New head gasket, do I *have* to replace the head bolts?

[Undert4ker]

Just like it says, do I actually need to replace the head bolts when I change the head gasket. Haynes Book of Lies says yes but I thought that was only for stretched bolts in high performance engines. The 1.4 APQ is a poky little thing but high performance it ain't!

Basically, the gasket needs doing yesterday but if I buy bolts too I can't afford the timing belt kit so hoping for some guidance...

Cheers

 

[techie]

Nothing to do with high performance its how the bolt tightens up, yes they have to be replaced or the job aint worth doing.

 

[Caffienated]

Yups, (most) head bolts stretch when you wind them in. They don't quite do the job second time around, which is basically just gonna give you another leak.

Dunno where you've priced head bolts... I did a head on a Polo a few years ago, and found a little engine-work place in Sheffield (where I was living at the time) who did me a full set for about £25, much much cheaper than the bigger motor factors' I normally used. Might be worth a half hour with the yellow pages. You might save on the belt kit too!

 

[cocadave]

have a word with sere motors on here

top guy

 

[ather`s]

also try GSF parts.

 

[Slimy]

Yes, definitely replace, and yes, they're not really that expensive if you shop around. As an example (not necessarily a recommendation), here is a set on Ebay;

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=130353623317

(just searched on APQ engine code)

 

[Fl@pper]

do you like talking it apart a lot ???

 

[HoopDub]

actually the bolts do not need to be replaced on APQ/AEX

 

[Undert4ker]

Alright, point taken, I'll go with the majority on this one! At least I've learnt something about head bolts Bits on their way from Euro Car Parts...

 

[ather`s]

actually the bolts do not need to be replaced on APQ/AEX

whys that then??

 

[HoopDub]

because they are not stretch bolts, so autodata says

 

[Caffienated]

To be fair, I don't know the APQ/AEX in detail, but the majority of reasonably recent engines stress the head bolts. Some, like the Rover K series actually pretty much hold the whole engine together with them!

I'd be surprised to find that the engine in question was old-school enough that it didn't matter, but it could be the case. It should be noted that even if you *ARE* planning to *try* reusing the bolts, they need to be carefully checked against a specified permitted variance from original spec. If *any* are out-of-range of tolerance, the whole set needs replacing. This even applies if the bolts are not designed as stretch bolts. They *will* have stretched.

Personally, I'd change them out of hand if I was heaving the head off. Depending on why the head was coming off, I'd probably also want the head crack-testing and checking to see that it was still the right shape, too...

Why? Same reason I wouldn't be re-using bolts that held safety-critical steering or suspension components together that were likely to see cornering loads, except that in the case of the engine it's only the engine that would be dieing if the bolts failed.

 

[HoopDub]

K series, ****cringe**** i totally recomend changing them, just saying that acording to autodata they dont have to be

 

[Fl@pper]

knowing how common teh engine is for overheating / blowing head gasket's and the fact that the heads are rare to find unless warped like a kids slide then for the sake of £15 or so if that i'd use new ones every time

better still while it's off get it checked and skimmed clean to be sure too

 

[Undert4ker]

Having read the tightening sequence (then actually done it) feel a bit embarrassed to have asked! Hey ho, live and learn...

Stupid question no 2 tho, should the new head gasket be delaminated along all the edges? The centres around the bores are fixed properly but the layers are separated for about half an inch all round the edge.

 

[Slimy]

Stupid question no 2 tho, should the new head gasket be delaminated along all the edges? The centres around the bores are fixed properly but the layers are separated for about half an inch all round the edge.

I don't believe it matters. The important part is the seals around all the bores. That should include cylinders, water and oil channels. The rest of it just holds the thing together.

Anyway, the amount of force you apply with the head will definitely take care of any separation!

 

[Fl@pper]

if its a multi layer one like this then no it will actually help if there if there any irregularities in the head

 

[Slimy]

That's a good pic, you can actually see some delamination at the edge. And I'm guessing that's a catalogue picture of some kind?

 

[Fl@pper]

google image : MLS gasket

Multi Layer Steel

 

[Undert4ker]

Nice one, puts my ind at ease!

Cheers for all the help, on to the next problem!