Hi again, I hope you are all well...

I just installed a new "Elring" head gasket on my B21F. The head has been bolted down to the proper torque of 110 lbs/foot (feet ?)

The manufacturer mentions the head gasket needs a 30 minutes "relaxation" time before proceeding to loosening and retorquing each bolt in turn.

Is that 30 minutes simply from the moment the head has been bolted/torqued on or does it imply running the engine for 30 minutes moreover?

Many thanks...

M. Aaro of Unitek would have you run the car for 30 minutes, shut it off and loosen each bolt in turn and retighten to the correct torque (I use the 90 degree past final torque) and observe the bolt has turned more than the first time. Do the full operation one bolt at a time. He feels that two or three cycles of this will not hurt and ensure full seating of any head gasket. I have done heads (mostly turbo) both with the heat cycle relaxation and without and had good luck every time. I do think there might be merit to the cycling though after talking with him.

Thanks Rhaire,

my bolts are the old style "hex" bolts, not the "torque to yield".

I will go for the "heat relaxation" procedure.

I really appreciate your quick and helpfull reply.

The older bolts are specced to be retightened, the newer ones are angle tightened first time and left alone.

Spec (according to Haynes) is to warm up the engine until operating temperature has been reached, then let it cool for 30 minutes and retighten. Personally, I've parted out enough engines and have plenty of new style bolts that on the rare occasion that I have to do anything to an "old style" engine I just replace the bolts with new styles and be done with it. No more mucking about retightening.

Bram

Thanks for your input, Bram.

I have a few used sets of the "new style" bolts as well. I thought I would use the "old style" to save myself the trouble of having to measure the "torque to yield " bolts for overstretching. Maybe I'll go for those the next time though.

Pierre the torque value you quote seems to be a bit high - I believe they are 80 ft/lbs or 11.5 metre/kgs, which is the unit I have to use with my torque wrench.
I have never retightened the early style bolts in twenty years of working on these engines. Never had a failure. The factory never retightened them, so I figured why bother? The later style are certainly set and forget.

You are right, Rhys, 110 ft/lbs would have been too high.

Luckily for me, I meant 110 newton-meters = approx 83 ft/lbs.

I think, judging from yours and from Rhaire's experience, that I might leave the bolts alone now.

Thanks...

That makes sense Pierre. Glad to hear that's what it was.