Car: 2010 Passat CC 1.8 TSI
Would it be a really big problem if I use the old cylinder head bolts or not?
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Sign up to join this communityYour Passat uses torque to yield bolts, so they must be replaced. The torque to yield bolts are considered "one and done". This is because during the torquing process, they are stretched beyond deformation, past their plasticity. If you try to use them again, they will fail. If you reuse them, not only will they fail, but you will most likely cause damage to the head due to warpage.
Do it right and get new head bolts.
Replace the bolts, this has been covered in detail on this site : here is one such post with lots of detail :
short term "no". long term "yes!". Why take the chance. Just replace them to make sure your torque is right so you don't have any problems in the future. The old ones will not torque correctly.
I once had to remove and grind the head of an Audi 4 cylinder ,overhead cam . Audi said I must use new head-bolts; but I used the old ones and it worked fine.