Spark plug blow out in 97 Camry

Our 97 Camry with about 80,000 miles on it blew a spark plug out. Very spectacular sound, dented hood from the inside and flaked off some paint. What am I looking at for repair? DIY with ‘anti-seize’ or what?

Carless in Seattle.

It depends. You could be lucky and it might have just not been screwed in and all you need is a new plug and put it in properly. Chances are it will need new threads and that is not expensive. Most shops have the right parts and tools to do it and unless the plug is hard to get to or you have some unexpected problems, you will be pleased at the price.

You’re probably going to be looking at a Heli-Coil, Time-Sert, etc. or something similar. Blown spark plugs usually means destroyed threads.

The cause of a blown out spark plug is either overtightening of the spark plug when previously changed leading to pulling of the threads, cross-threading, or ruined threads due to allowing the plugs to remain in the engine for a long time. This leads to them becoming galded in place and when finally removed the threads may be damaged from the simple act of unscrewing the plugs.

Thank you very much Joesph and ok4450! What a nice Christmas present!

The plugs would have (should have) last been changed at the 60,000 mile maintenance by the dealer. Possibly also since then by our trusted mechanic, Andy. I’ve never taken them out. My DIY with cars was limited and over many moons ago. Our towing service via USAA is still on the hook to tow the car somewhere. (The place they tried to tow it (Cross Country something), closed 3 years ago and everything else was closed, so its in front of the house now.) I’m inclined to tow it to Andy’s rather than try to hold the dealer responsible. (If responsibility comes into play here. I don’t know the statute of limitations for bad service from a Toyota dealer.)


The plugs should have been changed at the 60k mile interval. An careful examination of the spark plug threads (hopefully it’s still hanging around!) and the cylinder head threads should determine what happened.
My gut feeling anyway is that either the new plugs installed at 60k were either overtightened or the old plugs had galded in place. While your car does not have that many miles on it, time plays a factor in this also and 60k miles spread over ? years could have led to thread galding.

It’s going to be real iffy about holding the dealer responsible after 20k miles although it is possible the dealer could have been at fault. It is the mechanic’s duty IMHO to inspect all plugs that come out of the engine, both as to thread condition and how they’re burning. If a problem occurred while removing a plug then this is not the tech’s fault but the customer should be made aware of it at the time it occurs.
(While it is recommmended that new spark plugs be torqued properly, I never torque spark plugs since I feel that many torque numbers are a bit high and could lead to problems. I always use a stubby ratchet and palm the ratchet head. Never a problem that way.)

You might contact the dealer and lay your case out. I would advise speaking to the service manager, not the service writers. Be very polite about this but express concern that this should not have happened. If he, or she, mentions the long mileage interval simply point out that there is no set rule on when damaged threads may give up. It can be weeks, months, or years; it’s anybody’s guess. Bottom line is there is no reason for a properly installed plug to blow out of a cylinder head without a contributing factor.
Hope some of that helps anyway.

I looked up the records and learned it had been 20k miles since the last spark plug change at the dealer. (The 60k service). My mechanic indicated that at 15k there should have been another tune up.

The treads were still good since the plug torqued down solid, and the engine seems to run fine. (Also tightened the other three. All were a bit loose. Had our mechanic check my work. At this point I’m over blaming anyone, except me and just considering myself lucky. And thankful for this forum. I don’t have to be lonely about car problems again when my mechanic is not available.

Wheeled in Seattle.


Glad it worked out for you. But why does the mechanic think the needs a “tune-up” every 15K miles? Check the owner’s manual for that info.