Bolens QS-16, QT-16, QT-17 & 1900 Series Tractor Service Manual, 1983–1999 (P/N 552974-2)
94 Pages • 1 Printable PDF (English) • Download
Bolens Models Covered & Key Technical Specifications
Models: QS-16, QT-16, QT-17, 1900 Series
Models & Model Codes:
QS-16 — 1660 (Kohler K-341 AQS, Spec. 71172A & 71176A)
QT-16 — 1666 (Onan BF/MS, Spec. 2425 A thru C, 2938 D & E, and 3283 F)
QT-17 — 1666 (Kohler KT 17QS, Spec. 24106A, 24152 & 24197)
1900 Series — 1966 (Kohler KT 19QS, Spec. 49139)
Model Years: 1983–1999 (1983 ,1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999)
Serial Numbers: 1660 S/N 0100101 and later (start/run circuit), 1666 (QT-16) S/N 0100101 thru 0599999, 1666 (QT-17) S/N 0600101 and up, 1966 S/N 0100101 and later
Serial Breaks — Wiring: 1660 diagrams for S/N 0100101 thru 0199999 and S/N 0200101 and later. 1666 diagrams for S/N 0100101 thru 0499999, S/N 0500101 thru 0599999, S/N 0600101 thru 0700700, and S/N 0700101 and later. The last diagram also covers 1966 S/N 0100101 and later and includes a 1666 starter-wiring inset for S/N 0600101 thru 0999999.
Serial Breaks — Chassis and PTO: The front wheel hub illustration covers 1660 and 1666 S/N 0100101–0599999, with a separate assembly for 1666 S/N 0600101 and later and 1966. Front axle pivot adjustment applies to 1666 S/N 1000101 and later and 1966. The QT-16 uses an inside PTO idler at S/N 0100101 thru 0399999 and an outside idler at S/N 0400101 and up. Electric PTO clutch specifications distinguish 1666 S/N 0100101 to 0199999 from 1666 and 1966 S/N 0200101 and later.
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Engine displacement: 587 cc (Model 1660), 660 cc (Model 1666, Onan), 690 cc (Model 1666, Kohler), 770 cc (Model 1966)
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Engine power: 16 hp to 19 hp at 3600 rpm
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Engine type: Air-cooled 2-cylinder or 1-cylinder, 4-cycle
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Drive system: Hydrostatic transmission. Sundstrand In-Line for 1660 and 1666 S/N 0100101 thru 0499999. Eaton Model 11 for 1666 S/N 0500101 and later and 1966.
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Transmission capacity: 10 quarts (9.5 liters)
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Fuel type: Gasoline
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Brake system: Disc type
Bolens Manual Features & Selected Content Preview
This Bolens factory service manual covers the 1983–1999 QS-16, QT-16, QT-17, and 1900 Series tractors, including models 1660, 1666, and 1966. The April 1983 edition (P/N 552974-2) supersedes Form 552974-1.
PDF Navigation and Wiring Detail
Text search and diagram labels: PDF text search is unavailable. Two bookmarks open the added front page and the original cover. There are no chapter bookmarks. Small wire-color codes and switch-terminal labels in dense diagrams are easier to read when zoomed in.
The manual comes as one printable English PDF with 94 pages. The total includes one added front page, three original front-matter pages, and 90 service pages across eight groups. The service pages include the eight-page attachment section and a second copy of the drive-train troubleshooting page.
Hydrostatic Drive, Electrical Diagnosis, and Tractor Service
These selected service topics also sit alongside a wire-color guide and a fuel-flow diagram in the manual.
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Electrical diagnosis: Serial-specific wiring diagrams, start/run and charging circuits, seat-switch and PTO circuits, plus battery, solenoid, and switch tests.
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Hydrostatic drive: Sundstrand internal repair, Eaton hydro removal and reinstallation, and transaxle assembly with bearing and seal installation and gear-clearance checks.
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Hydraulic lift: Eaton and Sundstrand pressure tests, implement relief-valve inspection, lift-cylinder repair, and control-valve seal replacement.
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Engine and fuel systems: Onan and Kohler troubleshooting, engine removal and reinstallation, carburetor adjustments, and fuel-filter and air-cleaner service.
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Chassis and PTO: Steering gear rebuilding, front-wheel alignment, disc-brake linkage, interlock adjustment, attachment-drive belts, and electric clutch/brake diagnosis.
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Attachments: Mower deck leveling, gear-case and spindle repair, plus snow thrower and tiller drive-system disassembly and reassembly.
This manual is suited to mechanics comfortable using electrical meters and pressure gauges and checking gear clearances during assembly.
Engine Variants and Repair Scope
On model 1666, the switch from Sundstrand to Eaton came before the switch from Onan to Kohler. Checking both serial breaks helps match the tractor to the correct pressure test, lubricant specification, and carburetor procedure.
The engine section identifies front and rear rubber mounts and covers removal and reinstallation. Internal engine overhaul requires separate engine documentation. The manual refers QT-16 owners to Onan engine repair Form 8965-250, which is sold separately from this publication.
Hydrostatic Repair and Power Lift
The Sundstrand overhaul covers the charge-pump gerotor, cylinder blocks, swashplate, valve plates, and motor section, with an exploded view for assembly reference. For Eaton internal repairs, the publication directs readers to the separate Eaton Service and Repair Manual.
The Sundstrand installation notes warn that protective tape left under the oil filter blocks oil flow and can damage the hydro. The hydrostatic transmission flow chart listed in the contents is absent from this PDF.
The hydraulic section includes separate Sundstrand and Eaton lift schematics. The lift-cylinder procedure covers piston-rod seals. The control-valve procedure covers spool seals and the detent. The spool and body are a matched pair, so damage to either calls for replacement of the valve assembly.
Transaxle, Steering, Brakes, and PTO
Transaxle drawings identify bull gears, carrier assemblies, thrust bearings, shims, and oil seals. The clearance checks distinguish axle and cluster-gear end play from bevel-gear backlash.
Steering-sector repair covers bushings and shim selection. Brake-linkage adjustment explains the neutral interlock. The PTO section separates the QS-16 mechanical attachment drive from the QT and 1966 electric clutch/brake and warns that overtightening the locknuts can damage the brake flange.
Mower, Snow Thrower, and Tiller Repair
Mower gear-case procedures distinguish models 19209, 19210, and 19211 from 19212, with gear-case and spindle breakdowns. Snow thrower service covers chain tension, auger bearings, and gearbox work. Tiller coverage includes chain-drive and tine-shaft assembly with backlash and end-play checks.
Maintenance and lubrication charts cover cooling screens, spark plugs, filters, chassis pivots, and transmission fluids. Before service, use lifting equipment rated for the tractor's weight and disconnect the battery to prevent accidental engagement.
Transaxle and PTO Specification Examples
The transaxle assembly section specifies 30 ft-lb (41 N·m) for the four carrier side-plate bolts and 0.005–0.030 in. (0.13–0.76 mm) of end play for the cluster gear and axle shaft.
For the electric PTO clutch/brake on models 1666 and 1966, the troubleshooting section gives an armature-to-rotor air gap of 0.010–0.020 in. (0.25–0.51 mm) with the clutch/brake switch off.
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