So i was changing out my spark plugs in which case the passenger side was done first. Proceeded to the driver side just to find out that the owner before me changed the spark plugs and stripped out the allen head bolt so now i can't get the bolt out plug the other allen bolt that sits towards the back is torqued down. How can i get the stripped allen bolt out so i can replace it with a new bolt?

Also since the passenger side is changed out my car acted like it didn't want to start earlier today, now it also sounds like it backfires when redlining it while fly shifting

 

I just did my sons Is350 and didnt have any allens. If an allen is stripped try putting a vice-grip on it. My coil paks had 10mm's on them.

 

Not the coil packs on the intake manifold are allen bolts that is stripped out and the particular ones are in the hard to reach areas with a vice grip

 

You don't have to remove the intake manifold on the IS350 to change sparkplug. However, the design on the 250 required intake manifold to be removed to perform sparkplug job.
OP, you could use the bolt extractor the get it out. Auto zone or o'Reilly has it

 

I don't have the is350 I have the is250. Will the bolt extractor work in the wells for the allen bolts?

 

Slice a center cut down the middle of the head of the bolt and remove with a large screwdriver.

 

how can i put a slice down the center of the bolt head?

 

If it's the bolt I think he's talking about, I don't think he's going to be cutting it any time soon. It's surrounded on all sides by the manifold that sticks up about 3 inches around it. He can try using a punch and getting it to spin that way, or he can try to drill it out using a left hand drill bit set.

 

I will give it a try, but tomorrow i will be heading to the dealership to see about trading the Lexus is250 I have in for a newer one. I wanted an is350 but haven't lucked out for one yet but oh well the IS250 i am looking at is a really good deal and loaded so hopefully soon i won't be driving the lexus i have now in a week or two. If i don't get it I will try the punch idea and replace all of the allen bolts with regular bolts instead.

 

Use one of those reverse threaded stripped bolt removers.

 

here is what i'm talking about. Work really good on allen bolt