Jaguar coughs when it should purr . . .

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Sat 15 Feb 2003 14:57
Jaguar coughs when it should purr . . . - isobella greene
Having lost my Rover 827 last week (Head Gasket, say no more), I picked up a 1990 Jag XJ2.9 Auto, 11 months MOT yesterday.

It is only firing on 5 cylinders and there is a distinct air 'sucking or blowing' sound from the head.

My local garage have told me that it's not too serious but the head will have to be removed to replace a worn gasket which is allowing air to be sucked in and stopping the mid cylinder from firing.

Does this seem like a right diagnosis to you guys in the know ?

If so, can it be bodged and how ?

thanks
David
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Sat 15 Feb 2003 18:55
Jaguar coughs when it should purr . . . - Richard Turpin
I hope It is just the gasket. Is there oil in the water or vice versa. Or does "air" come out of the radiator if you take the cap off, particularly in "puffs". That is probably gasket. If not it sounds like a broken exhaust valve to me. If so cost about £800 to fix properly.
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Sat 15 Feb 2003 23:51
Jaguar coughs when it should purr . . . - Dizzy {P}
I can't recall the construction of your engine but I think it would be unusual for a head gasket to be blown between a cylinder and the outside of the engine to the extent that it would stop the cylinder firing and make a strong chuffing noise. I'd have guessed that a failure so severe would have connected with a coolant passage on its way through and shown itself in the radiator as Richard said.

I don't suppose there's an air hose going to the intake manifold in the vicinity of the misfiring cylinder, perhaps a brake servo hose? This would not be the first time that a leaking manifold air hose has caused a cylinder to 'miss' and a blown head gasket to be incorrectly diagnosed.

Air getting sucked in through a leaking manifold hose like this can make the cylinder nearest to it misfire while the ones each side of it can still draw in enough fuel/air mixture to fire, albeit on reduced power. Thus, in a six-pot, there could be one cylinder with almost no power, two with reduced power and three with more-or-less full power.
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Sun 16 Feb 2003 14:20
Jaguar coughs when it should purr . . . - isobella greene
Hi,

Thanks for your reply & advice. I'll go & have a look now.

The guy at the garage showed me a series of knurled, 'allen key' type bolts located across the head. Specifically, he showed me one bolt in particular, with a piece of gasket sticking out underneath. He said this damage was letting in air, causing the misfire.

I am looking really for confirmation that his explanation is credible.

As I said, my Rover 827 died last week and I've been thrown into a right mess. OK, I know buying an old Jag XJ2.9 is a bit of a gamble but it has a 50 week MOT.

Your help is truly appreciated.

thank you,

David
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