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03-14-2013, 07:05 AM
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#1
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Guru
Join Date: Apr 2009
Posts: 1,920
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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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Tim
Tampa Bay
Carver 355 ACMY Twin Cummins Diesels Sold
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03-14-2013, 08:35 AM
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#2
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Guru
City: Cape Cod, MA
Vessel Name: Island Seeker
Vessel Model: Willard 36 Sedan
Join Date: Oct 2007
Posts: 1,306
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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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03-14-2013, 08:40 AM
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#3
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Valued Technical Contributor
City: Litchfield, Ct
Join Date: Aug 2012
Posts: 6,786
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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.
David
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03-14-2013, 09:00 AM
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#4
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Guru
Join Date: Apr 2009
Posts: 1,920
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Quote:
Originally Posted by Brooksie
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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Good idea!
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Tim
Tampa Bay
Carver 355 ACMY Twin Cummins Diesels Sold
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03-14-2013, 09:11 AM
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#5
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Senior Member
City: Toronto & Nanaimo
Vessel Name: Island Eagle
Vessel Model: DeFever
Join Date: Dec 2012
Posts: 232
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Quote:
Originally Posted by Brooksie
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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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
Scott Welch
Island Eagle
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03-14-2013, 09:24 AM
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#6
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Enigma
City: Slicker?
Join Date: Oct 2007
Posts: 16,567
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Greetings,
What about a long piece of threaded rod utilized as Mr. Brooksie suggests?
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RTF
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03-14-2013, 09:54 AM
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#7
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Guru
City: Hotel, CA
Join Date: Sep 2011
Posts: 8,323
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Quote:
Originally Posted by RT Firefly
Greetings,
What about a long piece of threaded rod utilized as Mr. Brooksie suggests?
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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.
Sent from my iPhone using Trawler
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Craig
It's easier to fool people than to convince them that they've been fooled - Mark Twain
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03-14-2013, 11:14 AM
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#8
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Guru
Join Date: Jun 2008
Posts: 5,037
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A long tapered drift punch also works well for initial alignment
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Jay Leonard
Ex boats: 1983 40 Albin trunk cabin, 1978 Mainship 34 Model 1
New Port Richey, Fl
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03-14-2013, 11:39 AM
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#9
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Guru
City: Everett Wa
Vessel Name: Eagle
Vessel Model: Roughwater 58 pilot house
Join Date: Oct 2007
Posts: 2,919
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Quote:
Originally Posted by Brooksie
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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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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03-15-2013, 06:22 PM
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#10
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Guru
City: Spartanburg, SC
Vessel Name: Big Duck
Vessel Model: '72 Land-N-Sea
Join Date: Feb 2012
Posts: 535
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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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