Cylinder Head Nut Torque

[TyeGuy]

I am attempting to check my valve clearance adjustments on my 78' GS550 and my manual states to torque the 12 Cylinder head nuts to the torque setting listed in Table 4 of my manual before checking clearances. However, the Torque Specs in Table 4 doesn't show any torque settings for cylinder head nuts, nor the cam cover bolts. Can someone please tell me what ft-lbs of torque the 12mm cylinder head nuts and 10mm cam cover bolts get?

Also, another manual I found online says to "tighten the twelve 8mm nuts", but my cylinder head nuts are definitely 12mm.

 

[Nessism]

The factory manual has the spec in a couple of places. Engine section page 55 for example (16.5-19.5 ft-lbs) and again on page 147 under Tightening Torque. Before you try to tighten these nuts you need to break them loose by turning them backwards. Once they turn back, torque to tighten. Regarding bolt size, the rating is attached to the thread diameter, not the head size.

Good luck

 

[Guest]

pro tip, when you find the torque table, print it out and tack it to the wall of the garage....

 

[roeme]

pro tip, when you find the torque table, print it out and tack it to the wall of the garage....

Seconded. Quite handy.

 

[hannibal]

The factory manual has the spec in a couple of places. Engine section page 55 for example (16.5-19.5 ft-lbs) and again on page 147 under Tightening Torque. Before you try to tighten these nuts you need to break them loose by turning them backwards. Once they turn back, torque to tighten. Regarding bolt size, the rating is attached to the thread diameter, not the head size.

Good luck

Perhaps a silly question, but do you break all of the cylinder head bolts loose, then re-tighten them in the order stated in the manual?

Or do you go in the order in the manual and break each one loose and re-tighten?

 

[Nessism]

Perhaps a silly question, but do you break all of the cylinder head bolts loose, then re-tighten them in the order stated in the manual?

Or do you go in the order in the manual and break each one loose and re-tighten?

One at a time.

 

[chuck hahn]

You are doing valve adjustments. So my question is why the heck are you loosening and retightening any bolts?? Unless you removed the entire top end you shouldn't need to torque the cylinder bolts...or any others for that matter. Have you left out some information the original post???

 

[Nessism]

You are doing valve adjustments. So my question is why the heck are you loosening and retightening any bolts?? Unless you removed the entire top end you shouldn't need to torque the cylinder bolts...or any others for that matter. Have you left out some information the original post???

Read your service manual chuck. Torquing the head nuts are part of normal maintenance. If more people did it there would be a lot less head/base gasket leaks.

 

[2BRacing]

Read your service manual chuck. Torquing the head nuts are part of normal maintenance. If more people did it there would be a lot less head/base gasket leaks.

^ +1 Very true. I was guilty of NEVER re-torqueing the head nuts since I bought my 850 new in 1981. Cylinder head oil leak developed 2 years ago at about 40 000 km. After re-torqueing the head nuts (I marked the original position of the nuts, and after re-torqueing, some of them had turned further than before) the leak was gone.

Thing is, you cannot get at all the head nuts when the valve cover is still on. So the ideal time to check them is when you have the valve cover off to do valve adjustments.

 

[chuck hahn]

Ive read that they get rechecked after the break in but don't recall anything after that.

 

[Nessism]

Ive read that they get rechecked after the break in but don't recall anything after that.

From the FSM...

 

[Fjbj40]

Chuck believes anybody that reads a manual is a quack......

 

[Nessism]

Chuck believes anybody that reads a manual is a quack......

In his defense the manual does say to change the brake hoses every two years and we all know that's hooey. Torquing the head isn't though.