Understand that not everything is written in the manual. They would have stated a wet torque if they were to be oiled or otherwise, if its not stated its a dry torque. Also as a standard mechanical practice, you should tap every bolt hole on something critical anywhere on the vehicle. Crap in the holes leads to undertorque and something falling apart sooner than it should. Again believe who you want but I do this for a living and aircraft mechanics make fun of car mechanics for cutting corners to get the job done.

I dont agree... When servicing an engine you have to go through some serious extra steps to get the oil off of the bolts and the threads in the block.

From a practical standpoint if it was a dry spec it would be a bear to get all of the tapped holes free of residual oil on a valve job or an engine build up.

Same goes for re torque values. Once the engine is assembled some bolts are going to end up wet with oil. If you have some dry and some wet, then you have a very uneven head preload.

IMHO the factory did not address this and its not reasonable to assume its one way or the other.

As a backyard mechanic, i have built my motors with the fasteners lubed with engine oil ( unless using ARP studs). Compared to dry you dont have as large a risk of thread damage.

As an engineer, the correct solution to this issue is to read the bolt grade assume a oil lubricated steel thread into cast iron and make sure your torque spec is within the range of the fasteners clamping capacity.

That should include the stress level change incurred as the aluminum head expands.

Since Frank has put several motors together using lubed threads, its reasonable to assume that the preload he reached is withing the fasteners capability.

A sign that you have a problem is if you get the rotation to torque become non linear, AKA- you get to a certain torque value and for a given rotation you dont get the same increase in torque. When your non torque to yield bolts yield.

Also, on most fasteners, as you use them the friction level drops off. So for a given torque, the clamping load increases with each usage. After 50 or so cycles, this stops happening.

To be reduce preload scatter you need to specify a lot of variables. That's how we got TTY.

Kevin

What?

You said "Understand that not everything is written in the manual."

Then you said "They would have stated a wet torque if they were to be oiled or otherwise, if its not stated its a dry torque."

I also have a problem with this statement "if its not stated its a dry torque"

Where did you learn that? I'm a certified Honda outboard mechanic and never heard of that.

I'm with Frank, maybe I'm just to old to keep up with you young-ens.

Preservative oil...so they don't rust on an warehouse shelf before an unknown future sale date.




Per the U.S. DOT/FAA AC 43.13-1B/2A Sept 98 edition
Acceptable Methods, Techniques, and Practices
Aircraft Inspection, Repair & Alteration
(yes, it may be a version or two old)
Page 7-6, Section 7-40.b



So, every time you fly on an airliner...that is how the fasteners holding the aircraft together are tightened.



This is what I worked on today at work...




The bolt holding the blades on failed in flight. I did not assemble this, but it was done with a new bolt, and a torque driver. Looking at it after the failure, it was obvious there was lubricant on the threads inside the rotor head.

Kind of a leap to apply a spec for an aircraft to an automobile. Perhaps a flying leap? <img src="/forums/images/graemlins/wink.gif" alt="" />

The service manuals for cars are not nearly as rigorous as the service manuals for airplanes.

The most reasonable approach is to look at it as a design engineer and calculate the loading of the fastener. Second guessing what the person who wrote the manual meant is just that ... A guess.

So far real world testing of Franks method has been good. As backyard mechanics, we take the manual as a guide not a bible.

What the factory did can be improved upon and often need to be.

At least you can be confident it's a safe leap though...

Precisely why I don't fly my Monteros.

John B.

Safe as in not getting killed, yes. Safe for your wallet? Not a given.

I keep thinking about those who followed the original specs for rebuilding Mitsubishi engines produced in the '80s...... 72 lb-ft, wasn't it? As the head gasket blew, I can just hear them saying "But I followed the manual exactly". Later (I suspect after consulting dealer mechanics) Mitsubishi engineers realized that more torque was needed and changed the spec to 80 lb-ft.

Then, I'm reminded of Eddy's description of using a torque wrench of which you don't know the calibration accuracy at the setting you're using......... "Going wrong with confidence".

Another thing that changes with rebuilt engines is the little burrs and scratches that you might get when you run a tap into the deck threads. You can (and should) burnish bolt threads on a wheel brush, but there's not a practical way to smooth the deck threads if needed. Will that change torque results? Yes, but how much is a futile guess. A little oil probably helps.

Yes, the oil placed on the black oxide treated bolts is to prevent rust (as is the black oxide) - but it's still oil and is still a lubricant. It's not much - but that's the idea in LIGHTLY oiling the bolt threads - not so much you risk hydro-locking, but just enough to overcome resistance from imperfect threads. The method recommended by Victor Reinz is as good as any.

It's a great world that allows folks to decide for themselves how to do things. And, it's great to have books that attempt to teach the reader how to do things - but sometimes, experience will give a fellow a different view.

Frank

None of Frank's engines ever blew? <img src="/forums/images/graemlins/confused.gif" alt="" /> Just sayin'