Torque wrench off...thread damage?

I changed my oil yesterday, and when torquing down the drain plug , I felt like I began to feel the threads 'give'. I thought I had the torque wrench set to 30 ft-lbs, but it might have been at 40. I backed off the torque wrench setting, then reset it at 30, loosened and re-tightened the plug.

Any idea how likely it is that a 10 lb-foot over-tightening of the plug will have done actual damage? Since this is a steel pan, I thought it would be OK, but it sure felt like it began to yield.

I'm trying to decide whether I should have a new oil pan ready next time I change the oil...

 

If I had to guess and you din't totally white knuckle the plug in, there was a bit of crud in the threads that you pushed past and once that gave way, it turned easier.

Oil change shops frequently over torque those - my guess is way in excess of 40 ft/lbs. Hard to explain this move, but if you put a regular ratchet on it, grip it with the ratchet head in your hand (so you can;t get too much leverage) and try it and it doesn't move, my guess is you are fine.

If it spins or you see metal in the plug threads the next time you pull it, time to do something. They do make self taping oversize plugs if you want to avoid a new pan. Ask at your parts store and they should be able to set you up.

 

Check the threads on the drain plug. Torque wrenches are only for tightening, use a standard rachet or wrench for breaking nuts and bolts loose. The calibration could be off.

 

The drain plug washer is pretty soft and I'm guessing would take up most of that extra torque. If in doubt, change your oil again though. Last thing you want is that plug to be stripped and loosen enough that you start leaking oil.

 

Yes, standard socket or breaker bar for loosening, torque wrench for tightening. Re-used old gasket, which is (as far as I can tell) rubber coated aluminum. Based on its condition it will need to be replaced next time.

I guess I'll toss a piece of cardboard under the engine and see if I have drips...didn't see anything clinging to the drain plug this morning. I'd rather not have to change out perfectly good Pennzoil Platinum synth...

 

LOL. Yeah you are the first guy ever to strip a drain plug.

Even if you do booger the thread, it ain't a new oil pan, it's a new plug. Any good parts store will have oversize-threaded plugs for common vehicles. They are sometimes labeled +1

AND they have oversize oversize-threaded plugs for the next time you booger the thread. Labeled +2.

Ain't saying how I know, but I swear it's true.

 

I really doubt that you pulled threads at 40 foot lbs of torque.

 

I also doubt 40ftlbs woudl strip the threads.

...on a side note I also changed my oil this weekend. I broke out the torque wrench and set it to 30ftlbs. It was not breaking over. I loosen the plug and just hand tightened. Felt better about it. FYI.

-Al

 

I just use a ratchet with a short extension on it to tighten the plug that makes it very hard to overtighten.
It is not necessary to torque the drain plug, it just needs to be good and snug. If your torque wrench messes up or you have it set wrong with all of that leverage (length of torque wrench) it is very very easy to mess up the drain plug or even worse the oil pan.

 

When torquing such sensitive drain bolts and spark plugs I usually switch over to a torque wrench that measures in inch pounds, I find them more accurate at such low torque values. Some of the ft/lbs torque wrenches aren't too accurate at such low values - especially the ones that their scale don't start until 20 ft lbs or so.

To use inch pounds, take your ft/lbs value and multiply by 12.

Example: 30 ft/lbs * 12 = 360 in/lbs

Maybe a little OCD, but it hasn't failed me yet.

 

If there is a torque value and you know how to use a torque wrench...You can't really mess it up.
And on the same note- If they give a torque value and have the means to use it- Why wouldn't you??


A few folks have mentioned the +1 self tapping drain plugs- They are there for a reason- When folks just tighten them without checking what they are doing- Need a way to fix it.

 

That is exactly the point I was trying to make. You cannot overtighten using a rachet and a short extension, even if you try. If your torque wrench if not accurate, set wrong or just malfunctions you will mess up the threads because of the leverage the length of the torque wrench gives you.
I really appreciate trying to do things right but putting a drain plug in is not rocket science.
At least that has been my experience in my 30 plus years of working on cars, trucks, tractors, race cars, motorcycles and atv's.

 

Hmm... I've never used a torque wrench on an oil drain plug. I always just tighten it and I never put any grunt into it. Never had any problems.

If you believe you have a problem with the threads... get yourself a TAP of the proper size. Run the tap through it and it'll clean out the good threads and cut any burrs that might exist on the old/bad threads.

I highly doubt that torque difference messed the threads up.

 

same here...

 

This is the prime example of complacency- Your 30 years plus is great empirical evidence for your method...Until something does go wrong. THings still fail even if you torque them down properly- but if you do torque/set them properly...you know it's not install error that caused the failure.

It might not be rocket science- but the one time that a drain plug falls out- It'll most likely cost you a few grand- I'd rather spend the 5 mins to make sure I have a calibrated, correctly set torque wrench than 4-5K.

It's your truck...Do what ever you want.

 

I'm in the 30 year crowd too. What if the threads are already on the way out? Recommended torque could ruin them. I'll stick with Jansters method.
I haven't lost one yet but I've seen some pretty buggered up ones.

 

torque wrench on the drain plug? i just do it with my regular ratchet..snug it up..good. done.

i dont use it on spark plugs either.

 

I'm not an auto mechanic but I am a machine operator by trade...so I've put in a few nuts/bolts over the years.

There's a lot to be said about the *FEEL* of putting a bolt into threaded hole. Not everyone knows what to FEEL for. If something doesn't feel right or you get 'resistance' going in - then your gutt reaction should tell you to STOP threading it in further. Remove and inspect.
Some people keep going torqueing....and if you don't stop soon enough, you can bitch up the threads.

One of the main reasons why I don't use torque wrenches initially ...is so I can FEEL the bolt thread into the hole. I like to FEEL things go in smoothly before I torque on them.

THis stuff isn't necessarily something newer or inexperienced people are gonna know to look for.....

 

Concur with an initial hand threading- Plus it goes more efficiently that way. Only the last few turns need any sort of tool.

 

I know you don't know me from Adam, but I'm no beginner at this. I've been turning my own wrenches for about 20 years. The plug was not cross-threaded, it spun in fine by hand until finger tight, and then i used the torque wrench. (When I have a torque spec, I prefer to use it. Estimating using a plain ratchet is for emergency repairs on the side of the road, or tightening fasteners that are no where near their yield limits.)

The engraved marks on my torque wrench are a little hard to distinguish, and it was late at night. I stopped turning shortly beyond where it should have clicked for 30 foot pounds; at worst, it went to 35 or so.

Well, we'll see if there's any apparent damage in about two months when it's time to change the oil again. If it won't seat well at 30 foot pounds, or pulls the threads out...I'll know I screwed it up.