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Old 03-14-2013, 08:05 AM   #1
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Tapered bolts

Anyone who's done their own engine work will understand what I'm about to say.
Yesterday while reattaching my aftercooler (intercooler for you Cat and Volvo folks) I had to align the bottom attachment hole of the aftercooler to the engine block threaded hole that accepts the bolt that holds the aftercooler to the engine. The aftercooler is heavy and you can't see the holes, you have to do this by feel and the holes have to line up exactly. It took 45 minutes to get these two bolts attached. If the bolts had been tapered for the first 2 or 3 threads, it would have taken maybe 2 minutes.

I think it's a conspiracy with the engine manufactures and mechanics to boost the mechanics income.
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Old 03-14-2013, 09:35 AM   #2
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I've often had that same feeling...

Make up a tapered stud for next time. Screw it loosely into the block, slide on the aftercooler, install the remaining bolts, remove it and install the final bolt.
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Old 03-14-2013, 09:40 AM   #3
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Tapering the first two or three threads on a bolt means those threads will have little or no holding power. Particularly bolts that thread into aluminum need all of the holding power they can get. And often they have limited depth to achieve that holding power.

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Old 03-14-2013, 10:00 AM   #4
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Quote:
Originally Posted by Brooksie View Post
I've often had that same feeling...

Make up a tapered stud for next time. Screw it loosely into the block, slide on the aftercooler, install the remaining bolts, remove it and install the final bolt.
Good idea!
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Old 03-14-2013, 10:11 AM   #5
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Quote:
Originally Posted by Brooksie View Post
Make up a tapered stud for next time. Screw it loosely into the block, slide on the aftercooler, install the remaining bolts, remove it and install the final bolt.
Or just use the appropriate-sized phillips screwdrivers slipped into two of the holes to hold things aligned.

One very specialized tool that I've seen used by ship pipefitters (as well as structural steelworkers) is an adjustable wrench with a tapered handle, it's amazing how well it works to bring holes into alignment:

Klein Tools -10 Adjustable Spud Wrench

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Old 03-14-2013, 10:24 AM   #6
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Greetings,
What about a long piece of threaded rod utilized as Mr. Brooksie suggests?
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Old 03-14-2013, 10:54 AM   #7
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Greetings,
What about a long piece of threaded rod utilized as Mr. Brooksie suggests?
That would be the direction I would go. A little all thread rod goes a long way toward making job easy. Spud wrenches and alignment bars in a variety of sizes help too.

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Old 03-14-2013, 12:14 PM   #8
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A long tapered drift punch also works well for initial alignment
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Old 03-14-2013, 12:39 PM   #9
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Quote:
Originally Posted by Brooksie View Post
I've often had that same feeling...

Make up a tapered stud for next time. Screw it loosely into the block, slide on the aftercooler, install the remaining bolts, remove it and install the final bolt.

Make sure you have a nut above the thread yo are messing with, so the nut will re thread the area if needed.
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Old 03-15-2013, 07:22 PM   #10
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I think I'd grind a taper on like bolts and replace them one at a time with the real thing after the unit was in place.
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