Might have a cross-threaded plug

Post by **jtp** » 24 Jan 2018, 10:38

Today’s supposed to be get the wagon back on the road day. Hadn’t swapped out the plugs yet so I just went to take them out. Previous owner had them done at 100K it’s now at 141K, car needs plugs.

They all came out as expected except the #4 cylinder. I turned probably 1 1/2 rotations to he left, it felt like it was snugging up as opposed to breaking free. I was just moving down the line taking them out so it wasn’t a lefty righty mix up though I did double check that.

I stopped immediately and called my brother who works on cars full-time and is a darn good mechanic. He said try to tighten it back up a touch and then take it out again. It feels like it’s getting tighter either way I go now.

He’s gonna come look at it after work to verify my diagnosis that this thing is cross threaded.

If I’m right I’ll probably leave it as is, put the other plugs in and drive it to the local Indy Volvo guy.

I know if you take that cam cover off you’re in for a world of hurt.

Then after I’m down another thousand plus on this thing I’m gonna drive to the previous owner’s mechanic, kick him in the balls, and drive back home.

Not really but that would be funny and he’d deserve it.

Post by **abscate** » 24 Jan 2018, 10:57

Get some oil down into that plug hole - it isnt that big a deal to fix a cross threaded plug on an AL head.

Post by **scot850** » 24 Jan 2018, 11:10

When these plugs sit in the block for a long time they get very tight to remove. I have a project V70 that took me about 30 minutes to get one plug out as it was so tight. As suggested I wound it out a little until it started to bind, then sprayed low penetrating oil down the spark plug recess, tightened the plug all the way and then kept on repeating and each time I loosened the plug I wound on it a little harder and it eventually came out. It is a pain, but slow and steady will most likely get you the plug out without damage to the head. I then use a soft cotton lint free cloth and a long screw driver with the cloth over the end soaked in penetrating oil and carefully wind it in and out of the plug threads in each cylinder to remove build up in the threads.

Finally when inserting the new plugs I always use spark plug thread grease to prevent this happening again.

Good Luck!

Neil.

Post by **jtp** » 24 Jan 2018, 11:28

Got it. Was reading some old posts I see the penetrating oil, back and forth real slow has worked. Putting some penetrating oil in there now and then I’ll take it from there tonight after I run some errands (in another car).

2 different type of plugs appear to have been in there and the non-matching plug was a chore to remove but came out. I’m betting that one and this one have been in there for a lot longer than the 40K I was thinking based on the maintenance records I got with the car.

I’ll report back, thanks as always guys!

Post by **jtp** » 24 Jan 2018, 17:25

Yup, worked like a charm. You guys are awesome.

I turned the engine over twice with no plugs in to get the PB blaster out of the cylinder and it didn’t seem to get that much out.

I’ll trickle charge it and try tomorrow night after work. And when I start it back up run it and then change the oil, I put sea foam in all the cylinders since I gotta do an oil change anyway once I get the liquid out of the cylinders.

Post by **abscate** » 24 Jan 2018, 19:09

Outstanding red team , get you a case of beer for that one...

Post by **rspi** » 25 Jan 2018, 09:11

I have seen aftermarket plugs jam in the head as well. I guess the threads are just a little different which causes the problem. Will people EVER stop using after market parts that can cause harm?

Post by **scot850** » 25 Jan 2018, 10:18

Unfortunately we know that answer! We all like bargains and sometimes the wallet rules the head!

Neil.