Shopping for a 350hp tractor with less than £30,000 in your back pocket brings up precious few options in the UK.

But if you keep your eyes peeled you might come across the odd early 1990s Caterpillar Challenger C-series.

With up to 355hp under the hood, these certainly fit the bill in the power stakes and their bombproof build quality means they’ll give years of hard service.

However, their pricey running gear means a potential bargain can leave you well out of pocket if you don’t know what you’re looking for.

See also: NAAC farm contractor charges 2016-17

To uncover the usual problem parts we enlisted the help of Lincolnshire crawler specialist George Sly and Yorkshire used machinery dealer Richard Firby.

We got them to walk us round a 1995 Caterpillar Challenger 85C with a shade under 9,500 hours on the clock.

---

What to look for:

Hours

These tractors were built to last and provided they are properly maintained they’ll be good for 50,000 hours or more. Therefore, UK machines with less than 10,000 hours on the clock should give little cause for concern.

They also have precious few electrics, which are known to cause problems on newer models. You just need to make sure you pay the right price for a machine relative to the amount of wear on the running gear.

 Cab rust

Tinwork is generally pretty solid on Caterpillar Challengers, but the bottom section of the cab on the right-hand side is a notorious week spot. This is purely cosmetic, though, and someone that’s handy with a mig welder could easily graft in a new section.

Engine

The 10.3-litre straight-six Cat engine is strong and generally trouble free. However, some tractors with 7,000 hours or more on the clock can develop a water leak around the aluminium spacer between the block and the cylinder head.

This is fairly obvious to spot as you’ll see cooling fluid dripping down the engine and the water level will be dropping. It costs around £3,000 to have the seals replaced.

Transmission

Transmission problems are pretty much unheard of on the 85C and the fact it’s got separate oils for transmission, back end and hydraulics means it won’t get contaminated if a part fails elsewhere. Oil should be changed every 1,000 hours and there’s a sight glass on the left-hand side that you can see by peering through the track unit.

Steering

The 85C uses a simple hydrostatic differential steering system that rarely gives trouble. So if the tractor isn’t steering equally the problem is more likely due to incorrect track tension or uneven air suspension pressure.

Tracks

A set of 30in replacement tracks cost about £8,000, so it’s worth checking you’re buying a machine with plenty of life left in the rubber. On the outside, check for tread wear and any large cuts. If they’re generally in good condition, but have worn treads, they can have new ones fitted for £5,000 to £6,000.

On the inside, inspect the surface where the idlers run. This should be smooth, free from cuts and shouldn’t have any of the steel banding exposed. Inspect particularly carefully if the tractor has come from a farm with flinty soils.

Finally, check that all the guide blocks are in place and they’re not loose as this will cause the track to run out of line and can cause excessive wear. If the tracks are in otherwise good condition, it’s possible to have guide blocks bonded back on. A cruder and cheaper fix is to bolt them back on, which is a better bet for well-worn units.

Track tensioners

The 85C uses nitrogen-charged spring track tensioners mounted off the chassis just in front of the tracks. These get a fair amount of stick and the bushes can fail. Replacements only cost around £100, but the time taken to fit them varies massively depending how seized they are.

Over time the nitrogen charge can also seep out, causing uneven track tension. There’s a warning light on the dash that will illuminate if there’s a problem and you might also notice the tractor pulling unevenly.

If the units still hold gas, they can be recharged for less than £100, but it could be between £1,000 and £2,000 if they need to be rebuilt.

Air suspension

Track suspension is controlled via an air bag on each unit. These rarely fail, but if they do they only cost about £150 each to replace. Both air bags should be running equal air pressure of 60psi and if they’re different the tractor can pull to one side. These are simple to top up with a compressor using the valve on the top.

Idler wheels

Each track unit has eight idlers and it’s worth checking they’re in good condition as they’re about £300 each to replace with genuine parts. However, Sly Agri offers its own version for £130.

Firstly, take a look at the rubber and make sure it’s all there and in good order. A small amount of pitting is to be expected, but if there are large cracks or half of the rubber is missing they will soon need to be replaced. On average, a set of idlers should last 3,000 to 5,000 hours.

Idler hubs

This isn’t practical if you’re going to view a machine, but if you already own one it’s worth checking the level and condition of the oil in the idler hubs once a season.

You can do this by removing each of the grub screws when they are level. If you drive the tracks on to blocks of wood at the front and rear it will take the weight off the idlers so you can spin them round easier.

If you can spare half a day it’s also worth popping the covers off the hubs and checking the condition of the bearings. If there are any metal filings in the oil it’s worth changing the bearing before it seizes on the shaft. Refill the hubs with synthetic 50-weight oil.

Drive wheels

Rubbers can wear on the rear drive wheels, particularly in stony conditions or if tracks have been poorly adjusted. It costs about £500 per wheel to have new rubber fitted and a new unit is roughly £1,000. There’s also a sight glass in the centre of the drive wheel for checking the oil level and condition in the back axle.

Caterpillar 85C recommended service intervals

• Engine oil: 250 hours
• Transmission oil: 1,000 hours
• Back end oil: 1,000 hours
• Hydraulic oil: 1,000 hours
• Idler hubs: 1,000 hours (Up to 2,000 if refilled with synthetic 50-weight oil)

This machine

• Model: Caterpillar Challenger 85C
• Year: 1994
• Engine: 10.3-litre, six cylinder Caterpillar
• Power: 355hp
• Hours: 9,385
• Transmission: 10-speed powershift with two reverse
• Rear linkage: Optional Cat 4 linkage fitted
• Pto: Optional 1,000 rpm fitted
• Weight: 15.3t
• Spools: 4
• Tracks: 40%
• Price: £21,500

Another option

• Model: Caterpillar Challenger 85C
• Year: 1997
• Hours: 7,148
• Rear linkage: Optional Cat 4 linkage fitted
• Pto: No
• Spools: 4
• Tracks: 50% (not fitted with new tracks shown in picture at this price)
• Price: £26,000

Other models in the series:

65C – 285hp

75C – 325hp

85C – 355hp

Caterpillar built its C-series Challenger crawlers between 1993 and 1996, however production dates for each model did vary slightly. They were replaced by the D-series, which looked similar, but had a bit more power. The 85D was also fitted with a larger 11.9-litre engine that developed 370hp.

* Thanks to George Sly of Sly Agri and Richard Firby of JR Firby.{BOX ENDS}