Opening the Belly of the Beast, CAT 977K

[CliffordK]

Ok, a couple of months ago I purchased the CAT 977K. Running good, but bucket hydraulics weren't working. So it is now time to figure out what is going on.

I've tracked the leak down to a pipe/hose junction for the lower lift cylinders. And, of course in the most inaccessible location imaginable. It is buried in behind the tracks on the left side of the crawler. From the top side, I might have to split the tracks to reach it, and access still would be limited.

Leak appears to be coming from the inside part of the hose/hard pipe coupling (marked in red), as if the hard pipe was leaking somewhere. The bracket marked in blue to keep everything stable was also missing.

Hard pipe shown in red crosses under the crawler. The leak appears to be coming out from above the belly pan some place. But, it is hard to tell. Unfortunately the best access seems to be above the belly pan.

And, of course, that pan is about 3/4" thick steel. It won't be light. 200 or 300 lbs? It is slightly bent upward, but that is as problem for another day... or is it?

The front belly pan came to me missing, with the area it was supposed to cover completely packed with dirt (and a grease rag). Somebody worked the crawler quite a bit after removing that pan.

If the hard pipe is damaged, the only way to get it out is to remove the belly pan and disconnect it from both ends, which means above the belly pan.

 

[5030]

I know one thing for certain and that is your tracks are way too loose and need adjustment.....

 

[CliffordK]

Somebody mentioned the tracks earlier. First things first. Fix the hydraulics. Then work on the tracks. If I have to split the tracks for one reason or another then I won't want them tight.

I've also got several track bolts on the right side that are also loose, and need tightened or replaced.

That does bring up another question. Every track pin on the left side seems to have a rubber gasket and wooden dowel in it. Is that for lubing the track pins? Is that a normal maintenance job?

The right side may have those, but they would be hidden on the inside side of the tracks.

 

[CliffordK]

Ok, got the skid plate off. I was expecting it to be heavy, but perhaps only 100 to 150 lbs.

There was just as much dirt above this plate as above the missing plate.

Plus, apparently a catch-all for anything that vanished on the job. I got one screw driver, one wrench, and about 8 feet of chain + 2 hooks. Also a golf tee and an old pen.

The bottom 2" of dirt was black and well soaked with oil. The rest may have just been wet.

I'm still a bit puzzled about what was actually leaking. I think the hydraulics were all assembled compression fit with a single O-Ring. So, I'm now thinking possibly a blown O-Ring. I'm trying to decide if I want to fire it up with the bottom open so I can see what is happening, or just to try to open up the joint, and perhaps some cleaning, de-rusting, and painting.

It may be a sign that I should replace any inaccessible hoses and O-Rings whenever I get the opportunity.

 

[5030]

I'd start it up and get underneath and see what is pizzing and then replace those seals.

 

[CliffordK]

When I had it running earlier, it was pouring out a lot of oil.

But now it is almost open enough to see what is going on.

I have a feeling that just about everything leaks in a 50 year old CAT.

I only broke one 5/8" grade 8 bolt getting that plate off. That'll be fun to extract later. I now have a whole pile of new bolts to put in.

 

[4570Man]

I’ve had to replace several of the O rings in those fittings on my cat. I’d start with getting that cleaned up so you can actually see what’s leaking.

 

[4570Man]

I have a feeling that just about everything leaks in a 50 year old CAT.

.

The 955 I had for 2 weeks and sold was shockingly dry. No leaks on the whole machine. I wanted a rear engine job and still do but that machine was mint was the only reason I bought it. My D5 just got done at the mechanic. Hopefully it leaks less now.

 

[mikester]

This reminds me I still have a CAT 955K/L service manual binder on my shelf if someone is interested send me a PM.

 

[D&D]

Somebody mentioned the tracks earlier. First things first. Fix the hydraulics. Then work on the tracks. If I have to split the tracks for one reason or another then I won't want them tight.

I've also got several track bolts on the right side that are also loose, and need tightened or replaced.

That does bring up another question. Every track pin on the left side seems to have a rubber gasket and wooden dowel in it. Is that for lubing the track pins? Is that a normal maintenance job?

View attachment 856672

The right side may have those, but they would be hidden on the inside side of the tracks.

Is this a closeup of one of your track pins? How about rollers, idlers and sprockets?