Spark plug threads gone! Topic is solved

[pkc303]

I've got a Ford Expedition. I've had two pop out on it. I finally just changed them all myself, and torqued them down correctly. I think the previous technicians were afraid to really tighten them down on an aluminum head.

[mrjacobrussell]

The ford issue is because of a crappy head design they even sell kits specific to repairing 8 and 6 cylinder ford engines

[Wrenchinjoe]

Update: I removed the other spark plugs and the threads appear to be fine on the remaining cylinders. They were TIGHT though, and the threads were dry... no anti-seize compound was used when the Volvo mechanic installed them during the timing belt install 3 years and 45K miles ago. So was #4 overtightened or stripped a little, or perhaps was it not torqued down - like maybe he missed one? Coincidence? Makes me wonder....

Another mechanic buddy helped me tap the new threads to accept an insert repair sleeve. He has done this before (although not on a Volvo specifically) and prefers to use the sleeve type insert rather than the spring style insert. Although it was made by OEM (from autozone) it appears to be similar to the Time-Sert repair sleeve.

We cleaned up the problem spark plug well and ran the motor briefly to blow out any cleaner or debris left over from the spark plug blowing out in the first place. After confirming the piston was down and out of the way, he covered the tap with grease to hold any metal shavings and carefully ran the tap down into the stripped spark plug hole. Then, remove, clean the tap, regrease and repeat.

After the new threads were in place, we ran the motor briefly again to blow out any debris left over and installed the insert sleeve. The directions called for hi temperature RTV on the sleeve's outer threads. The top of the sleeve has a knurled couple of threads and once the sleeve is installed, you insert a tool that expands that knurled section into the head with a tool (part of the kit) and a couple of taps from a hammer. We let the RTV cure for 24 hours and then put the new plug in.

After clearing the codes, the engine fired right up, smoked a lot the first couple of minutes but appears to be fine. Total cost: $50 for the sleeve & tap kit, $10 for a new coil pack/spark plug insulator and a 12 pack of Sierra Nevada pales for my buddy - Total $75.

Now, for the big question: Is this a permanent repair or a bandaid? My trusty Volvo mechanic says he has never seen one of those repair kits hold for long and he believes I will be putting a reconditioned head on the car before long. That is disconcerting. We bought this particular car because the engine only had 65K miles on it. I knew that the car would need maintenance, they all do, but I rather expected this engine to be rock solid for a long time.

Any opinions or advice? Did losing the threads in the head for the #4 spark plug occur because the "Volvo mechanic" over or under tighten that plug? Is the sleeve repair a permanent fix, or are we looking at a bandaid fix as the same Volvo mechanic predicts? Where is that crystal ball when I need one?

At least for now the car is running and we'll certainly only drive it locally for a few weeks in case we have any more problems.

Thanks for all the advice so far.

[cn90]

TIMESERT is permanent repair so don't worry about it.
I always use anti-seize in spark plugs the last 25 years, zero issues.

In retrospect, the Volvo mechanic might have cross-threaded the sp plugs and did not tell you about it.

Re tapping and running engine to expel debris: not recommended as debris can damage valves.
Best is to tap with that particular piston at TDC.
Then make some tubing using appropriate size hoses/vacuum machine (duct tape or whatever), as long as you have a vacuum hose with OD slightly smaller than the sp plug OD, then you can vacuum all the debris once done.