Replace Head Bolts - 404?
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Thread: Replace Head Bolts - 404?

  1. #1
    1000+ Posts Dano's Avatar
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    Default Replace Head Bolts - 404?

    Whilst reading through workshop manual re: reassembling the motor, I notice the following (see below). It states that for engines prior to 1968, the head bolts should be replaced. I have never done or heard of this before, has anyone any thoughts on why this is required.


    I'd appreciate any feedback as to why the factory deemed this necessary.

    Cheers,

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  2. #2
    1000+ Posts Mike Tippett's Avatar
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    I have read that too but in the past when doing a minor KF2 404 engine rebuild I have (apparently) successfully reused head bolts. Sourcing a set these days of NOS bolts would be difficult, I think. But if you find a source, please let me know!
    1966 Peugeot 404 Coupť Injection post-restoration reassembly underway!
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  3. #3
    1000+ Posts robmac's Avatar
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    I've never replaced head bolts, never had one strip or break.

    But I do run a chaser tap down all bolt holes in the head, and have fitted timeserts to suspect bolt holes and replaced corroded head bolts with "good used spares".

    Time-Sert Thread Repair - Helicoil Alternative- Cross Tools Co

    I also blow out the holes in the block and use lanolin on the bolt threads.

    PS: If you feel replacement is necessary, you may find a HT bolt or cap screw to do the job.

  4. #4
    1000+ Posts Dano's Avatar
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    Cheers Mike and Robmac,

    Good advice Robmac, had thought of all the suggestions, except the Lanolin. I like it.

    As both said, I've never replaced them either, just thought I'd throw it out there. From memory though, it was also recommended for the early 504 Diesels engines.

    Cheers,

    Dan

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    One broken ever, removing from Renault 4CV engine. The threads were fine - the problem was accumulated junk along the shank inside the head - once the head was off, the stump unscrewed by hand from the block.

    Good idea to run a tap and to blow out the holes.

    I too have a good supply of old spares.

    Cheers
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    1000+ Posts robmac's Avatar
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    except the Lanolin. I like it.
    Lanolin is great stuff, good lubricant and anti seize, a quick remedy for burns, good when mig welding to reduce spatter, lubricant for cables when pulling into conduit virtually anywhere a non EP but tenacious lubricant is needed.

    I use it around the house on door hinges, taps, etc etc.

    In fact, my wife suggested using it on my toast the other day, but I drew the line and stuck with the Leather wood honey.

    Bunnings had three bottle of liquid and three jars grease on their clearance table at $2.00 ea a few years ago. I bought the lot.
    Last edited by robmac; 25th December 2015 at 08:10 PM.

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    1000+ Posts Dano's Avatar
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    Bruce Llewellyn, fellow QLD frogger suggested soaking the door-card and dash pads of the 404 in it, to make them supple again. Worked a treat. Bit of bugger to get off, but once cleaned up and polished they looked great. Before application the plastic creaked, after it was supple and spongy.

    Bit like fish oil, it has a million and one uses.

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    Old head bolts are like old elastic they have so long or so many times they can be stretched before they no longer apply the same yield force (spring back) when under tension.
    Using old bolts may contribute to early head gasket failure due to uneven or insufficient clamping force!

    Warning don't be tempted to tighten a little more to allow for this as this may simply stretch the bolts past their elastic limits.

    I'm sure there would be a new ARP or similar item that would fit or could be made to fit the 404

  9. #9
    1000+ Posts robmac's Avatar
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    Quote Originally Posted by steelsprings View Post
    Old head bolts are like old elastic they have so long or so many times they can be stretched before they no longer apply the same yield force (spring back) when under tension.
    Using old bolts may contribute to early head gasket failure due to uneven or insufficient clamping force!

    Warning don't be tempted to tighten a little more to allow for this as this may simply stretch the bolts past their elastic limits.

    I'm sure there would be a new ARP or similar item that would fit or could be made to fit the 404
    I believe this is the case with TTY bolts, but 404s were built and designed whilst the TTY design engineers were wearing nappies or possibly still twinkles in their father's eye.

    The only XN engine, afaik that uses TTY bolts in the SLI vehicles with Bosch K(?) Jetronic.

    We are talking an engine that has it's origins early 60s. And is very similar to an engine designed early 50s.
    Last edited by robmac; 25th December 2015 at 09:06 PM.
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  10. #10
    1000+ Posts Beano's Avatar
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    Quote Originally Posted by steelsprings View Post
    Old head bolts are like old elastic they have so long or so many times they can be stretched before they no longer apply the same yield force (spring back) when under tension.
    Using old bolts may contribute to early head gasket failure due to uneven or insufficient clamping force!
    You've got a good point there, but....


    Quote Originally Posted by steelsprings View Post

    Warning don't be tempted to tighten a little more to allow for this as this may simply stretch the bolts past their elastic limits.
    ...an old guy who used to work on XN engines once told me that once the head had been shaved too many times, instead of using an aluminium shim with gasket, he used to use two head gaskets and torque the bolts down to 90 lbs. He said he'd done it a fair few times. I did this once on a 504 and it was a pretty extreme torquing down. Doing the final quarter turn in one smooth action was pretty hard. But the bolts didn't break (or ...luckily..... strip the rear exhaust-side thread in the block......which is notorious for that).

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    Quote Originally Posted by robmac View Post
    I believe this is the case with TTY bolts, but 404s were built and designed whilst the TTY design engineers were wearing nappies or possibly still twinkles in their father's eye.

    The only XN engine, afaik that uses TTY bolts in the SLI vehicles with Bosch K(?) Jetronic.

    We are talking an engine that has it's origins early 60s. And is very similar to an engine designed early 50s.
    the tty bolts are the ones with torx head, aren't they? so the parts catalogue says that the only pushrod engines that had them are the ones with double barrel carburettors manufactured after 4/89, but not in australia...

  12. #12
    1000+ Posts robmac's Avatar
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    Quote Originally Posted by Beano View Post
    You've got a good point there, but....




    ...an old guy who used to work on XN engines once told me that once the head had been shaved too many times, instead of using an aluminium shim with gasket, he used to use two head gaskets and torque the bolts down to 90 lbs. He said he'd done it a fair few times. I did this once on a 504 and it was a pretty extreme torquing down. Doing the final quarter turn in one smooth action was pretty hard. But the bolts didn't break (or ...luckily..... strip the rear exhaust-side thread in the block......which is notorious for that).
    With two head gaskets you introduce a new issue, two gasket compressing and reduction in gasket thickness. And 90 lb/ ft torque is really running the gauntlet on a m12 boltwith a tapped thread in cast iron. The manufacturer recommends 58 lb/ ft IRRC.

    90 il/ft is over 50% spec. I use 60 lb/ft and hylomar on both sides of a single gasket. Never had an issue.

    I would never use two gaskets, I'd follow Thanos's recommendations of using a copper shim plate, after all, he has a history of building reliable cars and high performance , reliable engines.

    Do the job once and do the job properly has always been my approach.
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  13. #13
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    Need to reclarify clamping force and torque.
    Read Below I added many moons ago
    Read in detail about bolt stretching when over torquing

    Perfect Engine Sealing Starts With Proper Head Bolt Use - Engine Builder Magazine

    Happy torque year
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  14. #14
    1000+ Posts Peter Chisholm's Avatar
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    Good article. I've always thoroughly cleaned out the block bolt holes and bolt threads, and used a bit of WD 40. I've never had a stripped block thread. Touch wood.

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    Can also get it in spray cans - useful for water/rustproofing after restorations. Gets into the nooks and crannies quite well.

    Andrew
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  16. #16
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    Icon7 lanolin

    Quote Originally Posted by robmac View Post
    Lanolin is great stuff, good lubricant and anti seize, a quick remedy for burns, good when mig welding to reduce spatter, lubricant for cables when pulling into conduit virtually anywhere a non EP but tenacious lubricant is needed.

    I use it around the house on door hinges, taps, etc etc.

    In fact, my wife suggested using it on my toast the other day, but I drew the line and stuck with the Leather wood honey.

    Bunnings had three bottle of liquid and three jars grease on their clearance table at $2.00 ea a few years ago. I bought the lot.
    Also good as a lubricant when installing fixed glass panes...like 404 wagon side windows. anti corrosion too!

  17. #17
    1000+ Posts Beano's Avatar
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    Quote Originally Posted by robmac View Post
    I'd follow Thanos's recommendations of using a copper shim plate, after all, he has a history of building reliable cars and high performance , reliable engines.

    Do the job once and do the job properly has always been my approach.
    I see your point and agree....using two gaskets is rather extreme. And Thanos is the man with a proven history.

    I just thought I'd throw that story into the arena to illustrate how tough these older Pug cylinder head bolts can be.

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