Angle Torque question....

[ScCoghill]

My mercruiser factory repair manual calls for first pass torque with a regular torque wrench and then angle torquing. What is this angle torque deal? By the way, for those of you who helped me diagnois my 5.7 mercrusier water in oil problem, the block was cracked in the same place on both sides. Started at a water jacket hole from block to head and contiuned down into the lifter valley.<br />Angle torque anyone???<br />VR,<br />Scott

 

[Alumarine]

Re: Angle Torque question....

Here's a picture of a torque angle took from Snap On.<br /><br /> http://buy1.snapon.com/catalog/item...0&group_ID=980&store=snapon-store&dir=catalog

 

[Dunaruna]

Re: Angle Torque question....

Head bolts stretch, up to a certain point (called the plastic range), they will return to thier original length. Once past the plastic range, they stay stretched - very bad for headgasket clamping.<br /><br />Angle torquing (known as 'torque to yield') ensures that the bolt does not stretch too far. They are one use only, once loosened, they must be replaced.<br /><br />Also ensure that you begin with spotlessly clean threads and then lightly oiled.<br /><br />Aldo

 

[Don S]

Re: Angle Torque question....

The new "Prefered" method of torquing heads on the newer engines does not specify anywhere that new bolts are needed, or that they are of a one use only type. They are reusable.<br />I have run into engines that are one time, and some even say 3 times max. Others even give specs for length of bolts. All are diesel. <br />Any Chevy 5.0 or 5.7L engine can reuse the bolts.<br />Here is an image from a Mercruiser manual. The Volvo manual says the same thing, only harder to read.<br />Note at the bottom of the specs the "Optional Method"<br /><br />

 

[Dunaruna]

Re: Angle Torque question....

I didn't explain myself correctly. My bad.<br /><br />IF the bolts are taken beyong the plastic range, they are JUNK and must be replaced. Tensioning beyond specifications actually REDUCES the clamping load because the bolt begins to stress and therfore stretch. This is a very common reason for a headgasket failure. <br /><br />Is that better? <br /><br />PS. Torque to yield is not new, in the auto world, we have been doing it since 1980. especially motors with alloy heads.

 

[rodbolt]

Re: Angle Torque question....

angle torque has been around forever I think. some autos require new headbolts. most yam 4 strokes head and crankcase main saddle bolts are NOT reusable. thats also why its reccomended NOT to reuse rodbolts on most modern outboards. we used to tighten rodbolts with a <br />stretch gauge on certain SPS bolts. mercury has some v6 outboards that you torque the headbolts to spec then turn an additional 90*.<br /> its all about how much the bolt and the attaching threads can stretch,remain semielastic and still keep the load clamped.<br /> I dont question the design or the engineering I just use the correct service manual and the correct procedure and its rare to have a problem. <br /> its kinda like the old arguement over which works better head bolts or studs. I have raced both and both have advantages and disadvantages but I never saw any failures with either set up.