Hi guys, after some advice really.
I have basically finished rebuilding my G just have to completely refabricate the exhaust mani around the charger and I'm done.
I have gone quite far with it e.g. All new main/big end bearing shells new pump new rings, new head with new valve guides, all new gaskets obviously had the crank checked out honed the bores etc etc. I have also bought a few new parts, helix clutch new charger GT inlet mani.
Now having done all of the above and more like a bit of home porting matching the head with manifold's. I have bought some as advertised "g40 head bolts" for about 40-50 bucks if I remember rightly but i have been reading up on a few topics and the is a lot of hype about getting the right head bolts.
Now when I changed them I compared them to the old ones they were slightly shorter, is this due to them being stretch bolts and they actually stretch when you torque them up?? As my engine is back in my car now just waiting for the exhaust to be done and then turn it over I fear they could be the wrong ones and I have done all this work only to take it apart again because the HG had gone because I have the wrong bolts??
Could someone please let me know as I would rather strip it again now and replace them before running it.
Could some one help?? Thanks Jake.
If they are 2mm shorter then they aren't specific G40 head bolts. G40 bolts should be 13mm and i believe all head bolts will stretch.
Trying to find the topic why you must use the correct ones.
Have a read http://www.polog40.co.uk/forum/index.php/topic,6753.0.html
I would hope they are proper ones for £40-£50!! where did you get them from?
Just out of curiosity, has any one actually suffered a head bolt failure?
I have always used g40 specific ones.
Quote from: confusionhunter on June 09, 2011, 11:27:31 AM
Just out of curiosity, has any one actually suffered a head bolt failure?
nope and I'm not using proper g40 ones because at the time I assumed it was best not to when not using a g40 head gasket
i snapped one ( a new one ) about 5 years ago, as well as snapping a camshaft bolt too, basically had no idea how a torque wrench worked :lol:
had to whip the head off and just spin the snapped portion of the head bolt out, as luckily it hadnt snapped clean off in the block, but left a good 2.5/3 inches of meat sticking out of the block
Doh! fair enough but thats not a failure in use though is it. Im just wondering if anyone has actually had a failure on a G40 engine.....Good old vw/audi overspeccing everything!
Can always get uprated bolts for €40 from g-ladersite and bar tek.
Jezza- yeh they were only literally a couple of mm shorter hence why I thought that because they were stretch bolts then they were the right ones because I thought they stew he'd when they were torqued up??
Hayesey- I think I got them from bar-tek-tuning or GSF I can't remember it was quite a while ago.
What do you guys think?
Part of me thinks: Not worth taking the risk, just get the right ones and swap them if in any doubt..... now in theory, if you are not removing the head and swapping the bolts, you are not breaking the contact from the head gasket, so would you need to changethe gasket?
Other part of me thinks:
whats the worst that can happen?
Water in the oil? Loss of compression? The you'll have to do a head gasket and renew bolts, which is the only thing to do to fix the issue in the first place! VW tolerances are massive son unless you are running 200bhp plus. Id leave it and if it aint broke dont fix it!!
The only reason I doubt the need for it to be absolutely correct is that many many years ago Paul B and I did a piston change in the middle of the night 400 miles from home and a limited tool kit....and had no choice but to re use the head gasket and the head bolts etc. I needed to get home. And it got me home, and then took several hard turbo'd thousand miles later and 7 years on, (despite not having moved much) its still good and producing good power....! And when/if I get the car on the road again I'll continue to hammer it till it breaks! Or I upgrade the head bottom end or something!
I've used boggo GSF head bolts in mine, albeit with the thinner gasket.
Quote from: Andy on June 09, 2011, 05:13:29 PM
I've used boggo GSF head bolts in mine, albeit with the thinner gasket.
Me too I believe when I did my last head gasket.
Quote from: SamG40 on June 09, 2011, 06:04:38 PM
Quote from: Andy on June 09, 2011, 05:13:29 PM
I've used boggo GSF head bolts in mine, albeit with the thinner gasket.
Me too I believe when I did my last head gasket.
ditto
Yup me too, but I used the g40 gasket although I can't vouch for reliablilty as I havnt run it yet !!
You will certainly get less clamp load using non G40 bolts. Tps decided to supply me 9 G40 head bolts instead of the 10 I ordered so out of desperation I used 1 Gsf bolt. With all of the bolts torqued to the correct sequence I did an over checked with 100nm on the torque wrench and all the G40 bolts clicked off but the GSF bolt didn't and kept going.
next time the head comes of, be it from head gasket faliure or for any other reason i will defiantly be swapping to genuine bolts but the gsf ones will stayy in untill somthing goes wrong now
Quote from: Robin on June 09, 2011, 10:08:50 PMYou will certainly get less clamp load using non G40 bolts.
????
surely if you torque them the same then it's the same clamp load? But the weaker ones are more likely to break
What's the right torque load anyway??
I torqued mine up 60nm then 2x90 degrees or 1x180 degrees??
Yeah thats right 40nm 60nm then 2x90 or 1x180
Just had a quick scout on a couple of websites and I believe I got my bolts from bar-tek-tuning so they should be proper g40 spec bolts and they are torqued correctly cheers jezza.
So hopefully they should be fine (fingers crossed).
cheers for all the post's lad's
Quote from: hayesey on June 10, 2011, 09:15:22 AM
surely if you torque them the same then it's the same clamp load? But the weaker ones are more likely to break
maybe not the same clamp load if they stretch more???
hmm maybe actually since the last stages of torqueing are angles rather than lb/ft
Pete is correct.
Instead of clamping more the bolt is actually stretching instead.