Camshaft Bearing Cap bolt torque

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On my 1MZFE, installation torque is 12 ft-lbs with threads and bolt heads oiled. I removed just the end cap to apply FIPG as part of replacing the VC gaskets. I didn't measure the removal torque but it sure was a heckuva lot more than 12 ft-lbs. Is it normal for the removal torque to be so much higher than the installation torque? There obviously isn't any threadlocker or rust on the bolts, so why so much extra torque to break them loose?

Should I loosen and re-torque all of the bearing caps or can I just reinstall the end cap? Thanks.
 
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Normal, its from the head of the bolt binding on the bearing cap. Run it an equal distance and they will feel that way again.
 
Originally Posted By: morris
if its in aluminium use anti-seize compound on threads and bottom of bolt head.


Repair Manual says to use oil. Is anti-seize better?
 
I don't recommend using anti-seize. It's frictional properties are different than that of oil, leading to incorrect torque and possibly, stripped threads.
 
Originally Posted By: The_Eric
I don't recommend using anti-seize. It's frictional properties are different than that of oil, leading to incorrect torque and possibly, stripped threads.


Yep, I've never gone wrong following the Factory Service Manual, except once when the Lexus RX300 FSM had the incorrect electrical trouble-shooting specs for the IACV. I bought a new IACV unnecessarily but Lexus reimbursed me when I pointed out the error.
 
Removal will be higher than the tightening torque.

When working on Japanese bikes and cars over the years, I have found that the parts will do their job well, but do not over stress or over tighten them!
 
Originally Posted By: mechtech2
Removal will be higher than the tightening torque.

When working on Japanese bikes and cars over the years, I have found that the parts will do their job well, but do not over stress or over tighten them!


Yep. I double-checked my torque wrench calibration to make sure they get exactly 12 ft-lbs.
 
weather or not you use anti-seize compound you have to be able to tell if its getting to tight no mater what is on the threads. i know you know how to do that.
 
Originally Posted By: morris
... you have to be able to tell if its getting to tight ...


Not sure what you mean here. You mean make sure I don't exceed the torque spec?
 
If the parts are specially lubed, torque is much less. 20-30% less.
Put moly on the threads of small fasterners, and they will strip before final tq. is achieved.
 
Originally Posted By: mechtech2
If the parts are specially lubed, torque is much less. 20-30% less.
Put moly on the threads of small fasterners, and they will strip before final tq. is achieved.


The FSM says to lube the threads and bolt head with oil. I assume they mean regular motor oil or they would have been more specific.
 
Originally Posted By: morris
weather or not you use anti-seize compound you have to be able to tell if its getting to tight no mater what is on the threads. i know you know how to do that.


morris, I think I now know what you mean. I tried torqueing these bolts with my 1/2" drive torque wrench. I calibrated it at the spec so that wasn't the problem but I am going to retry when my 20-200 in-lb wrench gets here tomorrow. With the olied bolts, seems like you turn and turn and turn without getting the click. Then I stopped for a few seconds because I am concerned about over-torqueing. Then I put the wrench on the bolt and it immediately clicks loud and clear. I think what happens is the oil/lube get squeezed out while you torque so you don't get a linear response. This is also why (as another poster pointed out) that it takes so much extra torque to remove the bolt. I read that lubed bolts take 25% less torque to get the same tension. It is interesting to see how much of the torque is lost to friction in the threads and bolt head. Takes alot of practice and technique.
 
what are you doing with 1/2 inch drive wrench for such a low torque??? Torque wrenches are NOT supposed to be used at their lower end. First 20% is completely useless.

Get 1/4 inch torque wrench when you need to tighten up to 20-25 ft-lb.
 
If the FSM says lube the thread with oil they mean engine oil.
Use an in-lb torque and tighten in 3 steps.
Torque all to 50 in-lb following the correct torque sequence, the go over them to 100 in-lb and finally 132 in-lb (11 ft·lb)

The three step processes probably isn't mentioned in the FSM but it is accepted method causing less initial stain on the bolts that are under pressure of the valve springs.
It is also the accepted method on TTY bolts by slow incremental stretching the bolts.

If you used a 1/2 torque wrench you may have already ruined the threads on bolts that didn't appear to tighten.
A 1/4 inch tool is the correct tool for this job.
 
Originally Posted By: Vikas
what are you doing with 1/2 inch drive wrench for such a low torque??? Torque wrenches are NOT supposed to be used at their lower end. First 20% is completely useless.

Get 1/4 inch torque wrench when you need to tighten up to 20-25 ft-lb.


Fedex tracking says it will be here tomorrow. Why is the first 20% useless? Do you mean the calibration will be unreliable or it will not be repeatable from bolt to bolt? I calibrated it by hanging a known weight, even allowing for the weight of the wrench itself. It was only 1 ft-lb off. I was getting a sharp click at 11 ft-lbs when I knew I had 12 ft-lbs on the wrench.
 
Was that 1/2 inch or 3/8 inch? I was not aware of any 1/2 torque wrench having 11 ft-lb marking on it. In general torque wrenches are only to be used between 20%-100% of their scale. What gets confusing is that some manufacturer will "eat" that 20% themselves and will NOT show 0-20%. In that case, manufacturer has already accounted for the inherent inaccuracy at the bottom of the scale by removing the bottom portion of the scale.

Since you actually did the calibration yourself, you are better than the 99% of the users who never bother with that! Please do similar calibration with the new one even if it is a Snap-On!

- Vikas
 
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