Spark Plug Issue

[Pomorza]

Lads and Lassies

 

I've been experiencing a random issue when starting the Z in which it will miss on one cylinder or run on 5 for a few minutes. My first thought is ignition. The cap and rotor don't look to bad - though I think I'll replace them anyway here in the future as they're dirt cheap. This morning I went to pull the plugs to see the condition. One though five came out perfeclty simple, four had some pretty narly carbon build up on it (which was red, not sure why). When I got to six it was very difficult to pull out. I'm using basically a screw driver as I usually just finger tighten the plugs and then do about a quarter turn. Number six though just isn't budging, so I stopped. I haven't gone and pulled my rachet set yet as I have a few questions.

 

1. I used antisieze on all the plugs as in the past I've had issue where they've become very stuck. But is it possilbe I cross treaded the number six spark plug hole?

2. What are the chances that the plug will break, the threaded bit anyway) inside the head. I've seen it happen on an old toyota but that plug was rather rusted in there.

3. Can I retap the head with a 14mm tap to "fix" the treads or is this one of those cases where a machine shop needs to do some work on it?

 

Thanks mates

Jan

[siteunseen]

I have a N42 head with a Helicoil in one of the stripped out spark plug holes.  Didn't even notice until I'd rebuilt the motor and my Dad pointed it out.

 

I bet you can get it out with a socket when it's warmed up.  Good luck.

[CEgg11]

I am not an expert, but I didn't know you could remove a sparkplug with a screwdriver.

As for the plug, if you remember the #6 going in easy, then it isn't likely cross threaded.

Good luck!

[Mark Maras]

 Be brave. Take it out with a ratchet. If it doesn't spin free once it is loose, spray some lube at the base of the plug & retighten & loosen a few times to lube the threads. Repeat the procedure to remove the plug. I don't think you'll have much trouble because you used antiseize. Chasing the threads would be a good idea. If you fill the flutes of the tap with grease, it will trap any particles that could fall into the chamber. Also, I always pull the plugs when the engine is cold. There is less chance for damage due to the different exp. & cont. rates of alum. & steel.

[Kurbycar32]

I wonder if the red stuff on the spark plug is burnt coolant, indicating a head gasket leak.  You might want to run a compression check

[SteveJ]

Are you using a lead substitute? Look at the picture of the MMT fouled plug: http://www.classictruckshop.com/clubs/earlyburbs/projects/spark/plugs.htm.

[Zed Head]

 

I've been experiencing a random issue when starting the Z in which it will miss on one cylinder or run on 5 for a few minutes.

 

 four had some pretty narly carbon build up on it (which was red, not sure why). When I got to six it was very difficult to pull out.

 

1. I used antisieze on all the plugs as in the past I've had issue where they've become very stuck. But is it possilbe I cross treaded the number six spark plug hole?

2. What are the chances that the plug will break, the threaded bit anyway) inside the head. I've seen it happen on an old toyota but that plug was rather rusted in there.

3. Can I retap the head with a 14mm tap to "fix" the treads or is this one of those cases where a machine shop needs to do some work on it?

 

How long/how many miles on the plugs?  How red is red?  I get a reddish tint on mine, I've read that various pump gas additives can leave a residue. (Just saw the MMT page.  Same.)

 

I've found that Permatex anti-seize, the stuff in the gray tube, gums up when used on the spark plugs.  Mine were harder to get out than put in.  I don't think it handles the heat well although Permatex says nothing about it on the label.  I quit using it there and just use clean threads and a drop of oil now.

 

I'll bet a clean plug run in and out of the hole will clear the threads, along with a little solvent.  Gasoline is a good one.

[Pomorza]

Hey mates

 

To answer all the questions.

1. By screw driver I mean one with a socket on the end of it (14mm). As I stated above I tend to only go finger tight and then a quarter or so turn using either said driver or a rachet.

2. There was only red on the #4 plug. I have used EFI cleaner (lucas) in the past. I've been running premium fuel in my Z for ages so there is no change there. I also tend to run lean on the freeway (about 15.4 or so on the A/F gauge) as to get better gas mileage which would cause it to run warmer. By red I mean like a dark red, very dark pink color. It was rather hard (carbon deposit) which I cleaned up and regapped the plugs.

3. If I recall correctly, the plugs have maybe 10k on them, I don't have the records on my at the moment but that seems to be about right, or maybe a bit more. When I was installing them #6 was the only one that I actually had to use a rachet on, it wasn't too hard to put in but not nearly as bad as it is now.

4. As for burning coolant. Wouldn't that show up in the exhaust and in the coolant (as in exhuast gasses in the coolant, running hot etc.).

Thanks again

Jan

[Kurbycar32]

 

4. As for burning coolant. Wouldn't that show up in the exhaust and in the coolant (as in exhaust gasses in the coolant, running hot etc.).

Thanks again

Jan

 

If it were bad enough yes but a small leak would give symptoms identical to what you describe.  I would still do a compression test