Does anyone know what the torque spec is for the PRV head bolts? We had copper gaskets made by Ridgecrest Engineering and we want to tighten at the max reasonable number (if I only kenw what that is 
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PRV head bolt torque
- Thread starter ThanosK
- Start date
3 litre for XM (UFZ/UKZ) per 1996 year Citroen mechanics handbook is given as:
Pre-tighten to 6 m.daN
Slacken
Tighten to 4 m.daN
Angle tighten 180 degrees.
Bolts greased with Molykote G Rapide Plus
There is an order diagram and it shows work in a circle centre outwards.
I think this is different to what was done in the 2.7 in my Volvo years ago, so it may vary with specification. That was well covered in the Haynes Volvo 264 manual. I remember cracking the timing cover because I overlooked the advice in the supplement about a small machining change when using a 1979 cover on an earlier block.
Pre-tighten to 6 m.daN
Slacken
Tighten to 4 m.daN
Angle tighten 180 degrees.
Bolts greased with Molykote G Rapide Plus
There is an order diagram and it shows work in a circle centre outwards.
I think this is different to what was done in the 2.7 in my Volvo years ago, so it may vary with specification. That was well covered in the Haynes Volvo 264 manual. I remember cracking the timing cover because I overlooked the advice in the supplement about a small machining change when using a 1979 cover on an earlier block.
Thanks for that. This is very similar to the procedure outlined in the 604 manual, so it should be pretty close. We don't angle tighten, so I need to determine what this procedure corresponds to in kg.m. We would really want to tighten to 11 kg.m but we are not sure that the bolts and block threads will take it.
Here is an excerpt from the reference document that I use. Note that different motors use different bolts. I'm sure you will be able to find something suitable for your application.
2.5 without catalytic converter:
Tighten to 6daNm
Wait 3 minutes
Loosen all bolts
Tighten to 2daNm
Tighten 127 degrees
Run the engine until the cooling fans cut in.
Stop engine and allow to cool (minimum 6 hours)
Tighten an additional 25 degrees.
2.5 with catalytic converter:
Tighten to 6daNm
Wait 3 minutes
Loosen all bolts
Tighten to 2daNm
Tighten 106 degrees
Run the engine until the cooling fans cut in.
Stop engine and allow to cool (minimum 6 hours)
Tighten an additional 45 degrees.
2.7 litre oddfire, 2.8 litre oddfire:
Tighten to 6daNm
Wait 3 minutes
Loosen all bolts
Tighten to 2daNm
Tighten 115 degrees
Run the engine until the cooling fans cut in.
Stop engine and allow to cool (minimum 6 hours)
Loosen all bolts
Tighten to 2daNm
Tighten 115 degrees.
2.8 litre even fire:
Tighten to 6daNm
Wait 3 minutes
Loosen all bolts
Tighten to 2daNm
Tighten 106 degrees
Run the engine until the cooling fans cut in.
Stop engine and allow to cool (minimum 6 hours)
Tighten an additional 45 degrees.
3 litre except Turbo:
Tighten to 6daNm
Wait 3 minutes
Loosen all bolts
Tighten to 4daNm
Tighten 180 degrees.
3 litre Turbo:
Tighten to 6daNm
Wait 3 minutes
Loosen all bolts
Tighten to 4daNm
Tighten 180 degrees
Run the engine until the cooling fans cut in.
Stop engine and allow to cool (minimum 6 hours)
Tighten an additional 50 degrees.
2.5 without catalytic converter:
Tighten to 6daNm
Wait 3 minutes
Loosen all bolts
Tighten to 2daNm
Tighten 127 degrees
Run the engine until the cooling fans cut in.
Stop engine and allow to cool (minimum 6 hours)
Tighten an additional 25 degrees.
2.5 with catalytic converter:
Tighten to 6daNm
Wait 3 minutes
Loosen all bolts
Tighten to 2daNm
Tighten 106 degrees
Run the engine until the cooling fans cut in.
Stop engine and allow to cool (minimum 6 hours)
Tighten an additional 45 degrees.
2.7 litre oddfire, 2.8 litre oddfire:
Tighten to 6daNm
Wait 3 minutes
Loosen all bolts
Tighten to 2daNm
Tighten 115 degrees
Run the engine until the cooling fans cut in.
Stop engine and allow to cool (minimum 6 hours)
Loosen all bolts
Tighten to 2daNm
Tighten 115 degrees.
2.8 litre even fire:
Tighten to 6daNm
Wait 3 minutes
Loosen all bolts
Tighten to 2daNm
Tighten 106 degrees
Run the engine until the cooling fans cut in.
Stop engine and allow to cool (minimum 6 hours)
Tighten an additional 45 degrees.
3 litre except Turbo:
Tighten to 6daNm
Wait 3 minutes
Loosen all bolts
Tighten to 4daNm
Tighten 180 degrees.
3 litre Turbo:
Tighten to 6daNm
Wait 3 minutes
Loosen all bolts
Tighten to 4daNm
Tighten 180 degrees
Run the engine until the cooling fans cut in.
Stop engine and allow to cool (minimum 6 hours)
Tighten an additional 50 degrees.
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You need to determine whether your engine has TTY bolts, don't angle torque unless these are new.
Probably not.
I'd be inclined to err on the side of caution here. On one of those engines, my very experienced Peugeot mechanic once stripped a block thread .....after warning me about it years before that.
He managed to tap it out to a larger size with a long tap, without taking off the head. Not sure if he fitted a helicoil after that or used a wider bolt.
TTY bolts can never be reused.
The bolts have actually materially yielded / stretched
There is a maximum elongation specification that permits reuse of bolts if they are below the limit. When a bolt set costs around 30 Euro, it's probably false economy, but nonetheless permissible.
demannu, does your document refer to greasing the bolts?
demannu, does your document refer to greasing the bolts?
Hi All
When I built the 505 TT V6 with copper head gaskets I used the non-angle method and did them up to 75 foot pounds and again after a heat cylcle and cool down. I think this is 10.4 kg.m in your units. I may have gone higher but its a few years ago now and I'm not so sure. Bolts should be in good condition and lubricated, I use "Never Seeze" at the lube. I don't recommend others do this this, it is what worked for me under these conditions and the headbolts and threads in the block coped with no problem. This was a Volvo 2850cc oddfire motor.
In the newer evenfire motors with standard head gaskets I have been using the method posted by others above for turbo 3 litre evenfires, 45 ftlbs, then back to 30 ftlbs +180 degrees then +50 after running and overnight cool down.
When I built the 505 TT V6 with copper head gaskets I used the non-angle method and did them up to 75 foot pounds and again after a heat cylcle and cool down. I think this is 10.4 kg.m in your units. I may have gone higher but its a few years ago now and I'm not so sure. Bolts should be in good condition and lubricated, I use "Never Seeze" at the lube. I don't recommend others do this this, it is what worked for me under these conditions and the headbolts and threads in the block coped with no problem. This was a Volvo 2850cc oddfire motor.
In the newer evenfire motors with standard head gaskets I have been using the method posted by others above for turbo 3 litre evenfires, 45 ftlbs, then back to 30 ftlbs +180 degrees then +50 after running and overnight cool down.
Ahh yes, very good point. It does indeed. It says to apply engine oil to the thread and under the head of the bolt, for all of the listed engines.
This is a standard Renault practise for engines of that era.
Thank you all for the very detailed responses. Graham, these are not TTY bolts. They are in very good condition, only used once; we re-used them as we could not get new ones in the time we had available. David/Scott, we did use the lube as you describe. Rob, we will use 10.5kg.m as you did (I understand this is not a recommendation, thanks for sharing your experience).
For the benefit of future readers of this thread, I am happy to report that the head was torqued to 10.5 kg.m without issues. Again, my thanks to everyone for their contributions.