Need some help on stripped spark plug threads...
 

1997 Es300 235k.

Long story short;

Spark plug and coil pack exploded in cylinder 6 :eek2:

After hours of picking and cleaning debris
out of the cylinder sleeve, I was finally able to remove the dead plug but come to realize that
the threads in the cylinder are now stripped from the pressure.

Can anyone tell me what caused this to happen?
Also, what's the best approach I can take to repair the threads without removing the head?

All advice is appreciated, thanks!

You or your mechanic can use a Heli Coil kit to repair the thread. Do a YouTube search and you'll see plenty of videos on how it works.

In a way you're lucky as No 6 is very easy to deal with.

Make sure that you blow everything out of the cylinder and use a strong magnet to get every little bit out.

Any idea what happened?

Phil

Well... I was hoping you could tell me what happened haha.

My dad has been 'borrowing' my 3es for a few months now, so i'm not sure how his
driving habits were. Other than that, the plugs are less than a year old NGK, torqued at 13-ft lbs
and no other problems I was aware of. Besides a minor "tick" in the motor, which it had for a few
years now.

I spoke to a few other people about this issue and everyone is just as clueless as me :uh:

I was also considering the heli coil kit too, but was curious of what other members insight was on this issue.

I honestly don't know what caused that, only thing I can think of is maybe the plug was loose. They make kits specifically for repairing stripped plug holes, but like PFB said it is very important to get as much of the metal particles out as possible. A magnet will not work on most of the particles because the head is aluminum. To get the particles out take a plastic tube that is small enough to get into the cylinder and tape that to a shop vac.

The best repair kits are probably made by Time-Sert, don't use a cheap version it won't last!

I've tapped lots of stripped plug threads, but never one down deep in a head like that. It should be possible, you just have to be careful. I have a special tap that cuts the threads for the inserts, it starts by using the existing threads, then cuts larger so you can then put the insert in. You could use this, put grease on the cutting threads of the tap to catch a lot of the cuttings. I would start with that piston at TDC, and I would only cut 1/4 turn at a time, then pull the tap back out and clean it, put on fresh grease. Once you get all the new threads cut, I would use a vacuum with a smaller hose to try to suck out any more chips that are sitting on top of the piston.

I have no idea what caused that coil pack to let go like that.

The proper way to repair that would be to pull the cylinder head. Seeing it is the front bank not that bad compared to the rear.

Thanks for the feedback, guys!

I watched a few youtube videos on the heli-coil repair kits and it looks pretty easy and
straight forward to repair.

I will be purchasing the kit and attempting the repair this weekend.

I know, I know. The head should be removed to repair the threads, but i've never removed
camshafts before, let alone the head haha. So i will attempting this job with the head on.

KLF, you have a good idea with the grease on the threads of the tool, and Lex2000, another good
idea with the shop vac. I will definitely be using these ideas for the repairs.

I just hope this car isn't "Screwed".

Ill post back my results this weekend!

I feel like it could be valve train related. Maybe your exhaust valves didn't open and created too much pressure inside the cylinder, which caused the spark plug to pop. When was the last time your timing belt was replaced/inspected? I'm worried that this may happen again, after you repair the threads.

The timing belt waS replaced at 210k miles so it has A little oVer than 20k miles on it.

I can recall one incident where the motor sounded like it had a rod knock or stuCk lifter. The car sounded like crap and went away once it was warm. Never happened again.

I'm concerned this may happen again too...

I'll repair the threads and see what happens..

Which repair kit did you get?

I have not picked one yet. I'm going to see what the snap-on truck hAs for thread repair tools today. If not, I'm leaning towards the heli-coil kit.

Didnt you mention there was a slight tick in the engine for the past few years. Usually indicating that the valves need to be adjusted. Obviously in Toyota and Lexus no one really ends up adjusting the valves. Could be the valve train was too "loose" to open the exghaust valve like Mr. Booby said and all that pressure caused the spark plug to blow out,

I would pull the front valve cover and check how loose the valve clearance is. Might be the asnwer to your problem.

I was considering that thought alSo. For fears that may happen again, I just brought the car to a garage for them to figure out.

Stripped plug hole
 

what tool did you end up using to rethread hole I have same problem and every tool I get I can’t fit socket into plug tube to rethread hole?

what tool did you use to rethread hole Im having same issue every tool I get I can’t fit socket in tube to rethread