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Range Rover P38 1998 - Head torque sequence required please #

Posted by Bradley Kingsley on May 10, 2013, 9:02 pm

Year of Manufacture *: 1998
Engine Size and Code *: bmw 2.5 turbo diesel , straight six layout

Hi i have just had a disaster with a head job, dont know why but on test run it went bang and 7 of the 14 head bolts broke free from the block.

Can anyone give me their version of the torque settings as i am wondering if i could have overtightened them. I got my info from the autodata book so i cant imagine it being athe problem. The bolts were reused could this have been a factor. (they hadnt bottomed out)

Toque setting would be great and i can compare them to check if they are the same.
Regards Brad

Re: P38 range rover,Head torque sequence required please,

Posted by aidan birley <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT2879' width='330' height='300' border=0 style='border:none;'> on May 10, 2013, 10:02 pm, in reply to " P38 range rover,Head torque sequence required please,"
Aidan Birley

Hi Brad

this is the current AD online (assuming 256t engine code )

Is this the same as you used ?

Has the bolt snapped or pulled the threads ?

Aidan

Use new bolts and tighten in the following stages:

80 Nm
Slacken off 180°
50 Nm
90°
90°
Run engine for 25 min
Wait 2 hr
90°

Re: P38 range rover,Head torque sequence required please,

Posted by Alan Lange <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat3293' width='330' height='300' border=0 style='border:none;'> on May 10, 2013, 10:20 pm, in reply to "Re: P38 range rover,Head torque sequence required please,"
Alan Lange

Hi Bradley, that sounds expensive! I would've thought that if you over-tightened the bolts they would have stripped/sheared when you tightened them (not later on a road test). Could it be a mechanical (poss valve timing) or hydraulic lock (poss water/oil in intercooler) issues?

Re: P38 range rover,Head torque sequence required please,

Posted by Graham Bullock <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT2744' width='330' height='300' border=0 style='border:none;'> on May 10, 2013, 11:18 pm, in reply to "Re: P38 range rover,Head torque sequence required please,"
Graham Bullock

AutoVista says the same as Aidan said, except run engine for 20 mins, but for some reason it does not state to replace with new bolts which is something I would always do.

Graham

Re: P38 range rover,Head torque sequence required please,

Posted by ukat3153 <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat3153' width='330' height='300' border=0 style='border:none;'> on May 10, 2013, 11:22 pm, in reply to "Re: P38 range rover,Head torque sequence required please,"
Bradley Kingsley

Thanks Aiden, yes that is how i torqued it altho the bolts werent replaced. Can you confirm this has the small bolts around the chain area on the head.
Alan you may have a point but it had been run for the 25 mins first and it did a fairly big hill a good bit before the bang and with it being a auto it does get a good rev before it gets going. The engine appeared spot on right until it went bang. It did still run with just a slight misfire after but gaskett had cooked all over. If i was to number the bolts starting at cylinder 1 the first 3 on the left stripped and the last 3 on the right excluding the end one which stayed tight and also another third from the end on the left. Altogether 7 out of 14 lifted some as much as 5mm!!!

thanks for the help, Brad

Re: P38 range rover,Head torque sequence required please,

Posted by Steve Norman <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT5548' width='330' height='300' border=0 style='border:none;'> on May 11, 2013, 7:21 am, in reply to "Re: P38 range rover,Head torque sequence required please,"
Steve Norman - Administrator

Hi,
I have seen a similar thing when someone re-used old head bolts, just glance at the torque figures & you can see if the bolt has already stretched that much, it must get past it's yield point the second time around.
I have also seen the block cracked due to bolts bottoming out.

regards
Steve

Regards
Steve

Re: P38 range rover,Head torque sequence required please,

Posted by Bradley Kingsley <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat3153' width='330' height='300' border=0 style='border:none;'> on May 11, 2013, 10:27 pm, in reply to "Re: P38 range rover,Head torque sequence required please,"
Bradley Kingsley

Thanks again for your replys,
I am on the thought lines of stretched out bolts, Definatly not bottomed out in the block as there is plenty of space left.
Can you confirm they are stretch bolts as they are fairly short and thick with e14 torque on top.
They are a 1.5x 12 thread.

ta Brad

Re: P38 range rover,Head torque sequence required please,

Posted by Tony bickers <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT5143' width='330' height='300' border=0 style='border:none;'> on May 12, 2013, 12:37 pm, in reply to "Re: P38 range rover,Head torque sequence required please,"
Tony Bickers

Hi Brad,

As a rule, any tightening of a bolt that involves angle tightening is a "stretch to yield" use once only bolt,so yes they are definitely one use stretch bolts.

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