New to me ..never had one before...but a mate got a 4.2series3 dropped off at my shed the other day. He's picked it up very cheap but not checked the oil which was the first thing I did. It was like a very nice vinegarette. I assumed off the bat hat the head gasket had gone and still think so...but I'm trying to work out what's cause and what's effect before suggesting that I want nothing to do with it.
What I ( think ) I know
The car has been stood for decades, very low mileage...came from Hong Kong 27 yrs ago and I think it's done next to nothing since.

Could the vinegarette simply be the result of decades of occasional starting and mixing condensation into the oil ( If so, it's probably knackered everything internally anyway?)

The plugs come out all looking much the same...no sign of a steam blow into a particular cylinder. - not had time to do a compression test yet Will do later in the week

Starts OK..sounds OK ....exhaust not particularly steamy but .... as soon as it start it tries to push water up out of the header tank if the cap's off....but NO BUBBLES?

AND ..once warm ( cap back on ) reving it causes the top hose to collapse.

So...are the weird cooling system symptoms a consequence of a blown head gasket....or vice versa I wonder?

Since I don't know these cars I'm wondering what other people experience is of head gasket failure / collapsing top hose inter-relatedness is?

It's all a bit of a shame, it need welding but the floor and boot and all is really good....headlining is minted , interior supports the low mileage..I don't mind doing some welding..and maybe a head gasket change...but if we add a catastrophic cooling system failure to boot I'm losing interest.

Cheers...

 

Oh boy, you are cuatious, and I dont blame you.

The oil is probably as you have suggested.

The plugs is a good sign.

The running as "normal" is a good sign.

The purging and sucking is, may be as simple as NO thermostat. A blown head gasket, of course, but the running would be off.

Comp test the only sure fire way.

 

If you're willing to do a head gasket....which is not a pleasure cruise on these cars.....then the rest will be easy ! The cooling system is dirt simple.

Anyhow......

Agreed on the compression test, for sure, but a minor head gasket leak might not be revealed. I drove my Series III XJ6 for 6 months with a minor head gasket leak; the compression was within spec and the cylinders were within 5% of each other. The symptoms were having to top-off coolant every 4-5 days, one spark plug wet with coolant each morning...which meant rough running for a couple minutes.

Anyhow again.....

Head gasket failure is rather common on these cars. Frankly, if I ever bought another, I'd just assume it needs a head gasket (or will soon) and then feel lucky if it doesn't

If a car, any car, had been untouched for decades, I would also assume that it's gonna need full recommissioning, stem-to-stern, including a major servicing and full brake system overhaul.

Cheers
DD

 

Too true ...brakes are seized and of course I'd not thought about the fact that the rears are inboard and a total hassle as I understand it. Despite the low mileage I think being as it is a series III it's probably not worth it. Brake rebuild, welding ( although surprisingly little of that!) it's not charging, head gasket, possible cooling system problems....but , it would be a terrible shame to break a low mileage car with a nice interior.