924Board.org

[Meneer aard]

1500 km`s (1000 miles) ago i have a headgasket leak, so i replaced it.

Today i look into the haynes manual about re-touque the headbolts. This must be done with a Hot engine (normal operating temp)..? But that`s wrong??

My friend (good mechanic) told me that re-tourque the headbolts must be done with a cold engine? What is wrong and good?

Thanks in advice
_________________
Porsche 924 Euro 1977

[Tigger937]

As taken from Porsche "Technical Specifications" Booklet:

TIGHTENING SPECIFICATIONS - CYLINDER HEAD BOLTS - 924

Tightening sequence for cylinder head
_______________________________
|----8-------4--------2--------6-------10----|
|----x-------x--------x--------x--------x------|
|------------------------------------------------| ---------> Driving Direction
|----x-------x--------x--------x--------x------|
|----9-------5--------1--------3--------7-----|
_______________________________

Tightening Specifications using the turning angle method -924- Induction Engine

Tightening is performed in two stages, following the sequence shown in the diagram at each stage. Reverse sequence when undoing the bolts.

Turning Angle Tightening Method

Tightening in two stages:
1st stage 65Nm
2nd stage 180° = 1/2 turn
with screws with internal serrations


TIGHTENING SPECIFICATIONS FOR CYLINDER HEAD BOLTS - 924 TURBO

1. Tighten cylinder head bolts in prescribed sequence, in stages, to 40Nm, 80Nm and 110Nm.

2. Retighten cylinder head bolts after at least 60 minutes (to allow for setting of cylinder head). To do so, loosen bolt no. 1 (see tightening sequence) approx. 1/2 a turn and tighten to 110Nm. Repeat this procedure with the remaining bolts in the prescribed sequence.

Bring engine up to operating temperature (oil temperature approx. 80°C). Allow engine to cool and give cylinder head bolts a final tightening as described under 2.

-EDIT-
Note the different procedure given for 924 Turbos.
The Turbo Workshop Manual specifies tightening torque requirements for Cold Engine and with coat of oil on threads of cylinder head bolts.
Perhaps someone else with access to the 924 Workshop Manual can chime in with what that says about engine temperature torquing requirements.
_________________
1981 931 (Concours)
1982 931 (Daily Driver)

"Think outside the box"

[Porscheaddiction]

As taken from 924 workshop manual
before 1980

torque 72ftlbs cold
86ftlbs warm
if the cylinder head was removed the bolts must be retorqed after about
1000miles or 1600km
procedure as follows
warm up engine
using loosening sequence loosen cylinder head bolts about 30deg. and retorque one at a time to 86ftlbs.


Including 1980 and up
Requirement...Cold Engine
Lubricate cyclinder head bolts with oil slightly and tighten bolts in specified
sequence to 47ftlbs.
Mark position of cylinder head bolts
Tighten cylinder head bolts 180deg (half turn) in specified sequence
The cylinder head bolts DO NOT have to be retighened after installation.

hope that clears things up.
Chris
_________________
1981 924 NA (Restoring mode)
1984 928S (Enjoying the driving season)

[Meneer aard]

Thanks!

I have a haynes manual for the 924 from 1976 thrue 1982. But by the section breaking in and later maintenance, said only torque the headbolts after 1500 km or 1000 miles withe a warm engine.

When you first install the headbolts after replacing the headgasket.. you must torque it with 72 ft-lb. But after 1000 miles you must torque it with 86 ft-lb.
_________________
Porsche 924 Euro 1977

[Porscheaddiction]