In reply to a message from Perers sent Mon 1 Apr 2013:
I agree that the gunk you note in the oil filler tube is
100% normal for Jaguar XJ40s and is not indicative of a head
gasket problem. Oil ‘‘burning on hot areas’’ may simply mean
the cam cover gasket has cracked and oil is leaking onto the
exhaust manifold: another common issue on the XJ40 since the
engine is tilted toward the exhaust.
You don’t mention the mileage on your engine, but we’ll
assume it is getting up there, so there are no reasons not
to replace the head gasket preemptively aside from the cost
of the parts and the time involved. If you decide to
proceed, here are a few thoughts in addition to those
offered by others:
I have done XJ40 head gaskets three times and have never
removed the hood. It simply hasn’t been an issue for me.
I remove the air intake plumbing and throttle body and
disconnect the intake manifold and tie it back toward the
left fender but do not removed it entirely.
Before you loosen the head bolts, measure the valve
clearances and take careful notes for each valve. Later, as
you remove the valves to add stem seals, record the shim
thicknesses for each tappet. With this info you can
determine the new shims needed.
To remove the head by myself, I pad the right fender like
Pete, then I sit on the windshield (carefully) straddling
the engine. I lift the head up and over to the thick
padding on the right fender, then climb off the left side of
the car. I haven’t broken a windshield yet…
While the head is off, replace ALL the coolant hoses under
the intake manifold, the breather hose from the cam cover to
the oil filler tube, the silicone sealant on the water rail,
the O-rings on the oil cooler pipes or
cooler-bypass-fitting, the oil filter housing gaskets (or
silicone sealant if no gaskets are present), the silicone
sealant on the oil filler tube housing (the rubber bush that
seals the oil fill tube is no longer available from Jaguar
so be careful not to break it), the rubber sleeve at the
bottom of the oil dip stick tube (still available from
Jaguar but it’s just a piece of rubber tubing), the vacuum
hoses that are impossible to access when the intake manifold
is in place, and the hoses from the carbon canister purge
valve to the intake manifold and from the carbon canister
vacuum control valve to the fuel pressure regulator.
Seriously consider replacing the upper timing chain
tensioner blade, oil pressure sender and heater control
valve, and think long and hard about replacing the starter
since it will never be easier.
Lap/reseat the valves. It’s easy and only takes a cheap
suction cup lapping tool and some compound.
Clean the throttle body (see the archives for risks of
fouling the TPS with cleaning fluids). Clean the carbon
from the EGR port just inside the intake manifold. Clean
the MAF with MAF-specific cleaner spray. Use electrical
contact cleaner spray on all connectors and seal them with
Now, install the supercharger. (just kidding!)
The original message included these comments:
I have suspected potential cylinder head failure as
anytime soon ( classic oil and water mix evident in the
oil filler tube). The clincher the last few outings for
the car was a slight but persistent oil leak which was
burning on hot areas and producing smoke. The valve info
Don B : '93 VDP Flamenco Red 189K : (ex-'88 Sovereign)
Franklin, TN, United States
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