Has anyone else had problems with Autolite plugs cracking? About a year ago my wife'* Bonneville started having intermittent misses when under load in Overdrive. It progressively got worse until it finally threw a code. I checked that cylinder and the plug was carbon scored from a crack in the insulation. Replaced that plug and all was good. Now it is starting to do it again, exact same symptoms. I have 6 new plugs sitting at home waiting to go in there anyway, so if thats all it is so be it, but would there be a reason these keep cracking?

That is very odd, I haven't heard of it happening.

What Autolite plug are you using?

Nope...seen it happen...it is due to wrong angle when tightening the plugs and over torquing. It will create hairline cracks on the insulator. You should always tighten a plug with your fingers first, then use a proper socket or wrench.

It currently has the Autolite 606 copper plug. I will be replacing them with 605s on the chance that the higher heat rating is responsible for this problem. Both times this has happened, the problem has started while driving in a very hilly area out in the desert, where the motor gets hotter than average, although not to the point of overheating.

I would buy into the cracking while installing theory if these plugs were not over a year old when the first crack appeared. This latest one will be after more than 2 years in place. Cracks can certainly happen during installation, but I don't believe this is the case here.

Could you be cracking them while installing? I'm wondering if your spark plug socket still has that rubber piece inside.

I've never liked Autolite plugs.

A subsidiary of the "F" word car company.

I thought they were owned by Bendix. They still do a lot of OEM work with Ford, but I could have sworn they sold them off quite a while ago.

Except for this, I have had great luck with Autolite. My Buick has run a couple sets of them with no problems, and for the money, it'* hard to consider going with anyone else.



Are those the iridium plugs? At this point, I want to find out what is happening to damage these. I can live with replacing $1 spark plugs from time to time. I would get a lot more heartburn if I was replacing much more expensive iridium plugs for the same reason. And again, this is the only car I have ever had a problem with Autolites in. If I have problems with the next set, I may consider a different brand just for comparison'* sake.