Case Studies

Jaguar Engine – Broken Timing Chains, Bent Valves

This is an excellent example of what you do not want to see happen to your Jaguar, you’ll note the broken secondary timing chain, and consequently the damaged engine valves.

On the early XK8 and XJ8 Jaguar vehicles, there is a known flaw in the upper timing chain tensioner. What happens is that the chain tensioner fails, causing the chain to slip or completely break like you see here, causing damage to the valves.

A noticeable engine noise while idling or during a cold start can indicate a timing chain tensioner problem. The engine noise may also be accompanied by a rough or uneven engine idle. The Check Engine Light is often on, but may not present on all cars.

What Happens
On the early XK8 and XJ8 Jaguar vehicles equipped with the 4.0 and 4.2 liter motor (supposedly was improved on the 4.2 liter engines, but we have seen many of these now failing as well, there is a known flaw in the upper timing chain tensioner. The plastic/nylon guide plates on the chain tensioner fail, causing the chain to slip, or come loose and fall into the area between the sprocket and chain, causing timing chain failure. Failure of the chain will cause severe engine damage, as the engine valves are no longer synchronized, allowing them to strike the pistons, causing damage to the valves. This necessitates removal of the cylinder heads and rebuilding, or replacement of the complete engine assembly.

We have developed has released improved metal tensioners, forged roller chains, metal backed timing chain guides which are considerably more durable that the original design. It is important to use all updated parts, in particular not to reuse the tensioner bolts, as new designed bolts have been issued that must be installed.

Often overlooked, for durability and reliability, it is critically important that all the seals and gaskets associated with this job be replaced when the engine is open and apart, particularly the seals on the VVT arm for the intake camshaft, which has a Variable Valve Timing (VVT) mechanism, and that the arm be inspected for wear or damage. This job, when properly done, and regular, proper maintenance followed, this update/repair should last the life of the car.

Have Questions?
For more information on AGM batteries and other types of batteries, please call one of our Service Advisors, they can offer valuable information on various types of batteries and which battery works for you.

At Atlantic Motorcar, we’re all about providing our customers not only Great Service but also Value. We understand that “An ounce of prevention is worth a pound of cure.” (my mom would be proud I remembered that.), in other words, preventing, or catching problems like these brake lines early, can save you more than just money.

Questions, or if we can be of help in any way with service on your Audi, BMW, Mercedes, Mini Cooper or other European (and now Japanese) import, please contact us. Our team of Service Specialists is here to help, for even the newest autos! (207) 882-9969.

Knowing, not just “doing”, that’s the Atlantic Motorcar Center way.

The Atlantic Motorcar Center Service Team


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