Iceman4193

So I was doing a spark plug change and they where seized on there a bit due to an oil leak and some buildup. I got them out but the threads look a bit dirty, but still in good shape.

I don't want to install the new ones in dirty threads so I was wondering about any ways to clean them up without knocking crud into the cylinder?

Carb/brake cleaner? Shop towel on a stick?

Odin

If there's that much crusted up oil, fuel deposits and carbon in the threads you might want to purchase a spark plug thread chaser and clean them up. Part of the deposits could also be dried up anti-seize. I've used both the Wilmar/Performance Tool and Lisle 20020 on my 22re and liked the Lisle better. It won't enlarge the existing threads just clean out and straighten them up.

Pack the chaser cutouts in with grease and lightly coat the chaser threads to catch anything that gets broken loose. If you feel some resistance "slightly" back it out then feed it a little at a time to make sure there isn't a problem. Use common sense and if you suspect a problem back it out and have a look.
When you remove it check for small bits of aluminum in the chaser threads. Clean this out with small picks or a small screwdriver like what is used on eyeglasses. The end of a filed down nail can also work. You don't want to reintroduce those aluminum bits to the threads in the head.
It'll usually take a few passes per hole with the chaser to get it to thread in nice and smooth the whole way.

I'll clean the grease out of the head by spraying a paper towel with electronic contact cleaner and then thread it in and out until the threads are clean.

Iceman4193

Thanks man, I definitely need to clean em out a bit. This truck is just adding more and more to the repair bill lol

Odin

Any more I think when you purchase a used vehicle you have to assume you'll be dumping at least 1,000-1,500 into it fixing neglected and ill repaired areas no matter how much you paid for it. Usually the less you pay for it the more you spend getting it back into safe dependable trustworthy shape.

Odin

Once the threads are clean installing and getting proper torque is a piece of cake.
Often times threads that have deposits in them results in uncertainty of proper torque. Those deposits are causing resistance which creates a false reading.

It can cause loose spark plugs or stripped threads. It's also a good idea to have clean threads so that the plug is properly grounded.

Odin

From NGK: http://ngksparkplugs.com/tech_suppor...x.asp?mode=nml

The spark plug holes must always be cleaned prior to installation, otherwise you may be torquing against dirt or debris and the spark plug may actually end up under-torqued, even though your torque wrench says otherwise. Of course, you should only install spark plugs in a cool engine, because metal expands when it's hot and installation may prove difficult.


Note that the Toyota Factory Service Manual specifies less torque than Denso and NGK does. The Toyota Factory Service Manual only states the Spark Plug Torque at 13 ft-lbf with NEW plugs, there is no turns from seated specification given but both Denso and NGK recommend 1/2 of a turn after seated on an aluminum head.

When installing used 14mm aluminum gasketed spark plugs Denso lists the torque specification at 1/12 of a turn from seated. http://www.globaldenso.com/en/produc...ion/index.html

Also note that neither NGK or Denso recommend using anti seize on the threads.

Iceman4193

So go with the factory torque specs then a 1/2 a turn?

Odin

No.
One or the other.

Iceman4193

Gotcha, thank you.

The thread chaser worked awesome by the way.
I'm happy I didnt muck up the threads because I have never used it before.

Odin

No problem.


I love how you don't need to use a ratchet or plug wrench to run the plug all the way down after it's done.

I hope you already fixed that valve cover leak.

BigAxeJack

Here's a trick I learned to avoid cross-threading spark plugs. Take a six inch piece of vacuum hose or similar and push it over the electrode end of the plug. Use this to start threading the plug, this way you can never bung up the threads in the head.