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Dear all, I'm new in this forum and trying to help my friend Ivan with translation and tips for his XJS 5.3 v12, 1978.
The car was imported from CH few years ago with 114 000 km on the clock.
Ivan restored it with new paint , new interior , automatics transmission and brakes rebuild.
The car is really beautiful. This summer start making problems with ignition timing,
its lost timing few times. We found that distributor is loosing alignment somehow and decided to check
the gear giving the movement to the distributor ( fount tread about possible problem with worn teethes of this gear)
The removal of the heads is nightmare ;-), but with proper tool we made it.
So , the gear is OK , but we found plastic part of damping bracket inside the timing cover (pictures attached)
There are visible holes on this plastic part from teethes, so it makes sense the problem is discovered.
What is your opinion , is it common problem with those engines? It is 45 years old engine but kilometers are below 120000.
The chain tensioner looks ok , should We change it too ? What about another 2 damping brackets and chain, they looks fine, should we change them too ?
Best Regards
Stan
Welcome to the Forums. Please do an Intri in the New Members Area when time permits.
Not a lot of damage that I can see.
The Boomerang Tensioner is the usual culprit, usually due to some "fool" rotating the engine backwards. I would look VERY carefully at it, particularly the pivot pin end, that is where they usually fail. NOT cheap, but the hard work is done, you are IN there.
The other dampers look worn, and look almost, long way from here, like really poor oil change spec, or something.
That mileage is LOW by any language, so a lot of short mainly COLD running, the death sentence for a V12, sadly.
Mine have over 700K kms, on one, and over 400K kms on the other 2, and that area is untouched on all of them
The other issues:
The worm gear on the jackshaft (the one that drives the distributor) wears, thus causing odd events with the distributor.
The Driven gear on the distributor strips itself. Mainly caused by a seized or seizing distributor. That I have had twice, a very looong time ago.
Both the above are mainly?? caused by short cold running, and lousy oil usage.
That engine must get to operating temp EVERY time it is started. That can be awkward for some people, but fact is fact.
thanks for reply,
all gears involved with distributor are OK by us.
Check attached pictures.
Most probably broken damper part caused slipping between sprocket and chain and distributor lost timing (just my opinion)
According parts to change you convinced us to change all dampers and chain tensioner.
Some other suggestions?
10-25-2022, 05:20 AM
Ignitin timing problem
