I was driving my Burb one day, and suddenly he made a loud “clunk” noise! After that, it wasn’t running well. He started acting as if it had a vacuum leak somewhere in the engine bay. I could barely get it home! My first instinct was to check the condition of my spark plugs. The reason I would check the spark plugs first is 1) Because it’s the cheapest item to replace first. And 2) the easiest to remove.

Easily accessible spark plugs. On my 2001 chevy 6.0L V-8
If you have a repair manual for your vehicle, it gives you a helpful guide, showing you different conditions of the life a spark plug has spent in your engine. Why am I telling you this? It is very helpful to know the condition of the firing chamber between the piston and the head and when the spark plug fires the air and fuel mixture, it can educate you on the condition of your engine so there won’t be any surprises down the road

New plug vs old plug

NEW vs Old

This one may have an oil leak in the piston rings or worn valve guides into the combustion chamber. Causing hard starts, misfiring & hesitation.

This cylinder may need attention sometime.
Now here is a glimpse of the spark plugs I pulled out of my vehicle. Some of my spark plugs look fine, but a couple of them look pretty nasty. I have 3 or 4 of my spark plugs that look in normal condition – brown to grayish-tan color and slight electrode wear is a perfect firing spark plug. Now, the others have a little bit of carbon build-up and oil leaks may be the cause of the leaking valve covers.

looking worn and still being replaced.

Now here we have some oil on the threads and some glazing causing a conductive coating and then misfires at high speeds

Now here we have normal wear this cylinder isn’t too bad

Old looks okay but we’re still replacing it.
I’m going to replace all of the old plugs with new ones. The reason for this is because the truck has a lot of miles on it (over 200,000) I hope this narrows down the search for our misfire. So I can go back to enjoying my Burb again!

Here we have me brushing on some anti-seize on the threads so they won’t be stuck later.

Only use a tiny bit of Anti-seize on the treads.

Use the brush to add a small amount to the treads.
Unfortunately, this did NOT fix it! Now I move on to the next possibility on the list.