am I missing an access point for the tank drain?

Tank drain should be a hand pump on the right hand side.

 

[Reubenrr]

And here’s the rather shakey phone video. Unfortunately I don’t have a nice mount like ippielb has.
Hopefully you can see that shortly after starting to turn the tracks slow substantially.

 

[Reubenrr]

Cmark, I saw that, but was unable to get the knob to release. I’ll put some penetrating fluid on it next time I’m there and see if I can free it up. I tried a wrench on it, but I was destroying the ribs on the knob and was afraid I was going to break the knob off, so didn’t push it further.
Thanks!

 

[Cmark]

Two predictions;
1. The line will be blocked and you will have to clear it with compressed air.
2. You might have to take the pump off and soak it in a bucket of diesel.

 

[ippielb]

Does that old girl have rabbit and turtle mode? Seems fast to be in turtle.

 

[Nige]

On a related note, I could not find a Cat replacement for the cartridge style fuel filter, only a NAPA part - 3360. That was the part in there when I replaced it. I noticed that the maintenance manual says to clean the cartridge filter - was it originally a screen or some other type of filter?

If you are referring to the filter that is in the bowl directly below the fuel priming pump then yes it was indeed originally a washable metal screen that would only normally be replaced if it was found to be damaged or corroded. See attached for Part Numbers.

 

[Reubenrr]

Ippielb, I think it only has one speed. I saw that 973s can have 2 speeds in the manual, but can’t find a lever/switch/button for speed control. Do you know where it should be?

Cmark, are those predictions only for the hand pump? Is there any risk of damage if I use too high a pressure? Is it likely that the fuel lines to the engine are also plugged, or do you not see that often? Can those be blown out, too, or is there a screen on the tank inlet that could get damaged?

The forecast here is for 15-30” of snow this weekend, so it may be a bit before I can use her again.

Thanks,
Reuben

 

[Nige]

Ippielb, I think it only has one speed. I saw that 973s can have 2 speeds in the manual, but can’t find a lever/switch/button for speed control. Do you know where it should be?

On your particular machine the ground speed is directly related to the position of the transmission control lever. Engine RPM should always be at High Idle when operating. Think of the transmission lever as the control for a variable speed drive.
You have to remember that our Canadian member has a different model of 973 that is newer than yours and differs in many respects.

 

[Reubenrr]

Hi Nige,
Yes, thanks for the reminder on models. I do always operate with the throttle lever in the high-throttle detent, and control speed with the FPR lever.

Thanks also for the parts list for the screen. I had searched the Cat filters site but couldn't find anything for the primary fuel filter. The NAPA site had it, and when I removed the bowl, the same NAPA part was in there. So...do you think the NAPA filter is too restrictive and is starving the engine of fuel? I would guess it flows a lot less fuel than a screen since it has a fiber filter element in it.

Cheers,
Reuben

 

[Nige]

If it was mine it would get the correct parts in in and leave the secondary spin-on filter element to trap the fine particles. When you are investigating potential performance issues then really things ought to be standard so that you can rule stuff out, otherwise there will always be that "what if?" seed of doubt in your head.

Also I would suggest to get the fuel tank cleaned out as soon as you can, even if it means crimping a hose with a pair of vice grips while you disassemble something and put it back together again. That will remove another question mark.

 

[ippielb]

9M-2341

This is the screen for my model machine.

 

[Reubenrr]

Thanks. I found the screen for sale and will get one. They aren’t very expensive, especially for a reusable part, so worthwhile to at least test if the current filter is limiting flow.

 

[Nige]

Check to see if all the other internal parts are there. You may need other internal parts that the previous owner possibly threw away when the Napa filter was installed.

 

[Reubenrr]

Ok, finally got back to this. I feel like I dodged a bullet in getting the fuel tank pump unstuck without removing it. Definitely some corrosion inside, but it works. The first few pumps were pretty dirty, then it was nice and clean after that.

I also tried to get a pressure gauge on the fuel filter mount, but don’t have the correct fitting and need to find one. I measured the plug and it looks like 9/16-18, but it’s pretty close to M14-1.5. Is it safe to assume it’s English threads on this machine? Or can anyone confirm the thread on that fitting?

I also looked in the primary fuel filter and it appears all the parts in the diagram Nige sent are there - thanks Nige!
Cheers
Reuben

 

[Nige]

You mean Ref #4.?

 

[Reubenrr]

Yes, ref #4 in that diagram, and it says right there. Sorry for being blind!

 

[Reubenrr]

I got the fitting, and pressure is about 50psi at idle, drops to about 40psi when full forward, and about 35psi when full steer either way (one track counter rotating).

What should I check next?

Thanks
Reuben

 

[Cmark]

Next thing to check is the air/fuel-ratio control diaphragm. This is part of the device which senses boost pressure and restricts the maximum fuel delivery until boost is up. Disconnect the tube (#12) at the fuel pump end and rig something up so you can suck on the AFR fitting. You should be able to suck a vacuum. If you can't the diaphragm will need replacing. Also check the tube for holes.

 

[Reubenrr]

That’s a great diagram. The tube appears to be in good shape, but I could just keep pulling air through the fitting. Definitely now seal inside the housing. Slight hint of diesel taste in the air coming through.

can someone let me know the part number for the diaphragm? And, it’s definitely a rebuilt engine. The block casting has the number 4P623, and the injection pump has the stamped number E27525-07 on top. Are those the relevant numbers, or do I need to provide more info?

Thanks for all the help!
Reuben