Retorquing Cyl Head

[Rabbit TD]

I've been running my new T/D engine for a few days and I notice my reservoir goes down some, I only keep it about 1 1/2 in. deep the same as other engines I've had.  The coolant is coming out of the reservoir and not going through the engine and my N/A did the same thing when I built it and I torqued it about 10 lbs. more and never used anything in 3 years.  This engine has a new Top-Line head, block was magnafluxed, milled .005, 12 m/m ARP studs torqued to 80 lbs on a 1 notch fiber gasket.  I'm pretty sure a retorque will stop this small leak as I wouldn't know what else it could be after all I've done to it.  There is so much controversy on the ARP studs torquing specs and some have pulled them 100 ft. lbs. with no problems.
      My question is that ARP states 80 lbs. with their included moly lube or 120 with motor oil.  Doesn't that seem to be an extreme range difference just for the lubricants?  I don't want to get into all the debate over all the scientific aspects of this like I found on the search on this but I'm really wondering if the initial 80 with their lube is really enough.  I know what the slip says but it is for a Ford Escourt as well.  What do you guys torque your's too afterwards.  My engine isn't getting hot or anyting like that but I have seen the level drop a little and it spits it out the cap a little, pressure valves in cap are clean and seal ok otherwise.

[Turbinepowered]

ARP's Moly lube is really slippery, so I don't see anything weird with the disparity in numbers.

I did talk to a tech on the phone, and he said that you should at least check to make sure that the stud nuts are torqued to the proper value after running it for a while. He told me to run it for a week then recheck them, bring any that weren't up to 80 up to 80 (Actually 70, but mine were 11mm gasser studs), and then drive on.

Might your disappearing coolant be an air bubble working its way out?

[Rabbit TD]

I'm pretty sure it's pressure getting into the coolant just like it is 95% of the time and my other engine did this too and pulling a little tighter fixed it.  My big question though is that 120 lbs. is 50% more than 80 lbs. is.  If the moly lube is that good then theoreticly the 11/m/m bolts would only have to be torqued around 35 lbs. at that much of a difference between lubes.  I just wonder what those stretch bolts actualy have on them after all the extra turning.  I think I'm going to retorque and go at least 90 and see if it helps, anybody have any bad thoughts about this or how far have you gone up?

[theman53]

I have always wondered what the stretch bolts were up to. If somebody is doing a head gasket here in the next little while and has a breakaway dial style torque wrench might be able to tell us. I think 53Willy's put 100 or maybe more on his studs to get the MLS to seal.
Granted they are a bolt instead of a stud and they give, but I am a big dude and use a 24" breaker bar when I do them and it takes quite a bit of force to get the stretch bolts around. I don't know if I could do it with my 1/2" rachet with no cheater. I am with ya on this Rabbit TD I think you should be able to at least go 90 without problems. If ARP's alloys are as good as what they charge for them you should be able to pull the threads out of the block before you break the stud. Which the block is cast similar to so many SBChevys and you can torque them way over 100 without killing the block so I would think that you won't have any problem.

[Luckypabst]

Give it a shot. But I think all these attempts at outsmarting the engineers is not a good idea.

Torque values will be very much different between the aftermarket studs and the OEM bolts because of the different thread pitch. Less torque on the finer threads of the studs will give the same tensile pre-load as more torque on the OEM's coarse threads.

And again I'll state - if the threads pull from the block before the stud breaks, you have an issue with previously damaged threads. The studs are designed to break first, given sufficient thread purchase in the block.

Chris

[Rabbit TD]

I have always wondered what the stretch bolts were up to. If somebody is doing a head gasket here in the next little while and has a breakaway dial style torque wrench might be able to tell us. I think 53Willy's put 100 or maybe more on his studs to get the MLS to seal.
Granted they are a bolt instead of a stud and they give, but I am a big dude and use a 24" breaker bar when I do them and it takes quite a bit of force to get the stretch bolts around. I don't know if I could do it with my 1/2" rachet with no cheater. I am with ya on this Rabbit TD I think you should be able to at least go 90 without problems. If ARP's alloys are as good as what they charge for them you should be able to pull the threads out of the block before you break the stud. Which the block is cast similar to so many SBChevys and you can torque them way over 100 without killing the block so I would think that you won't have any problem.

 I forgot to add that my lowest cylinder during a cold test was 460 last week with about 100 mi. on it and a high of 480 so I think they are pretty equal in that respect.

Yes I thought the torque wrench in reverse check would work too but it's not a real accurate reading because it does take more force to get them moving,  but I know it was way over 80 lbs. on this engine when I tore it down, I have a extra long breaker bar and it was really tight even with it, way more than the ARP' nuts.  Another thing I don't agree with is the controversy over the finer pitch threads on the ARP' being able to have a tighter clamping force at a lower actual torque reading.  I've read this numerous places but to me whatever the torque wrench says it is that's what it is, it just takes more turning to get to that point with finer threads and I like that because it goes a lot smoother also but that's just my theory.  Ths motor should be as flat and true as you could get because it's a new head and the block milled .005, but then I read an older thread where Saurkraut torqued his Arp's to 50 with a metal head gasket, never retorqued and has a good bit of boost and never had a problem since but again that's with the metal gasket.  I read it takes a lot to get them to flatten out but he said he never had a problem so go figure.  And again thanks for your answer :wink:

[Rabbit TD]

Again I think I got more off the point on what my original question in my mind is  Does any body else think that the torque specs being 80 for the moly lube and 120 for motor oil seem a little extreme, obviously the bolts can go higher if they say that, that's a 50% difference in my mind and again those specs are for the gas motor they figure you are using them in to begin with and these ARP's are obviously stronger than the stretch bolts.

[Luckypabst]

It occured to me earlier that you didn't mention an initial retorque after warming the engine. Did you do this or not? A fiber gasket  must be retorqued after warming the engine and allowing it to cool. When the engine warms up, the block and head will expand, further compressing the head gasket. After the engine cools and everything contracts back to it's room temperature state, the gasket remains compressed and your studs will now be loose.


About the torque question - sorry to not keep it simple but there's a science to this and it dosen't need to be addressed with a trial and error approach:

The lower pitch angle of the fine threads gives a greater mechanical advantage for a given turning torque. Therefore, the same torque on fine threads will generate greater tension in the fastener. There is no debating this basic rule of physics.

Again, it's not a great idea to second guess the engineers. They know the friction coefficient for their moly lube vs. generic 30 wt. You and I and most everyone else don't know this information or how to properly apply it.

I think it was determined that ARP's torque values will generate approximately 75% of the yield strength of the fastener. You really don't know what torque will generate 90% or 100 % or even 110% of yield. In my opinion, blindly increasing the stud torque to 100 ft-lbs will bring you very close to that 100% point. It's very nice to keep a safe margin of error on something that you'd like to remain reliable and bullet-proof. And once you cross that yield point, you've permanently deformed and degraded the fastener as it crosses from the elastic state into the plastic state.

Chris

[53 willys]

It occured to me earlier that you didn't mention an initial retorque after warming the engine. Did you do this or not? A fiber gasket  must be retorqued after warming the engine and allowing it to cool. When the engine warms up, the block and head will expand, further compressing the head gasket. After the engine cools and everything contracts back to it's room temperature state, the gasket remains compressed and your studs will now be loose.



I think it was determined that ARP's torque values will generate approximately 75% of the yield strength of the fastener. You really don't know what torque will generate 90% or 100 % or even 110% of yield. In my opinion, blindly increasing the stud torque to 100 ft-lbs will bring you very close to that 100% point. It's very nice to keep a safe margin of error on something that you'd like to remain reliable and bullet-proof. And once you cross that yield point, you've permanently deformed and degraded the fastener as it crosses from the elastic state into the plastic state.

Chris

retorques are supposed to be done with the engine STILL WARM...not warmed then cooled back down.


I agree with you for the most part...but when 80lbs leaves your head to loose and you still leak coolant or cross contaminate then what???
I tq'ed my ARP to 110ftlbs...and would recommend anybody doing a MLS gasket to do the same......if not 110ftlbs I would at least go 90-100ftlbs...


my MLS gasket had LOTS and LOTS MORE crushing to do after 80ftlbs.. :wink:

my .02

[jtanguay]

Again I think I got more off the point on what my original question in my mind is  Does any body else think that the torque specs being 80 for the moly lube and 120 for motor oil seem a little extreme, obviously the bolts can go higher if they say that, that's a 50% difference in my mind and again those specs are for the gas motor they figure you are using them in to begin with and these ARP's are obviously stronger than the stretch bolts.

a portion of the torque you apply to tighten is lost due to friction.  the moly lube is very slippery, and thus will limit the friction variable by quite a bit.  MLS gaskets should be taken to about 100ft/lbs (or more) because as stated above, they need to crush to seal properly.  with the fiber gasket you should be okay with around 80.  taking it to 90 shouldn't hurt anything, if you want to see if that helps.  there is a possibility that your torque wrench is out of calibration and your 80 ft/lbs is more like 70 ft/lbs, or worse...

[Rabbit TD]

Yes I did originaly retorque the engine after it had ran for maby 20 minuets hooked to a cooling system before I put the engine in the car, just to make sure I didn't have any major problems and tying the car up more than necessary.  This was also done after the engine cooled down and I re-torqued it at 85 at that time.  This retorque I did today was also on a cool motor this morning and I pulled them to 100.  I have 2 wrenches a 250 lb click type and a deflecting beam craftsman and I really don't see any difference between them as far as accuracy other than the beam type will show a stud or bolt pulling or stripping where the click type doesn't.  90% of the information I've seen on this matter says to retorque when cold but I don't know why you couldn't do it warm either. It does seem to actualy have a little less power than before though and idles slower when warm than before, smooth but slower which I am going to post another thread on.

[Luckypabst]

The only time I've come across the warm retorque requirement is with stretch bolts.

Also, my MLS gasket sealed right up at 86 ft-lbs. (I've seen both 80 and 86 as the spec...)

Chris

[53 willys]

The only time I've come across the warm retorque requirement is with stretch bolts.

Also, my MLS gasket sealed right up at 86 ft-lbs. (I've seen both 80 and 86 as the spec...)

Chris

the warm retorque is for fiber gaskets...not stretch bolts...the bolts stayed the same when they went to MLS gaskets and have nothing to do with retorques...MLS gaskets do not normally need retorques..but fiber IMHO is a MUST EVEN more if you wanna run higher then stock boost levels.
my damn Thailand gasket took 110ftlbs to seal...must be the "made in China" thing..lol...


Dont forget...the warming of the engine on a fiber gasket is with NO COOLANT pressure!!(cap off).....my fiber gasket tqed to 80ftlbs blew on the test drive...with no retorque....IMHO if the fiber does not seal the first time and the exhaust gasses are pressurizing the coolant system...your done...the gasket is screwed...no it wont hurt to give it some more ftlbs..but honestly it may be a loosing battle??...I know when mine was doing this it ran GREAT....but the head gasket was blew in at least 3-4 spots!!! I took it from 80ftlbs to 90ftlbs to 100ftlbs...and it was still pressurizing the coolant system.

maybe I'm just little different about it since pulling my head off 3x because the gaskets did not get enough smash with 80ftlbs and ARP's


my .02 from my own experiences.

[Luckypabst]

the warm retorque is for fiber gaskets...not stretch bolts...the bolts stayed the same when they went to MLS gaskets and have nothing to do with retorques...MLS gaskets do not normally need retorques..but fiber IMHO is a MUST EVEN more if you wanna run higher then stock boost levels.
my damn Thailand gasket took 110ftlbs to seal...must be the "made in China" thing..lol...

Not to stray too far - the original problem was with fiber gaskets. The MLS gasket dosen't require a re-torque regardless of the fastener because it dosen't compress like the fiber gasket. I was speaking in terms of other non-stretch-bolt head installations. The VW is the first vehicle I've come across that specifies a hot retorque using OEM parts (all the rest had fiber gaskets as well but with "regular" head bolts).

Curiously, I found this as a general rule of headgasket installation (Obviously the VW procedure supercedes this when using OEM parts):

" If the engine has an aluminum cylinder head or block, however, wait to retorque the head bolts until the engine has cooled back down to room temperature."

Chris