Head bolt torque sequence

[jimjumper]

When I first installed a new head gasket on my YM240D, I was able to find a written specific sequence of head bolt torquing that was very useful. It showed the 3 torque stages, the specific nut sequence for tightening, and the number of re-torques and at what times. Is there such a thing still out there? My service manual says to install the nuts to 18ft.lbs. and then in the back it shows the final torque to be 130. But no sequence or steps?

 

[CalG]

When I first installed a new head gasket on my YM240D, I was able to find a written specific sequence of head bolt torquing that was very useful. It showed the 3 torque stages, the specific nut sequence for tightening, and the number of re-torques and at what times. Is there such a thing still out there? My service manual says to install the nuts to 18ft.lbs. and then in the back it shows the final torque to be 130. But no sequence or steps?

Find out the real torque value (18 to 130 is quite a large variation) it has to do with stud diameter!

Then, when tightening, go center , out. in three of four equal stages/

i.e/ if the goal is 18 pound feet torque. go 6, 12, 18. Always starting with the center head fasteners and work out alternately.

But find out the true head spec! I got caught on this once using a Haynes manual. Cost me big time!

 

[ponytug]

Find out the real torque value (18 to 130 is quite a large variation) it has to do with stud diameter!

Then, when tightening, go center , out. in three of four equal stages/

i.e/ if the goal is 18 pound feet torque. go 6, 12, 18. Always starting with the center head fasteners and work out alternately.

But find out the true head spec! I got caught on this once using a Haynes manual. Cost me big time!

@jimjumper I also remember reading a Yanmar torque sequence that had something like the usual inside out opposite bolt spiral torque setting, but in three or so sequential rounds of 18, 72, 110 (made up numbers). I'd never seen it before, (or since), but I can see the mechanical sense of it.

So, I suspect your memory is spot on, but I don't have the torque sequence.

All the best,

Peter

 

[winston1]

https://forums.yesterdaystractors.com/threads/torque-specs.2554/

 

[bmaverick]

When I first installed a new head gasket on my YM240D, I was able to find a written specific sequence of head bolt torquing that was very useful. It showed the 3 torque stages, the specific nut sequence for tightening, and the number of re-torques and at what times. Is there such a thing still out there? My service manual says to install the nuts to 18ft.lbs. and then in the back it shows the final torque to be 130. But no sequence or steps?

Yes, we use the JD650 as a guide for the smaller 2-cly machines and the JD850 guide for the 3-cly machines.

Also the YM-1 Service manual.

All are free on the YTOG.