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Maxxr6 |
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Age: 43 Posts: 50 Joined: 20th Aug 2005 Ride: ED XR6. XF twin turbo ute. Location: melbourne |
fine dont belive me dont come to me when its does another head gasket
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EDXR8 |
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Maxxr6 wrote: fine dont belive me dont come to me when its does another head gasket
I have done 100,000kms+ on a head gasket that wasn't retorqued and plenty of others I know have too, plus I know tons of guys who run alloy headed supercharged engines pushing 16+psi and none of them retorque either. But if you feel retorquing is usefull then go ahead. |
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tickford_6 |
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Posts: 6449 Joined: 11th Nov 2004 |
Maxxr6 wrote: fine dont belive me dont come to me when its does another head gasket
i've down enough falcon gasket replacments to know what i'm talking about. i've never re-torqued one and never had one come back |
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Maxxr6 |
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Age: 43 Posts: 50 Joined: 20th Aug 2005 Ride: ED XR6. XF twin turbo ute. Location: melbourne |
never had one come back to you, i wont be sending anyone to you to get there head done.
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tickford_6 |
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Posts: 6449 Joined: 11th Nov 2004 |
NO. never had one fail with in the 140 000km life span they seem to have.
oh and you must be the only person on this site that is right. we must all be wrong.. so must be every mechanic in the conutry. and don't worry mate i won't miss the work if you don't send people to me. I've got more then enough coming through the doors but just out of curiosity how dyou supose you re-tension bolt that are done up using the torque to yeild method. all you do is over stretch the bolt and achieve nothing. |
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Maxxr6 |
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Age: 43 Posts: 50 Joined: 20th Aug 2005 Ride: ED XR6. XF twin turbo ute. Location: melbourne |
as i said when you toque the head up it is cold, when it heats up it gets a little softer under the bolt hence the tention drops, when you retention the bolt again it resets everything back to normal, ever heard of a hardness test where thay check how hard the head is with a small steel ball, this checks how hard it is, if it is too soft it will compress to much and not hold enogh tention on the head. try it next time you do one you will see what i mean..
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tickford_6 |
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Posts: 6449 Joined: 11th Nov 2004 |
you still don't get it. you can't re-tension a bolt that has been done up in degrees of rotation because you will not get the right tension.
the whole point of using the degree of rotation method is that you stretch the bolt to yeild stretch it any further and looses tension because you have over streched it. a case in point is what happened when proton/mistubishi changed the head bolts for the 4G1 engine and didn't notify people when they got the new style head bolts. the torque settings where only 90degrees (1/4 turn) different. but it was enough to to over tension the bolts and cause necking. and in some cases breakages. by re-tensioning a bolt done up in degrees you risk the same thing. gasket makers like ACL are not stupid and know what they are talking. they have designed the gaskets to be a once only torque gasket. if you are donig and using a standard extra degree for you dodgy re-tensioning because of a very minor change in the hardness of the head you are causing more problems. the hardness will not change evenly across the head. if you want to use that as your argument you have to test the hardness of the head around every head bolt. but hey you do it your way and we'll all do it the right way |
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Timmeh |
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As for this retorqueing thing doesnt need to be done.
If a retorque was necessary it would be done in differently to what you all are saying. Normally if a retorque is required you would torque a bolt to a lower amount and then to the required final torque specified by who ever engineered the thing in the first place. There are special circumstances in which a retorque is done after the item has been in use but this will be specified. If only one torque is given then that is what is used. And obviously done in a diametric pattern for even spread of the load on whatever it is your doing. |
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Maxxr6 |
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Age: 43 Posts: 50 Joined: 20th Aug 2005 Ride: ED XR6. XF twin turbo ute. Location: melbourne |
if you do a bolt up to a degree of ratation to say 90 and it goes tight when its cold, then it gets hot the bolt stretches a little and the head compresses a little then its not going to have the same tention on it is it! if you have never retentioned a head before how is it possable that you know that im incorect, maybe you try it before you bag it
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tickford_6 |
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Posts: 6449 Joined: 11th Nov 2004 |
Maxxr6 wrote: if you do a bolt up to a degree of ratation to say 90 and it goes tight when its cold, then it gets hot the bolt stretches a little and the head compresses a little then its not going to have the same tention on it is it! if you have never retentioned a head before how is it possable that you know that im incorect, maybe you try it before you bag it
you don't think that is taken in acount when the initial torque setting is worked out by a qualified engineer. give up, the days of re-torqueing are gone. Last edited by tickford_6 on Sun Sep 04, 2005 10:38 pm, edited 1 time in total. |
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EDXR8 |
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Yes the bolt will stretch over a few heat cycles but that is built into the torque specifications, plus head gasket material is far better and more resilient these days allowing single torque gaskets.
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Maxxr6 |
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Age: 43 Posts: 50 Joined: 20th Aug 2005 Ride: ED XR6. XF twin turbo ute. Location: melbourne |
is anyone going to actually try retentioning a head before saying that its wrong?????????
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EDXR8 |
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Maxxr6 wrote: is anyone going to actually try retentioning a head before saying that its wrong?????????
Well I have both felpro and ACL head gaskets sitting here and both say no retorquing is needed, so I guess their techs are wrong. The felpro spill says: "Fel-Pro "PermaTorque®" head gaskets are made with top quality materials and designed to remain resilient so they retain torque. That's why retorquing isn't necessary. But even the best head gasket won't hold and maintain a tight seal if the head bolts have not been properly torqued. The amount of torque that's applied to the bolts as well as the order in which the bolts are tightened determine how the clamping force is distributed across the surface of the gasket. If one area of the gasket is under high clamping force while another area is not, it may allow the gasket to leak at the weakly clamped point. So the head bolts must all be tightened in a specified sequence and equally torqued to a specified value to assure the best possible seal." |
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tickford_6 |
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Posts: 6449 Joined: 11th Nov 2004 |
Maxxr6 wrote: is anyone going to actually try retentioning a head before saying that its wrong?????????
if it's not specified to do so then no. lets face it are you a better sorce of information then the the engineer who designed the gaskets and bolts. i think not |
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Timmeh |
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Retorqueing may break the elastic limit (tensile limit) of the bolt in which case its ability to grow and shrink when heat is applied will be destroyed and may end up with a snapped bolt or leaky head on your car.
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