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[GMCnet] Getting to the reason this 78 GMC runs hotter then my last 78. [message #326276] Wed, 22 November 2017 22:47 Go to next message
BobDunahugh is currently offline  BobDunahugh   United States
Messages: 1600
Registered: October 2010
Location: Cedar Rapids, IA
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Senior Member
Winter is closing in. Down to 16 last night, up to a balmy 39 today. The GMC is in it's home at 70. Time to go looking. Drained the coolant so I could put my inspection camera in the radiator. As I suspected. Plenty of corrosion in the cross tubes. Then checked the radiator out of the burned 78. Perfectly clean. Answered that question. Next. Pull the water pump out to see if it's the correct higher volume pump. So since its out. And has about 12,000 miles on it. I'll replace it no matter what's there. Next. Put a new harmonic dampener in since the timing mark has moved. So since all this stuff is out. Put the new electrically controlled fan/clutch in that I got at the Elkhart GMCMI rally. So now. Bring on the heat next Summer. Bob Dunahugh
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Re: [GMCnet] Getting to the reason this 78 GMC runs hotter then my last 78. [message #326277 is a reply to message #326276] Wed, 22 November 2017 23:03 Go to previous messageGo to next message
ljdavick is currently offline  ljdavick   United States
Messages: 3271
Registered: March 2007
Location: Fremont, CA
Karma: 1
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Bob,

Cool!

(I just couldn’t resist)

Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, CA
Howell EFI + EBL + Electronic Distributor

> On Nov 22, 2017, at 8:47 PM, Bob Dunahugh wrote:
>
> Winter is closing in. Down to 16 last night, up to a balmy 39 today. The GMC is in it's home at 70. Time to go looking. Drained the coolant so I could put my inspection camera in the radiator. As I suspected. Plenty of corrosion in the cross tubes. Then checked the radiator out of the burned 78. Perfectly clean. Answered that question. Next. Pull the water pump out to see if it's the correct higher volume pump. So since its out. And has about 12,000 miles on it. I'll replace it no matter what's there. Next. Put a new harmonic dampener in since the timing mark has moved. So since all this stuff is out. Put the new electrically controlled fan/clutch in that I got at the Elkhart GMCMI rally. So now. Bring on the heat next Summer. Bob Dunahugh
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Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy
Re: [GMCnet] Getting to the reason this 78 GMC runs hotter then my last 78. [message #326384 is a reply to message #326276] Sun, 26 November 2017 20:43 Go to previous messageGo to next message
Rick Staples is currently offline  Rick Staples   United States
Messages: 17
Registered: May 2014
Location: Johnstown, Colorado, USA
Karma: -1
Junior Member
While you're in that close, how old is your timing chain? Not much more excavating from there.
Rick Staples


Rick Staples, '75 Eleganza, Johnstown, CO "Advice is a dangerous gift, even from the Wise to the Wise, and all paths may run ill." -Tolkien
Re: [GMCnet] Getting to the reason this 78 GMC runs hotter then my last 78. [message #326385 is a reply to message #326276] Sun, 26 November 2017 22:06 Go to previous message
BobDunahugh is currently offline  BobDunahugh   United States
Messages: 1600
Registered: October 2010
Location: Cedar Rapids, IA
Karma: 11
Senior Member
Richard. The 403 was rebuilt by the PO in 1994. When I bought it in 2015. The engine had 1884 miles on the clock. Has about 12,000 miles now. The timing chain isn't of concern now. Normally you would have a good point. Bob Dunahugh


________________________________
From: Bob Dunahugh
Sent: Wednesday, November 22, 2017 10:47 PM
To: gmclist-AT-list-DOT-gmcnet-DOT-org
Subject: Getting to the reason this 78 GMC runs hotter then my last 78.


Winter is closing in. Down to 16 last night, up to a balmy 39 today. The GMC is in it's home at 70. Time to go looking. Drained the coolant so I could put my inspection camera in the radiator. As I suspected. Plenty of corrosion in the cross tubes. Then checked the radiator out of the burned 78. Perfectly clean. Answered that question. Next. Pull the water pump out to see if it's the correct higher volume pump. So since its out. And has about 12,000 miles on it. I'll replace it no matter what's there. Next. Put a new harmonic dampener in since the timing mark has moved. So since all this stuff is out. Put the new electrically controlled fan/clutch in that I got at the Elkhart GMCMI rally. So now. Bring on the heat next Summer. Bob Dunahugh
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