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Oliver 990 GM

Built: 1958–1961 · Series: THREE-DIGIT-SERIE

More machines from model year 1958

Source: https://www.tractordata.com/farm-tractors/000/6/8/686-oliver

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The 990 GM from Oliver is part of the THREE-DIGIT series. Production: 1958–1961. The engine delivers 85 hp (62.5 kW), has 3 cylinders, with a displacement of 3,487 cm³. Rated speed is 1,800 rpm. The machine is 3,657 mm long, 1,930 mm wide and 2,286 mm high. The unladen weight is 4,980 kg. The wheelbase measures 2,029 mm. Top speed is 20 km/h. The tank holds 113.6 litres. Transmission: 6 V/2 R. The engine is water-cooled. Tyres: front 7.50-18, rear 18-26. The fuel is diesel. The bore measures 107.95 mm. The stroke is 127 mm. The compression ratio is 17:1. Construction: frame construction. The gearbox offers 6 forward gears. There are also 2 reverse gears. The THREE-DIGIT-SERIE series covers 8 models. Rated output within it ranges from 27 to 86.6 hp; the 990 GM sits at the top of that range with 85 hp. Its immediate neighbours are the 950 below it with 68 hp and the 995 LUGMATIC above it with 86.6 hp. Unladen weight within it ranges from 1,268 to 5,101 kg; here the 990 GM sits at the top of that range with 4,980 kg. 70 Oliver models across 13 series are on record.

Oliver three-digit series (1958–1964) – 440 to 995 from Charles City: the hundreds number as size class, 990 GM and 995 Lugmatic with GM two-stroke diesel, petrol, LPG and diesel

The three-digit series was Oliver's programme of 1958 to 1964, the transition from the Super models of the 1950s to the four-digit ranges – and the period in which White Motor took over the maker from Charles City, Iowa, in 1960. The type logic: the hundreds number orders the size class in ascending order – 440 the small row-crop tractor (successor to the Super 44), 550 about 40 hp, 660 about 50, 770 about 55, 880 about 65, 950 about 80 hp – and the 990 GM and 995 Lugmatic are the big models with the 3-71 two-stroke diesel from General Motors (Detroit Diesel), which Oliver offered as an alternative to its own engines; Lugmatic denotes the version with torque-converter transmission. The own engines are three-, four- and six-cylinders of 2.3 to 4.9 litres, most available as petrol, LPG or diesel, at rated speeds of 1,750 to 2,000 rpm.

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The register lists 8 versions with 19.9 to 63.7 kW from engines of 2,288 to 4,942 cm³, unladen weights from 1,268 to 5,101 kg, lengths from 3,045 to 3,657 mm, widths from 1,695 to 2,055 mm and heights from 1,861 to 2,286 mm.

The series brought Oliver's hallmark of those years – the six-cylinder smoothness argument of the 770 and 880 against the competitors' four-cylinders – and the GM models are among the loudest and most sought-after collector tractors of North America.

On used tractors, originality, engine condition and carburettor or injection, blower and injectors on the GM two-stroke, clutch, gearbox and hydraulics, sheet metal and tyres count; parts run through Oliver collector dealers.

Sources: SpecCodex register, model data: Oliver Dreistellige Serie, Oliver Farm Equipment Company (Wikipedia)

Technical data

Engine

Fuel	dieselcorrect
Power	85 hp (62.5 kW)correct
Rated speed	1,800 rpmcorrect
Cylinders	3correct
Displacement	3,487 cm³correct
Bore	107.95 mmcorrect
Stroke	127 mmcorrect
Compression ratio	17correct
Cooling	water-cooledcorrect

Dimensions and weights

Length	3,657 mmcorrect
Width	1,930 mmcorrect
Height	2,286 mmcorrect
Wheelbase	2,029 mmcorrect
Unladen weight	4,980 kgcorrect

Drivetrain and chassis

Drive	rear-wheel drivecorrect
Gearbox	6 V/2 Rcorrect
Forward gears	6correct
Reverse gears	2correct
Front tyres	7.50-18correct
Rear tyres	18-26correct
Top speed	20 km/hcorrect

Working data

Fuel tank capacity	113.6 lcorrect

Origin and approval

Construction	frame constructioncorrect

Where this model stands

Power-to-weight ratio: 12.6 kW/t (62 kW / 5 t)

Power class: Universal (40–100 hp)

Stronger than 58% of the tractors in the register — out of 15,663 models with a stated power figure.

Calculated from the documented figures above — not a rating.

Frequently asked questions

How much power does the Oliver 990 GM have?

The Oliver 990 GM delivers 85 hp.

How much does the Oliver 990 GM weigh?

The unladen weight is 4,980 kg.

What engine does the Oliver 990 GM have?

3 cylinders, 3,487 cm³ displacement, Diesel.

How fast does the Oliver 990 GM go?

Top speed is 20 km/h.

What are the dimensions of the Oliver 990 GM?

3,657 mm × 1,930 mm × 2,286 mm.

When was the Oliver 990 GM built?

Production years: 1958–1961.

What to check before buying

Check the hour meter against the service records — a replaced instrument is the most common gap.
Compare the data plate and chassis number with the papers.
Check the weights in the papers against the figures here — attachments change them.
Check front and rear tyre sizes: mismatched pairs strain the drivetrain.
Shift the gearbox cold and warm — jumps only show up at temperature.
Load the hydraulics and watch for sag.
Ask about parts availability for this build year — the running costs hang on it.

A general list for this type of machine — no substitute for an inspection or an appraiser.

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This page carries 25 individual figures for this model. They come from 1 recorded source; every figure can be traced there. What we cannot document is not here — we leave gaps open rather than estimate them.

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