International Harvester

International Harvester 3688

The International Harvester 3688 is a row-crop tractor produced from 1981 to 1985 as part of the 30 Series. Built in Rock Island, Illinois, USA, it features a 7.1L 6-cylinder diesel engine delivering approximately 124-126 hp estimated engine power. It offers a 16-speed partial power shift transmission, two- or four-wheel drive options, and a standard cab with heat and air-conditioning. The tractor has a fuel capacity of 50 gallons and a hydraulic system capacity of 22.5 gallons. Dimensions include a 105-inch wheelbase, 184-inch length, and operating weight up to 13,200 lbs. It is equipped with rear PTO independent at 540/1000 RPM and a draft sensing rear hitch. The 3688 was built in a total of 2,572 units and had an original price of $45,000 in 1981.

Power125 hp[P]

Founded1981 - 1985

Model3688

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Technical Specifications

Detailed specifications and technical data for International Harvester 3688

Power

PTO (tested)	113.72 hp (84.8 kW)
PTO (claimed)	113 hp (84.3 kW)
Drawbar (tested)	99.21 hp (74.0 kW)
Drawbar (claimed)	100.2 hp (74.7 kW)

Engine

Type	diesel
Model	International Harvester D436
Cooling	liquid-cooled
Idle RPM	900-2400
Cylinders	6-cylinder
Rated RPM	2400
Air cleaner	dual dry elmement
Bore/Stroke	4.30x5.00 inches (109 x 127 mm)
Compression	16:1
Displacement	436 ci (7.1 L)
Oil capacity	14 qts (13.2 L)
Starter volts	12
Coolant capacity	26 qts (24.6 L)

Capacity

Fuel	50 gal (189.2 L)
Hydraulic system	22.5 gal (85.2 L)

Variants

3688 Hi-Clear	high-clearance model

Electrical

Ground	negative
Battery volts	12

Hydraulics

Type	closed center
Valves	2 to 4
Capacity	22.5 gal (85.2 L)
Pump flow	18 gpm (68.1 lpm)
Total flow	27 gpm (102.2 lpm)
Steering flow	12 gpm (45.4 lpm)

Mechanical

Cab	standard with heat and air-conditioning. Optional burgundy or western finish interiors.
Drive	Two- or four-wheel drive
Brakes	Hydraulic wet disc brakes
Final drives	bull gear
Power steering	yes
Differential lock	rear

Production

Type	Row-Crop tractor
Series	30 Series
Built in	Rock Island, Illinois, USA
Total built	2,572
Original price	$45,000 in 1981
Years produced	1981 - 1985

Transmission

Type	partial power shift
Gears	16 forward and 8 reverse
Clutch	355.6mm cerametallic disc
Description	Left lever selects gear, right lever selects high, low, or reverse range. Tractor may be shifted on the move without the clutch between gear pairs (1-2, 3-4, etc). Synchronized shifting, using the clutch, between gear pairs (2 to 3, 4 to 5, etc). The transmission is four-gear with the powershift provided by an electric solenoid actuated Torque Amplifier.
Oil capacity	90 qts (85.2 L)

Tractor hitch

Control	draft sensing
Rear Type	II

Serial Numbers

1981	501
1982	1743
1983	2482
1984	2695
1985	3068
Location	Serial number plate on the right side of the tractor frame, ahead of the rear axle.

Dimensions & Tires

Width	102 inches (259 cm) (Width at minimum tread.)
Length	184 inches (467 cm)
Rear axle	3.25 by 104 inches (82 by 2641 mm), 3.25 by 118 inches (82 by 2997 mm)
Rear tire	18.4-34
Wheelbase	105 inches (266 cm)
Front tire	11L-15
Rear tread	66 to 128.5 inches (167 to 326 cm)
Front tread	60 to 84 inches (152 to 213 cm)
Height (cab)	112 inches (284 cm)
Shipping weight	11300 lbs (5125 kg)
Ground clearance	13 inches (33 cm)
Operating weight	13200 lbs (5987 kg)