Torquing Drain Plugs w/Crush Washer

[Trav]

Quote:
but it does call into question the use of a torque wrench when you might be using it to the wrong spec anyway!

No not really. Unless otherwise stated torque specs are for clean dry threads, there are charts for the the amount of torque reduction using various thread lubricants.
Manufacturers torque specs take into account the type of plating or coating used by them in their products and factor in the appropriate torque values.

I know some manuals state the oil drain plug torque is for oil lubricated threads but i don't know about this particular engine so its prudent to reduce the toque slightly.

 

[Trav]

We went through a few pages of this silliness a while ago.
Let me get this straight. A click type torque wrench is no better than feel correct?
Didn't you also say that you would have no problem getting on a plane where the mechanic just tightened all the bolts by feel only?

 

[JOD]

Originally Posted By: Trav
We went through a few pages of this silliness a while ago.
Let me get this straight. A click type torque wrench is no better than feel correct?
Didn't you also say that you would have no problem getting on a plane where the mechanic just tightened all the bolts by feel only?


first off, why do you characterize it as "silliness"? Because you personally disagree with it? Umm...OK... That seems like a recipe for just being close-minded. That said, I'll answer your questions.

Read carefully what I wrote: I said it's "about the same". Sometimes it's a little better, sometimes it's a little worse. It depends on a fair number of variables (the fastener in question, the wrench being used are the big variables). But in ALL of the published literature, the difference is small ("operator feel" is normally a little better, but again--not always).

That said, using a torque wrench incorrectly (which is most likely the case here) is probably going to result in a bigger error. That's assuming Critic didn't dry the threads completely or use an OEM crush washer (the thickness and material of the crush washer can dramatically alter the friction torque spec).

Originally Posted By: Trav
Didn't you also say that you would have no problem getting on a plane where the mechanic just tightened all the bolts by feel only?


Again, you're putting words in my mouth. Where did I say that? Without looking, what I imagine I said is that I'd hope to #$%#$ that any important tension-critical joint would be tightened with something a heck of a lot more accurate than a friction-type torque wrench (don't worry, they are). As for the less critical joints, it doesn't matter to me--since it really doesn't matter if they're using operator feel or a clicker-type torque wrench.

Any aerospace fastener that's really important is either tightened with a load-indicating fastener or the joint tension is actually measured--not guesstimated by friction torque.

 

[sunfire]

I've seen youtube videos of people using big 1/2 ratchets, breaker bars, and long torque wrenches. Using something that big and if not careful can cause the socket not to align properly with the bolt. Which can cause slipping and rounding off.

My arm is a the best drain bolt torque wrench. I just use a small cmans 3/8 ratchet so can't possibly over torque. With the small ratchet I have more control and I can feel how much torque I'm applying. Tight enough so it doesn't leak is what I go for. Drive train bolts are a different story.

 

[mechanicx]

Originally Posted By: Bluestream
The crush washer can be used over many times. My 91 BMW still has the original crush washer and has had over 50 oil changes and never a leak. The owners manual says to use a new one each time...

Once you do enough oil changes you won't need the torque wrench any more. You will "feel" the torque in your hand and know when it right.


I know, I've reused these washers many times. Heck I've seen drain plugs on say a Toyota with the washer completely missing seal up many times lol. It really doesn't take much torque or a new crush washer to ensure the plug doesn't come loose and won't leak. With a new crush washer and 30 ft lbs of torque the drain plug could probably seal 1000 psi lol.

 

[johnsmellsalot]

If I was tightening a drain plug and felt that, I'd probably have a heart attack lol. Anyways, I change the oil on my mom's 2010 Honda Civic. I always use a new crush washer and torque it to 29 ft. lbs. I've never had a stripped drain plug.

 

[Trav]

Your own words!
Originally Posted By: trav
The next time i fly i wouldn't feel to comfortable if the guy repairing the aircraft just went by close enough "feel" tightening the bolts, would you? Honestly.

Originally Posted By: JOD
I'd trust them just about as much with 'operator feel' as with a clicker-type torque wrench--which is to say I wouldn't trust it very much!


Here is the whole thread.

https://bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2322968&page=1

Now you don't even bother giving credit to the guys book your parroting from.
No point in going any further with this thread hijack there are 6 pages of it for anyone who chooses to read it.

 

[Tegger]

None of you people seem to be familiar with Hondas and their notoriously fragile oil pans.

It is CRITICAL on a Honda that the correct torque spec (which happens to be 29 ft-lbs for the Fit) be followed each and every time.

It is CRITICAL that the torque be applied CORRECTLY. That means turning the torque wrench slowly and evenly until the click is felt. No tugging, jerking, or other swift movements. When the click is felt, STOP TURNING THE WRENCH. DO NOT add "just a little bit more". Just STOP.

Failure to torque the bolt in a correct manner WILL result in much-shortened oil pan life, with eventual stripping of the drain-plug threads. It won't happen for a few years, but it will happen.

The fragility of Honda oil pan threads means that it is extremely unwise to re-use the crush-washer. A 50¢ savings on the washer could cost you $300 in repair bills.

As for this discussion of wet-versus-dry threads, it has evidently not occurred to anybody that oil drain-plug threads are ALWAYS WET. ALWAYS. 100% of the time. Honda and ALL other manufacturers assume WET threads for the drain plug. ALWAYS.

 

[sunfire]

I wonder if the quick lubes are all privy to this information.

 

[JOD]

So, an obfuscation of what I wrote, followed by more add hominem snark, with no real content on the issue. I should have followed my instinct and not wasted my time responding to you. It's a mistake I won't make again.

 

[Tegger]

Originally Posted By: sunfire
I wonder if the quick lubes are all privy to this information.

Sure they are. But do their bottom-of-the-food-chain employees care to know it?

 

[mechanicx]

29 ft lbs is for the most part 29 ft lbs as far as the threads see whether a new washer crushes or not. The washer crush is why you felt the torque or "tightness" drop momentarily. It may be easier to overtighten the bolt with reusing the washer though, but overtightening is another matter.

 

[The Critic]

Originally Posted By: rationull
I used a torque wrench and Honda's plain looking aluminum crush washers on every oil change in my Civic and my wife's Mazda3 as well as a friend's (all with aluminum oil pans). I usually snug it with a ratchet and then tighten with a beam style torque wrench to ~30 ft-lbs since that's what the manuals call for. TBH I don't remember feeling this kind of thing -- I just remember the bolts getting tighter pretty evenly.

But, I have felt this on spark plugs, and also on my Subaru which has a steel oil pan and uses a steel (pretty sure anyway) crush washer with a "C" shaped cross section. Where the Honda aluminum washers seem to squeeze flat pretty evenly as you crush them, the steel "C" ones seem to have a definitive point where they crush that you can feel. Made me a little nervous the first time I did it.

What do these washers look like?

I paid $12 for a bag of 100 off eBay. They appear the same as the ones from the dealer, but I have no idea how the hardness compares.

So far, no complaints of leaks from my co-workers or friends.

 

[dishdude]

What is wrong with the built in rubber o-ring like the American cars use? You don't have to crank down on it and worry about stripping the threads, don't have to replace the washer and never have leaks.

 

[mechanicx]

Originally Posted By: dishdude
What is wrong with the built in rubber o-ring like the American cars use? You don't have to crank down on it and worry about stripping the threads, don't have to replace the washer and never have leaks.


Plus they don't fall off into your drain pan or roll aways if the drain plug is dropped.

 

[The Critic]

Originally Posted By: dishdude
What is wrong with the built in rubber o-ring like the American cars use? You don't have to crank down on it and worry about stripping the threads, don't have to replace the washer and never have leaks.


You still need to replace the o-ring on those each time, I had one on my previous Saturn.

If you do not replace the o-ring and crank down on the plug, the metal circle leaves a huge deep groove on the pan. A crush washer works much better as far as preventing this.

 

[antiqueshell]

Tegger, MechanicX, Trav and others I know a lot of people find technical discussions like the one in this tread boring and uninteresting but I LOVE getting deeper into the borderline engineering aspects of such things. I'd like to thank you all for the TREASURE TROVE of technical information you have. Keep up the amazing work, it is literally impossible to find the information you are giving anywhere else except perhaps in a manufacturer database.

 

[rationull]

Originally Posted By: Trav
Quote:
but it does call into question the use of a torque wrench when you might be using it to the wrong spec anyway!

No not really. Unless otherwise stated torque specs are for clean dry threads, there are charts for the the amount of torque reduction using various thread lubricants.


I don't think I was clear -- what I meant was that it's important to understand the conditions the torque spec applies to if you're concerned enough with precision to use a torque wrench in the first place. That seems legitimate to me, and the previous conversation at least brought the point up.


Originally Posted By: Tegger
None of you people seem to be familiar with Hondas and their notoriously fragile oil pans.


Do these "notoriously fragile" oil pans include just the older style steel ones, or the aluminum ones too? The aluminum pan + plug on my Civic didn't seem weak in any way compared to others I've seen. Not disagreeing, just looking for information.

Originally Posted By: The Critic
I paid $12 for a bag of 100 off eBay. They appear the same as the ones from the dealer, but I have no idea how the hardness compares.

So far, no complaints of leaks from my co-workers or friends.


I thought the washers were a good deal at my Honda dealer but that's killer! Those do look pretty similar to the OEM ones. Not sure what to think of the difference in feel.

Originally Posted By: dishdude
What is wrong with the built in rubber o-ring like the American cars use? You don't have to crank down on it and worry about stripping the threads, don't have to replace the washer and never have leaks.


I'm not a fan of the rubber o-rings because in my (admittedly very limited) they seem to be prone to tearing, drying out, and cracking. Single use crush washers seem easier to deal with to me as long as you can keep a good enough supply you don't run out.

 

[demarpaint]

I'm just wondering, if Honda felt that tightening a drain plug was better accomplished by feel, then why do they specify a torque number? Obviously they aren't confident enough in people having the right feel? I know strenght plays in, some people are bigger and stronger, or use longer tools which give more leverage. Others have no clue have much 29 pounds of torque is. I think in the end a torque wrench is a safer bet than feel. JMO

 

[Trav]

Quote:
what I meant was that it's important to understand the conditions the torque spec applies to if you're concerned enough with precision to use a torque wrench in the first place. That seems legitimate to me, and the previous conversation at least brought the point up.



True. If any of the conditions of the spec are unknown then any torque tools (not just clicker type wrenches) accuracy is questionable, even the amount of force generated and felt by hand sans torque wrench is different.
One example i remember is on a CBR1100XX, the FSM stated 35nm for the drain plug and the owners manual stated 29nm.
The FSM was stating a number based on new assembly with dry threads while the owners manual was taking oil on those threads into account.