Long story short, I have a stripped cylinder head bolt. Its NOT the part that sits in the cylinder block (THANK GOODNESS), its one of the bolts that also has the thread on top to use to secure the valve cover. Its a really strange bolt that serves two purposes: To secure head to block, and to secure valve cover to head with a cap nut. The top is stripped so I cannot secure the valve cover to the head on that corner. I can get a new bolt and nut, no problem, through Acura.

Since the aluminum cylinder head is prone to warping if mishandled or not torqued properly, my question is as such: Is it adviseable to simply remove the old bolt and install the new one (in 3-stages of torquing) WITHOUT removing and re-torquing the rest of the cylinder head bolts? The bolt I am replacing is the second-last one in the torquing sequence (of 16(?) bolts) so my thinking is that I should leave well enough alone and leave the other 15 bolts as they are, and simply replace the stripped one and torque it properly.

Any opinions on this matter?

Cheers,
Eric

 

Just replace the bolt. With that many head bolts, replacing just one won't make any difference to the head or the block. Plus.... part of the reason for a tightening sequence is so that all of the bolts stretch equally (that's right, the bolts stretch and actually, if you were using "used" head bolts, you wouldn't really have to do a 3 stage tightening sequence)(I digress). Get the new bolt and throw it in. Tighten it to the recommended torque figure, back it out (now that it's been strectched), and torqued it in one last time. Make sure the engine is cold and the bolt is dry (any fluid on the bolt can have an effect on the final torque figure). This is all my opinion of course, but based on years of (though years ago...) building high performance engines. I'm pretty sure that some things never change.

 

Thanks old man. I'll have to double-check the service manual but I recall (vaguely) seeing something about ensuring there IS oil on the bolt before inserting. I'll obviously check this as a dry bolt seems more logical.

 

Okay curls, how did you get a stripped bolt?

 

I was re-adjusting valve lash (valve adjustment) and either cross-threaded the cap nut (due to wife asking questions in my man cave while man working), or it was already damaged from when I had the short block replaced and the existing head mated to it. I didn't notice damage, but also didn't check for it initially.

It was a BITCH to get the cap nut off of there so I could remove the valve cover at all (to access the head bolt, which just let the cap nut spin freely). Had to resort to a Dremel tool to cut off the nut.

 

Kinda figured it was found doing a valve job.

Yea,...I know how you feel.

 

Ok well I just figured it out (yeah I was slow yesterday) that the bolt is NOT a head bolt, it's a bolt that holds the cams in place.

http://www.acuraoemparts.com/delray/...All&vinsrch=no

#9 in that diagram.

I figure this is easier to replace than an actual head bolt and I should be good to just remove and replace it. I'll have to double-check the torque specs at home.

 

Definitely check on the lubed bolt. That is something that certainly could be different, especially due to using a steel bolt in an alloy block. That didn't occur to me, but it may provide a chemical barrier between the two dissimilar metals (and I guess I'm curious about what may be recommended to use to coat the bolt).

 

All bolts must be lubricated before torqueing to proper specs. The purpose of torque isn't the torque, it's the load on the bolt. If you don't lubricate the bolt before installing, you'll get far more friction between the bolt and whatever you're screwing it into, resulting in lower load under the same torque applied.
Also, if you've loaded it beyond it's yeild point and stretched it, it's trash. You don't need to torque it twice. That's just extra work. The first time you torque it, it'll stretch under load, but will return to its original shape when the load is removed. Torqueing it a second time stretches it to the same length under load that it was the first time.

 

Are you speaking of the main head bolts, or ALL bolts on a car? I clarified in a later post that the bolt is the one that holds the cam cap to the head, not the head to the block. Would the same lubrication properties apply here even though we're talking about 22N-m (16 lb-ft) of torque instead of much higher amounts required for a head-to-block bolt?

 

It applies to every bolt in existance, not just the ones on a car. You can achieve the same load with a dry bolt, but it takes more torque. If I remember correctly, it's about 1.5 times the torque with a dry bolt to get the same load.

To answer your original question, you'll be fine just replacing that one and not retorqueing them all.

 

This is not true, at least in the case of Hondas. Honda's torques specs assume a clean DRY fastener. The ONLY time you lubricate a fastener before torguing is if specifically directed to in the Service Manual. (Cyl head to block bolts are one example)

 

Ahhh..... to be 27 and know it all. I won't quarrel with anything here, but.... you might discover that time and experience may change your opinion on a few of the concepts mentioned here.