Torque

[tjandoverguy]

what is the torque on the head bolts of a Yanmar 3gm30 and is there a sequence

also the do the springs on the drive plate face the engine or the transmission

[StuM]

Page 2 -16R of the service manual tells you. You can download a PDF copy (14MB) from

https://data2.manualslib.com/pdf4/80...2f&take=binary

Note, it says download says 1GM10, but the manual cover 1GM10,2GM20 and 3GM30.
.

[HankOnthewater]

You can download from here safely:
https://www.manualslib.com/manual/79...age=458#manual
torque for cylinder head is 32.5 ft-lb
you find that on page 459
this manual manual covers 1, 2 and 3 GM engines

edit: I see that StuM beat me to it
edit2: I see that above diagram shows different torque values than it shows on the manual I mentioned. So please check what is correct.

[StuM]

Originally Posted by HankOnthewater

You can download from here safely:
https://www.manualslib.com/manual/79...age=458#manual
torque for cylinder head is 32.5 ft-lb
you find that on page 459
this manual manual covers 1, 2 and 3 GM engines

edit: I see that StuM beat me to it
edit2: I see that above diagram shows different torque values than it shows on the manual I mentioned. So please check what is correct.

Looks like you read the wrong line. They agree. Both show 12.0 kgf-m for the M12s and 3.0 kgf-m for the M8s.
Your figure is for the Exhaust manifold nuts.

[Captsteve53]

When torquing down head bolts a couple of additional points to note

1) Always put few drops of oil on the threads and under the bolt head
2) Cylinder bolts should be torqued in three steps (not just tightened in one movement), the manual should provide the correct 3 step value torques to get to the final movement and final torgue,
3) Make sure cylinder head surfaces are clean and dry(No Grease/No oil/No sealant

Cheers Steve

Cheers Steve

[StuM]

Originally Posted by Captsteve53

When torquing down head bolts a couple of additional points to note

1) Always put few drops of oil on the threads and under the bolt head
2) Cylinder bolts should be torqued in three steps (not just tightened in one movement), the manual should provide the correct 3 step value torques to get to the final movement and final torgue,
3) Make sure cylinder head surfaces are clean and dry(No Grease/No oil/No sealant

Cheers Steve

Cheers Steve

See the attachment in my post above. It gives the sequence and the 3 step values.

[Captsteve53]

Now regarding your drive plate plate, I would have said 90% of them have the raised section facing the transmission, BUT in these pictures it would seem Im wrong!, This is an attempt to remove the drive plate as it was stuck in the flywheel, if you look at the picture after removal it's obvious from the non rusted side it goes raised flange/springs down into the Fly wheel, also it seem's obvious as the fly wheel is deeply recessed to accept the raised portion of the drive plate,

Most flywheels are basically flat so the drive plate can only fit one way(with the raised section/springs to the transmission, but not the 3GM

The very helpful manual states place the drive plate with the writing fly wheel downto the flywheel!!!

Cheers Steve

[jimbunyard]

Follow the service manual for lubricating or not lubricating (or sealing) head bolts.
It is very important that the head bolt holes are uniformly clean. Most 'official' mechanics will tell you to use a thread chaser, but I've always just used the appropriately sized tap, followed by compressed air. You should be able to screw the bolts all the way in by hand (or nuts all the way on, if you have head studs), but for ensured uniformity, I prefer the tap...