Cast Iron heads for 300TDi?

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Originally Posted by uninformed

what can one do to over come this John? studs instead of bolts?

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Studs can help with clamping load, but elastic modulus and creep are material properties (aluminium in this case) - creep (permanent dimension change) also increases with temperature and time.

Edit: I should also add that I don't advocate going to this trouble and expense - polishing a tvrd is an expression used on some other forums and comes to mind here.

Perhaps a periodic re-tension of the head?

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Originally Posted by Dougal

Perhaps a periodic re-tension of the head?

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How do you do that on bolts that were angle tightened (as per 300tdi head bolts)? You can retighten by a specified angle, however you don't know when the bolt will snap.

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Originally Posted by isuzurover

How do you do that on bolts that were angle tightened (as per 300tdi head bolts)? You can retighten by a specified angle, however you don't know when the bolt will snap.

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Slacken them off and again tension to the starting tension, followed by the corresponding angle.
If you get a greater rotation than originally, then either the head has compressed or the bolt stretched.

You should only do this a few times for any given bolts lifespan. I've reused my Isuzu bolts, they are visually still good. Same for the head bolts on one of my nissans. At $30 per bolt and 18 bolts for the Nissan it was an easy choice.

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Originally Posted by isuzurover

How do you do that on bolts that were angle tightened (as per 300tdi head bolts)? You can retighten by a specified angle, however you don't know when the bolt will snap.

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Slacken them off and again tension to the starting torque, followed by the corresponding angle.
If you get a greater rotation than originally, then either the head has compressed or the bolt stretched.

You should only do this a few times for any given bolts lifespan. I've reused my Isuzu bolts, they are visually still good. Same for the head bolts on one of my nissans. At $30 per bolt and 18 bolts for the Nissan it was an easy choice.
Some bolts are well into TTY (torque to yield) at the factory tension, all mine appear to still be in the elastic region, no visible or measurable elongation/necking so I keep using them.

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Originally Posted by Dougal

Slacken them off and again tension to the starting torque, followed by the corresponding angle.
If you get a greater rotation than originally, then either the head has compressed or the bolt stretched.

You should only do this a few times for any given bolts lifespan. I've reused my Isuzu bolts, they are visually still good. Same for the head bolts on one of my nissans. At $30 per bolt and 18 bolts for the Nissan it was an easy choice.
Some bolts are well into TTY (torque to yield) at the factory tension, all mine appear to still be in the elastic region, no visible or measurable elongation/necking so I keep using them.

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300Tdi head bolts are TTY AFAIK. The manual says to replace them when doing the head.

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Originally Posted by isuzurover

300Tdi head bolts are TTY AFAIK. The manual says to replace them when doing the head.

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Manuals always say that.:angel:

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Originally Posted by Dougal

Manuals always say that.:angel:

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yeah I didnt believe my manual when it said not to over fill the engine with oil. :D

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Originally Posted by Dougal

Manuals always say that.:angel:

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Not isuzu manuals ;)

from vague memory the 300 overhaul manual states head bolts can be re used s5 times.
For the price of a set though id put in new ones and use the old ones for mill clamp bolts!