I've recently purchased a Jaguar XJ8 4.0 liter V8 with 98,000. I've recently hit 101,000 miles. At about 100k miles, I had a "low coolant" level warning light on my dash. I've had little drops of water leaking. Then I filled it with coolant and I haven't had the coolant warning ever since. Today I had a "low oil pressure" warning light on my dash for a second and disappeared for less then 1 second. The car feels smooth , no unusual sounds from the motor.

What could this be ? Also, what are the symptoms of a failing tensioner ?

 

Welcome to the forum 100spokes,

I've deleted your duplicate thread from General Tech Help forum. This is the right place for tech questions about your model.

On the coolant drops. The V8 shouldn't leak and, as it's a low volume/high flow rate system, any leakages should be investigated. Overheating is a bigger killer of Jaguar V8's than failed tensioners!

The oil pressure sensor has been reported by a few members as an issue - either the harness connection or the sensor itself. Using an oil filter without a non-return valve can also cause a slow build in oil pressure from cold.

The symptoms of a failing tensioner can be the timing chain jumping a tooth but are more often a catastrophic failure. If you don't know the type of tensioner fitted to your vehicle then the best advice is to inspect a.s.a.p.

Please follow this link New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum to the New Member Area - Intro a MUST forum and post some info about yourself and your vehicle for all members to see. In return you'll get a proper welcome and some useful advice about posting to the forum.

Graham

 

This might sound like a silly question, but what's the level in your oil now? Is it normal, or very low? The light should only come on with loss of pressure, but if you've got an oil leak you don't know about and it's gotten down too far, that could certainly happen. That's just the first step to check, but figured I'd ask

 

First of all, if the secondary tensioners have not been upgraded in this car, your engine is on borrowed time with this mileage and this should be your first priority. This is something that needs to be done proactively, there may be no warning before major engine damage is done.

If the low pressure issue is at startup, it could be your oil filter does not have the proper anti-drainback valve.

If the low pressure is any other time, the most likely cause is the sump is clogged with plastic bits from the breaking up of the tensioners and chain guides or a faulty pressure switch.

You also should have you cooling system pressure tested to find the source of the leak. Overheating is another engine killer on these cars, so you should maintain your cooling system in top shape.

 

I appreciate the immediate response everyone.

I have also had electrical issues like the car alarming when I open the door after unlock and I have to open the trunk from inside or else it would alarm. Sunroof doesn't open.

I am hoping that the "low oil pressure" is just a faulty sensor.

 

+1 on tensioners.

 

If yours look anything like mine did, i could be you problem.
With the passenger side valve cover off I could see the drive side chain guide was gone. Found it in the oilpan and pick-up..

 

First thing I would do, pull the cam cover off and inspect the tensioners, if they are red, or not metal REPLACE BEFORE YOU GO ANY FURTHER!

Also, I would try a hard reset (disconnect the earth lead from the battery and touch it to the positive lead for 10 seconds and reconnect). Another thing to check is that your battery is producing the correct voltage.
If it is under 12v this will cause mysterious issues.

 

as I was driving the jag today, I haven't had any warning lights come on indicating my oil pressure. I will remove the covers once I get my vehicle home and take photos. I live on a military base and my license is currently suspended for off base so I can not bring the car on. I apologize for the day guys , appreciate all the insights.

 

And regarding the tensioners, is it located on the passenger side or driver side ?

 

They are on both sides, both valve covers need to be removed to access both secondary tensioners.

 

Hey everyone ! I removed both valve covers and the tensioners are intact , as a matter of fact, previous owner had them replaced to the later model OEM tensioners. The cause of the "low oil pressure" light came from a faulty oil level sensor ! What a relief. Makes sense because it only happens as I go over a big bump.

Thanks to everyone for their knowledge and input !

 

Won't ask why your license got suspended: but I can guess. Glad you could get to the car and check things out.

Keep an eye on the oil pressure: if it comes on again, pull the pan. See above for reasons why. Also, some time back, folks changing the secondary tensioners were putting a shop towel (on the left hand/US driver's side) just behind the VVT to keep nuts and stuff from dropping into the pan, then forgetting to pull the towel when they buttoned it up. Crankcase suction sucked in the towel; towel blocked the pickup screen for the oil pump -- low oil pressure.