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#1 |
Registered User
Join Date: Mar 2014
Location: Chattanooga TN
Posts: 121
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1971 chevy c10 custom I6 overflows coolant after each trip
Carburated I6 250. Every time I come back from a trip the radiator overflows coolant from the overflow tube near the radiator cap. I replaced the radiator cap immediately when I noticed this happening. Still happens with the new cap. Doesn't seem to be overheating yet. Still has a quart of coolant in the fill bottle in the engine compartment.
Is this a head gasket, or something else? I blew a head gasket once on a 4 cylinder truck, years ago. It did the same thing, but it often burned white smoke too. I suppose it just depends on where the gasket blows. I just bought the truck a month ago, so I don't know the history. Thanks! |
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#2 |
Senior Member
![]() Join Date: Feb 2002
Location: Tucson, AZ USA
Posts: 7,286
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Re: 1971 chevy c10 custom I6 overflows coolant after each trip
What temp is your thermostat? [195F* is stock]
What is your coolant mixture ratio? [50:50 is nominal] How may tiers in your radiator? Is it the L6 radiator? V8 radiators are wider. [Two-tiers thick might be standard for a small L6 in temperate climate, but not enough in a tropical climate.]
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Every 25 years I like to rebuild that 292, whether it needs it or not. |
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#3 |
Project Junkie! Fishing Poor!!
![]() Join Date: Dec 1999
Location: Olympia,Wa. 98512
Posts: 10,770
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Re: 1971 chevy c10 custom I6 overflows coolant after each trip
Stop refilling the radiator and it will stop leaking the fluid. When the radiator is filled with cold fluid then you start your truck up to warm it up the coolant expands because it is hot. There isn't any place for it to go so it goes out the overflow tube. If you hook up an overflow bottle, once the radiator cools back down it will draw the overflow back into the radiator. We have the collant recovery systems for $59.95
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On-line catolog Classic Heartbeat Pickup Parts WEHEPP@comcast.net Call us Toll Free (888) 338-2502 Like Us on Facebook No appointment necessary. 72 BB Chevy Custom Deluxe / Custom Camper 67 I-6 (Soon to be 5.7 LS1) Panel 68 BB Chevy Short Bed 72 6.0 LQ9 Short Bed Chevy 4X4 Olympia's fastest growing truck parts supplier. Olympia's home for Wayward Chevys |
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#4 |
Registered User
Join Date: Jun 2013
Location: West Virginia
Posts: 6,421
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Re: 1971 chevy c10 custom I6 overflows coolant after each trip
Wes is a great guy to deal with.
My truck will do this once I get it running again....I don't have an overflow tank either. |
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#5 |
Registered User
Join Date: Mar 2014
Location: Chattanooga TN
Posts: 121
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Re: 1971 chevy c10 custom I6 overflows coolant after each trip
I haven't been filling the radiator. The coolant bottle on the side of the engine compartment has been slowly depleting. I think it had 3 quarts in it when I bought it and it's down to 1 quart now.
I don't know if the radiator is stock, but I'm guessing it is. The engine has 94k miles on the od. So stock I6 radiator. I'm in Tennessee. Not tropical. Hell, not even warm yet. It's been a strangely long cold winter. |
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#6 |
Registered User
Join Date: Mar 2014
Location: Chattanooga TN
Posts: 121
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Re: 1971 chevy c10 custom I6 overflows coolant after each trip
Pints, not quarts. Sorry. I just checked the label. Photos incoming.
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#7 |
Registered User
Join Date: Mar 2014
Location: Chattanooga TN
Posts: 121
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Re: 1971 chevy c10 custom I6 overflows coolant after each trip
Photos attached. I have no idea how much of that is stock.
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#8 |
Registered User
Join Date: May 2013
Location: Post Falls, ID
Posts: 889
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Re: 1971 chevy c10 custom I6 overflows coolant after each trip
Head gasket? I'd run a leak-down test.
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#9 |
Registered User
Join Date: Jan 2013
Location: Mickleton, NJ
Posts: 1,776
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Re: 1971 chevy c10 custom I6 overflows coolant after each trip
You realize the bottle you took a photo of is the windshield washer fluid, right?
Stock, these trucks do not have a coolant recovery bottle. The overflow just goes to the ground.
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Shawn 1970 Chevy C-10 SWB, 350, TKO 600 5 speed My build http://67-72chevytrucks.com/vboard/s...d.php?t=559881 |
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#10 |
Registered User
Join Date: Aug 2010
Location: Edwards, CA
Posts: 7,503
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Re: 1971 chevy c10 custom I6 overflows coolant after each trip
That is the washer fluid bottle.
The radiator is an overflow design. This means during normal heating and cooling it stays contained in the design air pocket by short filling the radiator. Any excess is drained as in the case of an overfill or overheat. The design cold fill level is about 3" below the filler neck (see picture). I'd strongly suggest you buy a owners handbook (owner's manual) and download or buy a service manual. http://67-72chevytrucks.com/vboard/s...d.php?t=558016
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Thanks, Tim * VIN/Model Decoders * Power Team Charts (engine/transmission/gear ratio) * Post Your Pickup SPID ** Blazer SPID ** Suburban/Panel SPID * RTFM ... Read The Factory Manuals... download 'em here Highlanders ** Do you have a 1972 Plaid Pickup? ** Plaid Blazer ** Plaid Suburban Last edited by SS Tim; 04-26-2014 at 04:58 PM. |
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#11 |
Registered User
Join Date: Mar 2014
Location: Chattanooga TN
Posts: 121
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Re: 1971 chevy c10 custom I6 overflows coolant after each trip
I feel slightly stupid, but that's fine. I learned something. So, it's not normal for it to continue draining like this when I'm not filling it.
Is there anything that could be causing this besides a head gasket leak? |
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#12 |
Registered User
Join Date: Aug 2010
Location: Edwards, CA
Posts: 7,503
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Re: 1971 chevy c10 custom I6 overflows coolant after each trip
First thing to do is correct the level and just drive the truck. It should loose very little coolant over time (weeks/months) and it should not overflow.
You probably don't have a problem and the books should get you up to speed on a lot of the normal maintance needs your truck has. However if you think you have a cooling problem a visual check of the coolant while running for bubbles is a start. Talk to your local shop and see if they can run a block check for you (special tool). Basically it tests for combustion gases in the cooling system while running.
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Thanks, Tim * VIN/Model Decoders * Power Team Charts (engine/transmission/gear ratio) * Post Your Pickup SPID ** Blazer SPID ** Suburban/Panel SPID * RTFM ... Read The Factory Manuals... download 'em here Highlanders ** Do you have a 1972 Plaid Pickup? ** Plaid Blazer ** Plaid Suburban |
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#13 |
Registered User
Join Date: Jul 2011
Location: Des Moines, Iowa
Posts: 3,016
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Re: 1971 chevy c10 custom I6 overflows coolant after each trip
If you feel the running temp is beginning to climb and the radiator is puking coolant, I'd replace the radiator and see if the problem goes away. Radiators go bad too. idk if they can test them, but probably can.
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project: "my happy mess" |
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#14 |
Senior Member
![]() Join Date: Apr 2013
Location: Podunk, Texas
Posts: 748
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Re: 1971 chevy c10 custom I6 overflows coolant after each trip
SS Tim knows his stuff. I'll add that when I bought my '67 GMC from the original owner, he had a 9 pound pressure cap on the radiator - it would puke coolant on the ground out of the vent hose until the level was maybe 6 or 7 inches below the filler cap - it's supposed to be 3 inches as SS Tim said. I replaced the cap with a proper 13 pound pressure cap...then it started oozing coolant from pinholes on one side of the tank (details of my trials and tribulations and happy ending can be found here).
Good luck! |
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