All,

There is an interesting post in the "Beneath the Bonnet" forum on NAM.com about a spark plug apparently popping out of the cylinder head: "Help! I just blew out my no. 3 plug". Randy Webb just posted on his own website a recommendation that people check their spark plug tightness based on his experience of some plugs loosening. I bring this spark plug issue to this particular forum because most of us are making spark plug changes in search of improved engine reliability and performance and should heed the experience of others.

Last year I was testing Iridium and surface gap plugs and at one of the changes I found a plug that was loose and probably leaking. I wasn't proud of that lapse and it was my little secret until today. The above posts got me wondering if my experience last year was an isolated incident or whether I could be making a systematic error with my plug tightening practices. I had been tightening the plugs in the usual manner: tightening new plugs until I could feel gasket contact plus 1/4 to 1/3 additional turn. I also lightly lubricated the plug threads with Never Seize. It is easier to feel gasket contact when the threads function smoothly, with reduced friction. With already compressed plug gaskets on used plugs, I'd only tighten the plug 1/8 additional turn.

Tonight I checked the tightness of the new plugs with my torque wrench. All of the plugs had been installed to 10 ft-lbs of torque, the recommended value being 18-21 ft-lbs. My installation practice resulted in consistent but definitely too low torque values. A quick readjustment of the torque wrench to the 20 ft-lbs setting and about 1/4 turn of additional rotation brought all the plugs smoothly to a more correct torque of 20 ft-lbs.

I don't know how common plug looseness and leaking is, but I suspect that loose plugs are a more common problem than I might have imagined previously. I am going to take more care to torque my plugs in the future and not rely on techniques that are more prone to error. The MINI plugs are easily accessible and make torque measurements easy.

Regards,

John Petrich in Seattle

 

Installing plugs is definitely a job for a torque wrench. If anyone is planning on doing much of anything themselves, a torque wrench should be bought right along with your first mechanic's set of wrenches and ratchet drivers.

I'm waiting for my Denso Iridium plugs to arrive from Randy, and can't wait to put my torque wrench to good use.

 

That's the way I learned to do it. On my way to the garage.

 

I torqued my Denso IK22's to the recommended 21lb-ft in a cold head, and a few months later, I checked them again, to find my #1 plug backed out about a half turn from torqued, and had visible blow-by Needless to say, me being cautious, put the stock plugs back in. I'm not sure if it's the threads on the Denso's or the crush washer, but I don't plan on finding out either. Better to error on the side of caution than not.

 

Anyone have the TIS with the official BWM sparkplug replacement procedure?

 

Yes,

It is to torque cold at 21 ft/lbs.

Just as a side, I have seen this issue from cars straight from the factory, as well as the Bosch, Accell, and Denso plugs. I am waiting to hear from a good source on the issue and what might be causing it.

Moral of the story - get a torque wrench (a good one!), and chekc your plugs every so often. I might be conservative, but it seems like cheap insurance to me.

Hope that helps!

Randy

 

1 about 6. The rest 12-15. Not anymore.

 

>>Anyone have the TIS with the official BWM sparkplug replacement procedure?
27nm.

 

Thanks Randy. As always, good information. Where would we be without guys like you to help keep us riff raff from bouncing off the walls

Keep up the good work!

 

>>>>Anyone have the TIS with the official BWM sparkplug replacement procedure?
>>27nm.

27 Nm converts to 19.911 ft/lbs

We must have two different TIS versions - mine says 28 Nm! We found the reason there have been some loose !

Disclaimer: That's a joke - the 1 Nm wouldn't make a lick of difference

Randy

_________________

Click the pic to enter the world of Webb Motorsports!




This still ain't no disco!

 

I'd like to hear from more people on the spark plug issue. If this is a widespread occurrence even with stock plugs, it may be a head warranty issue.

For future protection I will check the torque on the plugs regularly. What do you consider a good enough torque wrench?- ovbviously, the dial it in on the handle type with a suitable range and not the type with the needle and gauge, but are you talking about the $160 model or is the $60 version OK?

 

I checked yesterday and the first one was a 1/4 turn loose. The rest were ok but I will check at oil change intervals from now on.
Dan

 

I've found the Sears Craftsman "click-click" type works great.

 

Just changed mine to the NGK V-power ZFR7F (equivalent to the Denso IK22s, I just dont like Densos). Didn't notice any loose stock plugs, but I will try the torque on mine later today to check.

 

>>Just changed mine to the NGK V-power ZFR7F (equivalent to the Denso IK22s, I just dont like Densos). Didn't notice any loose stock plugs, but I will try the torque on mine later today to check. <<

2Cool - Sure those NGK's are legal in STX? Better check with GoWest.

 

I have a torque wrench, but an unsure how to "check" torque on existing other than staring at a 1Ft-Lb setting and checking the plug, then adding a Ft-Lb each time. Does this sound right?

 

lol... say, have you got a can of gas I can toss on this fire?




Luckily sparkplugs are considered "free" mod items by the SCCA....

 

>>I've found the Sears Craftsman "click-click" type works great.
There are essentially two Craftsman "click-click" models for each of the 3/8 or 1/2 drives. Is the $60 model sufficient or is the $160 model recommended?

 

I have the $60 one and it works great.

 

dominicminicoopers,

The best thing to do would be to loosen each plug (with a regular socket wrench, not the torque wrench). Then, reinstall them, tightening to spec (click-click).

 

Or you can go on EBay and get a Snap-on for a little more.

 

I have this "digital" Craftsman Torque Wrench. 3/8 drive, $89.99



I went down to Sears today with my crusty old 3/8 inch ratchet along with a 4" extension that had become jammed onto my spark plug socket. I showed the salesman how the ratchet mechanism was about to give up and the frozen extension and socket, and he asked me to simply go and get new ones from the shelf!

I sure do love that Lifetime Warranty! I don't expect every Craftsman tool to last forever, but it is great to be able to go and get shiny new tools when you finally kill one of them!

 

What about if you have used a little antiseize? I've seen some posts that suggest that torque should be half of recommended dry setting ie: 21 ft/lbs dry = 11 ft/lbs with antiseize... 11 ft/lbs just seems way too little. Suggestions???

 

What... no one has any input as to what torque for spark plugs with anti-seize?

 

>>What... no one has any input as to what torque for spark plugs with anti-seize?<<

You are kidding, no?