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Compression Test



 
 
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  #1  
Old April 7th 05, 03:03 AM
griffin
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Default Compression Test

As some of you may remember my '85 CJ7 4cyl is not running properly. Quick
recap - stalled offroading ...turns over but won't start. Replaced a pile of
wiring/plugs/dist cap/rotor/fuel filter/etc. Got it running enough to drive
but it backfires. Parked it for winter. My guess and the mechanics guess
here is that the timing chain skipped from offroading (not to mention we
tried pull-starting it and it backfired pretty violently). Anyways ...before
we go and rip all that off and check, we did a compression test (with a
cheap $30 tester) and got 148/148/123/137. Is the lower numbers going to
cause this problem? There was also a deposit on the end of the plug on the
123 plug.

Anyways, if this is unlikely to cause the problem described then I'm going
to test Mike's last suggestion (regarding the distributor) and if that isn't
it the timing cover comes off this Saturday.

Thanks!


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  #2  
Old April 7th 05, 04:46 AM
RoyJ
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Posts: n/a
Default

Not great, not horrible.

griffin wrote:
> As some of you may remember my '85 CJ7 4cyl is not running properly. Quick
> recap - stalled offroading ...turns over but won't start. Replaced a pile of
> wiring/plugs/dist cap/rotor/fuel filter/etc. Got it running enough to drive
> but it backfires. Parked it for winter. My guess and the mechanics guess
> here is that the timing chain skipped from offroading (not to mention we
> tried pull-starting it and it backfired pretty violently). Anyways ...before
> we go and rip all that off and check, we did a compression test (with a
> cheap $30 tester) and got 148/148/123/137. Is the lower numbers going to
> cause this problem? There was also a deposit on the end of the plug on the
> 123 plug.
>
> Anyways, if this is unlikely to cause the problem described then I'm going
> to test Mike's last suggestion (regarding the distributor) and if that isn't
> it the timing cover comes off this Saturday.
>
> Thanks!
>
>

  #3  
Old April 7th 05, 05:09 AM
L.W.(ßill) Hughes III
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Posts: n/a
Default

Give it a couple of squires of oil in each cylinder to see if the
raises the compression, that will tell you if it is the rings. I'm think
with the barking, it's a blown head gasket between the to lower
cylinders, or they have bad valves that could easily have happen lugging
the little four banger trying to keep up with traffic.
God Bless America, ßill O|||||||O
http://www.billhughes.com/

griffin wrote:
>
> As some of you may remember my '85 CJ7 4cyl is not running properly. Quick
> recap - stalled offroading ...turns over but won't start. Replaced a pile of
> wiring/plugs/dist cap/rotor/fuel filter/etc. Got it running enough to drive
> but it backfires. Parked it for winter. My guess and the mechanics guess
> here is that the timing chain skipped from offroading (not to mention we
> tried pull-starting it and it backfired pretty violently). Anyways ...before
> we go and rip all that off and check, we did a compression test (with a
> cheap $30 tester) and got 148/148/123/137. Is the lower numbers going to
> cause this problem? There was also a deposit on the end of the plug on the
> 123 plug.
>
> Anyways, if this is unlikely to cause the problem described then I'm going
> to test Mike's last suggestion (regarding the distributor) and if that isn't
> it the timing cover comes off this Saturday.
>
> Thanks!

 




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