I have a 7mgte motor, and I recently snapped a water pump bolt and e.z out off in the block and have now drilled through them both successfully. Now my question is should I use a helicoil, or retap the hole? If I retap the hole, then how big should I drill the hole to tap it to the right size? I'm thinking about 1/16th. of an inch smaller than the size of the bolt, but I'm sure thread count and size is a factor as well. Does anyone have any advice? And another thing is, I have to buy a new bolt now and I'm not sure what type of metal the bolts are made of. I'm sure its carbon steel but Im not 100% on that.
Tap or Helicoil?
- Thread starter C-flo
- Start date
Helicoil Kits come with the correct drill for the job, and Helicoils are way stronger than re-tapping aluminum. As for the bolt, just get one from Toyota.
C-flo;1396776 said:
sounds like your drilling destroyed your original threads, in which case i would helicoil it. If you drilled in with a slighly smaller bit which drilled into the stud and left the threads unharmed but with the bolts threads still in it, you can clean it out with a tap of the same size as the original bolt.
For future references, if possible its almost always better to just leave it alone and bring it to a machine shop. A local shop did this recently for me on a liftgate pump, it was like 50 bucks for him to drill it out and retap it. Still uses same size bolt like it never happened.
It all depends on the tap as to what drill bit to use....
For example a 7/8-9 tap requires a 49/64 drill
a 7/8-14 tap requires 13/16 drill
if you do a good job drilling out the broken bolt then you may be able to helicoil back to the stock thread size...if not then you'll have to tap to a few boltsizes bigger...
For example a 7/8-9 tap requires a 49/64 drill
a 7/8-14 tap requires 13/16 drill
if you do a good job drilling out the broken bolt then you may be able to helicoil back to the stock thread size...if not then you'll have to tap to a few boltsizes bigger...
So with a helicoil kit all I need to know is the size of the bolt right? As far as retapping it goes, I know in the construction field I have had to tap threads into carbon still that never existed before in a hole in order to screw in cap screws, so my thought process with this was the same. I figured even if I did drill through the threads, I could tap brand new threads into the block even if I tap the threads into the little bit of broken bolt that is in the hole. A helicoil kit sounds a whole lot easier though. And I called Toyota a while back when this situation first occured, and they only sale the whole waterpump assembly bolts as a package for $80.00 instead of just single bolts. It might be a good idea to replace them all anyway though since one broke off I'm sure another will be ready to break as well.
So bottom line is...if you're going to helicoil then purchase a kit that includes tap and drill....
If you're just going to retap then let me or whoever know what tap you're going to use and I/whoever can tell you the proper drill size for said tap.
Tap and drill sizes are not exactly concreat either...depending on the material being tap'd then sometimes a larger drill bit helps limit the chance of a broken tap...if this is just aluminum then it doesn't matter but if it was the iron block then I'd personally recomend a drill that's a few thousandths bigger.
For what it's worth I'm a machinist ;-)
If you're just going to retap then let me or whoever know what tap you're going to use and I/whoever can tell you the proper drill size for said tap.
Tap and drill sizes are not exactly concreat either...depending on the material being tap'd then sometimes a larger drill bit helps limit the chance of a broken tap...if this is just aluminum then it doesn't matter but if it was the iron block then I'd personally recomend a drill that's a few thousandths bigger.
For what it's worth I'm a machinist ;-)
C-flo;1396812 said:
Keenserts/timecerts are a little more involved and require more material to be removed...if there isn't much wall thickness from around the pump then a timecert isn't really an option....timecerts generally are something that needs ordered as well as helicoils unless you have a machineshop supply company local....
Considering the bolt you broke doesn't see much heat then a timecert is overkill not to mention those bolts don't get much torque...helicoil will indeed be fine.
The advice is very very much appreciated, and If I can help you guys in anyway, let me know. One more thing. I always got the impression that a helicoil is basically a spring or a set of threads that you put into a blank hole. It sounds to me from what you all have told me is that you have to tap the hole anyway even with a helicoil, so it almost seems like you might as well just tap the hole and screw in the bolt.
A helicoil is like a spring but yes you need to tap and screw the coil in and then you'll have your original thread size...helicoil is a pretty strong design...some of the parts we make at work get helicoiled by design!
shaeff;1396876 said:
Timecerts are better....but you need to have enough material around said hole to install them or else you can cut into some other part of the housing and cause a leak or whatever....hard to tell which bolt he broke as there is no pic so I or us can't really tell him which route to take....some of the water pump bolts are pretty close to the actual pump portion of the housing.
I just don't want to tell him to go either way as I don't want him to breakthrew the wall into something that will leak.
Toyota will have, or can order individual bolts. 1619343010 for the 8MM bolts, 1619843010 for the 6MM bolts. Helicoil it, don't just overtap it.
Ok, thanks for the part numbers. I went to auto zone, and oreilly's a little while ago and used there bolt chart and if I'm correct, the bolt size is m6-1. I know that the head of the bolt is a 10mm socket, so 6mm should be the size of the bolt itself. The situation at hand now is making the decision to buy the kit that includes the tap, insert, and helicoil tool (these kits didn't include the drill bit) , or buy the items seperately and save money. My only question is is there a way to insert the helicoil without using the tool that comes in that kit? By the way the bolt that snapped is the bottom left bolt if thats a good way to describe it. I will try to get pics.
IJ.;1396973 said:
Indeed I agree! But sometimes shit in one hand and want in the other and see which one fills up first:-(
timecerts and helicoils will prevent that from happening which is why I personally recomend the helicoil as it's an easier product to use for this application "my opinion"...much more user friendly and limits the amount of material removed in order to work as timecerts are much thicker.
C-flo;1396966 said:
You'll need the tool....as there is a tab on each coil that bends toward the center, this tab needs to be broken off after instalation....I have a special spring loaded tool that snaps them in a jiffy but it wasn't very cheap $20 or so. The helicoil kit should atleast tell you what tap is needed and from that we can tell you what drill bit to use....hell I can mail you a drill if need be lol.
This is all you need! Comes with everything....it's a bit pricey but it has extra coils on the "just in case" situations....
http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=1648924&PMT4NO=69831724
http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=1648924&PMT4NO=69831724
The website you gave me shows the drill size to be 1/4" which if you convert from metric to standard (since my bolt is metric) is the same size as my bolt. I thought you were supposed to drill your hole a little smaller than the bolt size and then tap the threads. I can only assume that the helicoil insert shortens the diameter of the hole to the proper size in order for the bolt to thread in snug? And the tab at the end of the insert that you snap off once you get the insert threaded in, I was thinking maybe I could grab it with needle nose pliers or something to that effect to thread the insert in, instead of buying the helicoil tool.