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post #1 of (permalink) Old 07-04-2001, 07:10 AM Thread Starter
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258 Timing Chain

Hi all,

When does one consider the timing chain to be worn? I've read posts in the past which said anything over 5 degrees play. Mopar says anything over 10 degrees and I've even seen 10- 15 degrees.

My chain seems to have 10 degrees play (5 notches on the timing scale on the engine) measured by turning the crank back and forth and watching the rotor on the distributor. Done this several times to make sure I had the correct measurement.

I am asking this as I don't want to unnecessarily rip the front of the engine apart.

Hooch

'83 CJ-7 258/TR/TF999/D300 in Land Rover Country

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post #2 of (permalink) Old 07-04-2001, 04:46 PM Thread Starter
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Re: 258 Timing Chain

btt

Surely some of you must know what the limit is...

Hooch

'83 CJ-7 258/TR/TF999/D300 in Land Rover Country

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post #3 of (permalink) Old 07-04-2001, 04:55 PM
 
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Re: 258 Timing Chain

To be honest, I have never herd of checking the timing chain this way, It is usually measured with the front of the motor off by moving the slack side of the chain back and forth measuring the distance it can travel!

Rodney C
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post #4 of (permalink) Old 07-04-2001, 07:14 PM Thread Starter
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Re: 258 Timing Chain

Well, this ain't too hard to figure out... Since the chain is responsible for correct timing and makes the rotor on the distributor go round, it figures that you can measure the slack by rotating the crank --> timing gears --> cam shaft --> distributor shaft --> rotor clockwise till the number one cylinder is on it's compression stroke and the timing scale at 0 degrees tdc. Now when turning the crank counter clockwise ,the chain will first take up the slack before it will start turning the rotor again, which you can then measure on the timing scale. Off course you will get the sum off all the slack of all the components involved and not a true chain slack measurement, but if you are fairly sure that the other components involved have not too much play, it will give you a reasonable idea of the state of the chain. Short of ripping the front of the engine apart to see and measure the actual chain, it is the next best thing to give you an idea... The Mopar handbook advises to remove the mechanical fuel pump so you can watch the cam shaft movement which takes a few components out of the equasion and gives you a slightly better measurement, but still not 100% true.

Hooch

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post #5 of (permalink) Old 07-05-2001, 10:00 AM
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Re: 258 Timing Chain

The timing chains that I have replaced on a 258's have been replaced because they begin knocking (chain slapping the passenger side) on the cover. It seems kinda common on engines with over 80K miles. PAW offers a double roller replacement which you may want to consider if you anticipate getting a bunch more miles before a rebuild. I am not sure if your has the plastic gear or not, but if it does, I would sure change it. My .02.

post #6 of (permalink) Old 07-05-2001, 10:20 AM Thread Starter
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Re: 258 Timing Chain

Well, I can't say that I can hear the chain slapping and I am also not sure about the actual mileage or whether it has the plastic gear. I suppose I better look into it, rather than wait. It can only improve matters...

Hooch

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post #7 of (permalink) Old 07-05-2001, 10:31 AM
 
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Re: 258 Timing Chain

with the oil pan removed, you can see the bottom sproket and reach the chain to measure slack.
oil pan is easy to remove/replace and like most 258s with age and miles, it probably leaks from there or the rear main seal anyay.

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post #8 of (permalink) Old 07-05-2001, 10:41 AM Thread Starter
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Re: 258 Timing Chain

Well, that is about the only part that doesn't leak on mine [img]/wwwthreads_images/icons/smile.gif[/img], so I'd rather leave it well alone... As a matter a fact, the only thing that leaks is the plastic valve cover. Gotta git meself a nice shiney ally one [img]/wwwthreads_images/icons/smile.gif[/img]

Hooch

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