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Thu Sep 29, 2022 6:51 pm

I'm replacing my spark plugs. The first three came out easily and new ones went in easily. The 4th one was pretty stiff so I gave it some penetrating oil and let it soak, then after a little bit of wiggling back & fourth I was able to get it out. The new one screws in about 4mm and then just keeps turning without going in any further. What's going on?

Thu Sep 29, 2022 7:05 pm

Probably stripped head threads that are now in the old plug threads. Get a Time-Sert kits to install a solid insert.

Start using a quality never seize on the spark plugs from now on.

Thu Sep 29, 2022 7:11 pm

Eric&Barb wrote: Probably stripped head threads that are now in the old plug threads. Get a Time-Sert kits to install a solid insert.

Start using a quality never seize on the spark plugs from now on.

I would try a spark plug thread chaser tool first (inexpensive), before I even thought about installing a solid insert; I used mine on a neighbor's Toyota after he'd fussed for 2 hours trying to thread in one of his plugs.

Anyway, I do run a solid threaded insert on #2 on my 1835cc engine, and it's held and worked fine for over a decade. I didn't use Time-Sert - considered the best - because it needs special install tools. I just used a steel solid threaded insert with red Loctite on the insert's outer threads and never-seize on the spark plug threads.

Thu Sep 29, 2022 7:57 pm

Eric&Barb wrote: Probably stripped head threads that are now in the old plug threads. Get a Time-Sert kits to install a solid insert.

Start using a quality never seize on the spark plugs from now on.
I use a drop of oil from my dipstick to lube the sparkplug threads.
Never had one get stuck, either out or back in.

Hint: If your installing a sparkplug and it feels stiff threading in.
STOP and try again, to align the threads, correctly.
Forcing the sparkplug into the head is, just asking for future trouble.

Thu Sep 29, 2022 9:13 pm

Ugh, this is not good news. Please tell me I can tap in a steel threaded insert while the engine is in situ?

Thu Sep 29, 2022 9:29 pm

Purple Martin wrote: Ugh, this is not good news. Please tell me I can tap in a steel threaded insert while the engine is in situ?
Yes, you can install a solid threaded insert with engine in place - I did.

But I would still try a thread chaser tool first - with engine in place.

https://www.autozone.com/test-scan-and-specialty-t...lsrc=aw.ds

Fri Sep 30, 2022 8:44 am

I had a shop thread for an insert with the engine in place. He used a generous amount of really sticky goop to catch the shavings. Risky, but it worked. Eventually I had to replace the heads but it lasted several years.

Fri Sep 30, 2022 1:17 pm

I used this kit on both 3 and 4 cylinders. Still going strong almost 2 years after the repair. I did have the engine out at that time.

https://www.amazon.com/Heli-Coil-Helicoil-5334-14-Thread-Repair/dp/B0002SRF4O

Fri Sep 30, 2022 1:27 pm

AirHead1966 wrote: I used this kit on both 3 and 4 cylinders. Still going strong almost 2 years after the repair. I did have the engine out at that time.

https://www.amazon.com/Heli-Coil-Helicoil-5334-14-Thread-Repair/dp/B0002SRF4O

Will advise against the Heli-Coil solution. Dealt with way too many of those coming out with the male threads when taking apart again. Since one is supposed to take out plugs for cleaning, inspection, adjustment and if need be replacement every 6,000 miles at every other tune up, there is too much chance of failure that way.

Solid inserts have various ways to be locked into place.

Fri Sep 30, 2022 1:32 pm

Eric&Barb wrote: AirHead1966 wrote: I used this kit on both 3 and 4 cylinders. Still going strong almost 2 years after the repair. I did have the engine out at that time.

https://www.amazon.com/Heli-Coil-Helicoil-5334-14-Thread-Repair/dp/B0002SRF4O

Will advise against the Heli-Coil solution. Dealt with way too many of those coming out with the male threads when taking apart again. Since one is supposed to take out plugs for cleaning, inspection, adjustment and if need be replacement every 6,000 miles at every other tune up, there is too much chance of failure that way.

Solid inserts have various ways to be locked into place.

Agreed, however if you look at what I posted, you will see that it is infact a solid insert. It is not the traditional spring- like Heli Coil.

Fri Sep 30, 2022 2:53 pm

AirHead1966 wrote:
Agreed, however if you look at what I posted, you will see that it is infact a solid insert. It is not the traditional spring- like Heli Coil.

Hard to tell from the one image, and both the title and web address have "Heli-Coil in them.

Fri Sep 30, 2022 3:30 pm

Yep, that is the trademark of the company that makes it. Different product, same company trademark. The thing that I like about this over others like this (I have used it on a number of different vehicles) is that it comes with an anvil that expands the head and wedges the insert in the threaded hole. So you end up with threads, red loctite and the wedged head, all three, holding the insert in the hole.

Sat Oct 01, 2022 3:25 am

I've had a solid insert in #4 for 10+ years. No issues.

Sat Oct 01, 2022 4:37 am

I have both solid inserts and Heli-Coils in my engines for well over 10 years with no problems.

Sat Oct 01, 2022 9:08 am

First did you get the old plug out? And what do the threads looks like? Then if you can see what do the threads in the head look like? You can try running a chaser through the head. Use some oil to lube it and run the chaser. If you’re concerned about shavings then use a vacuum in the thread area and see if you can get any shavings out.