head bolts not torquing!

30csl

30csl

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Two of the head bolts on the head seem to be taking many more turns to get up to 60nm of torque. I am worried about continuing to tighten them. They are next to each other at the front of the engine on the intake side.

Any advice guys?
Thanks

Rohan
 
TAKE THEM OUT NOW!!!! They are about to break off. Then you have to pull the head to fix it....Ask me how I know!
Buy a new set They are cheap insurance.
FWIW
Dave Ganzer
 
These are new Dave, were you doing a head gasket replacement too? I made sure threads in block were clean etc, all the others were fine but these required more turns, they are tightening though and are at about 45nm. I would have thought breaking the bolt would be much more noticeable/ require more strain? Sorry to be vague! Thanks
 
Mine was a used headbolt. It pulled up to about 5ftlbs from full torque and then wouldn't take any more torque. Stretched the threaded part. It was very noticeable when I took it out. Never had a new one do that though....
Be careful....
DaveG
 
30csl said:
Two of the head bolts on the head seem to be taking many more turns to get up to 60nm of torque. I am worried about continuing to tighten them. They are next to each other at the front of the engine on the intake side.

Any advice guys?
Thanks

Rohan
Click to expand...
Hi,

I concur with Dave, take them out now and get a new set. Given the hassle if they break, it's worth getting a new set on the off-chance that you had two defective bolts.

You mentioned that you cleaned the threads in the block but do you know the condition of the threads? If they are worn or corroded, they may not take torque. Also, is it possible that the two offending ones were lubed and the rest dry? Lubed threads require lower torque to achieve the same stretch.

Does ARP make head bolts that will fit these engines? I have used their products in the past and can attest to their quality. On my Austin Healey I used ARP bolts and studs internally throughout. Terrific products.

Regards.
 
Where did you buy them from? I used aftermarket from GSF in my e30 and had a similar problem. Bought a new set from BMW and had no problems.

JP
 
try to use a good brand of bolts, such as victor reinz, or the original bolts from bmw (probably they will be victor reinz too),

then, as you said very good cleaning of the thread holes in the block, using gasoline + compressed air

then the three stage torque sequence (that ends in 72N.m), or the other reccommended sequence using torque + warm up + angle

it seems impossible that two bolts present a different behaviour, but if you have found this issue you should stop and start again

the price of the bolts does not deserve a bigger problem

regards

yes, i did my head three weeks ago, and i even retorque them one month ago, and the behaviour of all the bolts was exactly the same
 
i may disagree on sfdon

there are several torque procedures, just choose one and go !

probably the best compendium is in the following thread in a post by mr.mmercury:

Dang, please take a look at the '86 bulletin. You will note that there are at least two variations of head bolts [long and short shouldered] and (for all I know) possibly more. I think the point being, not to mix them up. :wink:
HEADBOLTp1.jpg
HEADBOLTp2.jpg


more literature:

http://www.e9coupe.com/forum/showthread.php?t=10288&page=3
 
Hi guys,

I followed the instructions that came with the gasket (Elring). First torque to 58-62nM - leave for 15mins and then 30 degrees. Once warmed to 80 degrees celcius torque angle to 32 (from memory) degrees.

I have yet to start the car and do the last step however.

I bought the head bolts from W&N, the threads were clean and free of corrosion as i ran the bolts through them before putting on the head.

Its quite strange but i called a buddy out to the garage and he wasnt put off by it.

Fingers crossed for the start up!

Thanks,

Rohan
 
Dowel pins

While we have everyone's attention on heads and head bolts... What is the function of the dowel pins that BMW says should be placed in some of the bolt bores when loosening or tightening the other bolts? Where would one get those dowel pins?
 
Luis A. said:
While we have everyone's attention on heads and head bolts... What is the function of the dowel pins that BMW says should be placed in some of the bolt bores when loosening or tightening the other bolts? Where would one get those dowel pins?
Click to expand...

hi luis
i assume their function is centering the head, and you need them because the bolts obviously have some difference in diameter that may lead to some minor disalignment
 
Thanks DQ. Did you use them when you replaced your head gasket? I've not heard anyone on the board ever mention the dowels...
 
to tell you the truth i didn't
but considering that the new style bolts are those of the stretched type, i used the old bolts in the four corner positions to center the head, and then started placing the new bolts
i did this because the old type bolts maintained the nominal diameter as the thread diameter so the difference with the hole is smaller
hope it helps
 
Hi guys,

thanks for all the help.

I got the car started last night and there were no leaks of water/oil or fuel so far.

I have yet to do the final torgue of 30 degress - it says to get the car to 80 degress celcius first - Do i tighten while the car is warm or does it just have to have been warmed up once?

It started remarkably easily considering it has been idle for a year!

Thanks,

Rohan
 
sfdon said:
Check the date- this is the info from 03/95.

http://www.bmwtechinfo.com/repair/main/741en/index.htm
Click to expand...

For those keeping score, this '95 version covering "M30 engines" ("Film No. 01 51 9 780 741; No. 11-12/3.4") is similar, but not identical to the '86 service bulletin.

60NM/43 ft lbs - wait 20 minutes
80NM/58 ft lbs - wait 20 minutes

80NM/58 ft lbs - run engine 25 minutes - torque angle 35 degrees.

Elsewhere, presumably from the same '95 manual, the recommended torque angle is 35 degrees +/- 5 degrees. (See SFDon's diagram below)

IMHO, the deviation between all of the recommended torques and torquing procedures is small. For all I know, adding additional torquing steps might improve the reliability of the installation, but it would be for the statisticians to determine whether any measurable improvement would outweigh the time/labor investment of any busy (for-profit) shop. Reaching the final torque evenly across the head is the end game. There are several means of reaching that goal, and conventional wisdom "currently" favors the torque - wait-torque-wait -warm up - angle torque method - until someone finds an even different (possibly more practical?) method. And note well BMW's advice that each head bolt be washed (clean) and oiled and not necessarily "washed in oil". :wink:

From another thread cited at the bottom of DQ's '86 tech bulletin post, SFDon posted the following:
attachment.php




I believe centering dowels can be extremely helpful but are not absolutely essential. I would use them if I have them, but I have installed a few heads without them.

The head and block mating surfaces, and the head gasket, are all susceptible to scarring if the head is repeatedly moved into the correct or final mounting position. In theory, I suppose the dowels are designed to prevent or minimize damaging any of the surfaces. Thus, the dowels could be essential for a single mechanic who is too tired or weak to carefully position the head on top of the cylinder head without damaging any of the surfaces. Of course, if the mechanic is clumsy enough, he can scar metal surfaces by dragging them against or across the dowels (imagination required). :wink:
 
Butt there are two locating dowels in the block to secure the position prior to torquing down the head? Are these not enough seen as its just two points?
 
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