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Broken piston ring? by boysatt
Started on: 06-23-2014 04:09 PM
Replies: 2 (99 views)
Last post by: Purple86GT on 06-23-2014 05:48 PM
boysatt
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Report this Post06-23-2014 04:09 PM Click Here to See the Profile for boysattSend a Private Message to boysattEdit/Delete MessageReply w/QuoteDirect Link to This Post
Customer brought in his 86 GT V6 5 speed a couple weeks ago. It ran rough and oil was literally pouring out of it. Had to drop the cradle and weld both manifolds and drill 7 broken exhaust studs, replace egr tube, valve cover gaskets, intake gaskets and oil pan gasket. It ran perfect after that, had some minor blowby but its a old car, so was to be expected. Owner picked it up and 3 hours and 40 miles later it was towed back in non running shape. Was doing 70 down the interstate and started losing power until it stalled. Restarted after cooling but would not hold idle and you would have to give it part throttle to get it to fire off. Motor defiantly has a miss on 2 or more cylinders and barely has enough power to pull it into the shop. I pulled the oil cap off the front valve breather tube and when running its like a smoke machine from the engine. I'm leaning toward the fact it may have 1 or more bad rings and so much blow by it will barely run.

Compression is:
cyl
1-140
2-100
3-60
4-100
5-120
6-110

Any other input?
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Gall757
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Report this Post06-23-2014 05:46 PM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
There seems to be plenty of good used 2.8s available, so you should not put another dime into that one.
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Purple86GT
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Report this Post06-23-2014 05:48 PM Click Here to See the Profile for Purple86GTSend a Private Message to Purple86GTEdit/Delete MessageReply w/QuoteDirect Link to This Post
Well, #3 is a no brainer, it's shot.

10% variation between cylinders is the max of what is considered acceptable. I would say it's probably rebuild time. Did I overheat?

Drop a bit of oil in the cylinders to see if compression goes up. if it does, it is the rings for sure.

Good luck!
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