OEM head bolts frustration

[zaq123]

I finally mated the head to the block and did a final head bolt install. OEM gasket, OEM BMW bolt kit, 22ft.lbs; 90' and 90', correct sequence etc. Used ARP bolt lube on bolts, block holes were clean.

3 bolts (#2, #12 and #13) gave me a weird feel at the end of the second 90'. It felt like the tension got released at the last 20-30' of the turn. Almost felt like I broke a bolt.

I set my torque wrench to 60ft.lbs and all other bolts were holding that torque fine except the above 3, they started to spin a little under 60ft.lbs. I wasn't happy and panicked a little...... decided to back #2 out and see if it was broken.
It was not. I put that bolt back in and decided to crank it to 60 ftlbs and then to 70ft.lbs as all other bolts (except 2, 12 and 13) were holding 70ft.lbs just fine. All 3 bolts took 70ft.lbs just fine.

My question: I know reused bolt #2 is compromised as it's TTY. Did I screwed up with torquing them down instead leaving them alone? Should I bite the bullet and start from scratch (new gasket and bolts)? Again, 60 and 70 ft.lbs did not move 11 bolts that felt fine during the install, only the weird 3 were able to move under 60ft.lbs. The above mentioned #2 bolt that I backed out, stopped about 120' degrees past were it initially stopped with 22ft,90-90. #12 and #13 that I did not back out, stopped about 50' degrees past were they initially stopped with 22, 90-90.

[15Michaeljoseph]

I'm sure this is the kind of issue where everyone has a different opinion, but I think that by backing off that bolt/ using a torque wrench, you might have messed the job up. I replaced the head gasket on my car, with new bolts and all just like you did... Torqued to 20ftlbs, 90-90 however... My angle guage BROKE on the last three bolts. No biggie, I thought... Use my torque wrench on reverse to figure out the torque on the bolts that were totally done, and tried to pull them all up evenly.

The gasket didn't end up sealing and I had to redo the whole job in a month.

The reason why the bolts are angle torqued instead of a torque number value is because they each have a slightly unique stretch value... When it's disturbed, bad things happen.

It MIGHT be fine... But if I were you, I'd either re-do it with new stock bolts, or pony up for ARP studs. When I re-did the job I used a new gasket with copper spray on it, and bought ARP studs because they have an actual number torque to rely on rather than risking screwing up the tty angles. Car has been perfect since.

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[zaq123]

Should I do just bolts or bolts and new gasket?

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[e30davie]

Did you clean out the threads good before you put the head on? What is a set of bolts worth? like 60bucks?

When i did my m20 headgasket i was a moron and forgot to put the washes under the head bolts. I bought a new set and swapped out the bolts one by one and ive never had any issues. Back when BMW swapped from the normal bolts to the TTY bolts, i believe there was a recall and bmw specified swapping the bolts one by one as per the tightening procedure in order to avoid swapping the gasket.

What i am getting at is you can leave the gasket where it is, and get a new set of bolts and swap them one by one as per the tightening procedure. Torque to yeiled bols are about stretching the bolt slightly during installation in order to get pre-load on the bolts. pre-loading the bolts helps keep a good seal in fatigue loading, ie holding down a headgasket. Thus i wouldn't get too concerned about the initial torque, as long as it is close. torque on bolts is not an exact science, highly dependant on surface conditions, even a smidge of oil on the bolt can change the torque value.

Also when you do the 90deg + 90deg you are literally stretching the bolt, thus it can feel that its getting easier to turn as it wont be tightening up like a normal bolt. don't be too concerned, i experienced this too a little bit i think.

[Old525i]

I got these for my 525i 1990 just because I always hated the torque to yield bolts.

No regrets so far after two years of service.

http://arp-bolts.com/kits/ARPkit-detail.php?RecordID=4601

[jlevie]

If you didn't chase the threads in the block and clean them well with solvent and compressed air thread friction could be higher than bolt strength, causing early yield.

While you could simply replace the questionable bolts one at a time and reuse the head gasket, I don't know where you could get a tap long enough to chase the problematic bolt holes.

If it were me, I call it a lesson learned, pull the head, chase and clean the threads, and reinstall using a BMW or Goetze head gasket. The VR head bolts are an acceptable and cheaper alternative to the BMW parts. As a side note, don't forget to replace the oil return tube o-rings.

Old525i: TTY bolts are actually better at clamping the head in place (assuming the threads are clean and lightly oiled) as thread friction doesn't come into play like it can with torque readings.

[zaq123]

Holes very chased with the thread chase, got Craftsman metric chase kit for nuts and bolts just for this rebuild. Holes were spotless. I didn't go with ARP as I do not need them for this built, thought oem bolts will do. I also washed all factory storage lube off and relubed with ARP threat lube.

As far as TTY goes, I still think it's easier and more accurate to stretch stationary bolt with a nut vs. trying to strech bolt itself.

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[digger]

Did you clean out the threads good before you put the head on? What is a set of bolts worth? like 60bucks?

When i did my m20 headgasket i was a moron and forgot to put the washes under the head bolts. I bought a new set and swapped out the bolts one by one and ive never had any issues. Back when BMW swapped from the normal bolts to the TTY bolts, i believe there was a recall and bmw specified swapping the bolts one by one as per the tightening procedure in order to avoid swapping the gasket.

What i am getting at is you can leave the gasket where it is, and get a new set of bolts and swap them one by one as per the tightening procedure. Torque to yeiled bols are about stretching the bolt slightly during installation in order to get pre-load on the bolts. pre-loading the bolts helps keep a good seal in fatigue loading, ie holding down a headgasket. Thus i wouldn't get too concerned about the initial torque, as long as it is close. torque on bolts is not an exact science, highly dependant on surface conditions, even a smidge of oil on the bolt can change the torque value.

Also when you do the 90deg + 90deg you are literally stretching the bolt, thus it can feel that its getting easier to turn as it wont be tightening up like a normal bolt. don't be too concerned, i experienced this too a little bit i think.

it is permissible to change bolts one at a time without removing the head, there is a sequence to it, people did it to change from the hex head to torx with the recall. i dont know what the sequence is

the question id be asking is why did the 3 bolts have issues and not the others? is it a bad batch of bolts etc....or was it thread prep or something else? were they genuine OE bolts or VR?

[zaq123]

it is permissible to change bolts one at a time without removing the head, there is a sequence to it, people did it to change from the hex head to torx with the recall. i dont know what the sequence is

the question id be asking is why did the 3 bolts have issues and not the others? is it a bad batch of bolts etc....or was it thread prep or something else? were they genuine OE bolts or VR?

genuine OE bolts. I reused old washers so may be they are culprit?

[digger]

genuine OE bolts. I reused old washers so may be they are culprit?

i dont see how they would

[digger]

Also when you do the 90deg + 90deg you are literally stretching the bolt, thus it can feel that its getting easier to turn as it wont be tightening up like a normal bolt. don't be too concerned, i experienced this too a little bit i think.

i'm wondering if this is it, but then they should all feel the same.

the last few times ive done it was with ARP because they can be reused even though you have to unscrew the studs and remove them before lifting the head off when the head is being done in the car

[zaq123]

i'm wondering if this is it, but then they should all feel the same.

the last few times ive done it was with ARP because they can be reused even though you have to unscrew the studs and remove them before lifting the head off when the head is being done in the car

I had ARP kit and returned it...thought it would be an overkill for the stroker....should've kept them I guess. Oh well...probably just bite the bullet and go back to ARP +new gasket

[15Michaeljoseph]

I had ARP kit and returned it...thought it would be an overkill for the stroker....should've kept them I guess. Oh well...probably just bite the bullet and go back to ARP +new gasket

I think this is the best bet. While in theory you might be able to get away with reusing the current gasket, there is a chance you over torqued those old problematic bolts, which would have unevenly compressed the gasket (think- combustion chamber o-rings) and new bolts won't provide adequate clamp on the uneven gasket. It doesn't take much for a HG to leak like this... So I'd just pull it all off and start fresh. This job isn't fun to do over once it's all together and you find out something is wrong.

The ARP's arent overkill in my opinion, it's all up to preference. After my poor experience with new stretch bolts, I decided to go ARP on my fresh bone stock rebuild. I just didn't want to go through that again. And the studs are designed to have minimal fatigue stretch, so they are almost always reusable just in case the head ever has to come off again. Also, I believe it is just as accurate with regard to clamping force, if not moreso, than using the stretch bolts. With the studs, you're torquing a fresh, lubed nut to a clean stud, rather than a bolt directly into the block, which is rather difficult to clean out in the first place. In my eyes, that makes for better torquing conditions.

*To clean out block bolt holes: If you cut a slot alog the threads of one of your head bolts, it becomes a free 'thread chaser' for cleaning.

Also, I'd recommend the Goetze head gasket. I've seen and held VR and Elring M20 HG's and the Goetze definitely seems to be a more robust gasket.... Pro tip: Fel-Pro M20 head gaskets are repackaged Goetze.

I'm not really sure who makes the genuine gasket.

Good luck


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[zaq123]

new oem headgsket and ARP stud kit later, I figured out what was my previous issue (or not an issue).....I had the same moment with arp.
As one torques bolts, bolt washer can rotate/slip on the head surface so slightly and reposition the bolt in the hole. Basically bolt straightens out a little and let some tension off, providing the same filling at the wrench. I did notice that studs weren't perfectly dead center in the hole once fully installed. Something one can't see with OEM bolts
With ARP bolts, I was just repeating the bolt sequence until all of them came to 70 ft/lbs. With OEM bolts......well...there is no final torque so once the washer slips, one has no idea what tension there is after that last 90' of the turn.
I probably was ok with torquing my previous OEM bolts to final 70 ft but that would be taking BIG HUGE chances.....(I will just keep telling it myself as new gasket and studs weren't cheap)

All ARP hardware (studs, nuts, washers) were lubed up as per ARP instructions.
Do you guys normally revisit head bolts after some run time (once the engine cools off)? ARP instruction say that isn't not necessary.

[Old525i]

No.