[Cloud9...68]

The threads for one of the bolts holding my water pump to the block is in fairly bad shape - not quite stripped, but it can't hold the required 10 nm, either.



What do you guys recommend for fixing this thread? I assume I'm going to have to re-tap it, but, in all my years of working on cars, I've nevver had to do this before. Is heli-coil the best option? I checked, and I can fit a drill into the opening between the thread and the front of the car under the hood (the radiator is out), so tapping it is certainly an option. Do you guys have any recommendations as to the best product to use? Please try to be as specific as you can, as my knowledge of tools is all strictly self-taught; in other words, far from professional grade. Whatever I buy, I'd like to practice on a scrap block of aluminum stock first. Thanks.

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[flash]

heli-coils actually are capable of holding more torque than the original threads, if installed correctly



orchard sells a complete kit that works very well

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[Cloud9...68]

Thanks; yes, I've heard the same thing about heli-coils. Could you please elaborate on what you mean by "installed correctly"? Any tricks to the installation process? Obviously, you have to get the drill bit as perpendicular to the block as possible. Anything else to look out for? As I said, I plan to practice on a piece of aluminum stock first.

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[flash]

drilling and tapping for the coil needs to be straight, slow, and clean - bugger that and you'll be in a worse spot than you were when you started



also, be careful not to drill through into something you don't want to



if it's in an odd place and you can't get a dead straight shot at it, go out and get a 90 degree drive



feel free to get ahold of me if you run into trouble or have other questions

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[rustech]

For the 10nm required for one of those bolts, I'm sure JB Weld would do the job quite well. You could just reform the threads. I personally think a helicoil would be an overkill, but would definitely do the job.

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[gryphon]

I have had good luck with helicoils, but have always drilled/installed them on a bench and with a drill press. It is easy to bugger them up without good access and alignment.



Tom

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[Ryan]

Did you run a tap it to clean up the remainin threads? Could you tap it to the next size up and get a new bolt? I have not used JB Weld for this purpose, but it could be worth a shot. I feel for you...

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[Cloud9...68]

Hmmm... Some thought-provoking inputs. Yes, while I can fit a drill in the opening relatively easily, I do worry about the alignment, and the overall awkwardness of my access.



As I indicated in my first post, the thread was certainly holding - no sign of a leak in several weeks of driving, and there are ten other bolds holding the water pump in place. The JB Weld idea sounds interesting, and possibly quite a bit less risky. Could somebody please elaborate on exactly how to use it in this application? For example:



Do I need to clean up the thread first with a tap of equal size to the existing thread?

How exactly do I get the thread to form in the JB Weld after applying it to the hole, without having it stick to the bold I use to create the thread? Do I have to apply a release agent to the bolt first?



Again, please provide as specific and detailed information as you can, as I'm definitely a newbie at this, and the stakes are pretty high, given the priceless nature of the block. Thanks!

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[rustech]

There are two ways that I can think of. The first is as you said using a release agent either with a thin coat of wd-40/grease or similar. The second way would be to simply coat the inside of the hole with jbweld, let dry, and then clean up and form the threads with a tap.

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[Cloud9...68]

Well, I took a close look, and found that I really can fit my drill in the space in front of my engine, with the drill in the proper upright position, with the bubble levels showing, so I'm pretty sure I can cleanly drill out the thread. Plus, I went to the local Porsche dealer today to pick up the new water pump gasket, and I talked to a mechanic, who strongly advised that I use a heli coil, so I went and bought a kit. It really doesn't look too hard, so hopefully I will take care of it asap.



Now if only I can figure out exactly why may car's coolant isn't flowing (see my LONG thread in the heating & cooling category).

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[flash]

use something in the hole to tell you what angle it is at - probably not level to the ground



go fairly slowly with the drill

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[Cloud9...68]

[quote name='flash' post='54594' date='Jun 12 2008, 07:47 AM']use something in the hole to tell you what angle it is at - probably not level to the ground[/quote]

Great point. I'll pick up a longer version of the bolt, thread it in, and place a bubble level on the top and side, and try to match the positions to the bubbles on my drill.



The heli coils are only about 1/4" tall, so I don't want to drill much more than that into the bolt hole, do I?

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[gryphon]

Cloud, you only need sufficient depth to make sure that the helicoil is flush with the surface after installation. Otherwise you would need to grind off the protruding portion. I'd suggest marking your drill bit with a piece of masking tape equal to the depth of the helicoil, allowing for the conical taper of the drill bit at the end.



Tom

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[Cloud9...68]

[quote name='gryphon' post='54739' date='Jun 13 2008, 04:29 PM']Cloud, you only need sufficient depth to make sure that the helicoil is flush with the surface after installation. Otherwise you would need to grind of the protruding portion. I'd suggest marking your drill bit with a piece of masking tape equal to the depth of the helicoil, allowing for the conical taper of the drill bit at the end.



Tom[/quote]

Tom,



Thanks for the confirmation. I was planning to do exactly as you're suggesting, marking the drill bit with tape to reflect the depth of the heli coil.

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[Cloud9...68]

Did the heli coil, and it did the trick - the bolt is now comfortably holding the required 10 nm. The drilling and tapping were very easy - thanks, Flash, for the tip tio check the level of the thread. The only difficult part was getting the driver tool out of the hole, as the coil's tang bit into the slot in the tool as I was twisting the coil into the newly-cut thread. The same thing happened on the piece of aluminum stock I used to practice, so I was prepared for it, but it didn't make it any easier to yank the tool out. I finally got it, though, and, as I said, the thread is now holding nicely.



I managed to get about 3/4 of the way through the reassembly of the front of my engine. I'll finish it up this week after work, and then get back to troubleshooting my very stubborn overheating problem. I'm back to thinking I somehow managed to inadvertantly suck some air down into the cooling system, so I'm going to throw the book at it with my mega-bleeding technique. Details to follow on my thread in the heating and cooling folder...

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