I have had my xj 5.0 supercharged for years and 74k miles and zero issues outside of replacing water pump

i noticed a knocking noise only under light load from around 2500 to 3000 rpms and even then intermittent but when it does it it us LOUD almost like rod knock

i checked oil level as its been 10 months and 7 k miles and it said underfilled. I added 1.5 quarts. Drove 20 miles, checked it again still said underfilled so i added one more quart and it STILL says underfilled

this can't be right. Im changing the oil in the morning and will measure how much drains out as i don't want to drive with overfilled engine

no smoke from exhaust, no visible leaks. I was worried it was rod knock but its just intermittent and only at those rpms

i popped the hood and had my wife rev it slowly. Sounds like its coming from supercharger but its a knocking sound and again only at thos
e rpms

pulled the codes and there are none

im at a loss. Im assuming the oil level detection system is shot

what does this sound like to you all. Im thinking about ditching the car before it really starts acting up as its been near perfect for years

 

I had knocking noises at ~1500 rpm under light load (when I applied accelerator or removed foot from accelerator). Was transmission and engine mounts bad in my case. Not sure if it’s the same sound you’re hearing. Engine mounts looked much worse than the transmission mount, but transmission mount replacement made the biggest difference.

Best of luck

 

I had added 3 quarts of oil and at oil change only 4 came out

car was down to one quart of oil and never warned me

oil level monitor after filled works properly...very odd

there is a large active leak the pan under the car was hiding. Within 5 minutes of sitting off with cover off bottom there was a 3 inch diameter oil spot

car is at my Ferrari mechanic as he is only one i trust. Hes hoping its a oil cooler hose and that the rod bearings aren't damaged

he said the 5.0 supercharged engines in jags and range rovers are fine when new but when the mileage comes on then its time to dump them

looks like the 100k dollar car when new is worth 13 to 15k now

i have loved this car for 4 years. I really hope it can be fixed and i can get 2 more years out of it

if its compromised then its going to carmax ASAP and ill have to go car hunting

 

Scary. Hope it’s not major.

 

Well oil use is not common but anything is possible at 100K and above. Sounds like yours had a big leak and you didn't know it.
Might pull the oil filter since it's so easy and take a quick look?
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He said it looks to be the vacumn pump. It is streaming out oik

he said engine sounds fine and no codes

ordered part. Replacing friday and we will see. He said im lucky but it might be best at 73 miles to maybe keep another year and dump it as he said these 5.0 supercharged engines, especially the early ones are just a PITA

 

My engine made a "knocking" sound at the supercharger and replacing the front coupler in the snout fixed the issue.

 

was it always present or busy at certain rpm

 

You will only hear the SC knock on shutdown or start up.
The BEST way to check it and it's easy is to do is to remove the SC belt. You can rock the SC back and forth and it's real obvious if it's knocking.

If it was not for this forum I would not even know mine was making noise. It makes the most noise on shut down but if you don't have the drivers door open and the radio off when you switch the engine off you won't hear anything.
Then I swapped SC pulley's and moved the SC by hand it was definitely making a noise.

Yes the vacuum pump is a known oil leak. You can just change the O-ring and usually you don't even need to do that. Just remove the cover. Clean everything up and re torque the cover.
I see this more on higher mileage cars but thankfully it's a very minor problem/repair unless you lose a lot of oil from the leak.
You can check for this very easy too. Just get a flash light and look straight down at the front of the engine. The vacuum pump is under the crank pulley so what you are looking for is oil in that area.
If it's dry you are good to go.
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You had a near miss. This is not the first time I heard about modern Jaguar not warning about low oil. Allegedly, V8 had an oil pressure sensor eliminated as it was too close to exhaust and as a result would not produce low oil pressure warning.

I would recommend doing an oil flush, if low oil sent extra metal through the engine, you want that flushed out before it causes damage. Codes won't tell you condition of bearings until something completely fails.

 

There is a coolant pump issue, brittle plastic coolant lines issue, timing chain tensioner and guides issue. If you sort these 3 issues, then the engine is solid - however any one of these could total the engine.

There is also a SC coupler issue, but that makes a lot of noise before becoming in any way dangerous. The chain can be also heard at startups, but many people don't know how timing chain issues sound.

 

thanks and agreed. I just changed the oil yesterday. Supposed to be fixed by end of day tomorrow

i hope there is no real damage. This is the first daily driver i haven't gotten sick of within two years and its been great otherwise

 

ive sorted the coolant pump and brittle lines issues.

does the sc coupler only make noise at shutdown..

my engine knocks intermittently from 2500 to 3k rpms.... i think it may have always done this but now im hypersensitive to it

i have zero noise at shutdown. Does that rule out the coupler