Repairing tapped holes in cast iron
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  1. #1
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    Default Repairing tapped holes in cast iron

    The air cleaner on the 205 I am currently resuscitating is mounted, partially, on the exhaust manifold. In the accompanying photo you will see three bosses, which are drilled and tapped. Two of these are used by the air cleaner support bracket. Whether they previously accepted 6mm studs or bolts I don't know - they are long gone. On the way out they "worked" in the holes, so new bolts or studs are a VERY loose fit. Only the bottom few threads have any hold at all, and Loctite will be no help, because of all the heat in this location.

    I have a couple of choices:

    1) I can drill and tap, to accept a 7mm or 8mm stud or bolt. I would prefer a stud. How hard/successful will this be in "heat-treated" cast iron? Any tips?

    2) I can re-insert some new 6mm studs, along with some sort of metal epoxy filler, to take up the loose space. There should be enough thread left to retain the goop. What such products exist, and how successful is this going to be in such a hot spot?

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    Alternatively, you may have better ideas. Is it time to fit a K&N pod? Rob, does Windows offer a solution, maybe carried over from DOS 6.22? Is there a suitable adaptor cable?

    Cheers,

    Tim
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  2. #2
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    Quote Originally Posted by tcusack View Post
    The air cleaner on the 205 I am currently resuscitating is mounted, partially, on the exhaust manifold. In the accompanying photo you will see three bosses, which are drilled and tapped. Two of these are used by the air cleaner support bracket. Whether they previously accepted 6mm studs or bolts I don't know - they are long gone. On the way out they "worked" in the holes, so new bolts or studs are a VERY loose fit. Only the bottom few threads have any hold at all, and Loctite will be no help, because of all the heat in this location.

    I have a couple of choices:

    1) I can drill and tap, to accept a 7mm or 8mm stud or bolt. I would prefer a stud. How hard/successful will this be in "heat-treated" cast iron? Any tips?

    2) I can re-insert some new 6mm studs, along with some sort of metal epoxy filler, to take up the loose space. There should be enough thread left to retain the goop. What such products exist, and how successful is this going to be in such a hot spot?

    Alternatively, you may have better ideas. Is it time to fit a K&N pod? Rob, does Windows offer a solution, maybe carried over from DOS 6.22? Is there a suitable adaptor cable?

    Cheers,

    Tim
    Something mixed up here with two posts???

    I'd consider a helicoil in the existing hole if the meat on the casting land is marginal.

    Otherwise go for it with bigger stud and drill and tap oversize.

    Dare I suggest that 1/4 inch Whitworth taps are a nice tight fit in stripped 6mm hole!

    You could made a stud out of 1/4 BSW bolt and run a die over it to make it M6 and consistent.

  3. #3
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    BSW is very old school. Even older than DOS 6.22. And who can remember such classics as DOS 5.0 with Xtree Gold on top! I would drill 6.0 and tap M7x1. Later 2L manifolds have this thread also. The cast iron is quite easy to drill & tap.

    '92 205 Mi16
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    Budding Architect ???? pugrambo's Avatar
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    i think i still have a copy of xtree here somewhere
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  5. #5
    1000+ Posts robmac's Avatar
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    Quote Originally Posted by PeterT View Post
    BSW is very old school. Even older than DOS 6.22. And who can remember such classics as DOS 5.0 with Xtree Gold on top! I would drill 6.0 and tap M7x1. Later 2L manifolds have this thread also. The cast iron is quite easy to drill & tap.
    Completely agree on both counts. I still Ztree (which is the rip-off of XTG but for windows) You must also remember setver.exe as well.

    The reason I mention 1/4 bsw is that bolts are readily available, it's a nice coarse thread (20tpi from memory) very suited to soft cast iron and no drilling should be required. Thus the spigot on the manifold won't be weakened. You run a die over the stud and make it M6 at the other end.

    M7 1.0 is a much harder to come by and 1mm pitch is a bit fine for cast iron anyway. That is , unless you are Citrun fixer.

    Anyway being older is not necessarily a bad thing if still works well.
    Last edited by robmac; 11th April 2011 at 05:06 PM.

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    Quote Originally Posted by pugrambo View Post
    i think i still have a copy of xtree here somewhere
    I believe I still have the three 1.44 floppies that install DOS 6.22. I used them to install DOS onMicrosoft Virtual PC.

  7. #7
    1000+ Posts PeterT's Avatar
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    Quote Originally Posted by robmac View Post
    M7 1.0 is a much harder to come by and 1mm pitch is a bit fine for cast iron anyway. That is , unless you are Citrun fixer.
    There's heaps of M7x1 bolts on a 205!

    Setver.exe uses valuable memory unnecessarily.

    '92 205 Mi16
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  8. #8
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    Yes, I was surprised these weren't 7mm!

    I still use Xtree - doesn't everybody?

    And I have lots of 6mm drills, and a 7x1mm tap - in my bolt box, in Moorooduc, at the other end of Australia. That bolt box, btw, is worth about $2k. But handy around Frogs.

    Tim

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    Quote Originally Posted by PeterT View Post

    Setver.exe uses valuable memory unnecessarily.
    Unfortunately it's necessary in many cases.

    Haven't you you heard of himem.sys and devicehigh and loadhigh ?

    This solves nearly all DOS memory problems.

    With advent of the 286 processor memory was never an issue .

    Anyway let's stop immediately in case I become "unnecessary " again in Tim's thread - sorry Tim

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    Quote Originally Posted by robmac View Post
    Unfortunately it's necessary in many cases.

    Haven't you you heard of himem.sys and devicehigh and loadhigh ?

    This solves nearly all DOS memory problems.

    With advent of the 286 processor memory was never an issue .

    Anyway let's stop immediately in case I become "unnecessary " again in Tim's thread - sorry Tim
    Think I'll get an iPad. They don't have these conversations.

    Tim

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    Quote Originally Posted by tcusack View Post
    Think I'll get an iPad. They don't have these conversations.

    Tim
    Ah! but they problems of their own

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    1000+ Posts Pugnut403's Avatar
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    Drill and tap.
    Piece of cake to do, but do try to use a cutting oil on the tap. Failing that, even WD40 will help in a pinch.
    Pugs Rule!

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    Tim,

    what about a coat hanger? (No not the plastic ones)!
    Present fleet:-
    Peugeot 93' 205 Gti 16v
    Peugeot 73' 504 Ti from new
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    Renault 72' 16TS from new
    Renault 69' 10
    Renault 71' 10s
    Renault 68' 10 from new

    "Be reasonable do it my way!"


  14. #14
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    Quote Originally Posted by BIGRR View Post
    Tim,

    what about a coat hanger? (No not the plastic ones)!
    But I'd have to take one from somewhere else in the car, where it might be doing a major structural job.

    If the bonnet didn't get in the way so much, I would tie the air cleaner to a star picket and lay it across the guards.

    Tim

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    Quote Originally Posted by cusack View Post
    But I'd have to take one from somewhere else in the car, where it might be doing a major structural job.

    If the bonnet didn't get in the way so much, I would tie the air cleaner to a star picket and lay it across the guards.

    Tim
    Tim,

    you are not just a pretty face .
    Present fleet:-
    Peugeot 93' 205 Gti 16v
    Peugeot 73' 504 Ti from new
    Peugeot 08' 407 Hdi Coupe from new

    Previous fleet:-
    Peugeot 95' 605 Sv
    Peugeot 92' 205 Gti
    Renault 72' 16TS from new
    Renault 69' 10
    Renault 71' 10s
    Renault 68' 10 from new

    "Be reasonable do it my way!"


  16. #16
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    The question has become moot. The manifold has developed a crack, and will need replacing.Can they be welded? Successfully?

    Tim

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    No they can't.
    Adrian Wuillemin

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    Quote Originally Posted by tcusack View Post
    The question has become moot. The manifold has developed a crack, and will need replacing.Can they be welded? Successfully?

    Tim
    Told you not to tap M7

    At least it cracked before you started. The last 504 manifold I replaced a flange stud on, after having battled to get the old stud out and carefully cleaning up with a tap, fell off the bench and hit the deck breaking a piece off an exhaust port flange.

    Far better to have it cracked before starting and start with a goodie.

  19. #19
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    There ios a POR (PPC) product for repairing cracked manifolds that looks interesting.

    If you can't find an uncracked one might be worth a try.
    Adrian Wuillemin

  20. #20
    1000+ Posts PeterT's Avatar
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    Just buy a 2L version. All the 1.9L manifolds are now cracked. I've welded them with cast iron rods but they end up cracking again.

    '92 205 Mi16
    '90 Mi16x4

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    Quote Originally Posted by PeterT View Post
    Just buy a 2L version. All the 1.9L manifolds are now cracked. I've welded them with cast iron rods but they end up cracking again.
    I've yet to crack a 1.9 405 or 205Si one.
    Graham

  22. #22
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    Iron manifolds can indeed be welded, but if it is a stress point then it is likely to crack again...
    Doing a really good job of welding an iron manifold is not easy either.
    I would be looking at that POR stuff myself too...
    Click here for the POR Fireseal page.
    Pugs Rule!

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  23. #23
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    Thanks for these tips guys. My mind has been elsewhere. The roadworthy guy didn't even pick up on the manifold crack - said he could see I had bigger problems with my life, if I was reduced to driving such a POS, and he assumed that I would get around to fixing such an obvious and annoying problem eventually.

    (Actually, he said he worked on these cars in the dealerships when they were new, and what a joy it was to drive, once you got it warmed up and idling - "just like a new one, so reponsive".)

    He couldn't find the engine number, so I'm just going to stamp the number that is on the rego papers, somewhere visible. Naughty!

    And Rob, no, the crack wasn't a result of my efforts to D&T. It appeared after a visit to the muffler shop for a replacement front resonator. Either the blow from the resonator was masking the blow from the manifold, or they managed to crack it in their wrangling - hard to point the finger.

    Tim

  24. #24
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    Quote Originally Posted by tcusack View Post
    Thanks for these tips guys. My mind has been elsewhere. The roadworthy guy didn't even pick up on the manifold crack - said he could see I had bigger problems with my life, if I was reduced to driving such a POS, and he assumed that I would get around to fixing such an obvious and annoying problem eventually.

    (Actually, he said he worked on these cars in the dealerships when they were new, and what a joy it was to drive, once you got it warmed up and idling - "just like a new one, so reponsive".)

    He couldn't find the engine number, so I'm just going to stamp the number that is on the rego papers, somewhere visible. Naughty!

    And Rob, no, the crack wasn't a result of my efforts to D&T. It appeared after a visit to the muffler shop for a replacement front resonator. Either the blow from the resonator was masking the blow from the manifold, or they managed to crack it in their wrangling - hard to point the finger.

    Tim

    I was jesting. I don't doubt you competence. Just to set the record straight.

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