Help Evaluating '74 Cat 951c

Hey all -

I'm a landowner looking at potentially buying a machine to clear and level forested land, lay in a drive, drag timber around, etc. on a budget. Ideally I'd like to buy a machine, get good use out of it for a year or so without major work on the machine, and then make the call to sell it or keep long term.



I looked today at a 951c at a good price ($5k) that for the most part is in reasonable good shape. I had an equipment inspector run through everything with me, and we came up with a list of maintenance issues, larger issues, and potential dealbreakers. I'm looking for feedback on the issues we found to see if any are bigger warning signs, and most importantly any advice on the two larger dealbreakers to see if it'll still fit my needs. I'll work from bigger issues down the list -

Dealbreaker - There's a delay in movement when going into 2nd or 3rd gear in both forward and reverse. In 1st the machine moves immediately as expected, but when moving into 2nd or 3rd it sits for 3-5 seconds and then starts rolling. In 3rd it also seems sluggish once it starts moving. During that delay there's no sound, grinding, etc., it just sits. The movement of the shifter stick seems fine, as far as I can tell. I'm not sure how the transmission works on these machines, so I have no idea what could cause an issue like that. Is this a common issue? Is there some sort of relatively simple fix? If not, opening up the transmission to repair/replace larger parts will be a dealbreaker for me on this machine.

Potential Dealbreaker - The drive sprocket teeth on both sides are quite worn - this was pointed out to me both by the dealer and the inspector. The track pins are also worn. What I want to gauge is how much life this has left - can I get a year of moderate use out of what's left on this sprocket? At the end of that, what kind of cost / effort am I looking at to repair or replace the sprocket? From what I've seen, the more common choice is to re-weld a new sprocket rim on instead of replacing the whole sprocket due to ease of replacement. Photos here -




Other concerns I'd like feedback on, but seem less severe given my needs -
Blow-by described by my equipment inspector as moderate, not terrible.
Mild leaks from 2 hydraulic cylinders.
Moderate oil leak somewhere in the transmission area. Wasn't actively dripping but clearly there.
Apparent diesel leak near the feed into the engine (hose or connector presumably).
Lot's of side play in the upper bucket arms (not sure the correct name, but not the main lift arms), but according to my inspector they didn't have enough slop to worry about them snapping.
Quite worn track plates - none worn through, but not a lot of ridging left on the plates.
Loose plates / track bolts (every ~5th track piece on average).
White smoke from exhaust after engine warmed up for ~10 minutes or so, along with an occasional miss from the engine correlating with this. Inspector thought maybe an injector issue.
Aside from those issues, the machine cranked up in the very cold (~15F) quite quickly. The dealer employee who jumped it (batteries nearly dead in the cold was no surprise, it's been sitting) used ether, but I don't think it was probably necessary. The engine looks clean, not a lot of oil/crud in the engine bay. The body is in remarkably good shape for the age. The bucket has some broken teeth but is otherwise solid. There was no moisture in the engine oil (black, so needs changed, but no moisture), and what appeared to be only moderate rust in the coolant. If not for that transmission concern, and feeling like the drive sprocket is right on the edge, I'd feel pretty comfortable moving forward with it.

So, hopefully that provides enough information! What I'm hoping to get is feedback on specifically the transmission / gear issue, and if this machine looks like it's in shape to be a performer for a year before needing any major maintenance. If I need to replace some track bolts, injectors, oil change, etc. that's no big deal. It's the big stuff that I'm trying to avoid as much as reasonably possible with a machine this age. I also have a video if it running here -
https://youtu.be/2WQVSxUyW4E

Clearly I should have used links instead of image embeds, so I apologize to anyone opening this thread.

For private use tracks will usually run a long time beyond where the industry standards used to determine life have been exceeded from what I have seen. The wear on the sprockets and pins in your pictures indicates to me it is beyond 100% worn if properly measured, by the book specs. If you replace sprockets you need to repair/replace the track chains as the sprocket teeth won't match the pitch of the worn links and wear on both will be accelerated. And the rollers and idlers should be done at the same time for best life. As far as how the sprocket gets replaced you need to research that. It might be a weld on ring or it maybe a complete sprocket, I don't see it bolted on as segments would be. If your equipment inspector was familiar with crawlers he should have been able to measure the undercarriage for you and tell you where it is at wear wise.

Here is an article explains undercarriages and how to measure them. It is a Dresser document, but is common to all crawlers. Cut and paste this in your web browser (remove the * from between tractor and parts before searching). http://tractor*parts.com/pdfs/undrcarguide.pdf

Remember you are looking at a $5000 Cat 951. There is a reason it is priced at that amount.

As for your pictures, you just need to reduce their size. I use Paint to change the pixels from over 4000 (yours) to 1000 pixels on the largest dimension of these.









And here is a chart of wear to life of chains from on line. It may or may not be correct for that machine, I won't say, but it give you an idea of what it may be.

On my 941B I welded on new sprocket rings--not a hard job--or there are sprocket weld in cups you can get to build up the teeth. The transmission has filters and a screen on the pump suction. make sure they are clean and there are test ports on the transmission to check the pressures
My rails were over 100% worn and i didn't change them--so far i have gotten over 400hrs on them, i built up the rollers and idlers myself by welding

guys have covered everything but your question on the track pads,, those are street pads (used on loaders often and can be driven on pavement and concrete with no damage, they get Good traction) they do not have much more to them when new they are fine

Anyone have insight into the transmission / shifting issue?

(quoted from post at 14:28:06 01/10/21) Anyone have insight into the transmission / shifting issue?

Click to expand...

I would guess it has high hours, regardless of what an hourmeter says. The issues could be related to the leak you mentioned, could be low on oil, could be a plugged filter, weak pump, weak convertor, leaking seals; May be all it needs is some adjustments, maybe it is on the borderline for major failure. There are many things it could be and it is hard to say without doing proper diagnosis. How familiar are you, and your inspector, with the operation of these? If you are not used to them, can you find someone who runs, or has run, similar Cats and have them try it for you and see what they say about how it acts. Is it at a Cat dealer or general used equipment dealer? If it is at a Cat dealer ask what they think about the transmission and how far they will stand behind their opinion. JMHO

linkage adjustment,dirty filters,clogged screen.--one of the first things to do to analyze a suspect bad transmission is to drain the fluids and check for any metallic particles---cut open the filter also to look for particles

The transmission has five clutches, one forward, one reverse and three speed clutches, in other words each speed is shared by both forward and reverse, the transmission lagging could be the linkage or the filters and suction screen need service, for what I see of the undercarriage there is a bit of life left in it, the sprockets are starting to get sharp and the bushings are starting to wear, the rails look ok, now would be the ideal time to have the pins and bushings turned and put put on two new sprocket rims, for farm work it will probably do what you need as it is, you got lots of loose pads that need tightening up or you will lose them, .
AJ

Ok, went out and ran the machine again today for close to an hour. I'm more comfortable that I was after the first visit, and I have a strong suspicion that the shifting issue is linkage related. Here's what I found -
No issues in first at all, and will spin the tracks in place when I pushed into a hill, although granted we're hard frozen here so it's not hard to spin.
The issue with second was interesting, and I've included a video at the end - when shifting from 1st to 2nd, it would only engage sometimes, but if I moved to 3rd and then back to 2nd, 2nd worked just fine. No issue when driving or steering in second, it's just the engagement itself. The fact that 2nd works all the time when shifting in one direction, but not always from the other, is what makes me suspect linkage. That feels to me like something not slotting int place correct. See the video at the end here of what that looked like on the machine.
Engine continued to run and look good, no major leaks there other than what appears to be a small fuel leak. Not concerned about that one.
There are two leaks of transmission and / or hydraulic oil under the machine. One comes from the shaft going from the engine to the rear transmission / assembly (note in the video I say hydraulic pump but the shaft is going into the trans or torque converter). The other is up the right side of the machine somewhere. See the second video at the end here. I assume the first is a bad shaft seal and probably a bear to deal with, but I'm not particularly concerned if I can keep topping off the oil for the time being.
Engine cranked in < 5 seconds with a jump and no ether, cold, in 30*F.
Steering and handling all good. See the third video for a short function demo.
At this point I'm leaning toward picking up the machine, but again am interested in any input on the shifting issue still and those leaks. Does my inclination that it's a linkage / adjustment issue make sense?

https://www.youtube.com/watch?v=Pw-jJTlbeLs&feature=youtu.be
https://www.youtube.com/watch?v=F4xoQAIJGGk&feature=youtu.be
https://www.youtube.com/watch?v=KJursEfzSHI&feature=youtu.be

i would say the shifting issue is from linkage--my D3B has had a similar issue for over 10 years--won't always go into reverse and sometimes try up to 3 times for it to engage ----- the oil leaks need a good power washing--make sure the drain plugs are tight---My 941B was traded in partially because of a transmission leak and it was just a loose drain plug

I have replaced just about every cylinder outer seal as they all eventually started leaking

On a related note - does anyone know if there's free as in beer copy of the service manual for these machines floating around, or is buying it the only option? I have a copy of the parts manual but haven't seen any non-paywall copies of the service manual.

Ya it looks like a linkage issue, the oil seal on the input shaft to the torque can be replaced by removing the 4 biscuit couplings and the flange will pull off, prise out the old seal and tap in a new one, the other leak I can't say as I did not see the source, the machine needs a good bath, the hydraulics looked to be very slow in the video, was the oil cold or were you not pulling the lever fully, it is not unusual for the pump on those machines to scream when the oil is cold which is why they like a warm up before working.
AJ