Simple job = Nightmare

[Narnian]

Last night I went to replace the thermostat and made a mess. The threads for one of the bolts in the aluminum Edelbrock manifold was stripped. Which is why I was finding antifreeze on the manifold last month.

I don't have a tap and die set, but I had one tap someone gave me years ago and it was just the next size bolt up, so I figured I'd just make a bigger hole and put a fatter bolt in. I guess the tap was brittle, because I barely got it into the aluminum when the tip snapped off in the manifold!!! http://www.ifsja.org/ubb/frown.gif

I then spent 5 hours trying to get the tip out, and made a bigger mess than I'd started with. I ended up drilling small holes around the big hole to get the tap out, then used a longer bigger bolt that's barely grabbing the manifold. After that, I was in such a mess from being up so late that I managed to strip the other hole! I wanted to cry http://www.ifsja.org/ubb/frown.gif I spent another hour carefully drilling the other hole a little wider, and then I just forced a bigger bolt in. Turn it in a little, let it out, turn it in a little, let it out. Kinda self-taps in aluminum.

It's working, but just barely. I think it's still leaking a little bit, and I know the first bolt I "fixed" just barely has any bite. What is the correct way to fix this? I don't need to change the manifold do I? Someone tell me there is some kinda method for fixing this kinda mess. Please!

If not, I'll just add antifreeze every 500 miles.

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81 Laredo,
360 w/Holley Fuel Injection, Edelbrock man, 219, 3.31, 33's, no fuzzy dice (yet)
86 Corvette
87 GMC Jimmy (Gotta Mechanic Coming)

[JeepFreak]

If I were you I would go ahead and use a real large bit and drill out both holes. Then you can thread those holes. Then using a liquid metal fill both holes. You must be sure to tape the holes first or the liquid metal will have nothing to hold to. Then when the liquid metal sets you can drill and tap. My experience with liquid metal is that you are better off to use a helicoil for threads because the liquid metal doesnt hold up well over time. If you have enough aluminum left you may be able to helicoil the excisting holes instead. If this doesnt work or sounds to difficult you can take it to a machine shop where they will do the same thing except they will probably fill with aluminum. I had to have this done to an AMX offenhauser intake and it worked great. Hope this helps some.

Almost forgot to tell you when you get ready to tap the new holes be sure to put the thermostat in and the housing on and mark the holes. When you get ready to drill start with a small bit and work your way up to the final size. This will ensure that the holes stay where they are supposed to be.


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JeepFreak

[This message has been edited by JeepFreak (edited November 29, 2000).]

[BobBarry]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Narnian:
Last night I went to replace the thermostat and made a mess. The threads for one of the bolts in the aluminum Edelbrock manifold was stripped. Which is why I was finding antifreeze on the manifold last month.<HR></BLOCKQUOTE>

It's at this point in the message when I was hoping to see the phrase "So I installed a helicoil...". Anything else is just jumping from the frying pan into the fire. In fact, it's common practice to install helicoils in any aluminum component (intake, heads, timing cover, etc) where a screw might be regularly removed and replaced, as the aluminum threads are regularly sacrificed to the steel bolts.

They're expensive in the short-run, but cheap in the long-run.

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Bob Barry<UL TYPE=SQUARE>* '78 Cherokee 4-door
* '88 Grand Wagoneer[/list]http://studentweb.providence.edu/~rbarry/wheels/

[JeepFreak]

I agree with Bob. Helicoils should always be used in aluminum intakes. I know a few guys that don't even take the chance on the threads stripping and install helicoils first.

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JeepFreak

[Narnian]

I don't even know what helicoils are, or I guess I wouldv'e done that!

Are these some commonplace invention I missed out on? Do I get them at Autozone? I'll happily redrill the dang holes and pop these things in if that's what you guys think I should do.

[JeepFreak]

Just go to a good parts store and tell them your problem and they can tell you what size will work. If you get the kit it will come with directions and drill bit and helicoils and tap. They are bit pricy for what they are but well worth it in your case. A helicoil is just some metal threads that screw into the excisting hole. they can handle the ware and tare that the aluminum can't. Be sure to get new bolts that match the helicoil size.

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JeepFreak

[This message has been edited by JeepFreak (edited November 29, 2000).]

[MonsterMash]

I feel your pain. This sounds something like the great broken sparkplug adventure I had years ago. It just kept getting worse and worse to the point of pulling the head and taking it to a machine shop. So much for simple repairs. Fortunately as the guys pointed out a careful installation of a couple of heli-coils will fix you right up. You'll wonder why you ever thought it was even remotely difficult when you have the right parts. Luckily the school of hard knocks grades on a curve!

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'84GW360--"Spinner"
Bigger tires and better stereo but pretty much stock
Most everything works some of the time!
1st Annual Jefferson FSJ Mud Run:

http://home.earthlink.net/~worthservices/index.html

[JeepFreak]

Something else you might do is to use studs in place of the bolts. This is after you have repaired the holes of coarse. Then you wont be putting undue stress on a already problemed area. Just gets 2 studs and nuts to go on them and thats it.

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JeepFreak

[Narnian]

That is a good idea JeepFreak. I'll have to stop in at Autozone tonight and pick this stuff up.

[reddog]

Some days it doesn't pay to get out of bed!!
I would say that your either very luckly or very young to not know what a helicoil is!!

You didn't say in your post if you drilled out the hole to the correct size before you tried to run the tap in. Often the correct drill bit size is on the tap itself. The tap will not enlarge the hole even in aluminum. The hole must be the correct size before you start with the tap
I hope the holes aren't too big to get the right size coil in there. Studs are a great idea. I would suggest that you use locktite (the permanent type) on the helicoils.

[This message has been edited by reddog (edited November 29, 2000).]

[Millerluck]

It sounds to me that a helicoil is to late.
The drill used for a helicoil is much the same size as a striped hole of the size you started with. A helicoil is a spring made of wire that is diamond shaped. &lt;&gt; Lets say you strip a 3/8 bolt, the drill for a 3/8 helicoil tap will be darn close to 3/8.


I have a way to tell what size drill to use when tapping a new hole. It will get you very very close.
Threads are triangles right? So it does not matter on the pich or the size.

Lets say you need to tap a 5/16-18. Take 1 diveded by 18. = 0.05555. The closest fraction in inches is 1/16 =.0625. Take 1/16 from the bolt size(5/16) and you get 1/4. That is the tap drill size for 5/16-18.
18 being number of threads per inch.

Here is another. 1/4-20.

1/20=.05

.25-.05=.2

13/64 drill =.203

The tap drill size for a 1/4-20 =13/64


And one more. 1/2-13

1/13=.0769

.5-.0769=.423

27/64=.422

The tap drill size for a 1/2-13= 27/64


If you have a thread chart great. If you don't this works.


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88GW "Mississippi"
Black,360,727,NP229
D44 F/R,3.31gears,
Tracklok F/R,
Superwinch hubs,
4" Skyjacker no blocks,
31x10.5x15BFG AT's.
TEAMRUSH UPGRADE,
MSD SUPER CONDUCTOR wires,BLASTER TFI COIL
Thorley headers,
3"exhaust,
Flowmaster

[This message has been edited by Millerluck (edited November 30, 2000).]

[Narnian]

Autozone didn't have "Helicoil", they had the same thing under a different name, I guess "Helicoil is a particular brand?

I'm not sure if it's too late or not. I bought a kit for the correct size and the next size up just in case. I didn't get loctite to go with it though. Maybe I should go back to the store before I pull it apart again? I was thinking about buying some of that metal repair stuff (like JB weld) to put around the coil if there is a loose spot. They had one that said aluminum on the box. Whaddaya think?

I guess in the past I've been lucky, or I missed that class. I've only stripped a hole like this once in the last ten years of driving, and all we did was drill a new hole and tap it to the next size bolt.

[JeepFreak]

As long as it is thread repair kit than thats ok. If you have to spot fill a few places the alumiweld would work fine. Let us all know how this all turned out.

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JeepFreak