Should head bolts be lubed or un-lubed? What about thread sealer?

All books call for dry torque unless otherwise specifically stated.

The torque difference between wet and dry can be up to 60% easy I believe.

No engine I have ever owned called for lube.

Mike

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All Toyota factory engine manuals I've ever seen call for a light coat of oil on the bolts, I've never seen them call for thread sealer.

To quote the factory procedure: " Apply a light coating of oil to threads and underside of cylinder heat bolts." This is pretty much standard procedure because lubricated threads have a far more predictable coefficient of friction than dry. I can't at this time think of any engine that calls for installing the head bolts dry, but there may well be. If the bolts go into water passages case sealer is essential. The sealer is a half-assed lubricant. An example would be the ubiquitous Chevy small block. For a couple random samples I looked up a 92 Honda Civic and they called for lubing the head bolt threads but NOT the bolt heads or washers (???). A 4.6 Ford V8 called for lubing the bolt heads but not the threads. I think the mandatory new head bolts come with the threads coated in this case which is common.

Don

Mike Romain wrote in news:4685a9b4$0$26704$ snipped-for-privacy@unlimited.newshosting.com:

All Honda and Toyota engines require all head bolts and any associated washers to be lubricated with engine oil prior to installation and torquing.

Ask me how I know. C'mon, ask me.

I've seen some shop manuals direct you to dip the bolts in engine oil before installing, but I'd certainly believe that some spec it one way and some another. The last engine I actually put together was a Studebaker V-8 though so I wouldn't hazard a guess what standard modern practice is. I'd defer to the FSM, unless you are using aftermarket fasteners like ARP, in which case I'd follow their instructions.

FWIW, ARP fasteners, or at least ARP's VW rod bolts, *are* torqued with lube.

nate

How do you know?

Doc wrote in news:1183169809.551597.153770 @k29g2000hsd.googlegroups.com:

'Cause I READ THE FACTORY SHOP MANUAL. That's how I know.

Did _you_ read the factory shop manual? Do you even have one?

Don wrote in news: snipped-for-privacy@4ax.com:

My factory manual for that car calls for engine oil on the head bolt threads and the "washer contact surface" (yes, singular).

Previous models' factory manuals I have call for you to "apply engine oil to the cylinder head bolts and the washers", without specifying surfaces.

Honda is also very particular about crankshaft bolt lubrication, stating that you should lube the crank bolt threads, but not the part of the bolt that contacts the washer.

I love Honda. Not as weird as Citroen, but getting there...

curious - on my race car (sbc) we just use engine oil on all the head bolts - never had any leaks, but always wondered if I should be using sealer instead. Depending which manual and which mechanic I talk to, I get slightly different answers, but all sbc manuals I've seen specify engine oil and/or sealer on the head bolts.

Ray

We used to use Loctite stud & bearing mount to secure the head bolts into the block on the old air cooled VW's (1960's) cylinder jugs. Used a more removeable loctite to secure the heads to the bolts. Never had one loosen up.

NOTE: This TSRM calls for 58 Ft Lbs of torque. Most people rebuilding/replacing the head gasket say to torque to 72 Ft Lbs.

If you joined the SOGI/ snipped-for-privacy@supra.com group like I suggested when you started this project, bounce a message off them and ask them. There is a LOT of knowledge on the 7M-GE there!

(chuckle)

RTFM. That always seems to work for me.

Chris