'06 OBW head bolt torquing?

[jonathan909]

Hey, folks, been away for a few months, but now that spring is struggling to break through, I've got some catching up to do.

First in the queue is doing the head gaskets on this NA 2.5 for a friend.  But I'm seeing conflicting information in the various docs I have here.  The Haynes manual (yeah, I know) has a modified procedure from the previous years (i.e. up to 2002) I'm familiar with, but still treats the center bolts differently than the corners.  The FSM, however, just applies the sequence to all six bolts without exceptions for the two middles.

What's the truth?

[edit]  Correction to above:  This FSM still treats the two center bolts differently than the corners; I just missed it because the manual was badly laid out and they bumped the last torquing step to the next page even though they still had room to spare on the first page.

Edited April 25, 2022 by jonathan909

[heartless]

11 hours ago, jonathan909 said:

What's the truth?

the FACTORY service manual, of course - written by Subaru..

honestly, you should just toss that Haynes manual in the trash, i would not trust it for anything more than the most basic of things, like spark plugs, lol

Edited April 23, 2022 by heartless

[jonathan909]

I'm generally wary of the quick, easy, and obvious answer, because there's so often something wrong about it.

Yes, Haynes blows, and moreso with every new edition, it seems.  As things get more complex they just seem to bother less, and that's reflected in the books getting progressively thinner.

But I remain weirded out by what seems like a radical change in the torquing procedure, which I'm not certain is from the right (year) FSM, because it says to pull the rockers before unbolting the head, and that doesn't make any sense to me - it's not necessary.

So can someone actually confirm what the correct torquing procedure is for this engine?

 

Edited April 23, 2022 by jonathan909

[ocei77]

2) Tighten the cylinder head bolts. (1) Apply a coat of engine oil to washers and bolt threads. (2) Tighten all bolts to 29 Nm (3.0 kgf-m, 21.4 ft-lb) in alphabetical sequence. (3) Retighten all bolts to 69 Nm (7.0 kgf-m, 51 ft-lb) in alphabetical sequence. (4) Back off all bolts by 180q in the reverse order of installation, and back them off again by 180q. (5) Tighten all bolts to 49 Nm (5.0 kgf-m, 36 ftlb) in alphabetical sequence. (6) Tighten all bolts by 80 — 90q in alphabetical sequence. (7) Tighten all bolts by 40 — 45q in alphabetical sequence. CAUTION: Do not tighten the bolts more than 45q. (8) Further tighten the bolts (A) and (B) by 40 — 45q

FSM : Index of /Auto/Japan/Subaru (jdmfsm.info)

Basically after you tighten them all to 36 ft lbs. You do the angle tightening of 90 deg.

Then ALL for 45 deg.

Then ONLY the center 2 for an additional 45 deg.

O.

[heartless]

20 hours ago, jonathan909 said:

I'm generally wary of the quick, easy, and obvious answer, because there's so often something wrong about it.

why would you be wary of a factory service manual, written by the manufacturer???
the FSM is NOT an aftermarket thing, nor was it written with general public consumption in mind.. it is written by Subaru for Subaru Techs in authorized Subaru shops.

[el_freddo]

What year/EJ25 engine are we talking about? 

I follow the FSM - on the two EJ251s that I’ve done HGs on following the sequence in the FSM (and using the MLS HGs as per GD’s recommendations, they’re going very well without any issues thus far. 

That part about backing off the head bolts x degrees as referenced by ocei77 will most likely remove all torque or tension you put into the bolts during the steps prior from what I recall. 

All the best with it!

Cheers 

Bennie

[ocei77]

9 hours ago, el_freddo said:

....

That part about backing off the head bolts x degrees as referenced by ocei77 will most likely remove all torque or tension you put into the bolts during the steps prior from what I recall. Bennie

You misread the post. It's not talking about backing off the bolts, but the tightening.

O.

[el_freddo]

8 hours ago, ocei77 said:

You misread the post. It's not talking about backing off the bolts, but the tightening.

O.

Didn’t miss read - just miss represented what I was trying to convey. 

In my experience after loading up the two first rounds of torque settings, when you back off the full 360°s in two rounds of 180°s each, the bolts end up finger tight. 

This might not happen for you for whatever reason but it did for me on two different engines, reusing the head bolts each time. This is what I was trying to say in my original message. 

Cheers 

Bennie

[jonathan909]

On 4/24/2022 at 5:11 AM, heartless said:

why would you be wary of a factory service manual, written by the manufacturer???
the FSM is NOT an aftermarket thing, nor was it written with general public consumption in mind.. it is written by Subaru for Subaru Techs in authorized Subaru shops.

Why?  Because they make mistakes too.  Everyone makes mistakes, including manufacturers, including Subaru.

I can point to an example (that I've explained here a few times over the years) in which Subaru made a mistake in the FSM, and Haynes (trusting them as do you) dutifully reproduced the error in their manual.  So the error propagated, and I discovered it when I compared the two manuals against the engine.  Now, in that case you might argue that the error was not significant, but that's a completely different argument from the one you're making now:  That they're infallible.

[jonathan909]

On 4/24/2022 at 6:35 AM, el_freddo said:

What year/EJ25 engine are we talking about? 

See subject line:  2006

On 4/24/2022 at 6:35 AM, el_freddo said:

That part about backing off the head bolts x degrees as referenced by ocei77 will most likely remove all torque or tension you put into the bolts during the steps prior from what I recall.

Yeah, I've always found all that pre-torque bolt-spinning to be curious, since at the end of it the bolts are all more-or-less finger-tight.  So why bother?  I think it has to be one (or both) of two things:  There may be some pre-compression of the gasket involved; that it gets all the bolts to a "baseline setting" from which they will all behave similarly (in terms of degrees of rotation, and thus evenness of gasket compression) during the actual final torquing steps.

[jonathan909]

On 4/23/2022 at 9:14 AM, ocei77 said:

2) Tighten the cylinder head bolts. (1) Apply a coat of engine oil to washers and bolt threads. (2) Tighten all bolts to 29 Nm (3.0 kgf-m, 21.4 ft-lb) in alphabetical sequence. (3) Retighten all bolts to 69 Nm (7.0 kgf-m, 51 ft-lb) in alphabetical sequence. (4) Back off all bolts by 180q in the reverse order of installation, and back them off again by 180q. (5) Tighten all bolts to 49 Nm (5.0 kgf-m, 36 ftlb) in alphabetical sequence. (6) Tighten all bolts by 80 — 90q in alphabetical sequence. (7) Tighten all bolts by 40 — 45q in alphabetical sequence. CAUTION: Do not tighten the bolts more than 45q. (8) Further tighten the bolts (A) and (B) by 40 — 45q

FSM : Index of /Auto/Japan/Subaru (jdmfsm.info)

Basically after you tighten them all to 36 ft lbs. You do the angle tightening of 90 deg.

Then ALL for 45 deg.

Then ONLY the center 2 for an additional 45 deg.

Believe it or not, this is closer to Haynes' specs than it is to the FSM I have on disk (previously downloaded from jdmfsm.info).  The only difference is in step 5 - where you say 49Nm, Haynes says 42Nm.  Otherwise the procedure is identical.

My copy of the FSM, though is completely different.  Not even close.

I have to sort this out.  I hate crap like this.

Edited April 25, 2022 by jonathan909

[jonathan909]

I think I'm getting a handle on this.  In this version of the FSM:

http://jdmfsm.info/Auto/Japan/Subaru/Legacy_Outback/2006/Legacy 2006/

There are two different torque specs for the H4 - one for the SOHC and the other for the DOHC.  The "H4SO" spec agrees with Haynes.  The "H4DO" specs (there are two of them, probably one for NA, the other turbo) agree with oeci77's numbers (above).  So that discrepancy was simply due to misunderstanding about which engine we're talking about.  Since I pointed out that the FSM says I'm (unnecessarily) supposed to pull the rockers first (which the DOHC doesn't have), I thought it was clear that I was talking about the SOHC.  Sorry for the confusion on that front; I should have been more explicit.

However...

There's another version here as well, for the "USDM Legacy":

http://jdmfsm.info/Auto/Japan/Subaru/Legacy_Outback/2006/USDM Legacy FSM 2006 (BP-BL)/2006 USDM/2 ENGINE SECTION 1/MECHANICAL MEH4SO/20 Cylinder Head.pdf

This is the one that's totally different from the others, and thus (it would seem) the one not to be trusted - despite being an actual official Subaru FSM.  Can someone explain to me which engine it applies to?  I wonder how many other people have (almost) been gotcha'ed by it.

Edited April 25, 2022 by jonathan909

[ocei77]

Can't answer that question, but I have used the specs as I gave them for  2 different SOHC blocks.

One from a 2005 which was Fed emissions, but I have an 05 with the the CA emissions.

Put my heads on it and ran it for at least 30K, but the rings were going bad and I was burning a lot of oil.

Finally got another block with a little over 100K and again put my heads on it. Running like a top, A little over 2k since install.

O.

[jonathan909]

Then, strictly speaking, you've been overtorquing in step 4 by 7Nm (5 ftlb).

Probably not enough to make a difference, but I sure don't have the experience to say so with any authority.

[jonathan909]

On 4/24/2022 at 5:11 AM, heartless said:

why would you be wary of a factory service manual, written by the manufacturer???
the FSM is NOT an aftermarket thing, nor was it written with general public consumption in mind.. it is written by Subaru for Subaru Techs in authorized Subaru shops.

So in light of what I found today, it would be reasonable to add (to my previous answer) that it's hard to know which FSM to trust when there are three different versions of the same story.  In this case we would seem to have narrowed it down to one "most likely correct" answer, but that still leaves us with an "extra" FSM and without a clue which engine it applies to.  Every reason in the world to be wary.

Or as the saying goes:  The great thing about standards is that there are always so many to choose from!

Edited April 26, 2022 by jonathan909

[heartless]

8 hours ago, jonathan909 said:

The great thing about standards is that there are always so many to choose from!

right, and knowing WHICH version you should be looking at is also important.

being you are in Canada, which does not have its own version, do you look at the USDM, or European? it is a little easier for me, being in the USA, i go with the USDM version..

then there is the issue of stock engine, or replacement?
and if a replacement, what year/version/market?

so yeah, there will always be questions.. but I would be far more inclined to follow the FSM over Haynes any day of the week.

and i never said they were infallible... no one is ever perfect. you do the best you can with what you have.

[jonathan909]

2 hours ago, heartless said:

being you are in Canada, which does not have its own version, do you look at the USDM, or European? it is a little easier for me, being in the USA, i go with the USDM version..

We get the same ones you do - they have the "Made in Indiana" stickers in the windows - modulo the required metric speedo, etc.

In this case, though, your automatically reaching for the docs filed under "USDM" would appear to be a mistake.  That's the set that has the radically different procedure, and without understanding why (or which engine it's intended for), I don't think it should be trusted.

[jonathan909]

Now a different question without actually going OT:

I'm doing this one in the car, and these 45 degree torque specs are rather harder than the 90s specified for the older engines.  I've tried using my cheap little dial torque angle indicator, but it isn't a good fit.

Has anyone tried this (relative) cheapie or anything like it?  I've looked at a lot of indicators that attach to ratchets, breaker bars, etc., and nothing's impressing me much.

https://www.harborfreight.com/12-in-professional-flex-head-digital-angle-torque-wrench-56683.html

 

[heartless]

dont have the angle ones from HF, but do have the regular ones (both a half drive ft/lb model, and the smaller 3/8 drive in/lb), and they are fine for most things.

Probably would not want to trust it for a high dollar turbo race engine, or everyday use in a professional capacity, but a DIY NA daily driver? should be fine..

[jonathan909]

I have the usual assortment of "good" and "just okay" torque wrenches, but the question was specific to torque angle wrenches.

Edited April 27, 2022 by jonathan909

[GeneralDisorder]

https://arpinstructions.com/instructions/260-4701.pdf

When using Subaru head bolts we use a modified ARP sequence. The guys have found through testing and empirical evidence that a sequence of 30, 60, 85 followed by an additional torque to 90 on the center bolts works just as well as anything Subaru has published.

You MUST ensure that NO creaking takes place. We use Amsoil Assembly Lube on the threads.

GD 

Edited April 27, 2022 by GeneralDisorder

[jonathan909]

GD:

I hope I'm remembering this right - that a handful of years ago you spoke on the subject and said that you used the ARP lube.  When I asked them about it, they cautioned that it was only to be used with their bolts, otherwise the reduced friction risked exceeding the tensile rating on Subaru's bolts.  So you're saying that the stock bolt+Amsoil combination is a good one.

I'd like that a lot.  Torquing to an actual torque value instead of the torque angles would be a whole lot less PITA.

[edit]

As long as we're here, may I ask a couple of other questions?  First, do you apply those same torque specs to both the SO and DO engines?  And would it be safe to assume that a good degreasing (e.g. Brakleen) of the block holes, bolts, washers, and head-washer mating surfaces, followed by a coat of the Amsoil lube on all of the above, is appropriate?

Edited April 27, 2022 by jonathan909

[jonathan909]

Oh - and do you still do the (factory) initial torque steps (before backing them out again), or do you just dispense with that business?

[GeneralDisorder]

On 4/27/2022 at 1:09 AM, jonathan909 said:

GD:

I hope I'm remembering this right - that a handful of years ago you spoke on the subject and said that you used the ARP lube.  When I asked them about it, they cautioned that it was only to be used with their bolts, otherwise the reduced friction risked exceeding the tensile rating on Subaru's bolts.  So you're saying that the stock bolt+Amsoil combination is a good one.

I'd like that a lot.  Torquing to an actual torque value instead of the torque angles would be a whole lot less PITA.

[edit]

As long as we're here, may I ask a couple of other questions?  First, do you apply those same torque specs to both the SO and DO engines?  And would it be safe to assume that a good degreasing (e.g. Brakleen) of the block holes, bolts, washers, and head-washer mating surfaces, followed by a coat of the Amsoil lube on all of the above, is appropriate?

We switched to the Amsoil assembly lube and have better results with it. Cheaper too. We use it with the factory bolts, yes. It has the least propensity for creaking of anything we have used. 

Same torque regardless of SOHC or DOHC. 

We degrease the bolts and we also brake-clean the block threads and chase them with a head bolt that has several die grinder vertical slots cut into it. 

I generally apply the Amsoil assembly lube in two vertical lines up the threads 180 degrees apart. And lube between the bolt head and washer - washer to head is left dry although some lube often finds it way there and isn't an issue. Don't over-lube the bolts - this can hydraulically damage the block if there is too much in the bottom of the hole. 

GD

 

[1197sts]

GD, thanks for the info on torque procedure. When you use the modified ARP sequence, do you first do the initial torque and back off 180 degrees twice?