Torquing Head Bolts

[decorn33]

I have read in some recommended maintenance procedure publications that the head bolts should be loosened and re-torqued to manufacturer's specs.  To my knowledge, the heads have never been off my bike, so it may make sense to go through the exercise.  Would I be correct in assuming that the operation would involve only one bolt at a time? Is there a recommended pattern?

[Barry]

There are mixed views on this but I don't risk regular re-torquing. I only do it when setting rocker end clearance which is very infrequent.

One theory goes that the BMW engineers knew best and you should re-torque but it was the BMW engineers that designed an engine where pulled studs are not exactly unheard off.

If you are going to do it slacken one bolt half a turn and re-torque then move around the sequence. Some use a slightly lower than spec torque. I think I chickened out at 23ftlbs last time.

[nhmaf]

+1 what Barry said.   Do not EVER go over 25 ft-lbs/35 N-m on these as the potential is pretty good for pulling a stud, and the repair is a major PITA.

Note that the studs/nuts at locations 1,2,3,4 in Barry's picture also hold the blocks for the rocker arms, so if you mess with those you should recheck your valve clearances, though  some have suggested that if you kept #5 and #6 at full torque while individually slackening and retorquing the others you won't need to.   I'd still just step through them all in that sequence and recheck, myself.

I used to retorque at each valve adjustment, but now I just check that the nuts aren't falling off and don't retorque them all unless the valve clearances have really changed quite a bit, or I'm doing the rocker end clearance thing.

[decorn33]

Very useful Barry, thank you for the information.

[decorn33]

I attended the Airhead Supertech session in Boyertown PA this February and was able to watch Tom Cutter do a demo on setting the rocker arm clearances. My valves are in pretty good shape right now, but I thought about the head bolts in a flash of inspiration. Now I'm thinking about that old saying, "If it ain't broke, don't fix it."

[DanMay]

I just went through the process of installing two helicoils on the top left cylinder of my R65LS.  The studs were stripped out by the previous owner.  I used this rental jig from Cycleworks http://www.cycleworks.net/index.php?main_page=product_info&cPath=29_33_51&products_id=376

It made the job much easier.  Give Dan @ cycleworks a call if you need the tool.   Make sure you mention it is a R65/R45 so he sends the stud spaces for the shorter studs.

And yes, I never go over 25ft lbs on the head torque.  

[Bob_Roller]

It hasn't been mentioned in this thread, but it is recommended to torque the cylinder head nuts in three steps .

Choose whatever final torque value you desire, then tighten them to 1/3 the final torque value, then 2/3's, then your final torque value .

[Mike V]

decorn,

I would torque the heads during final reassembly then again after approximately 600 miles and forget about them.  My (personal) procedure for torqueing any bolt is in stages (2-3) as Bob mentions.  Barry, Bob and Mike have included important information in this thread that should be normal operating procedure and practice.

I sometimes check the head bolt torque by setting my torque wrench 2 to 3 Ft-Lb below the preferred setting and turn in a counterclockwise direction.  If the torque wrench clicks before the nut shows any movement - I leave it alone.  Some may disagree with this practice. If a re-torque is necessary, yes, I loosen the nut a 1/4 to 1/3 turn or so and re-torque, in stages.

I would rather have a leaky head gasket than a pulled cylinder stud.  I just don't think re-torqueing head bolts is necessary as a periodic maintenance procedure.  If they're loosening after 600 miles from initial setting and several heat-cold cycles there's a problem somewhere that needs to be resolved.

Make sure your torque wrench is operating correctly and cared for properly. Checking it is quite easy with a known weight and some minor calculations.  Attached is my personal torque chart, YMMV. Some of the information on my chart is never used such as spark plugs, drain plugs, valve adjustment (tappet) nuts, etc., but included in the chart as a mental marker when doing these by feel.

Obvious caveats apply in regards to my torque values.  I believe they're in substantial agreement with proven standards and practices.  Even though the chart is labeled for my /7, I've applied the same values to my R65 successfully.

[decorn33]

Thank you for your insights Mike. Very helpful.  I particularly liked the idea about setting the wrench 2 - 3 lbs less and testing the tightness on the bolts in place.

I'm not avidly looking for things to do on the bike, I just wanted to check and confirm from others that I was not overlooking a maintenance that was considered vital to long term health of the top end.