For 1990-2009 cars

# REVISED:HT4100 SERVICE ENG. ASSEMBLIES

#### VEHICLES AFFECTED: All 1982-87 Cadillacs With HT4100 Engines

* This bulletin supersedes 86-641-102 which should be destroyed.

The following is a revised list of HT4100 Service Engine Assemblies available from GM Parts to accommodate 1982 through 1987 Cadillacs. These production hot tested assemblies incorporate all of the design refinements and updates released at the time of their manufacture. Some of these updates will affect future service on these engines.

#### Model Service Engine P/N ----- ------------------ 1982 Eldorado and Seville 3634705 1983-84 Eldorado and Seville 1985 Eldorado and Seville (Except Calif.) 1984-85 Eldorado Convertible (All) 3634703 1985 Eldorado and Seville (Calif.) 3634707 1982 Deville and Brougham 3634704 1983-84 Deville and Brougham 1985 Brougham (Except Calif.) 3634702 1985 Brougham (Calif.) 3634706 1985-86 Deville and Fleetwood (FWD) 1986 Eldorado and Seville 3634698 1987 Deville (FWD),Eldorado and Seville 3634699 1987 Allante 3634700

Service Engine Assemblies include: cylinder block assembly, connecting rods, piston and liner assemblies, crankshaft, crankshaft balancer, camshaft and lifters, cylinder head assemblies including valve trains, camshaft and crankshaft sprockets with chain, front cover, water pump, oil pump, oil pan, intake manifold, oil filter, and instruction sheet.

1. Transfer Parts

The following components must be transferred to the replacement service engine: engine vehicle identification plate, exhaust manifolds, throttle body, distributor with thrust washer, EGR valve, generator, power steering pump, vacuum pump (if so equipped), air pump, A/C compressor, flexplate, and all brackets, pulleys and belts.

- when assembly 3634698 is installed in an 1985 FWD "C" chassis or an 1986 FWD "C" chassis before 4252323, the oil filter adapter must also be transferred.

- when assembly 3634698 or 3634699 is installed in an Eldorado or Seville the thermostat housing must also be transferred.

- engine lift brackets in some cases may have to be transferred to accommodate accessory mounting requirements of the vehicle.

2. Special Distributor Gear Note

Before installation of the distributor, the distributor thrust washer must be transferred from the original engine to the service engine and a new distributor gear (10499163) must also be installed. The new distributor gear must be lubricated with prelube (P/N 992704).

3. Items Ordered Separately

1982-84 Eldorado and Seville

992704 Distributor Gear Prelube 10499163 Distributor Gear 412485 EGR Valve Gasket 1624583 Throttle Body Gasket 1630830 Crankcase Breather Hose 1626761 PCV Hose 6487779 PCV Valve 1629941 Throttle Cable Bracket * 489106 Cap-Vacuum Tee 1631153 Vacuum Pump Bracket 2044779 Clip - Evaporator Pipe Attachment 22527475 Screw - Evaporator Pipe Attachment

* 1982 ONLY

1982-1984 RWD Devilles and Broughams

992704 Distributor Gear Prelube 10499163 Distributor Gear 412485 EGR Valve Gasket 1624583 Throttle Body Gasket 1630830 Crankcase Breather Hose 1626761 PCV Hose 6487779 PCV Valve 1629940 Throttle Cable Bracket * 489106 Cap-Vacuum Tee

* 1982 ONLY

1985 FWD Devilles and Fleetwoods originally equipped with stamped metal valve covers.

992704 Distributor Gear Prelube 10499163 Distributor Gear 412485 EGR Valve Gasket 1620870 EFE Grid Gasket 1630831 Crankcase Breather Hose 9438373 PCV Hose 6487532 PCV Valve 1628916 Vacuum Pump Outlet Pipe 1631225 Power Steering Pump Bracket

1985-1986 All Models originally equipped with cast valve covers.

992704 Distributor Gear Prelube 10499163 Distributor Gear 412485 EGR Valve Gasket 1624583 Throttle Body Gasket (Longitudinal Engine) 1620870 EFE Grid Gasket (Transverse Engine)

1987 All Models except Atlante

992704 Distributor Gear Prelube 10499163 Distributor Gear 412485 EGR Valve Gasket 1620870 EFE Valve Gasket

1987 Allante

992704 Distributor Gear Prelube 10499163 Distributor Gear 1636127 Upper Manifold Gasket

4. Dipstick Considerations

- longitudinal service engine assemblies (3634702 through 3634707) are not supplied with a new dipstick. The original parts must be transferred. See chart below for revised applications.

- P/N's 3634698 and 3634699 are equipped with a dipstick calibrated for 1986 Devilles after 4252323 and 1987 Devilles respectively.

- if 3634699 is installed in a 1987 Eldorado or Seville, transfer the dipstick from the replaced engine (1640020).

- if 3634698 is installed in a 1986 Eldorado or Seville transfer the dipstick from the replaced engine (1640020).

- if 3634698 is installed in a 1985 Deville or a 1986 Deville before 4252323 install dipstick 1629282.

The following chart summarizes HT4100 engine oil dipstick revisions for 1982 through 1987 applications.

Application Tube Dipstick ----------- ---- --------

82-83 "C" 1618780 1640021 84-85 "D"

85 "C" & 86 "C" 1636933 1629282 Before 4252323

86 "C" After 1636933 1638398 4252323 & 87 "C"

82-85 "C/K" 1618780 1640022

86-87 "E/K" 1636933 1640020

87 "V" 1636933 1638874

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.