son just bought 1990 soverign 6cyl. cyls 5,6 0 presure 1-4 180 lbs. Guess I am looking at head gasket, poss valve job, poss guides, poss timing chain and tensioners. never been in a jag, what am I going to find, where to buy parts, what is common, good manual to lead me in,,,Fred

 

Well I would first determine if your looking at a valve issue or a worn rings issue.

Pour a bit of oil in the 5 and 6 cylinder and retest compression. If you have compression your rings are bad. If you still don't valve train is the issue.

 

Ran comp check like all of us old timers would 2-3 lbs diff with oil on 1-4 5,6 still dead. Have talked to pre owner he claims he was taking the car to the jag dealer when the engine crapped. His temp had been running very cool but car running normally. Enroute it began to run rough, and loose power. filler cap had moisture on it. car towed, oil change, no water in oil. I located a complete eng in calif. 51000 mi. one owner for $1,000.00 and shipping, what do you suggest. I still haven't seen the car, my son is doing the grunt work until I pick it up this weekend in Brevard, N.C. call me if convenient at 251-752-0056 Fred

 

I have the same car you almost definately have a blown head gasket. You have two choices here, either repair your engine,or buy a used one. I lost both #5 and#6 cylinders(blown head casket). What caused the problem was that the catalyc converters were pluged up(rear upper and both lower converters). The lower units have a co mingled exhaust thus they both pluged.So if and when you repair your car you most likely will have to go for a complete exhaust as well.