Head Gaskets Anyone Tried This Method.

[steve56]

Has anyone used the head gasket torquing method demonstrated by Mike Bauer on Youtube. Hes doing it on a ej25 but it should work on ej22 also.

 

Step 1) Using regular Subaru torque sequence, draw all 6 bolts down to just snug on the head.

Step 2) Using regular Subaru torque sequence, torque all 6 bolts to 11ft lbs. Check them a second time to make sure you have achieved 11ft lbs.

Step 3) Using regular Subaru torque sequence, torque bolts one and two to 25 ft  lbs.

Step 4) Using regular Subaru torque sequence, turn All Six bolts 45 degrees twice....your done.

 

This method is if your reusing head bolts, which most people do.

His logic is the standard torque to 22ft lb, then torque to 51ft lb then back off bolts 180 degrees twice is not needed. The reason its not needed is because that procedure is assuming your using new head bolts that need to be stretched.

 

Most people reuse head bolts, so they have already been stretched and cycled thru 100k miles of driving.

[Fairtax4me]

Torque-to-yield head bolts don't stretch until you reach the final torque step.

The whole idea of torque-to-yield bolts is they're designed to be X tensile strength and to stretch once they reach that limit, but then they can be stretched further and still maintain the same clamp force on the head as the other bolts. It ensures that the clamp force is even all across the head.

 

When torqueing a bolt, the clamp load is dependent on how smoothly the bolt turns. If the threads are dirty or have some corrosion in them, such as older engines often do, when you tighten all the bolts to X torque with a torque wrench, they quite often will not all produce the same clamp force on the head. So those extra 90° turns are used in order to get the bolts up to their yield strength. Once they reach that yield, you can turn them quite a bit farther, and it will not increase the clamp force on the head. Turn them too far though, and the center will break. This is why they say not to turn more than 180° total. You CAN turn it more, usually quite a bit more, but the more you turn it, the closer you get to its break point.

 

The back-off step in the Subaru torque sequence is designed to produce even seating of the gasket, and prevent warping the cylinder head. The majority of the force pushing back against the head comes from the center of the gasket between the two cylinders. The two bolts on the center have a slightly higher torque step after that back-off, because they have to seat BOTH fire rings in the center of the gasket, whereas the outer bolts only have to seat the ring closest to them.

This also ensures that the center bolts reach their yield point First, which helps to prevent the head from warping and causing a breach of the fire ring.

 

The fire ring is the hardest part of the gasket to compress. That's where most of the clamp load on the gasket is placed.

The rest of the gasket, oil and coolant passages, really don't need any more clamp force than any other gasket on the engine. There's normally 16lbs of pressure in the cooling system. You can feel that if you've ever opened a radiator cap on a hot engine. It's pretty easy to push against that.

Oil pressure maxes at about 75 psi when its cold, the rest of the time its in the 20-40 psi range, unless you're running at redline all the time.

 

Combustion chamber pressures can be in the thousands when the engine is running, especially on a forced induction engine. The fire ring is responsible for containing that combustion pressure, and contending with the heat of the combustion. Proper seating of the fire ring is the most critical part of installing the head gasket, because if the pressure from the combustion gets past that ring, it will almost instantly carve out a path between the gasket and the block or head surface, which then creates the area where coolant, or sometimes oil, will flow through and into the cylinder when there is no pressure in the cylinder during the other two strokes of the 4 stroke process.

Edited November 1, 2015 by Fairtax4me

[hzimmerman1111]

Nothing like the detail of Sooberoo's post, but I did use Mike Bauer's method on EJ25 rebuild in May '15, 6 Star headgaskets - that same torque pattern with used bolts.  OK at 9K miles for what that's worth. . I take it you are looking for poll numbers in your feedback?  The engine kit I got did come with aftermarket bolts, which I chose not to use.  The reason is feedback from various places and that the aftermarket bolts were all the same vs. Subaru OEM that have the center ones colored differently than the rest.  Many suggestions were for just re-using the head bolts so went that way.

[Fairtax4me]

Speaking of head bolts, and the difference between aftermarket and OEM.

The two center head bolts have a slightly larger washer. Not immediately obvious unless you really pay attention.

 

Aftermarket bolts all have the same size washers, which tend to be smaller than the small washers on the OEM bolts.

Edited November 1, 2015 by Fairtax4me

[steve56]

Thanks for the clear and thorough explanation of the Subaru head torquing process and why its important to follow the service manual on this. I always like to know the reasons behind why certain procedures are called for. When to follow directions and when you have other options, like reusing oem head bolts.

[idosubaru]

others on here, or another forum maybe, have mentioned using one final torque value before rather than the back off procedure.  but i've never done it. 

 

+1 on not using aftermarket head bolts - there's no reason, the bolts are a non-issue on these engines.

[mdjdc]

Why try to use another torque when Subaru calls for a higher final torque.  Just follow the original pattern and you are done in no time at all.  For what it is worth the second phase of torquing is center two to 25 ft- lbs and the outer four to 11ft-lbs  Then you turn each bolt 90degrees in sequence TWICE.  I don't see how two rounds of 45 degrees is going to hold the pressure over the long term.  Personally, I always follow the recommended  torque sequence and use 6 star gaskets.  I have no problems with HG failures.