Diesel Engine - Head Gasket Evolution
86peugeot01BULLETIN NO. 195
DATE: October, 1986
SUBJECT: 506 DIESEL READ GASKET EVOLUTION
Beginning with March 86 Production, XD3T engines, and with April 86 Production, XD2/XD2C and XD2S engines are fitted with a new head gasket. This head gasket is identifiable by a bead of red silicone sealant.
This new head gasket requires a higher torque load on the head bolts which has brought about the following additional changes:
- new head bolts with longer threaded section, - a new head torque procedure.
The engines incorporating these modifications can be identified by the letter V on the valve cover edge opposite the No. 1 injector (visible with valve cover in place).
HEAD BOLT IDENTIFICATION
INTERCHANGEABILITY
Installation of the new head gasket requires applying the new torquing procedure which in turn requires:
- new head bolts
- a cylinder head with threaded injectors (the cylinder heads with strap type Injectors will NOT sustain the increased torque load).
Procedures for in service vehicles:
For XD2 engines with strap type injectors:
There is no change in the head torque requirements. There is a change in the gasket selection based on the piston protrusions as shown below.
Engine Piston Protrusion "d" Gasket selection P.N.
(in. mm)
XD2 d<0.79 1.53 mm 2 notches 0209.31
d>0.79 1.63 mm 3 notches 0209.32
XD2-XD2C-XD2S-XD3T with threaded injectors. Install a new type head gasket selecting the thickness in accordance with the table below based on the highest protruding piston. The gaskets are supplied as kits with new head bolts, washers and thread lubricant.
Engine Piston Protrusion "d" Gasket selection Kit
(in mm) P.N.
XD2 d<0.79 1.53 mm 2 notches 0209.59
0.79
XD2C d>0.89 1.73 mm 4 notches 0209.61
XD2S d<0.72 1.53 mm 2 notches 0209.59
XD3T 0.72
d>0.82 1.73 mm 4 notches 0209.61
Note: The difference in the protrusion measurements for the different engines is directly related to the difference in compression ratios.
HEAD GASKET INSTALLATION
- Clean out the head bolt passages using a tap
- Install the head gasket dry
- Degrease and dry off the bolt bosses on the cylinder head
- Replace all the head bolt washers with those supplied in the kit
- Install all 22 bolts of the new type, supplied in the kit coating then with the lubricant provided or MOLYKOTE G RAPID P.N.9732.05.
HEAD TORQUING
- Pretorque all the bolts in the order shown to:
3mdaN (22 Ft. Lbs.)
- Torque the bolts in the order shown to:
7adaN (52 Ft. Lbs.)
- One bolt at a time, and in the order shown, loosen each bolt by 1/4 turn then retighten to 7mdaN (52 Ft. Lbs.)
- Install the rocker arm assemblies and adjust the valves:
Intake: 0.15 mm (0.006")
Exhaust: 0.25 mm (0.010")
- Refill the cooling system and run the engine for 10 minutes at 3000 rpm.
- Shut engine off and allow it to cool down for at least 3-1/2 hours.
FINAL TORQUE (requires removal of rocker arm assemblies)
- Release cooling system pressure
- One bolt at a time and in the order shown loosen head bolts 1/4 turn and retorque to 7 mdaN (52 Ft.Lbs.)
- One bolt at a time and in the order shown, tighten each bolt by an additional 120~ (use angle gauge J 36 384 P.N. 91.62).
- Reinstall rocker arm assemblies and adjust valves:
Intake: 0.15 mm (0.006")
Exhaust: 0.25 mm (0.010")
- Refill cooling system
There is no further retorquing of the cylinder head required after the above.