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I've just got back from Repco enquiring about a Full Gasket set to suit an EJ22 and the bloke there said that I would need to purchase a complete set of new Head Blots as the old ones are supposed to stretch after being installed and then taken out.

I thought that this was a good sales pitch untill a Motor Mechanic that was picking up some parts also confirmed that they needed to be replaced... He said that it was due to the thread on the bolts, apparently they lock in and hold tight when new and if they arn't replaced, they will gradually let go and cause the heads to blow gaskets.

So ... TRUE or FALSE

Is it worth replacing them.

John

true, on an old ea81 we had we checked the head bolts and sure enough they needed tightening,

But yes it is best to replace them i have also been told this by my uncle who is a mechanic when we were going through the resto process

Very true. They are what's reffered to in the industry as a "torque to yield bolt", in laymans terms you can't trust the buggers if they've previously been torqued up.

They will be pricy too, I think I sold a set to Subarino for about $100 a year ago, so retail would be a fair bit more than that I imagine.

I can see head studs being used here.

It is true that you "should" replace them. I haven't for more years than I can remember though. I know of motors that I put together plenty of years ago with pre-loved head bolts that are still going strong. Probably just jinxed myself but that is my 2c worth.

Well, I'm not convinced that you "should" replace them actually. The factory manuals don't say that you should, whereas they definitely specify other items that shouldn't be re-used, like gaskets and seals - there is no mention of not re-using the head bolts at all. The engineers presumably know what they're doing.

The other question is - is the Subaru system actually a "torque to yield" system? The instructions merely say to torque up to specified figures, back off, torque up again and then two stages of a further 80-90 degrees.

Edit: this is also discussed here on the USMB:

http://www.ultimatesubaru.net/forum/sho ... hp?t=56385

I was told the same as the previous replies by an old fashond mechanic who knew his stuff. But he said years ago, when you did NOT throw everything away that's not 100%, that every now and again, you would re torque the head bolts. Apparently was quite common in particular models.

I think that would be fine on a cast iron block, but an alloy one would put a fair bit more pressure on the thread, if it was over tightened.

Thanks for all the comments guy's, looks' like I'm going to reuse the old head bolts after all and hope for the best.

I've had no issues with other motors in the past when reusing head bolts, FSM dosn't state that the head bolts need to be replaced, so I'll follow the manual and see how it goes...

John

I talked to that same mechanic today (as my earlier post), as I was asking about something else. I had commented that I had posted the info on the forum that he had quoted some time ago.

He suggested that it would be fine to re torque the head bolts (on alloy head and block engines) anytime after a couple of thousand kilometers, but make the torque settings on the wrench, slightly lower than what it was put in at. (by a couple of nm)

This way, it would tighten any loose bolts, but not over tighten any that don't need adjustment. He said that any alloy head , particularly if it hasn't had new head bolts, should be re torqued around 20,000km to reduce head gasket failure... Who'd have guessed. May be the older bush mechanics know how to head off trouble.

He said his specialty is fixing other mechanics problems Older and wiser ???

Just passing it along

Thanks Fury for the info, I will certainly be checking the Torque on the head bolts every 10000K's, just to be sure.

I must admit that I've only used head bolts that tighten into a cast iron block through cast and aluminium heads. So it is a little strange to all of a sudden be told that I need to replace all the head bolts because its a boxer motor...

Certainly have learnt to treat the Subaru Boxer Motors with the respect that they deserve, nothing but admiration for them though.

Thanks again to all who commented.

John

be checking the Torque on the head bolts every 10000K's, just to be sure.

You can't really do that, because there is no final torque setting for the head bolts. You could put paint marks on them to see if they have moved, I suppose.

Just some experience over the last couple of years, the type of head gaskets has changed from where you need to re-torque them after a few 100 kms. The newer material composite only requires it to be torqued once.

With the bolts, it just seems standard patter to replace bolts with head work.
Cheap insurance if you have gone to this much trouble.