Re: [Peugeot-L] 86 505 N9TE meltdown, 3000k from home

Hi Kevin,

Peugeot introduced torque-to-yield bolts for the diesels in 1986. They have made a huge difference in holding the headgaskets on diesels, and they are recommended for any diesel with screw-in injectors which is still using the old style bolts. Even there Peugeot, perhaps uniquely among manufacturers, says the TTY bolts may be reused up to five times. I haven't heard of any failures in those bolts. The N9T series does not use TTY bolts. The 405 XU9 series apparently do. In no case does Peugeot recommend changing bolts to my knowledge.

Now the fact that Peugeot does not recommend changing bolts is not ipso facto a reason not to; after all they don't recommend changing timing belts either! But we have regular examples of the failure of timing belts run too long. I just haven't heard of the problems with headbolts not changed. Perhaps someone else has.

I have seen plenty of problems with cracked heads on turbos (and indeed on all the iron block engines).

Brian Holm

At 06:42 PM 8/16/2005, Pug NZ wrote:

>Hi Brian,
>Some info I have (admittedly from a supplier of bolts/gaskets)
>differentiates between the old style head bolts as used on the 504 (eg
>torque to x , then to y ) which are tight but not stretched when
>installed, and so okay to reuse, and the newer style bolts which are
>tightened to yield point, (eg torque to x , then tighten another 90° etc).
>Since the newer style bolts yield as they are tightened, they should not
>be retorqued, neither should they be reused.
>I have no idea what the N9T uses, but someone should have the tightening
>sequence that should indicated which style they are.
>Also, the older style tend to be a plain shank on the bolt, while the
>newer style have a thinner part in the shank
>Kevin
>
>Brian Holm wrote:
>
>>You may know something that I don't, but I have sold a lot of heads and
>>head gaskets, but have never been asked for a head bolt for an N9T. I
>>can only remember one or two blown head gaskets on gas turbos where the
>>head wasn't cracked. If the bolts were stretching I would expect to see
>>more bad head gaskets.
>>
>> Peugeot does not recommend replacing the bolts, but they are still
>> available @$23 each if you want to go that route. Gasket manufacturers
>> love to recommend new bolts
>>
>>Gas turbo heads do not crack between the valves (diesels do) -- they
>>crack from the exhaust valve across the gasket face of the head to the
>>water jacket on one or both center cylinders. I have seen several really
>>badly welded turbo heads, which failed soon. I hope that's not the case
>>with yours.
>>
>>Brian Holm
>>
>>
>>
>>
>
>
>
>
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Brian Holm, Parts for Peugeots
at Peugeot Holm, since 1969
2120 Maple Hill
Plainfield, VT, 05667
802-454-7132, fax -1310

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