Messing up the spark plug threads on an aluminum block sucks

Depending on the vehicle, it can usually be done without pulling the engine or even removing the heads...Drill and tap, and install a helicoil...Ford 4.6 and 5.4 are bad about that...

ALWAYS START SCREWING IN BY HAND!!!

That's what she said!

Just epoxy that bastard in there and call it a day.

No need to pull the engine.

Spark plugs in the block? Nope, they go in the cylinder head. I suggest you consult a mechanic.

righty tighty lefty loosy.....

As soon as I saw the post I clicked to see if it was an older Ford modular. I've been there!

That's the first thing I thought.....helicoil.

People will practically give you their vehicle if it blows the plugs out of it, and it can be repaired in a day for a little bit of nothing...

Last Edited by BRIEF on 08/23/2021 10:07 AM

Helicoil. I had to fix my Stang 2 weeks ago. I almost bought a new cylinder head

Last Edited by SuperNowun on 08/23/2021 10:21 AM

Check your gap

A new head will build more pressure than the old one causing an imbalance, possibly...Better you repaired the original

I had this happen in the early 90's with my Dodge 024, which had a 2.0 4 cylinder with aluminum head. We ended up tapping the hole and using a helicoil. I had to use a different sized spark plug. It did run fine after that, once we fixed a vacuum issue with the carburetor. I sold it shortly after and the new owner blew the engine. Dodge 024 was lemon deluxe. I had so much trouble with that car in the short time I owned it.

Last Edited by Freth on 08/23/2021 11:16 AM

happened quite a few times w/ my mini bike in the 80's

those cheapo tap sets really work

they even work on hard steel threads, aluminum is easy

no need to really drill it, as then you would need a plug or something, just rethread, tap it is good enough

the anti freeze compound will keep compression test compression

Be smarter than the plug hole and the spark plugs lol! Seriously, always hand tread a bolt/screw lightly, when you feel resistance, back it out and look carefully you are aligned correctly, reinserting plugs can be very difficult if you have limited experience. Some plugs in old big block muscle cars had to be installed though the wheelhouse of the vehicle. Plus prior idiots may have screwed up the threads. It is an easy fix, or difficult based on your mechanical experience. I have bought, sold, parted out well over 1000+ vehicles, I never had to replace a head, engine because of damaged spark plug threads. We make money on people like you, fixing their mistakes that they give up on without seeking FREE ADVICE. I have fixed vehicles when the seller said it had a BLOWN engine by replacing a spark plug that backed out, or a rocker arm that became loose...and ran perfectly. You are smart to ask...

yup, and dont forget the loctite.
Edit:
On the helicoil, for gods sake dont put it on the plug!

By going left first, you will feel the plug seat. Then you can slowly begin to tighten it. If you feel resistance..stop, rinse, repeat.

That's why I wont buy ford!!

A repair shop fucked mine up and I had to replace it with a solid thread insert.

Call the Thread Doctor tell him Matt sent you

[link to www.threaddoctor.com (secure)]

Please dont use a helicoil they dont hold to the torque sequencing and then they pull out.

Use a solid metal sleeve like Time Sert.

Loctite prevents the "pull out".
Not trying to get into a pissing contest. I`ve just installed them this way many, many times.

[link to www.henkel-adhesives.com (secure)]

Loctite 266 definitely helps. High heat and high strength. I just had too many helicoils fail since it is just a spring steel. Especially in head bolts and spark plugs. They are great for non torque applications.

I would not buy a new Ford...I have a Ford 6.9 Diesel that I won't part with...

This. Don't take the engine out. IIRC, there is more than one kind of helicoil. Ask the parts guy.