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Thread: Best way to fix stuffed aluminium threaded sensor hole

  1. #1
    Junior Member Automotive Encyclopaedia stidnam's Avatar
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    Default Best way to fix stuffed aluminium threaded sensor hole

    So an oil sensor was snapped off in the aluminium sump piece that I just bought. Tried to removed it with the torx bit trick but the sensor was brass so it just ate out the sensor. Ended up die grinding out as much of the sensor as possible but now am left with this



    Hard to see but there is bits of brass still in the threads. Didn't want to go deeper as the aluminium thread was starting to show.

    So I've come up with 2 ways of fixing it.

    1. Drill out hole so it is free of brass and then get it welded full and retap a new hole

    2. Drill out the hole and retap for a helicoil assuming that I can get a helicoil to suit the sensor thread. Not sure what the thread of the oil pressure sensor is but will measure it tomorrow with the thread gauge at work.

    Any other options?

    Also need to remove the grub screws to clean out the oil galleries but they wont budge and I wasn't game to use more force as the 8mm allen key was starting to slip in the hole. Any ideas on how to get these out?


  2. #2
    doctor ed Conversion King ed's Avatar
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    Default Re: Best way to fix stuffed aluminium threaded sensor hole

    ten bucks says the sensor is a taper pipe thread

    id just drill it out, throw a dob of weld in there and tap it again

    the other threads... butane torch, hex driver, tap with hammer, remove
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  3. #3
    Forum Member 1st year Apprentice
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    Default Re: Best way to fix stuffed aluminium threaded sensor hole

    If this was my car I would drill it out, tap it and insert a time sert that will allow the sensor to screw in, but when fitting the time sert into the engine I'd coat it in loctite 518 or similar to seal it, you could use a helicoil but I feel you would have dramas with it leaking.

  4. #4
    Junior Member Automotive Encyclopaedia stidnam's Avatar
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    Default Re: Best way to fix stuffed aluminium threaded sensor hole

    Looked at the time sert site and it doesn't look like they have a insert to suit as I've found that the oil pressure sender is 1/8bpt(british pipe thread).

    I'm leaning towards drilling and getting the hole welded up so I can retap it to the sender.

    Still need to remove the grub screws to clean out the metal bits from the die grinding or else it wont be pretty when I start the engine for the first time

  5. #5
    Chookhouse Chooning Automotive Encyclopaedia Hen's Avatar
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    Default Re: Best way to fix stuffed aluminium threaded sensor hole

    If the thread in the aluminium is not yet stuffed, one (slightly dodgy) technique I've had some success with in the past is to VERY CAREFULLY drill out the centre of the brass piece, with increasing drill sizes until you have removed all the brass out to the minor diameter of the threads. Then pick the rest of the brass out with a sharp point and run a tap through the hole to clean things up.

    It is pretty tricky to get right without damaging the thread, but got me out of a couple of tight spots.

    Hen
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  6. #6
    Junior Member Backyard Mechanic
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    Default Re: Best way to fix stuffed aluminium threaded sensor hole

    You could try warming up the sensor with a blow torch or oxy because it might be stuck in with either loctite or some type of sealant. A bit of heat should melt the sealant so it comes out easily. I would heat the other plugs as well. You can usually smell the loctite when it melts, plus it will smoke a bit.

  7. #7
    Junior Member Backyard Mechanic
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    Default Re: Best way to fix stuffed aluminium threaded sensor hole

    I agree with the light heating. When the thread size is so small I've only tightened these up by hand as they do lock in with the taper thread.

  8. #8
    AVGAS DRINKING Carport Converter 30psi 4agte's Avatar
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    Default Re: Best way to fix stuffed aluminium threaded sensor hole

    I agree with hen........ thats how id tackle it too. If you get all the brass out and the alloy is stuffed then i have it welded and re tapped. An half decent machine shop worth a grain of salt will beable to do it. Hell if you were in SA id do it.

    As for removing the plug............. heat is the only way. The tap with a hammer trick works but i prefer to shrink it........ works every time.

    Basicly heat the plug then spray it with some WD40. this will quickly shrink the plug from the expanded steel and you will find it will wind straight out.

  9. #9
    Estranged Member Chief Engine Builder mullett's Avatar
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    Default Re: Best way to fix stuffed aluminium threaded sensor hole

    If the hole has some depth, you can drill it out, *CAREFULLY* and re-tap. The damaged thread will be OK, because the taper can be over-cut.

    Edit: Beware of over-tapping also if the sensor-thread clearance is low...you won't be able to screw it in far enough. Loctite make an awesome taper-thread sealant that will fix this

    -RM

  10. #10
    I definitely ain't a Chief Engine Builder wagonist's Avatar
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    Default Re: Best way to fix stuffed aluminium threaded sensor hole

    I think a few posts up the point has been missed that he has already drilled/diegrinded out the brass sender.

    Though the suggestions would be useful for next time.

    now that the bulk of the sensor is gone, the thread "should" almost spin out using some fine screwdrivers & gentle tap with a hammer.

    Personally, though, I'd finish drilling it out, weld up the hole & re-tap it.

    I had this done on a WRX engine to fit temp sensor in from the car it was going into (needed a bigger hole).

    Though during this drilling process, I'd try to get some old oil into the galleries to try to collect/control the swarf from the drilling.
    Overfill the engine until it upto that point, tip the engine slightly, then when done, tip the engine towards the hole so most of the swarfed oil comes out that hole, cleaning it on the way out.
    (Feel free to comment on the pros/cons of this)

  11. #11
    3RZFE-T Backyard Mechanic
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    Default Re: Best way to fix stuffed aluminium threaded sensor hole

    Drill it out enogh to get rid of the brass. Go down to auobahn and buy the metal putty shit.
    Bung up that hole then drill that shit and tap it out. Wallah

  12. #12
    Village Idiot Automotive Encyclopaedia
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    Default Re: Best way to fix stuffed aluminium threaded sensor hole

    the hen method works
    what i've found is sometimes with drilling it out the thread collapses and you can unscrew it.
    have you tried an ezy-out : ie: drilled into it and then reversed it out?

  13. #13
    Junior Member Automotive Encyclopaedia stidnam's Avatar
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    Default Re: Best way to fix stuffed aluminium threaded sensor hole

    Ok so this is fixed of sorts. I took it up to the metal fabricators I use and got them to have a look at it and fill weld it if it was totally stuffed. They just cleaned out the threads a bit and then ran a tap through it. I couldn't screw out the remnants due to the first bits of the aluminium thread being damaged by something hitting it and locking in the brass sender.

    The replacement sender now screws into the thread but the first few lines of the thread are not 100 complete partly due to the damage to the threads when I got the sump & partly due to removing the brass. Will thread lock it in place when I am ready to use the sump.

    Got the other plugs out by heating them to loosen the thread sealant. I didn't realise that with thread sealants they melt above a temperature which is why people say to heat them to loosen them.

    I've blasted out the galleries with compressed air to clean out the swarf but am going to run some petrol/oil through them to clean them out more.

  14. #14
    Village Idiot Automotive Encyclopaedia
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    Default Re: Best way to fix stuffed aluminium threaded sensor hole

    stiddy - definately make sure the galleries are clean.

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