Over torqued head bolts due to faulty torque wrench (not known at the time). Was suspicious so stopped tightening-thinking I well below required torque. Went and bought new torque wrench. I got clicking right away on some bolts and only slight tightening on others which tells me I am approximately at proper torque but not exact with all. I was hoping I could back off slightly and retorque to proper ft lbs without replacing head gasket...or do I need to get new gasket and start over? Thanks in advance, K
Not enough info. Most engines today are made of aluminum. Over torquing ruins the block threads. In addition, modern head bolts are torque stretch. They are not reusable. Over torquing also ruins the head gaskets. The bolts cannot be simply backed off. The gasket has been compressed. Loosening it up will cause leaks now.
If it were on my car or truck and the engine hasn't been started or filled with coolant, I would back 'em up 1/2 turn and come back to correct torque. If your engine uses TTY bolts that have been over tightened, you may as well pull the heads and put in new gaskets and head bolts. If this is a for-pay customer's car your only choice is to replace the gaskets while it is still handy to work on. Otherwise, it is damn near guaranteed to fail at 2:30am next to a 10 foot snow drift 83 miles from home.
It's my own 2000 Honda Odyssey. Head bolts are brand new Honda bolts (all new parts are Honda). They are only slightly overtightened....might I be better off to just leave them? I have one more question regarding removing the water pump If anyone can help it would be much appreciated. For those who may be familiar, the replacement instruction call for using the battery clamp bolt to hold the timing belt auto tensioner. There is the tensioner and then pivot pulley next to it. There is no mention about removing this pivoting pulley but
Your problem with torquing the head bolts is at least a problem with distortion/warpage of aluminum heads and/or cylinder block as well as head bolt failure. If these are TTY, they are spec'd to be very near the yield point. Beyond that, they begine to have reduced clamping force (become weak) or even pop the heads off after the engine is heated a few times. If they are not TTY, they should be back off and correctly set. If they are left over torqued by 10% or more you rish block and head warpage. If they are TTY, you risk bolt failure in addition to warpage problems. One risk you face with excessive torque is over compression of the water and oil passage ferrels and grommets in the head gasket. You should be OK up to about +10% on this. Most of the torque specs allow for tool/operator error up to about 10%. Beyond that, your luck will run out pretty quickly.
One last thing to consider is how much and what kind of lube
- if any - was used on the threads of the bolts and how clean the threads of the holes and bolts were. This will greatly affect torque. Using something like engine oil to lube clean threads when a clean dry thread is spec's will almost certainly result in over torquing or even failure of the bolt or threads. I have seen more than one bolt stretched to look like an hour glass or break before specified torque was reached after applying unspecified or incorrect lube. Double check this procedure before you go any further with the head bolts. A new head gasket may not be worth the risk even on your own vehicle in the Honda.
Only a few pounds? I think it would be ok. You would probally be supprised at the cars running around right now with a lot of miles on them with head bolts that have loosened up.Some of them, it would take hardly any effort at all to remove them. cuhulin
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