Impossible you say? I’m here to tell you otherwise. The problem is not necessarily in engineering, and more likely in decisions made at the end of the day by bean counters trying to save money and do everything they can to help the fuel economy of a nearly 5000 pound sedan with a v8. When running properly the ajv8 is a fantastic engine with dual overhead cams, and VVT (fairly similar to V-tech, yo) but it has its weak points. Luckily the parts you’ll need to address these weak points can be found through your local dealer and online, both OEM and aftermarket brands. With some patience and time these fixes are all within the scope of the average DIYer. For this phase of the project it took me one evening with my girlfriend assisting me. A few nights before, I had cleaned my garage, organized the tools I would need, and removed the hood for convenience. Another tip is to put everything, no matter how well you think you will remember, in a labeled plastic bag. I’ve never really done this before, and it probably took about an hour off of the work time because everything is right there where you want it and labeled.
Plastic, plastic everywhere. Well maybe not quite, but in the engine bay you will likely find plastic parts that do not belong, depending on your vehicles date of manufacture, and any parts a previous owner has updated. The parts you’ll want to replace are, the plastic thermostat, the water pump with the plastic impellar, and the dreaded plastic timing chain tensioners. Some of you may know my girlfriend and I purchased this Jaguar sometime last week. Well, that night I opened the hood and proceeded to snap off the top of the thermostat cap within less than 5 minutes. Also the bolts for the thermostat cover just rotated in place.
Honestly it was a God-send that I did, as I had planned on driving the car a bit more before I dove into it. This could have ended badly. I began to remove various trim pieces, hoses and finally dropped the oil pan as I waited for mail order parts, and this is what I found
There were two small pieces of plastic in the pan itself, along with the usual sludge of a car that’s sat for 2 years at least with no oil change (tags had expired in ‘13), but what was in the oil pickup was the real issue
These are all plastic pieces of the original tensioners(one with electrical tape on it? and some gasket/sealant chunks), nearly clogging the pickup tube and causing a slight lifter tick. Even if you bought your early ajv8 with metal timing guides already swapped in, drop your oil pan and check your pickup, it’s only 18 bolts and the engine does not need to come out. Many mechanics entirely neglect to do this, and is extremely important. You can choose to either clean it with kerosene or a parts washer, or just order a new one for ~$50. Breaking mine while attempting to clean it made my decision for me. I also gave the oil pan a nice thorough cleaning in the parts washer while it was out. You may want to prime your oil pump to be safe while you still have the pan off, just siphon some oil up into where the pickup tube bolts in.
The next step is to remove everything on the front of your engine (not necessary to remove alternator, ac, or ps pump), as well as your valve covers, and if you like to make life easy, remove the intake manifold. I’m not going to go too in depth on the timing chain itself as there are guides elsewhere on the internet, it’s long enough to make its own seprate post, and my phone died halfway through so I missed out on any picture opportunities, so skip ahead to when you’ve replaced your chains and tensioners.
This is, in my opinion, the worst and most tedious part, and is important any time you disassemble any engine. You need to clean your mating surfaces, starting at the timing cover. Seriously, clean the hell out of them, make them nice and shiny. I cannot tell you how many times I’ve seen people change gaskets only to immediately spring more leaks, and require doing the entire job over, including purchasing new gaskets again, just because they weren’t thorough in their cleaning. You probably don’t really want to have to remove the timing cover again later so do yourself a favor.
The mating surface of the head before
Having someone to assist you with this part is what makes it possible to finish this job in one evening. My technique is to use clean shop rags, along with 99% isopropyl alcohol, and a bit of elbow grease. Be careful not to let the gunk fall into your engine.
Once you’ve got your chains and tensioners in, and you have a nice clean motor where it counts, it’s time to start putting things back together, including your new water pump, and aluminum thermostat. I decided to replace the rear most bolts on the thermostat with some slightly shorter, 10mm hex bolts. I did this for 2 reasons. The first is that now you won’t need to remove your intake manifold should you ever have to remove your thermostat housing again, the second, is that 10mm is a more common tool size.
Finish putting together the rest of the engine and add your fluids. Don’t forget to bleed the air from your coolant. If you elected not to change spark plugs, make sure their area is clean and oil free before putting your coil packs back on. My assistant replacing the coil packs
Total parts cost was under $500, though you could easily spend more depending on how and where you source parts. The timing chain kit for a Lincoln LS is exactly what you would want, as the engines are basically the same, and was $200 vs $550 or more for a kit for Jaguar or a Land Rover. Be smart when ordering parts, always go for OEM, and shop for other cars that share parts to get the best deals. You’ll also want to buy an updated water pump, and thermostat (obviously) as well as a gasket set, and likely any other wear item since you’ll be right there. You may want to consider an oil pump as well depending on mileage, and if you’ve ever had oil pressure issues.
This writeup was written on a ‘98 XJ8 Vanden Plas, and applies directly to any vehicle with the 3.9 v8 in the Lincoln LS, any jaguar made between ‘97 and ‘03, and any Land Rover of the same vintage with a v8.
Let’s see some reliable British DDs out there!