1984 Cat 931 Help

[surferboy120]

I am looking to buy a 1984 Cat 931 with an engine serial of 45V31446 and trans number 1AA01241. I believe this year had the 4 cyl diesel so I wanted to verify if someone had a way of looking this engine serial up for me? The owner said the machine does not have blowby common with the 4 cyl but he didnt know alot about the unit as he too used it for farm clearing which is also my plan. Tank clearing and push cedar\juniper and moving small piles for burning. No issues with the machine although hour meter didnt work 3 years ago when he got it but since put one on and put 120 hours on it over 3 years. Starts right up no leaks and only issue is the left track needs periodic tightening which is done when he greases it to tension. 16k for the machine and this is my first dozer type machine although I run skid loaders and tractors. I plan to use for a few years and sell once my work is done as well.

 

[surferboy120]

If it helps the machine serial is 29Y1109

Thank you for the help in advance. Based on what I have seen the price seems inline with others if not lower for my area.

 

[OzDozer]

It's a 931B and they're a good little traxcavator. 29Y1109 makes it a 1981 year of build, by my book.

The engine is a 3204 direct injection model and the 45V31446 engine serial number is for a 3204DI, and appears to be correct for the machine.

They only used 2 ring pistons from the factory, this is a "low-friction" design, but most owners rebuild them at overhaul with the later 3 ring pistons.

$16K sounds about right for a 931B in good operating condition with good undercarriage. No leaks is good. Sounds like the track tensioner seals need replacing.

Post some photos and we can likely give you more pointers. The condition of the undercarriage is what primarily governs the value of a tracked machine.

 

[Welder Dave]

OzDozer posted while I was typing.

I don't have my serial number book handy but my 1st thought is it's older than 1984. First thing to check is the undercarriage. If the engine is original and hasn't been worked on 3204's are known to have more blow-by due to only using 2 piston rings. It sounds like the left track adjuster needs new seals but the shaft could also be rusted. You could see if the tension release bolt might be a little loose. How does it steer? Should only need light toe pressure.

 

[surferboy120]

 

[surferboy120]

 

[surferboy120]

Thank you both for taking the time to respond and share your experience. I go next weekend to view and possibly purchase this machine. He has been really good to work with.

 

[surferboy120]

 

[surferboy120]

 

[surferboy120]

 

[surferboy120]

 

[Welder Dave]

Overall it looks pretty good except for missing windows and doors. Not a bad machine if you wanted to clear some bush. The undercarriage has been worked on/replaced and improved by changing the sprocket hub to use bolt on segments. It doesn't have the sprocket counterweights but that's not a big deal. The pads are from a dozer but not really high grousers so should be fine. Tall dozer grousers are hard on a loader because they put extra stress when turning. Dozers don't turn near as much as loaders. Rails look to have good height but hard to tell if the rollers are hitting the pin bosses. Marks could be from small rocks or something hitting the pin bosses inside the rock guards. Speaking of the rock guards, unless you're working in lots of rocks it's best to remove the rock guards. They just trap dirt and mud and can contribute to increased track wear. Can't see the condition of the bottom rollers or the bushings on the rails. Judging by the sprockets and rail height I think the bushings are likely in good shape. It doesn't look too abused. Sheet metal looks pretty straight and it has the engine side shields which aren't bent and dented. A bunch of hoses were replaced too. 16K seems reasonable if the transmission and steering/brakes work properly. Can you run it for 30 minutes or more to see how it runs at operating temp.? It looks like a decent machine.

 

[OzDozer]

That's a very nice little tractor that shows it's been looked after, and not abused. If only mine looked that good!
It'd be interesting to find the reason why the owner installed dozer track shoes on it.

You have to find the reason for the hit marks on the pin bosses. The track chains are in excellent shape, but if the track rollers weren't replaced when the track chains were, then the roller flanges will be hitting the pin bosses, and that's not good.

Roller flanges hitting pin bosses makes the track pins fall out, eventually - and the rollers will be near the end of their life and be liable to fail.
When the rollers get worn out, the seals fail, all the oil runs out, and then the roller is toast.

The marks on the pin bosses may be caused by a track guard - but even so, the reason must be found, and the problem fixed.
Track guiding guards are good to keep trash out of the track rollers and chain, but if working in deep mud, the mud gets in and can't get out, it block up the tracks, so better to take them off.

Don't forget to check the bucket cutting edge and the underside of the bucket. These are constant wear areas, and they need to be kept in good shape.
If the track rollers are good, the tractor is certainly worth $16K. Check that the serial number tag on the engine matches the number on the loader tower.
The tag is located on the rear upper LHS of the engine block, up near the head gasket.

 

[surferboy120]

 

[surferboy120]

I can’t say enough about how I appreciate you both providing some fantastic information. Once the deal is done I will share a couple more details that should contribute to this being a good deal. I have a good list of what to check and will be asking. Although he didn’t have the machine much throughout its life he knew that the machine was not abused. With that said the historical reasoning for things may never be know but I will ask. I don’t know much about flanges or rollers but I am going to make sure I research it more so I can develop an eye to help me understand what to look for and provide good updates here. I am excited to have this old machine which to your points does seem to be in relatively good shape.

 

[surferboy120]

What’s funny is there is a JD 455g 91 model for 22k with 3k original hours and is much closer but I am still drawn to this older Cat. The JD looks good but has a slow right turn until warm and starting to get a leaky cylinder.

 

[surferboy120]

The JD is probably less abused work wise over its life as the first owner used it to move mobile homes apparently and the current owner only did a few odd jobs and hasn’t put 100 hours on it. I just don’t think the maintenance has been as good as the Cat despite the information but I will at least look at it although the Cat seems to align better. 22k for the JD

 

[OzDozer]

That 931B cutting edge is in reasonable shape, but some hardfacing on it wouldn't go astray.
Plus, the wear level on the underside is important. There are wear plates on the underside that need to be kept in good shape.

A good book to acquire if you can find one, is an older Cat Custom Track Service Handbook - especially one around the year of your tractor.
They are a goldmine of valuable track care, track maintenance, and track repair advice. Plus they have specs for wear in there.

1982 CAT Caterpillar Custom Track Service Handbook 8 tractor manual D4 D3 D6 D8 | eBay

Updated to 1982.

www.ebay.com.au

The Cat is a better buy than the JD. Around here JD products don't have the same level of resaleability as a Cat.

 

[surferboy120]

Huge Thank you again!

 

[Welder Dave]

You can get bolt on teeth adapters and teeth or bolt on cutting edge segments for the bucket. They both use the same holes that are on the existing bucket. The bolt on edges come in 3 pieces, center and 2 ends and are reversible. I think they're 8" wide, maybe 10" so will last a long time. I have both but took the smooth edge off because I found my skid steer is better for finishing things like the jump faces on my MX track. I'd recommend teeth for general purpose work and digging. A smooth edge is good for loose material and finish back blading. You'll just wear the bucket edge out the way it is. If you go with teeth I can't tell if your bucket has holes on the side for corner guard teeth where the adapter straddles either side of the bucket side plates and uses 1 big bolt through the side plate. These style teeth save the front corner of the side plates.

I've heard the JD G series are pretty good machines. The 455 in the pic. looks to have lever steering which would be a hindrance for loader work. Pedal steer lets you have 1 hand on the bucket control and 1 hand on the trans. or throttle at all times. The JD has wet steering clutches and brakes. It may just need adjusting but could be more serious if it's slow to respond until warm on only 1 side. With 3000 hours it will probably need undercarriage in 1000 hours or so. In small track loaders I'm not sure if there's a lot of difference in resale between Cat and JD. The JD is 10 years newer and track loaders are similar to skid steers. If they still work they come down to a certain price and stay there unless they're in really poor shape. It might be good to check on parts availability on the JD. Cat generally has much better support for older machines although some say it's not as good as it used to be.