cylinder head bolts. are they stretch or can they go again?

barks · 11-03-2015, 03:27 PM

Hi,
New here.
Word of warning. My cam chain guide just snapped. Jamming the intake cam, destroying all the intake lifters, exhaust cam sprocket rounded and pistons burred.
For the sake of a £14 new guide check it,,,,

Question is are the head bolts stretch or can they go again. There in good shape. Also what is the torque and is it in stages and the pattern please,

Many thanks.
Barks

JFP in PA · 11-04-2015, 02:11 AM

Quote:

Originally Posted by barks

Hi,
New here.
Word of warning. My cam chain guide just snapped. Jamming the intake cam, destroying all the intake lifters, exhaust cam sprocket rounded and pistons burred.
For the sake of a £14 new guide check it,,,,

Question is are the head bolts stretch or can they go again. There in good shape. Also what is the torque and is it in stages and the pattern please,

Many thanks.
Barks

No, the bolts should be replaced, preferably with ARP bolts, which are much better quality.

barks · 11-06-2015, 12:06 AM

Thanks for your reply,
I was told that the neck on the bolts was designed to stretch if over torqued and if they are removed correctly which I assume means not over torqued then they can be reused.
Does anyone know the pattern and torque down procedure for the new bolts.

Cheers
Barks

JFP in PA · 11-06-2015, 05:08 AM

Quote:

Originally Posted by barks

Thanks for your reply,
I was told that the neck on the bolts was designed to stretch if over torqued and if they are removed correctly which I assume means not over torqued then they can be reused.
Does anyone know the pattern and torque down procedure for the new bolts.

Cheers
Barks

You need to get success to a service manual to get the torque sequence as reproducing it is a violation of intellectual property rights which Porsche's legal department loves to shut down websites over.

Torque specs are for new bolts only and are a four step process:

30 Nm or 23 ft=lb.
Loosen completely
+60 degrees, +/- 2 degrees
+60 degrees, +/- 2 degrees

barks · 11-06-2015, 08:36 AM

Many thanks,
Barks

barks · 11-08-2015, 01:27 PM

Just in case anyone takes this as correct there is a step missed.

After they are loosened off. They must be tightened to 20nm. The rest is correct.

Sorry to correct you but wouldn't want anyone to follow that and do it wrong.

Pattern is logical.

Cheers barks

barks · 11-11-2015, 02:22 PM

If anyone's interested the manual states if the head bolts are 234mm long then always replace them or replace them with 230mm bolts.
If the head bolts are 230mm long then they can be reused.

I measured all my bolts today and they are all 230mm long so I'm reusing them......

If it doesn't work ill let you know, not that anyone seems particularly interested.

Barks

JFP in PA · 02:53 PM

Which manual are you using? We never reuse them, preferring to go with ARP bolts as mentioned earlier.

barks · 11-11-2015, 11:46 PM

Hi,
I've got the Porsche boxster technical manual that porsche use,
Everything from wiring diagrams to replacing pistons,

Also every other porsche made....

Cheers

Barks

JFP in PA · 11-12-2015, 02:16 AM

Yes, but what date or version? I think you may have one that is out of date (lacking the 100 or so supplements).

SeaDweller · 11-12-2015, 03:06 AM

Quote:

Originally Posted by barks

Hi,
New here.
Word of warning. My cam chain guide just snapped.

How many miles on the engine?

barks · 11-12-2015, 02:09 PM

Hi,
I would of thought if they are specifying a slightly shorter bolt as reusable it would of been superseded.
I'm going to show porsche the manual when I'm there on Saturday morning collecting some parts.
I've sent you a link to see what you think. It's pdf engine from 15.

120k miles on clock with full porsche history.

Cheers
Barks

JFP in PA · 11-13-2015, 12:15 PM

Quote:

Originally Posted by barks

Hi,
I would of thought if they are specifying a slightly shorter bolt as reusable it would of been superseded.
I'm going to show porsche the manual when I'm there on Saturday morning collecting some parts.
I've sent you a link to see what you think. It's pdf engine from 15.

120k miles on clock with full porsche history.

Cheers
Barks

I've seen this before if not mistaken, and I think you are going to find that this is a 1999 manual set with no supplements. I also think you will find that the engine's came with either set early on and then switched to the 230MM later on.

afterburn 549 · 04:11 PM

This info is good for most engines -
Clamping force is applied by the elasticity of the bolts.
Once the bolt has yielded to just static force there is no clamping force left and sooner or latter bolts start breaking.
This happens to most OEM bolts over time , that is why ARP fasteners are suggested
I am sorry about your circumstances.