Cylinder Head Bolt Torques

[opticaltrigger 52]

Hi guys,

The time has come with the project where were going round everything and double checking nuts and bolts etc.

Anyway when the engine was built some time ago I only tightened the head bolts to 25Nm just to give it a pinch but now it's time to torque it down properly.

 

XU9JA 1.9ltr Gti 8 Valve. (Torx drive bolts.)

 

The problem I have is that I've heard a few different torque and angle setting combinations and while I'm sure that they are all fine I did read an article which stated that the factory settings were excessive and risked damaging the threads in the block.I did find that hard to belive,but I cant just dispense with it untill I know better from people with more experience than I have.So I wanted to ask some of you guys what you feel is the best way to go about this in terms of what torques and angles and in what order.

 

Hope someone can help

All the best O.T.

[Tom Fenton 1,542]

I use the standard settings without a problem. Make sure the threads are lubricated and when on the angle setting part I do it in three 90 degree stages rather than pulling them to 300 deg in one go.

[opticaltrigger 52]

Thanks once again Tom.I feel alot better now that I've got some advise onboard regarding this.I didnt know that there could be so many different aproaches to it.But I'm going over to the workshop in a bit and I'll use those settings you use.

 

All the best and thanks again

O.T.

[Tom Fenton 1,542]

It works OK for me!

 

To clarify, when doing the angle tightening, I go round and do all 10 to 90 deg in order. Then again another 90 to get to 180 in order. Then the final 90 "plus a bit" to get to 270 "plus a bit" = 300.

 

I always tap the block threads out and lubricate to give the alloy the best chance.

[steve@cornwall 100]

I was advised years ago to go to 60 lb ft in sequence then another 90deg. - works well for me.

[smithy 1]

i just used the factory settings but like tom do the angle in stages.

 

did you use new bolts?

 

also be careful with the torque figures as for some reason there are 2 different settings depending if you have torx or standard head bolts,dont mean to patronise you but also make sure the spacer is on bolt at rear of head by timing cover.

[opticaltrigger 52]

Thanks all for the advise,I've torqued it down with the standard settings.

Yeh!!!...That 300 degrees is a painful process,but it did feel better doing it as Tom said in stages.Doing it all at once would be terrible.

 

Anyway thanks very much for the help guys.

O.T.

Edited May 16, 2011 by opticaltrigger

[Stu 18]

Ive done mine a little differently in recent builds, i put 25lbft on, leave it 20mins or so, then put 50lbft on. Leave it overnight and torque down to 75lbft. I seem to recall Miles doing it this way, ive never had a problem yet, no worries about that final 300degree angular torque, and reasonable assurance that all the bolts are torqued equally.

[opticaltrigger 52]

Thats another one.I hadn't heard that one Stu but then I haven't come across another engine with as many different approaches to cylinder head tightening as this one.

After thinking about it for a while though I've sort of accepted that with cylinder heads,basically tight is tight as long as it doesn't exceed the limitations of the fastener or the thread I guess.

 

O.T.

Edited May 16, 2011 by opticaltrigger

[Anthony 1,003]

That's the way that I do it too Stu as Dave Baker (Pumaracing) used to recommend, although I don't leave such a time gap as that between the different tightening stages.

 

Whether or not that's any "better" than the Peugeot specified method I don't know, but it seems to work fine and I've not had any subsequent issues with engines I've done.

[opticaltrigger 52]

Hi Anthony,

Thats quite interesting as it was a Puma racing article that I was given to read sometime ago where I read that bit I mentioned about the standard settings being excessive and running the risk of damage to the threads in the block.

I thought at the time that was a brave statement however it came from someone with a great deal more experience of these engines than me so I had to investigate it further.But the standard settings worked just fine it seems.

 

O.T.

Edited May 16, 2011 by opticaltrigger

[petert 587]

Thats quite interesting as it was a Puma racing article that I was given to read sometime ago where I read that bit I mentioned about the standard settings being excessive and running the risk of damage to the threads in the block.

 

 

If you run a tap through the holes, use new bolts and put moly grease on the threads and under spacers/bolt heads etc., you won't have any trouble pulling around to 300 deg. in one go. The few engines I've seen that have used the 75ftlb method have leaked water. This may be due to being on the high side of the liner clearance, but isn't that what tolerances are all about?

[opticaltrigger 52]

If you run a tap through the holes, use new bolts and put moly grease on the threads and under spacers/bolt heads etc., you won't have any trouble pulling around to 300 deg. in one go. The few engines I've seen that have used the 75ftlb method have leaked water. This may be due to being on the high side of the liner clearance, but isn't that what tolerances are all about?

 

Well said at the end there Peter,I couldn't agree more.

The process you mentioned is exactly what I did save only that I did the angular section in stages as Tom recomended and as you say it worked just fine.

Edited May 16, 2011 by opticaltrigger