shawnp

I've recently picked up a 1998 GT (not coil on plug) with 230,000km. As far as I know, its got the original spark plugs. I understand this mustang does not issues with spark plugs breaking, but apparently it has issues with spark plugs stripping threads on the way out. How often does this actually happen? I was just wondering if any of the experts here could give me some pointers on how to reduce the risk as much as possible of this happening? Flood the holes with penetrating oil? carb cleaner? Cold engine I would assume? Also, if it does happen, can I use the lock and stitch kit to re-thread and install inserts with the heads on? Or will the debris from reaming/tapping collect in the bores and destroy my engine? any advice is welcome and appreciated.

uberstang1

If you have an air compressor just shoot some air down in the holes to remove the loose dirt and debris, when installing the new plugs just attach rubber hose to the end of the plug and thread them in by hand as far as you can before torqueing them down and you should be fine. Timeserts are known to be far more effective than a helicoil kit for reparing a stripped spark plug port. If you are that concerned about it you can just take it to a shop to do it, this way if one gets stripped its on them.

vanbibber

Used timecerts in my heads as well, twice as many threads and no issues so far.

lizzyfan

Same here
Even the upgraded PI head threads have been known to fail

nickmckinney

Romeo NPI heads probably fail the least of all heads for spark plug threads. I would remove them cold and install new ones with anti-seize.

cliffyk

Torque-wrench

Preferably a 1/4" drive unit good to 200inlb; proper torque is 11-13ftlb (132 to 156inlb).

This is not very tight in the overall scheme of things, hand tight and 1/16th turn additional--which is what gets people into trouble...