Front Spark Plug

Hiya,

I've searched the forums to try to help, but some of the threads have been deleted, so I thought I'd try posting - apologies if it has already been covered...

I wanted to change the plugs today - the previous owner did all his own maintenance and according to the schedule shoudl have been replaced 2k ago, but I though I may as well...

Undid the front rad bolt, moved it forward to get access, got a socket onto the plug, and it was very stiff to undo - got it off in the end. Put the new one in, and tightened it up, definately wasn't cross threaded, but, it was staying the same tightness - couldnt get my torque wrench on, but didnt feel too tight. The rear was smooth, and nipped up nicely - but the front was different...

The old plug had quite a lot of crud around the thread - maybe I should have applied some wd40 to the new one???
It runs fine though - but I want to get it right - didnt tighten it too far as obviously didnt want to cross thread it.

What should I do? Leave it? Or take it out, clean it up and lube?

Cheers all.

Billy.

[yorkie_chris]

I use coppaslip on plug threads since watching my mate writhe the head off one in a ford OHV block...

If you do play with it be very careful, heads are expensive!

Originally Posted by yorkie_chris

I use coppaslip on plug threads since watching my mate writhe the head off one in a ford OHV block...

If you do play with it be very careful, heads are expensive!

Good idea - got some coppaslip in the garage - knew it would come in useful!

Does / has anyone else had this problem? or am I just a numpty? Actually I know the answer to the second question...

[Sid Squid]

The plug recess had some crap in it which you've likely just wound down the plug thread, pull the plug out a few turns and with an air line blow out the recess completely, then pull the plug out and check the thread carefully. If there's any damage chuck it away and fit a new one, grease is a good idea but won't counter any crap in the hole.

[yorkie_chris]

You could also try wash the crap out of the threads with WD or whatever, but the last time I tried this it resulted in one impressive backfire even after leaving it overnight to let the solvent evaporate... (not on an SV but was still an engine...)

Originally Posted by Sid Squid

The plug recess had some crap in it which you've likely just wound down the plug thread, pull the plug out a few turns and with an air line blow out the recess completely, then pull the plug out and check the thread carefully. If there's any damage chuck it away and fit a new one, grease is a good idea but won't counter any crap in the hole.

Thanks Sid - havent got an airline, but I'll figure something out.

Just a question tho - how easy is it to strip the thread? When it happens, do you know about it? Is there a crack followed by it turning easier?

Sorry for the novice questions, just want to make sure I do it right.

Thanks.

[yorkie_chris]

If you strip it, it usually follows crossthreading, so it feels tight, then all of a sudden spins as the threads get munched out of the way...
Wind the plugs in by hand to make sure theyre going in properly thats how I've always done it, seems the safest bet.

Also possible to strip by using too much torque, but that takes more effort than the crossthreading...

Originally Posted by yorkie_chris

You could also try wash the crap out of the threads with WD or whatever, but the last time I tried this it resulted in one impressive backfire even after leaving it overnight to let the solvent evaporate... (not on an SV but was still an engine...)

Was thinking of doing that...maybe not now...lol - Worried about crap getting into the cylinder too.

Hope thats the reason for it not nipping up - thought Id really messed up my pride and joy!

Originally Posted by yorkie_chris

If you strip it, it usually follows crossthreading, so it feels tight, then all of a sudden spins as the threads get munched out of the way...
Wind the plugs in by hand to make sure theyre going in properly thats how I've always done it, seems the safest bet.

Also possible to strip by using too much torque, but that takes more effort than the crossthreading...

Don't think Ive managed to cross thread - I was pretty careful at first, and didnt use the ratchet - just by hand.

The other thing is that the cap at the end of the spark plug lead - the one that fits into the cylinder head recess - doesnt seem as deep as the rear cylinder - I think water could easily get in - again pointing to the fact that the plug is prob not in enough - mind you, still runs ok...

[Sid Squid]

Originally Posted by Biker_Billy

Just a question tho - how easy is it to strip the thread? When it happens, do you know about it? Is there a crack followed by it turning easier?

Specifically in the case of a plug, which is steel, (harder), and the cylinder head which is aluminium alloy, (softer), the thread in the head goes first unsurprisingly, which is why it's so important to be careful, if there's ANY resistance to the plug turning by hand until seats, stop immediately and find out why
If the thread truly is stripped then it'll just turn uselessly and not tighten at all, but realistically you should never get to this point - if it's not turning easily you wouldn't continue. Yours doesn't stripped - yet. But there's clearly something amiss, if the thread has some damge now, you'll need to be sure that it's treated very carefully when removing the plugs in future. Very carefully remove it as I said above and make sure it goes in right.