Cross Threaded?
Discussion
Hey guys,
Just fitted a new Thermostat to my MG ZS180, due to its location I had to remove the front bank inlet manifold when putting the manifold back on 6 of the 7 bolts go in fine but the 7th always stops about 5mm from the manifold. I guess the thread has been crossed and this means its not going all the way in, the bolts are at an angle and its an ally head.
Typically the bolt in question is at the back of the manifold right at the base of the V so you have to work a socket between the rear bank manifold and can only get at the bolt from an angle (good old brit design).
Any simple fixes? I have taken the manifold back off and I am guessing the head is going to need to be retapped....so much for a simple job lol
Just fitted a new Thermostat to my MG ZS180, due to its location I had to remove the front bank inlet manifold when putting the manifold back on 6 of the 7 bolts go in fine but the 7th always stops about 5mm from the manifold. I guess the thread has been crossed and this means its not going all the way in, the bolts are at an angle and its an ally head.
Typically the bolt in question is at the back of the manifold right at the base of the V so you have to work a socket between the rear bank manifold and can only get at the bolt from an angle (good old brit design).
Any simple fixes? I have taken the manifold back off and I am guessing the head is going to need to be retapped....so much for a simple job lol
I take it all the 7 bolts were the same length?
Check the hole is not full of crap by sticking something in there & making sure you can feel the bottom of the hole.
Try this home made thread chaser if there's little or no room for a real one.. Get another bolt the same or longer as the one you're using. Then with a hacksaw cut 2 or 3 equally spaced groves from the start of the thread back as far as you can go towards the head of the bolt. Cut these groves at about a 40 degree angle so they spiral round the bolt. Wind the bolt in & then remove, hopefully your thread will be repaired enough to use.
Edited for idiocy.
Check the hole is not full of crap by sticking something in there & making sure you can feel the bottom of the hole.
Try this home made thread chaser if there's little or no room for a real one.. Get another bolt the same or longer as the one you're using. Then with a hacksaw cut 2 or 3 equally spaced groves from the start of the thread back as far as you can go towards the head of the bolt. Cut these groves at about a 40 degree angle so they spiral round the bolt. Wind the bolt in & then remove, hopefully your thread will be repaired enough to use.
Edited for idiocy.
Edited by smartphone hater on Friday 16th November 16:58
jimmyboy85 said:
If the bolts screwing in and feels pretty firm, can you pack the space between the bolt and the manifold with washers so at least it will tighten down, torque up?
Its a proper botch but should be ok until you can get it sorted.
i would do this, wouldnt call it a botch by any means just doing what you have to do!
Its a proper botch but should be ok until you can get it sorted.
i would do this, wouldnt call it a botch by any means just doing what you have to do!
Edited by jimmyboy85 on Friday 16th November 16:14
Thanks for the suggestions guys!
All 7 bolts are the same length, with the manifold off I tried all 7 of them in the hole and they all stop at the same point so looks like it is cross threaded. I am not supprised as the hole is at an angle and you cant get a socket straight on the bolt because the rear inlet manifold gets in the way (nice design). Will try and get hold of some thread chasers, any idea where I can pick them up? I have done a search but can only find ones for sparkplug or sensor threads which will be too big.
All 7 bolts are the same length, with the manifold off I tried all 7 of them in the hole and they all stop at the same point so looks like it is cross threaded. I am not supprised as the hole is at an angle and you cant get a socket straight on the bolt because the rear inlet manifold gets in the way (nice design). Will try and get hold of some thread chasers, any idea where I can pick them up? I have done a search but can only find ones for sparkplug or sensor threads which will be too big.
If you've got the room & don't fancy using a home made one then I'd just use a normal threading tap like this, but obviously get the correct size & pitch..
http://www.ffx.co.uk/tools/product/Han8340%20Tap%2...
http://www.ffx.co.uk/tools/product/Han8340%20Tap%2...
Garybee said:
Have you checked to make sure the hole is clear as suggested above? If you've dropped some fluid into the (blind) hole you could be doing lots of work here for no reason.
Yeah double checked that, will be triple checking it when I get some light (no power in the garage 
) turns out my old man has a tapping set so if it all goes pear shaped he is on hand, just got to wait for him to get off an oil rig. Just done some measuring of the bolt width and manifold thickness, it looks like the minimum size bolt I can go with is 1.7mm in length. The current bolts are 2.5mm in length, just got to see how far the bolt will screw in to see if I can just get away with a shorter bolt.
Looking forward to moving house so I can have power in the garage and do all this stuff in the evenings and not have to wait until the weekend!!!
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