my 1987 420 SEL have 87000 miles and is running smouth.

At what frequency (milage) should I replace the timming chain and why?

thanks in advance

Christian

They say every 100k. If yours has truly that many miles, but is that old and never been done, it should be done soon.

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1984 300SD Orient Red/ Palomino
1989 560SEC
2016 Mazda 6 6 speed manual
1995 Ford F-150 reg cab 4.9 5speed manual

thank you.

Hi there,
I don't think the chain is the problem, it's the plastic guide rails that need replacement as the plastic gets brittle. There is plenty in the archives, do a search. I believe 10 years or 100,000 miles is a rule.
Good luck with the car

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Reinhard Kreutzer
1987 420 SEL (126)

Heat causes the plastic to become brittle. The main problem is the inner chain guide on the drivers side. If the chain and guides flop around, the guide breaks and gets sandwitched between the chain and the sprocket. If this happens, the timing slips, the top of the cam cover breaks and the valves hit the pistons. Engine rebuild is next, a replacement engine or junk the car.

Chain Guides Replaced

It's not that hard but you do need some tools.

Checking is easy.

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Regards

Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.