Jaguar Repair: 84 Vanden Plas 6 cyl coolant in one cyl., intake manifold gasket, old dog new tricks

Question
QUESTION: How prone to cracks in head or liners/liner seals are these engines? Your opinion appreciated, also need specs and procedure.
This one runs , but accumulates coolant in one cyl. after sitting for a while, off. Seller claims it's a head gasket , and it looks good otherwise. Price is right, and this a favor for a buddy. Have no other info on this car. Thanks.

ANSWER: Hi John,
A leaking head gasket is possible but so is a leaking intake manifold gasket. Head or block cracks are also possible but less likely.

First test is to put the test dye in the radiator (available at any auto parts store) and run the engine to see if there is a leak from the head gasket or cracks. It tests for CO in the radiator and if there is no CO then you can assume it is most likely a intake manifold gasket.

Don't attempt to put a head gasket on this car without a manual, you can get into a lot of trouble.

Howard

---------- FOLLOW-UP ----------

QUESTION: clue on intake manifold was an eye-opener, thanks! can you steer me to a good source for a manual? (84 xjs 4.2l) ps, my last Jag valve job was circa 1970!many thanks.

Answer
Hi John,
As for the manual, Bentley or the Jag manual are good and if you have done a 6 cylinder valve job on a Jag before, the procedure is basically the same. The 4.2 procedure is the same as all of the 6 cylinder engines all the way back to 120 Jag. But you should get a manual for the 4.2 just for the specs.

I started work in a Jag dealership when the XK-150 was still new on the showroom floor. FDR Jr. was the importer and I serviced two MK II Jags for Eleanor Roosevelt and met FDR Jr. I still work on Jags up to the ser.III XJ-6 but no model after that. Can't teach an old dog new tricks or something like that.
Howard