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#16590 02/10/2004 5:26 AM | Joined: Jul 2003 Posts: 101 Wrench Fetcher | | Wrench Fetcher Joined: Jul 2003 Posts: 101 | My 51 GMC has a L neck that runs into the back of the upper tank, unlike Chevys I think, that fill from the top. It's a "new" rig for me, so before when I took it out for a long hilly run yesterday I filled it to within an inch of the top of the fill neck. In theory the top tank should have still had a couple inches of air in it since the fill neck attaches near the bottom of the top tank. The temp guage seemed to stay on about 190 throughout the 40 mile trip, up hill or down, although I guess I wasn't watching it going downhill. From time to time I would stop, and notice a little fluid running out of the overflow tube. At the end of the run I could see the antifreeze level was near the bottom of the top tank and would guess I lost 1/2 gallon or so on the trip.
My maintenance manual mentions a "water level test cock", which I don't see, so I'm wondering if it just didn't push out all the fluid down to the proper level.
I'm running a 180 degree thermostat with a hole drilled in it, a newly recored radiator, it is apparently a pressure system as my overflow tube cannot overflow unless the cap is overpressured. I don't know what the cap is rated, but I think 8 lbs.
After this long rant, I guess my only question is how high should GMC radiators be filled? | | |
#16591 02/10/2004 5:49 AM | Joined: Sep 2003 Posts: 1,820 Shop Shark | | Shop Shark Joined: Sep 2003 Posts: 1,820 | There was a post on this dated February 06, one page back. The post is "Radiator Blues". Check it out.
"Truckin' Around .......... Since 1937!" My name is Joe and I am addicted to Classic Country Music. I just can't hep myself.Operators are standing by to take your calls! Now cruising in the Passing Lane | | |
#16592 02/10/2004 2:59 PM | Joined: Dec 2001 Posts: 1,745 Member | | Member Joined: Dec 2001 Posts: 1,745 | Radiator water levels are a few inches from the top of the radiator. So, it sounds normal. 8 lbs sounds high for the cap.
54 3100 with 235
62 flatbed dump C60 with 261
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#16593 02/11/2004 4:22 AM | Joined: Jun 2003 Posts: 56 Member | | Member Joined: Jun 2003 Posts: 56 | GMC radiator petcocks are at the top front of the radiator.
When you fill the radiator have this petcock open, when water runs out of it, stop, it is filled as far as it should go.
Close petcock.
Some coolant will usually run out no matter what you do.
180 degrees is too hot, these trucks and older farm tractors use 160 degree thermostats which
are readily available at your friendly auto parts
store.
'31 Chevy 1 1/2 ton,
'42 GMC 2 1/2 ton 6x4,
'52 GMC 2 1/2 ton 6x6,
'53 GMC 5 ton
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#16594 02/11/2004 4:24 AM | Joined: Jun 2003 Posts: 56 Member | | Member Joined: Jun 2003 Posts: 56 | GMC radiator petcocks are at the top front of the radiator.
When you fill the radiator have this petcock open, when water runs out of it, stop, it is filled as far as it should go.
Close petcock.
Some coolant will usually run out no matter what you do.
180 degrees is too hot, these trucks and older farm tractors use 160 degree thermostats which
are readily available at your friendly auto parts
store.
'31 Chevy 1 1/2 ton,
'42 GMC 2 1/2 ton 6x4,
'52 GMC 2 1/2 ton 6x6,
'53 GMC 5 ton
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#16595 02/11/2004 4:26 AM | Joined: Jun 2003 Posts: 56 Member | | Member Joined: Jun 2003 Posts: 56 | GMC radiator petcocks are at the top front of the radiator.
When you fill the radiator have this petcock open, when water runs out of it, stop, it is filled as far as it should go.
Close petcock.
Some coolant will usually run out no matter what you do.
180 degrees is too hot, these trucks and older farm tractors use 160 degree thermostats which
are readily available at your friendly auto parts
store.
'31 Chevy 1 1/2 ton,
'42 GMC 2 1/2 ton 6x4,
'52 GMC 2 1/2 ton 6x6,
'53 GMC 5 ton
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#16596 02/11/2004 5:56 AM | Joined: Jul 2003 Posts: 101 Wrench Fetcher | | Wrench Fetcher Joined: Jul 2003 Posts: 101 | I think a 160 thermostat may be the ticket. I've been worrying that I might overheat in the summer, even though I had my radiator recored. It just seems like a 302 would need more cooling than the stock 228. The fan that came with the 302 is 5 blade and larger than the 228 fan so I assume it will help too. | | |
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