torque wrench settings for head bolts?

[timrosser]

Hi everyone,

I had my head gasket replaced about 2 years ago and I'm not sure the bolts have been adjusted since. Do any of you have the torque settings that the bolts should be set too?

Thanks

Tim

[jamesy12345]

Link here or maybe better to look in the Haynes manual for your engine

http://www.matthewsvolvosite.com/forums ... hp?t=55943

[brinkie]

Keep in mind that there two settings, one applies to B18/B20 petrol engines (Renault F3N/F3P/F3R) and one that applies to D19T Diesel engines (Renault F8Q).
Petrol engine cilinder heads need to be adjusted to 30 Nm first, then 70 Nm, then wait 3 mins, slacken, tighten to 20 Nm and finally tighten with 123 +/- 2 degrees (90 - 160 Nm)
All other figures refer to Diesel engines.

[timrosser]

Thanks as always guys, Ive never tried this before and the bolts are in place and the engine runs, just just not as sweetly as before the head gasket blew.

Im guessing that Im wrong to assume that you can just tighten the bolts up to the required tension? The link / haynes assume you start with a fresh bolt and go through the 3 stages of tightening?

Many thanks

Tim

[jamesy12345]

Personally I would slacken the bolts off then just complete the last two steps, in the sequence shown in the link above

[Jay-Kay-Em]

Personally I would slacken the bolts off then just complete the last two steps, in the sequence shown in the link above

I don't recommend that for two reasons :

1) If the water jacket seal is loosened, you may fill a piston with coolant. When you go to start the engine, you could hydraulic lock and bend a con rod.

2) My Haynes manual has a five stage tightening procedure. Stage 5 is an angle, not a torque. When an angle is quoted, they are stretch bolts. Use stretch bolts once and throw them away. The worst case scenario of applying further torque to an already stretch-ed stretch bolt is that it will stretch no more and snap!

I would say do not touch them, and run a compression test if you are in any doubt. If the cylinder head bolts were not doing their thing, compressions would be all over the place, as would oil and coolant levels. If compressions are good (100 psi + similar across all four) then rough running is something else.

[Alan 480]

Personally I would slacken the bolts off then just complete the last two steps, in the sequence shown in the link above

I don't recommend that for two reasons :

1) If the water jacket seal is loosened, you may fill a piston with coolant. When you go to start the engine, you could hydraulic lock and bend a con rod.

2) My Haynes manual has a five stage tightening procedure. Stage 5 is an angle, not a torque. When an angle is quoted, they are stretch bolts. Use stretch bolts once and throw them away. The worst case scenario of applying further torque to an already stretch-ed stretch bolt is that it will stretch no more and snap!

I would say do not touch them, and run a compression test if you are in any doubt. If the cylinder head bolts were not doing their thing, compressions would be all over the place, as would oil and coolant levels. If compressions are good (100 psi + similar across all four) then rough running is something else.

I'd second that, the torque is to be done 'quite soon' after re-build not after a few thousand miles (well thats my opinion) !

[jamesy12345]

Fair do's chaps just a personal thing not a recommendation

At work we do hot bolting when needs must - removing one bolt at a time from a flanged joint while a line is under pressure. In most cases this works great unless the remaining bolts are not in good condition..!

Nice thread below on whether bolts stretch or not, the torques implied above might stretch* an M12 8.8 grade but may not bother a 12.9

http://www.volvo-480-europe.org/forum/v ... 11&t=33483

*exceed elastic limit

[timrosser]

OK Im delegating this to my garage Thanks for the insights though guys, very helpful as always.

Tim