Head Bolt Torque Specs

mrbnew · Post by **mrbnew** » Fri Nov 18, 2005 3:18 pm

Does anyone know the torque spec for head bolts on a lanos 1.6 DOHC?

lanos2001 · Post by **lanos2001** » Fri Nov 18, 2005 3:24 pm

off the top of my head i have no idea. actually i never knew.

but if no one answers by tonight i might be able to look it up in my service manual. if i can find it in there. i hate looking threw that thing sometimes.

nick

mrbnew · Post by **mrbnew** » Fri Nov 18, 2005 4:33 pm

I take it you have done it before with using a torque wrench? I would have to think that if I use a torque wrench on anything it should be the cylinder head.

lanos2001 · Post by **lanos2001** » Fri Nov 18, 2005 4:43 pm

nope never done it before on the head what so ever. but i have used a torque wrench before.

nick

tango · Post by **tango** » Mon Nov 21, 2005 12:39 pm

Head bolts torque is

18lb-ft + 60? + 60? + 60? + 10?
or
25Nm + 60? + 60? + 60? + 10?

This means that you tighten initially to 18lb-ft or 25Nm and then wait a few minutes for the bolt to stretch. Then you put on a further 60degrees of turn on it. Wait another few minutes for the bolt to stretch, then add another 60degrees. A third 60degree turn is made after some more stretching time, followed by a final 10degree turn.
They could naturally say put on 35lb-ft in one shot but that would put a lot of pressure on the bolt which might cause it to break. Another thing to note is that GM doesn't recommend the re-use of old bolts because they use materials that are very stretchy and the old bolts are likely to be longer than new ones. If this is the case the above torquing would be insufficient and may cause premature headgasket failure. I've re-used my bolts during my rebuild (taking a chance of sorts) so who am I to tell you not to do it? What does GM know anyway? LOL.

mrbnew · Post by **mrbnew** » Mon Nov 21, 2005 2:24 pm

Thanks alot Tango,

I ordered new bolts along with a new gasket. It's my daily driver so I want to make sure everything is right.

Post by **PrecisionBoost** » Mon Nov 21, 2005 11:47 pm

My manual says to tighten in seqence to 25 N-M ( 18 ft-lb ) then 70 degrees + 70 degrees +30 degrees

That's pretty much the same as what Tango said except that my manual shows different degrees of rotation.

Here is the sequence which must be followed for the 1.6L DOHC...

Perhaps this would make a good "how to remove and install cylinder head on 1.6L DOHC" if someone wants to write it up.... I will also post the sequence for bolt removal in the tech album area in case anyone needs it.

tango · Post by **tango** » Tue Nov 22, 2005 2:16 pm

The difference in rotation depends on which car is in question. The Lacetti manual says +70+70+30, and the Kalos manual says +60+60+60+10. The thing is that they both add up to 190degs of turn. I opted to use the less drastic of the two because smaller turns mean less initial pressure. Either seems to be acceptable though.

Post by **PrecisionBoost** » Tue Nov 22, 2005 5:06 pm

No... I'm quoting from a manual for a 2000 Daewoo Lanos.... not a Lacetti or Kalos.

70+70+30 = 170 not 190

tango · Post by **tango** » Wed Nov 23, 2005 3:01 am

LOL ...OOPS! Bad mathematics there...

mrbnew · Post by **mrbnew** » Mon Nov 28, 2005 5:53 pm

Thanks guys, put my woo back together and she's purring like a kitten.

The only thing I didn't do was put the timing belt cover back on. I broke the bottom half when I was taking it off and can't find a new one. I have noticed from pictures that some people run without them... How bad is it to run without the cover?

MMamdouh · Post by **MMamdouh** » Mon Nov 28, 2005 7:31 pm

the belt will be more exposed to the elements (dust, water, etc) and that might affect its service life... also it is much volunrable to snap (or atleast mess the timing and cause problems) if something as a broken alternator belt got into the timing belt's way.

MMamdouh