BMW R1200R R1150R/T F800 K1200R R1100R/T R1250R RnineT Message Board

jonmaddux makes a good point, if you are a power/airframe mechanic, your name goes on that repair. If the planes crashes and you are at fault your arse is grassed.

But onto more down to earth issues......I haven't used a torque wrench on a spark plug in 30 years. I have developed the "touch". The important thing here, in the case of the BMW's, is that you have a steel plug on an aluminum head. If you overtighten, the threads on the head will be rolled, or worse stripped....Ouch....

The reason for the torque is to insure that the gasket that comes with the plug is crushed.....one way to do it is tighten, remove and look, a little at a time until the gasket is crushed.

If you don't change plugs regularly and haven't tdeveloped the "touch", by all means invest in a torque wrench.........

boxermania wrote:jonmaddux makes a good point, if you are a power/airframe mechanic, your name goes on that repair. If the planes crashes and you are at fault your arse is grassed.

But onto more down to earth issues......I haven't used a torque wrench on a spark plug in 30 years. I have developed the "touch". The important thing here, in the case of the BMW's, is that you have a steel plug on an aluminum head. If you overtighten, the threads on the head will be rolled, or worse stripped....Ouch....

The reason for the torque is to insure that the gasket that comes with the plug is crushed.....one way to do it is tighten, remove and look, a little at a time until the gasket is crushed.

If you don't change plugs regularly and haven't tdeveloped the "touch", by all means invest in a torque wrench.........

Right on Boxer...
I don't think I've ever actually used a torque wrench on a spark plug...it's
all about feel.
It's just that using the cheap oem socket does not give me that feel, not to mention you must dig it out from under the seat, it has no cushion for the plug body (anal, I know ) and the high-tech screwdriver-for-a-handle thing just annoys me....

Just to beat a simple topic into submission:

While working for International Harvester many years ago, we did an experiment. We torqued spark plugs to the value stated by the manufacturer. The values ranged across the board.

Now comes the interesting part. We noticed that just as soon as the plug started to tighten, it was 1/4 of a turn to reach the desired torque. This worked for everyone of the hundred or so we tried. This was going into alloy heads, cast iron heads, alloy with cast inserts, etc. If it was a used plug one would reach the correct torque with 1/8 (half of the 1/4 for those who had Miss Reinwald for math) of a turn.

A & P mechanics have to always be concerned about being in court, we on the other hand do not.

Frank

riceburner wrote:

jonmaddux wrote:What brand of spark plug socket is everyone using for plug changes? My Craftsman 5/8" will not fit in the tunnel (single spark). Too big OD. Wrench in the toolkit can remove a socket but won't let you use a torque wrench for re-install.

BMWRT.com site search talks about a Kobalt/Lowes socket with thinner walls. Any experience?

you shouldn't need a Torque Wrench - in fact, I'd advise STRONGLY against it.

do the spark plug up by hand/fingers as tight as you can (use the toolkit wrench but without anything to add leverage) - then 1 quarter turn more with the toolkit wrench. That's ALL it needs.


HTH.

Here is why you need to use a torque wrench and fresh crush washers (if applicable, e.g. oil drain plug). This is especially true for steel plugs in aluminum holes.

What you are looking at in the above photo is the drain plug and its receptacle in an aluminum oil pan (same setup as in our bikes). The right side shows what used to be the threaded hole in the oil pan but now with the threads pulled out. The left side shows the steel plug, with threads intact, and the aluminum threads that were formerly associated with the aluminum oil pan siting in a neat coil beside the plug.

Cost to repair? About $1K.

Cause? I believe the independent shop that did several oil changes on this vehicle did not use the factory specified torque setting one or more times and probably tried to reuse the crush washer. I can't prove that but their excuse was that the oil was 1 year old and caused the threads to fail. Total BS.

I always wondered what the crush washer does and often considered skimping and reusing the old one. Now I believe that the crush washer yields at the specified torque and by doing so prevents the threads from yielding. Remember the threads in the plug are steel and won't yield before the aluminum.

Mark

That's a scary pic Mark.

Think I'll invest in a torque wrench

mbohn wrote: ...Cost to repair? About $1K......
Mark

Mark,

Don't mean to make you feel bad.
If you helicoiled the hole, it would have been a few bucks.

Paul

HeliCoil site

I have on a few ocassions welded the hole up and re-tapped. This is not easy because there are two things that must happen.....

A) The aluminum must be clean

B) The part must be preheted to ~ 375 F

the good side is that the end result is like new.......

Yep....Helicoils are the answer when you cross the line.

BMWkidd wrote:

mbohn wrote: ...Cost to repair? About $1K......
Mark

Mark,

Don't mean to make you feel bad.
If you helicoiled the hole, it would have been a few bucks.

Paul

HeliCoil site

Paul
I asked the mechanic about that and he said they don't last. Alternative was to take it to the Acura dealer and let them do a more lasting repair. The car is my mother's and I was fighting this thing long distance so my options were limited. Except that she won't be going back to him.
Mark