Questions about 1991 Sovereign

[etcetera]

I'm looking at a pretty nice low mileage 1991 Sovereign. I'm not very familiar with Jaguars, so was looking for some advice. Is the Sovereign basically a nicer version of an XJ-6?

What should I look for? The car has about 70,000 miles and runs and drives great. It has a slight tick, sounds like an injector or tappet. Everything works.

I've heard lot's of nightmare stories about Jaguars, are they even remotely true? I can fix just about anything on a car, so I'm not worried too much, but it looks like parts can be a bit expensive.

I can pick it up for $800 USD. It needs the following parts: Drivers headlight assembly, grill, drivers taillight assembly, hood. The hood is very fixable, but if I can find a nice one I'd rather just replace it. Somehow it was involved in a 4 car accident but didn't damage anything else.

Thanks

 

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More specifically, it has the 4.0 straight six.

 

[John S Farrington]

The Sovereign is just another trim variation of the XJ6. No differences mechanically or electrically. The series of XJ6s between 1990 and 1994 are very similar and have a good record for serviceability and reliability. It sounds like yor are getting a good deal for $800 but make up your own mind, as you price the various parts that it needs for the initial fixup, as to how expensive spare parts are. They can be very pricey if bought new.

 

[etcetera]

Well, the deal is done. I lucked out and found a local guy parting out another 91 sovereign. Got all the parts I needed and a few more for about $400. Even the right color for the hood, and while I was at it I pulled the moonroof lid and most of the parts. The one on mine had a small bubble of rust on the corner. I also picked up the rear bumper, along with both rear tail lights.

I originally was thinking of buying this to sell, but it drives so nice, maybe I'll keep it for a while.

I'll be burning the midnight oil getting everything back together. Also doing oil, tranny fluid, radiator flush, new battery, cap and rotor, plugs.

I've ordered a service manual. Does this motor require a valve adjustment?

Thanks

Eric

 

[John S Farrington]

The valves are adjusted by hard tappet shims between the cam lobes and the top of the valve stems. The specification for the adjustment is .012" to .014" of valve lash. You need a bucket full of shims about the size of nickels and graded into .001" thicknesses. Since the head carries 24 valves, it is an interesting but not small job unless you have a selection of shims. You will also need a micrometer for the measurements. Once set up the valves rarely need adjustment under normal useage. You can open up the valve lash specification to about .011" to .0115" with no consequence but do not go tighter than .011".

 

[John S Farrington]

P.S. During the adjustment procedure DO NOT rotate the cams independently of each other while in place in the headsince there is an interference fit between the valves and the piston tops if not in timing sync. You also need a camshaft timing tool. Also do not rotate the engine with the top timing chain tensioner being positioned in the head. You will also bend valves this way as they will get out of sync due to the slack in the chain. The adjustment is a very precise and unforgiving operation and I would recommend that the first time through you have somebody that has previous experience. The procedure that applies to the valve lash on the earlier XK head with 12 valves is very similar. The shim dimensions are not the same however. Good luck.

 

[etcetera]

Thanks for the tips. I've done valve adjustments on other vehicles, but this sounds a bit different. I'll check it anyways, I don't have shims, but there are 5 Jaguars at the local junk yard right now. I'll bring my mic and check some after I check my car. It does have what sounds like tappet noise in probably 2 cylinders. Not a rod knock or anything like that.

My check engine light came on today as well. The car sat for quite a while before I started driving it. Autozone checks codes for free, let's see if they can check Jags.

Eric

After seeing Jag parts prices, I'll be stripping those cars at the junk yard.

 

[John S Farrington]

Eric, Your 91 Sovereign will not accept an OBD 2 diagnostic scan: there are no provisions for it. You can check engine fault by turning the ignition off and then turning it on without starting it and punch the VTVM?? button on the dash. (I forgot what the button label is but it will be obvious to you with an owners manual) That button will give you a fault code number and with a Jaguar manual you will have an explanation of the fault cause. It works very well but you need a shop manual for starts to read the code number. You should get an owners manual, shop manual and all the documentation you can lay your hands on. Your jag is not a problem car but it is highly computerized without OBD2. It is a unique system. Junk yards are not a source for getting tappet shims. You need at least 3 each of each thickness from .085" to .105" to get started. Trying to get shims out of a salvage car is not the way to go.

 

[etcetera]

Shop manuals are on the way. The check engine light went off by itself after I replaced the battery, and so far it hasn't come back on. The car did sit for about 6 months so who knows what sensor may have wigged out. Hopefully it stays off.

You are right about the OBDII thing. Autozone only checks oBDI for a few cars.

Thanks
Eric

 

[John S Farrington]

Eric, The check engine light went off because when you pulled the battery 12 volts from te ECU and that resets the ECU. That is one way to reset the ECU but a more convenient way is to pull the fuse that is labeled instrument panel. With the ignition on, remove the fuse that is the instrument panel and wait with the fuse out for about 15 seconds until you notice that your tach and speedometer have a slight downward travel of the needle to zero. When that happens, the ECU has reset. You can reinstall the fuse and the check engine light will be extinguished. If you have not corrected the fault, it will probably turn back on after a short period of time with the engine running. (The fault sensor will be taking another reading and turn on.) The fuse for the instrument panel is located in the center fuse box in the console storage box. The fuse is either dead center or towards the left hand side depending on model year. In order to accurately check a Jag with OBD2 diagnostics you must have Jaguar proprietary software. Generic software that most scanners use does not cut it. The 95 XJ6s and more recent have the OBD2 but your 91 has the unique system that is controlled from the dash board.

 

[etcetera]

I thought the error was fuel 24. It hasn't come back after replacing the battery the other day.

According to my owners manual, fault 24 is ignition drive. Still haven't recieved my shop manuals.

The battery that was in it was almost dead, even after a charge.

Anyways, I'm crossing my fingers.

Eric