Yesterday I drove my 02 (130k) about 90 miles on the interstate, when I pulled off and down to idle speed at the corner, the low oil pressure warning light/message came on. Car was still running, give it a bit of gas and light went off, but with noticable rattle coming from under the hood. Managed to get to safe spot to pull over and park it and shut it down.

I'm making an educated guess that I lost at least a piece of a chain tensioner and the rattle is the chain slapping the cover as there's never been a record of the tensioners being changed.

Beyond that possibility, what else could I be looking at and how much potential damage is there if the motor still starts and drives? Could I be so lucky to just have to replace the tensioners and be back on my way? I assumed I would need to do that eventually anyway, but there hadn't been any real noticeable ticking noise from the motor thru years I've owned, was pretty much waiting to hear some signs before changing.

 

If a chain broke the engine would not run. A tensioner may have failed resulting in the rattle and loss of pressure. Whatever you do, do not attempt to start the engine again. You may have been very lucky so far, but the next time you start it a chain may skip sprocket teeth resulting in bent valves and piston damage.

Your car being a '02 should have the metal tensioners, but inspect to be sure.

 

pickup might’ve got blocked with something

 

You don't mention dipstick reading. Is your oil at correct level?

 

Yes, sorry, forgot to mention that - it was @ correct level.

 

02 model has the new metal tensioners and are not known to break. But of course it can happen.
But there are no reason that a broken tensioner or guide should give you low oil pressure, other than if you are unlikely unlucky so that the broken pieces block your oil pickup, or that the tensioner has fallen apart and all the oil goes "out in the open"
Take off your oil pan and valve covers and see if you can spot the problem - before you assume anything

 

Plastic parts of the tensioner/guides of even the newer style can clog the pickup as xalty mentioned.

Oil pan removal and inspection is the easiest/cheapest first step.

 

And when you think you found it an oil pressure gauge fitted would be a good idea.

 

my 2002 had tensioner failure at about the 115,500 mileage mark, just before I purchased it. I suppose the switchover to the better tensioners might have been dependent on the engine build date. In any case, the previous owner had to shell out a few thousand dollars to get the car functioning again. I think the experience soured him on keeping the car, as he put it up for sale some 500 miles later.

it all worked out for me as I was searching for a 4.0 liter XKR that had already had the known issues dealt with.

Z

 

Mechanic called me today and stated I've spun a bearing, quoted me 8k to put a 77k used motor in.

Looks like I have a project on my hands.

This brings up new questions. As the motor still ran, is it feasible to replace and repair the rod bearing? I know we're talking engine removal anyway, but I do have access to a shop/lift to do the work.

Or is transplant the best option? Also, have not used the search function yet, but can I fit the 4.2 from 03-06 in the 02? Lot of thoughts going thru my head currently on possibilities.

 

If you do not understand the bearing selection and complex crankshaft bearing replacement, then I suggest you download and read my copy of the ENGINE COURSE 168 I had copied from my student guide from Jaguar training.

A selection matrix depends on the journals of the crank and block.

Too large to upload here but it is ALL OVER THE INTERNET.

Gus has it on his site.

jagrepair.com

 

You can access the big end bearing with the sump off and change the bearing.BUT it depends on the condition of the crankshaft surface . If its scored then you are wasting your time. The size of the bearing shell will be marked on the rear of the bearing or you can measure the big end with a micrometer. If you do change it you might as well change the lot.

 

You certainly can replace a bearing provided that the crankshaft bearing surface is still in good condition, although that is rather unlikely so the job would will probably be much bigger than you might be hoping for. However, I would not be surprised if, apart from the one bearing, there is other collateral damage.

Richard

 

I'd buy a used engine on eBay for a grand. Pay a mechanic 600 or 700 to swap it in and be on my way.

 

I would recommend you do the LS Swap and make that XK8 a real sports car It will cost a lot more but the end result is definitely worth it!

 

That's where I'm leaning, but the place that the car is sitting at now wants over 8 Grand to do just that.

Need to locate a motor and talk to my local mechanic yet, waiting for him to call me back.

I also have the tools and area to do the work myself with a buddy just not sure I want to do it 🙂

 

I would get the car towed from the current shop. They are trying to skin you alive.

I don’t blame you for not wanting to do the job, there’s a lot of stuff to unhook and / or remove. But as posted, you should be able to find a more reasonable shop.

Z

 

I had my mechanic replace the blown 4L engine in my '97 coupe in 2021. The total cost from initial diagnosis to back on the road plus a few odds and ends was $8700 Canadian. Money well spent considering how much I love driving the car.

 

Thanks everyone for the replies and added insight.

​​​​Car is still sitting at initial mechanic, but wheels are in motion (pun intended) for second opinion at my local mechanic just to ensure it is indeed a spun bearing.

Local mechanic is putting together a labor quote for the job and I'm searching for the donor. Looks like there may be a similar mileage (135k), tested unit at a salvage yard 100 miles or so south of me. I need to call tomorrow to confirm. Motor is listed under $1K

Another option about 100 miles north of me is a complete 99 XJ8 with a bad transmission. Car has 89k on it with a pretty strong service history (although no records of tensioner update - no big deal if pulling anyway, can check and replace if needed during). They are asking 1200 or best offer on the car.

I'm thinking about going this route with the possibility of parting out any good interior/exterior components, plus sell the car to a salvage yard for a couple hundred bucks.

My questions are these - if unconcerned about the donor car condition/salvagability, how quickly could a semi knowledgeable shade tree mechanic (aka me) pull a motor? Secondly, I think thru my research that 99 XJ8 is a clean swap correct?

 

Any AJ27 Normally Aspirated 4,0 engine from X100/X308 will fit.

The later engines did have the MORSE STYLE silent running chains and the timing/oil pump/blocks are different but an ENTIRE engine is plug and play.
Just some internal parts are different.