View Full Version : Re-using head gasket and bolts
If you've fitted a brand-new HG and head bolts a week ago, and since then all the car has done was idle for literally just 15 minutes would it be ok to re-use the same bolts and HG?
No you would definately have to use new bolts because they are stretch bolts and have a specific tightening sequence, you could use the old gasket if you needed to but i wouldnt advise that either because they do become flattened somewhat by the head!! If you dont do it correctly then you might end up with leaks/mixing of oil and water. You might not but its always better to be safe than sorry.
Why you taking the head off again?
MatBrown
06-01-2007, 02:23
They don't look like stretch bolts.
Mat.
I didnt realise you could tell by looking? You have to leave them for a minute or two mid tightening sequence which suggests that they are stretch bolts. Also, most bolt that has a torque setting and then a set degree turn afterwards i.e. 100nm + 90 degrees are stretch.
Cant remember what mine looked like when i did it but most head bolts ive found are stretch bolts, may be completely wrong mind but itd still be better to replace!
Clio_GTT
06-01-2007, 12:55
easiest way would be to measure them when you take them off. But to save you a whole world of hassle just get a new gasket and bolts. Last thing you want to do is rip the head off for a third time to do it again :x
VIPERONE
06-01-2007, 13:52
No you would definately have to use new bolts because they are stretch bolts and have a specific tightening sequence, you could use the old gasket if you needed to but i wouldnt advise that either because they do become flattened somewhat by the head!! If you dont do it correctly then you might end up with leaks/mixing of oil and water. You might not but its always better to be safe than sorry.
Why you taking the head off again?
they can be reused, ive seen several ppl reuse the bolts, 2live is one of them, think winston may be another.. i wouldnt really reuse a head gasket, unless it looked to be in prestine condition.
I would never re use head bolts they are stretch bolts, hence as above why you tighten, leave, loosen and re-tighten, non stretch bolts you leave the engine running to warm up, cool down and then check torque
Also for the price of a head gasket thsoe botls are done up tight so it is gonna get flattened, i'd ALWAYS use new of both of the above.......easier than haveing to do it again when the head gasket goes
Stop being tight, it cost around £30 for bolts and gasket :)
Bolts are stretch bolts...they cant be re-used (it may work, but clamping force wont be correct, and bolts will be liable to failing...this would be especially true ona tuned engine where cylinder pressure iss higher)
I wouldnt advise re-using HG.
Stop being tight, it cost around £30 for bolts and gasket :) .
Unless you go to renault, who want £9 per BOLT!!!!
VIPERONE
06-01-2007, 14:29
lol 2 lives is still running to this day with reused bolts.
i personally used brand spankers on mine.... there cheap enough bought as part of a kit.!
£12 per set for FAI parts from most factors.
Im not disputing it wont run...but like I say, it will be liable to failure especially if he tunes it.
All bolts stretch, thats how they work....a simple nut and bolt works by a tensile force being applied by the bolt stretching as it opposes the load.
Head bolts are usualyy "stretch to yield"...this means when they are set to a specific extension or torque, the material is taken to just passed the yield point of the material, into the plastic region...which means once the load is removed it doesnt return to its original length...hence they stretch.
Just thought i'd try to clear that up!
Lee Keefy
06-01-2007, 15:15
Stop being tight, it cost around £30 for bolts and gasket :)
Bolts are stretch bolts...they cant be re-used (it may work, but clamping force wont be correct, and bolts will be liable to failing...this would be especially true ona tuned engine where cylinder pressure iss higher)
I wouldnt advise re-using HG.
i agree,it seems like a bit of a risk to go through the procedure of replacing the head gasket without actually doing it,sure you may be lucky an get away with it but if your not its more work again,if the head is of it makes sense. :wink:
All bolts stretch, thats how they work....a simple nut and bolt works by a tensile force being applied by the bolt stretching as it opposes the load.
Head bolts are usualyy "stretch to yield"...this means when they are set to a specific extension or torque, the material is taken to just passed the yield point of the material, into the plastic region...which means once the load is removed it doesnt return to its original length...hence they stretch.
Just thought i'd try to clear that up!
Thanks for that Stan always wondered what made a stretch bolt a erm stretch bolt!
cliolord
06-01-2007, 17:59
as craig said, why you being so tight dude :lol: if you want no problems, replace the head gasket again and use new head bolts at least. You know what a pain it is to do the head gasket on these, total sl4g!
Technically one a metal is past its yield point inot eh plastic reagon its failed, certianly in structural steel this is the case, and after the plastic reagon is the point of total yield whihc is where the cunt breaks
Why you taking the head off again?
Bloody oil leak to the exterior of the engine.
Cheers I'll buy new stuff. Just have to wait 'till next month.
There is a guy on e bay selling the complete head gasket set for £29 and the stretch head bolts for £13. £5.50 delivery, they have a shop on e bay, the gasket shop its called iirc.
:lol:
lol.just to clear it up a bit.
yes i have re-used the head bolts......once
i used em to fit the valver head to my car....it was for 2 weeks only....i had no bolt set kicking about, and needed it urgently.
the head on now has had new bolts in.....as all other heads i do have. if they stayin there.iif its jus for emergency runnin for a few days or so then i will re-use again.
and id never re-use a head gasket.
must also point out........that the initial 2 weeks i thought the valver head would be on for.......and the re-used head bolts..were actually on the car for about 8 months......lol.....and it didnt miss a beat, even managing a couple track days ;)
Jonnyboy
01-02-2007, 09:43
am naughty then, i reused a set at least 3 times. but never the gasket.
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