[xj40] O2 Sensor No Start '94 XJ6

XJ40
21

In reply to a message from Brazierje sent Sat 21 Jan 2012:

Mmmm… There’s something wrong here.

The factory manual gives the torque for the cam cover screws
as no more than 3 Nm which is 2.213 lbf/ft which is 26.5 in/lbs.

If you applied 100 inch/lbs you over-torqued them!

I’ve never used a torque wrench on those screws. I’m
conceited enough to think that I can judge when they are
‘tight enough’ to avoid crushing (‘squishing’) the rubber
gasket.

One thing I did learn the hard way is that some of those
screw holes in the head (the front two?) are ‘blind’ holes.
You have to ensure that they are clean and dry before
fitting the cam cover because if you get any oil down those
blind holes the screws tend to ‘hydraulic’ and you think
they are tight enough but in reality they are not and you
get a seal leak.–
The original message included these comments:

In the Haynes manual the torque for the cover screws is 89 to 106
in-lbs. I torqued then to 100 in-lbs, the two forward center screws
didn’t make it. (I said a few choice words when it happened)
I’ll clean up the area with a Dremmel and try the JB weld. I the
meantime I’ll look for a replacement just in case.

–
Bryan N, '91 Sovereign 4.0 L, RHD
Cambridgeshire, United Kingdom
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22

Hi Bryan,

It appears that there is conflicting information in the various Jaguar
Service Manuals on the torque of the cam cover screws (like the
differing torque for cylinder head bolts ;-). My 3.6 paper manual, Vol
2, p. 12-73 specifies 1.5 Nm. JHM1126 (old XJ40 CD) specifies 1.5 Nm
at page 12-20, but afterward consistently specifies 9.5 - 12 Nm at
pages 12-28, 12-37, 12-43 and 12-46.

The XJ-S CD, JHM1127, specifies 9.5 - 12 Nm for the same 4.0L engine.
That is up to ~ 9 ft.lb. or 108 inch lb.

I believe that the higher figure is correct, but I would agree with you
that I would do it by “feel,” simply turning “wrist tight” (not pulling
with arm or body) using no more than a 4" long handle on a 1/4" socket
set, or a screwdriver handle. In my experience, you have to “go around
again” several times, as the gasket compresses, and if you only
tightened each screw once, you would find them loose in a few minutes.
Also the screws should be re-torqued a week or two later, as a few heat
cycles further compresses/shrinks the gasket.

George Balthrop, Clifton, VA USA
89 and 85 XJ-S Coupes; 89 XJ40 VDP-----Original Message-----
From: Bryan N sophistic@btopenworld.com

Mmmm… There’s something wrong here.

The factory manual gives the torque for the cam cover screws
as no more than 3 Nm which is 2.213 lbf/ft which is 26.5 in/lbs.

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

23

In reply to a message from George Balthrop sent Sat 21 Jan 2012:

George,

I believe all of the references in JHM1126 to a torque of
9.5 - 12 Nm for cam cover bolts (or screws) should apply
only to the 2.9 litre SOHC engine. That is clear in the
section devoted to torque figures in Volume 1 on page 06-02
for the SOHC engine (9.5-12Nm) and page 06-03 for the DOHC
engine (1.5 Nm)

The three engines covered in that CD, 2.9, 3.2 and 4.0
litre, each have their own page 12-20 and pages 12-20 for
the DOHC 3.2 and 4.0 litre engines show the torque on the
cam cover screws as 1.5 Nm.

However, in the later pages you mention, they obviously
never got around to amending the text for the corresponding
pages for the 3.2 and 4.0 litre engines because as you say,
they are quoting 9.5 - 12 Nm which I believe is incorrect.
[But that is presumably where Haynes got that high number from!]

The later CD, JHM1153, in the ‘General information’ section
covering the '90 - '92 models has exactly the same
illustrations quoting 9.5-12 NM for the SOHC 2.9 litre (page
06-02) and 1.5 Nm for the DOHC 3.2 and 4.0 litre (page
06-03).

However, in that corresponding section covering the '93 -
'94 models the torque for the cam cover screws is raised to
3 Nm (page 06-06) the figure I quoted to ‘Brazierje’ who has
a '94 model.

I believe that change was introduced for the different
design of cam cover on the '93 - '94 models (the one with
the oil filler).

Irrespective of all of that, I still hand tighten those
screws down until I judge that they are just tight enough,
and no more. And, like you, I re-visit them after a few
miles of running just to make sure! :-)–
The original message included these comments:

It appears that there is conflicting information in the various Jaguar
Service Manuals on the torque of the cam cover screws (like the
differing torque for cylinder head bolts ;-). My 3.6 paper manual, Vol
2, p. 12-73 specifies 1.5 Nm. JHM1126 (old XJ40 CD) specifies 1.5 Nm
at page 12-20, but afterward consistently specifies 9.5 - 12 Nm at
pages 12-28, 12-37, 12-43 and 12-46.

–
Bryan N, '91 Sovereign 4.0 L, RHD
Cambridgeshire, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –

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24

In reply to a message from Brazierje sent Sat 21 Jan 2012:

The JB Weld and washers large enough to cover the cracks did the
trick.

Thanks for the valuable help.–
The original message included these comments:

in-lbs. I torqued then to 100 in-lbs, the two forward center screws
didn’t make it. (I said a few choice words when it happened)
I’ll clean up the area with a Dremmel and try the JB weld. I the

–
Merlin 1994 XJ6
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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