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Up Topic American Welding Society Services / Technical Standards & Publications / cast iron engine block botched bolt hole
- - By eclipse99 Date 05-06-2007 07:06
I had recently purchased a rebuilt motor for my car.  the block is cast iron.  out of the 5 holes in the block where the water pump bolts to it, one of them is twice the size and oval in shape.  it is supposed to be threaded m8-1.25, instead it is about 11mm wide with no threads.  since this is a significant difference, it would be hard to thread and bolt the pump this way due to space limitations.  what is the best method of reducing the size of the hole to where it can be used and seal properly. ive heard from baking and welding it to applying jb weld and drilling it.
Parent - - By webbcity (***) Date 05-06-2007 11:38
eclipse99 , if i paid for the engine and it's not the correct one i would return it and get the one that would fit . there are many ways you could scab it up and possibly make it work but would you trust it ? good luck . willie
Parent - - By eclipse99 Date 05-06-2007 17:06
it is the right block, but wrong year, will still fit though.  the issue is one of the holes appears to have been drilled out as if a bolt was previously broken in it
Parent - By aevald (*****) Date 05-06-2007 19:18
Hello eclipse99, there are a number of different thread-saver type systems that are available, Keensert is one of the makers, Helicoil is another way that you can go. How badly the hole is wallowed out will likely determine the route that you will need to go. I have in some instances drilled and tapped the hole to the closest size that will work based on the condition of the hole, then I have taken a bolt of the same size and thread pitch, cut a section of it off and drilled and tapped the center of this bolt to the size of the original threaded hole making it into a threaded insert. Get a good grade of loctite and install this into the hole, allow it to set as required by the grade of loctite and then bolt the assembly together. Just a thought on how you could make this work. Regards, aevald
Parent - - By billvanderhoof (****) Date 05-07-2007 05:53
Before you do anything check with the rebuilder.  He may prefer to repair this himself or if it's a major company, replace it.  This is a warranty issue, the engine is unsuitable for service as it now is (look up warrant of merchantability).

If you get no joy the method aevald suggests works well.  I wouldn't weld it (too likely to get hard spots that will be difficult to drill or tap).
Bill
Parent - - By DaveBoyer (*****) Date 05-07-2007 06:56
I would absolutely talk to the rebuilder first. Aevald's methods rely on being able to get a round hole in the same location as the original hole - it may be too late in the game for that. If by the time You get a round enough hole that You can tap it, the location is WAY off You can plug with a regular soft bolt, cut it off and file flush, then drill a new hole where it belongs and tap that hole. The plug must bind up tight in the tapped hole so it can't turn, or it will be a *BITCH* if You ever have to take it apart. There is allso a possibility that there is a piece of broken off easy-out or tap in the hole, drilling these out is a real problem.
Parent - - By eclipse99 Date 05-07-2007 15:04
i can see from my recent experience trying to repair two other holes also that working with cast iron is a bitch.  i have already retapped one hole to a size bigger and another i just redrilled slightly to the left.  i tapped that one to the original size m6-1.00 and the tap has broken off twice in it.  i am trying to see if i can get a large enough bolt to fix in the original hole i mentioned though, seems like the helicoil kit is the best bet
Parent - By aevald (*****) Date 05-07-2007 16:14
Hello again eclipse99, after reading others post to your problem I would add these additional comments. As the others have said if the rebuilder has liability in providing you with a block that doesn't have these issues then I would work that angle and try to get a different engine. If you are stuck with what you have there are a few other things that you could do to help with locating and drilling and tapping this buggered up hole. I would first make a template of the hole pattern of the waterpump out of some 3/8" to 1/2" plate, either clamp the plate to the back of the water pump and drill holes through the pump holes to provide correct hole locations or use transfer punches. Then determine the size of hole that will best work for oversizing the bad hole in the block(this would be the tapping diameter that you would need for using a Keensert, Helicoil, or the threaded bolt), bolt this plate to the front of the block and use this for a drill guide to drill out the bad hole and locate it properly. Whatever you do, if you are tapping in any type of material use a good quality of tap, in many instances you will have better success in tapping in cast iron if you do the tapping or drilling dry without oils or tapping fluids. This is likely a blind hole, so remove the tap every couple of turns or so and blow the chips out before proceeding. Good luck on your project here. Regards, aevald
Up Topic American Welding Society Services / Technical Standards & Publications / cast iron engine block botched bolt hole

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