Timing chain issues - F-type is not immune
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Timing chain issues - F-type is not immune
Earlier versions of AJ133 engines used in jaguars (XKR, XJ) had a serious issue with a timing chain and tensioner. Fortunately by the time F-type was released updated design was already in use. Well, now there are reports of updated designs failing as reported on XJ forum.
Blown rings are relatively mild damage, as chain issues can cause severe detonation and/or pistons hitting valves resulting in a shot block and totaled engine. Still, it is huge hassle to fix, as this is engine-out procedure.
Fortunately, it is easy to avoid this issue by changing oil more frequently.
When I removed the tensioners, I found quite a bit of sludge behind them. There is a perfect place for it to accumulate behind the tensioners. This buildup is a problem. The tensioners essentially have two pistons. One is the spring loaded, ratcheting piston that keeps constant tension on the chain guides. The second, encases the first piston and is hydraulically actuated by engine oil. So the design is to apply light tension continually and significant tension immediately when the engine is started. Obviously restricted oil to the tensioner would allow the timing chain to slack and jump at engine start, as mine did. Incidentally the miss timed ignition created enough detonation to blow out the rings on the driver side 4 cylinders.
Fortunately, it is easy to avoid this issue by changing oil more frequently.
Last edited by SinF; Jan 13, 2020 at 11:21 AM.
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Memory fades, yet as I recall this issue with my XK8, those before certain serial #'s (in the 1997 - 2000 era) were candidates for this failure. It had to do with plastic in the tensioners, so the repair update was to a metal replacement. After 2000 the new engines came with the metal ones.
Any other history of this with the current F or XJ models?
Any other history of this with the current F or XJ models?
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Earlier versions of AJ133 engines used in jaguars (XKR, XJ) had a serious issue with a timing chain and tensioner. Fortunately by the time F-type was released updated design was already in use. Well, now there are reports of updated designs failing as reported on XJ forum.
Blown rings are relatively mild damage, as chain issues can cause severe detonation and/or pistons hitting valves resulting in a shot block and totaled engine. Still, it is huge hassle to fix, as this is engine-out procedure.
Fortunately, it is easy to avoid this issue by changing oil more frequently.
Blown rings are relatively mild damage, as chain issues can cause severe detonation and/or pistons hitting valves resulting in a shot block and totaled engine. Still, it is huge hassle to fix, as this is engine-out procedure.
Fortunately, it is easy to avoid this issue by changing oil more frequently.
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