3gm30f rebuild

[Boatyarddog]

Originally Posted by four winds

And I'm wrong yet again.

I think it's time for me to stop posting on the forum.

We are always learning. Hopefully.


Sent from SV Cloud Duster

[Seymore]

Originally Posted by sailorchic34

Might want the google that. Here's one link Perfect Engine Sealing Starts With Proper Head Bolt Use - Engine Builder Magazine

It's pretty standard practice to lube the threads of the head bolts, least with older cast iron blocks. If you don't oil or lube the threads the threads will stick / gaull and will prevent proper head torque.

As someone who learned from my dad and have several rebuilds under her belt including my 3gm30f with over 250 hours on it, I'm pretty sure I'm right.

It's spelled gall.

[Seymore]

Well, OK, let's look at the Yanmar Service Manual for GM Marine Diesel Engines, which should be pretty definitive for us here. The last four pages are packed with fine print, detailing torque settings for all the bolts and pipe threads and things, and the last page is labelled "Packing Supplements and Adhesive Application Points", telling us where to put anti-seize and thread locker. Excerpts....

Cylinder Head Intake and exhaust manifold bolt threads "Screw Lock Super 203M"
Exhaust manifold stud bolt thread "Screw Lock Super 203M"
Rocker arm support stud bolt (Nothing)

Cylinder Block Cylinder head bolt stud (Nothing)

[four winds]

Seymore, yes I started to post that the other day. Knew I wasn't wrong, just Cruisers forum wrong.

Main caps, rod caps, and head bolts... meticulously clean and dry. Unless the manual says otherwise, which it will on occasion.

Before installing the head, run the bolts in by hand to verify. If you can't easily run them in by hand the block threads aren't clean. Wire brush like a bore brush for a firearm, low speed on a drill and some PB Blaster works wonders if someone put something on them last build.

Clean and dry means the only torque inaccuracy will be the calibration or use of the torque wrench.

Thing is, if you lube them and overtorque you'll never know it. Because it won't be much and the bolts can bear it without a problem usually.