ISlo300

Hello all, I just purchased a 2008 isf with 197k miles. Haven't picked up the car yet but to get to the point the owner somehow blew out the sparkplug on the 6th cylinder. He took it to a Lexus dealer and they said it came to lose with an oil leak and stripped out the plug. They also stated he would need a new motor because they can't just use a time insert due to the high mileage.I plan on getting a spark plug insert if the threads are actually stripped. My question is how long are the spark plug threads and what do yall think of this

UCrazyKid

I don’t know how long the threads are but I think I read about this car in another forum or FaceBook. The advice the guy got was just to repair it with a helicoil or similar kit. There is nothing to lose if the alternative is to buy a new motor! The key issue will be to keep as much filings from falling into the cylinder during the repair. Use a shop vac and a scope to check. Make sure there is no damage to the cylinder walls or piston. Weird to lose a plug like that. Also try using heavy machine grease on the tap so much of the metal filings cut just stick to it and come out with the tool.

The dealers comment about mileage and not repairing the threads sounds like bull****. How do they think really old classic cars motors are repaired and rebuilt. The metal will not be thinner or more brittle with 197k miles. Dealers do not know how to repair, they only replace. And there is much better money for them in it to do it that way. If you are uncomfortable doing the work. I would look for an engine builder or automotive machine shop or restoration place to get it done. I hope you got the car for a good price and don’t find the plug was blown from abuse (forced induction, bad tune, nitrous, etc)

UCrazyKid

Yup, looks like it is the same car. And it looks like it had a tune and some mods.

ISlo300

Yep that's the car haha, didn't wanna post there until it was in my possession completely. It seems that grease tap and rethread is the thing to do, it don't trust the heli coil as it is just a spring coil. Im gonna take it to my shop and do a time sert. I have to use a cylinder scope to check them out. Weird to see this. Do you think a valve cover gasket leak coulve caused this?

UCrazyKid

Ha, small world. Valve cover gasket leak, I do t think so, I’m not an expert but I e never heard of it and I’ve had my F for 10+ years and following Club Lexus.

Jwconeil

This is more likely from poor installation. He must have stripped the threads when he put them in. Check the rest of the cylinders.

ISFpowered

Whoever changed the spark plugs I’m willing to bet they didn’t use a torque wrench and thought the old “feel” was going to be good enough lol. Those techs crack me up.

ultimase

A long time ago I did a 5vz swap into an a second gen 4runner. When I had the motor out I did the timing belt etc before swapping it. I put in the old spark plugs in hand tight when working on the motor on the stand, just to keep debri out of the motor. It was lucky I did this as the ceiling of the garage ended up falling on the motor.

In my excitement to drive the car I never torqued the spark plugs down to spec. Well a few months of driving it and I had a spark plug leave while on the freeway. I thought I had stripped the head, but luckily it had just backed out of the head with no damage.

Ok long story short, do you have the vehicle in your possession? If you do I'd bore scope it and take a look at the threads, or very carefully and only hand tight, take a spark plug and run it down into the head. Stripping the head takes a good bit of force. I'd be surprised if it could strip the threads by the engine just running, but if a mechanic or owner just cranked down on the ratchet while swapping plugs it's certainly possible to strip the threads.

lobuxracer

iTrader: (2)

It's HARD to strip spark plug threads. It's usually a problem with short life plugs getting swapped out every 5 or 10k and every time they take a little aluminum with them.

Timesert is what you want to do if it really is stripped. I have my doubts about that. No need to remove the head, and no magic. Helicoil plug thread repairs don't work IME.

I worked at a motorcycle cylinder head machine shop for a few years and did a number of these. No Loctite, no backing out, zero issues with Timeserts. The only hard part is the plug hole is pretty deep so you need a pretty long tap handle. Other than that, piece of cake.

Reach on these plugs is well documented, just look up the specs for the spark plug - 26.5mm for the OEM FK20HBR11.

SubOrbital

Many years ago I reconditioned Subaru STI Brembo calipers and used TimeSerts for that. Definitely a high quality thread replacement. Backstory is that the mounting ears on those calipers don’t have a steel insert leading to galvanic corrosion between the aluminum threads and steel bolt. Some folks used HeliCoils, but that’s just not as reliable as a TimeSert IMO.