1971 chevy c10 custom I6 overflows coolant after each trip - The 1947 - Present Chevrolet & GMC Truck Message Board Network

trevarthan · 04-26-2014, 02:24 PM

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!

**'68OrangeSunshine** · 04-26-2014, 03:06 PM

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.]

**Classic Heartbeat** · 04-26-2014, 03:14 PM

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

WES

In The Ten Ring · 04-26-2014, 03:23 PM

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.

trevarthan · 04-26-2014, 04:08 PM

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.

trevarthan · 04-26-2014, 04:15 PM

Pints, not quarts. Sorry. I just checked the label. Photos incoming.

trevarthan · 04-26-2014, 04:20 PM

Photos attached. I have no idea how much of that is stock.

Greasey Harley · 04-26-2014, 04:32 PM

Head gasket? I'd run a leak-down test.

Lattimer · 04-26-2014, 04:47 PM

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.

SS Tim · 04-26-2014, 04:50 PM

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

trevarthan · 04-26-2014, 04:58 PM

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?

SS Tim · 04-26-2014, 05:23 PM

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.

litew8 · 04-26-2014, 05:53 PM

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.

**jabborabbo** · 04-26-2014, 06:45 PM

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!

litew8 · 04-26-2014, 08:27 PM

^ So you're saying your radiator went bad.

**jabborabbo** · 04-26-2014, 09:06 PM

Quote:

Originally Posted by litew8

^ So you're saying your radiator went bad.

More like FUBAR....

trevarthan · 04-27-2014, 04:52 PM

I checked my receipts. Autozone sold me a 7616 rad cap: http://www.autozone.com/autozone/par...fier=4437_0_0_

Instead of the 7016: http://www.autozone.com/autozone/par...6_177823_2695_

One says 16V on top, the other says 16. Otherwise they appear identical. I have no idea if that was a problem, but I'll drive it some more with the correct cap (7016) and see if that helps.

04-26-2014, 02:24 PM	#1
trevarthan Registered User Join Date: Mar 2014 Location: Chattanooga TN Posts: 121	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!

04-26-2014, 03:06 PM	#2
'68OrangeSunshine Senior Member Join Date: Feb 2002 Location: Tucson, AZ USA Posts: 7,441	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.] __________________ Every 25 years I like to rebuild that 292, whether it needs it or not.

04-26-2014, 03:14 PM	#3
Classic Heartbeat Project Junkie! Fishing Poor!! Join Date: Dec 1999 Location: Olympia,Wa. 98512 Posts: 10,766	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 WES __________________ 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

04-26-2014, 03:23 PM	#4
In The Ten Ring Registered User Join Date: Jun 2013 Location: West Virginia Posts: 6,421	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.

04-26-2014, 04:08 PM	#5
trevarthan Registered User Join Date: Mar 2014 Location: Chattanooga TN Posts: 121	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.

04-26-2014, 04:15 PM	#6
trevarthan Registered User Join Date: Mar 2014 Location: Chattanooga TN Posts: 121	Re: 1971 chevy c10 custom I6 overflows coolant after each trip Pints, not quarts. Sorry. I just checked the label. Photos incoming.

04-26-2014, 04:20 PM	#7
trevarthan Registered User Join Date: Mar 2014 Location: Chattanooga TN Posts: 121	Re: 1971 chevy c10 custom I6 overflows coolant after each trip Photos attached. I have no idea how much of that is stock. Attached Images

04-26-2014, 04:32 PM	#8
Greasey Harley Registered User Join Date: May 2013 Location: Post Falls, ID Posts: 898	Re: 1971 chevy c10 custom I6 overflows coolant after each trip Head gasket? I'd run a leak-down test.

04-26-2014, 04:47 PM	#9
Lattimer Registered User Join Date: Jan 2013 Location: Mickleton, NJ Posts: 1,776	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. __________________ Shawn 1970 Chevy C-10 SWB, 350, TKO 600 5 speed My build http://67-72chevytrucks.com/vboard/s...d.php?t=559881

04-26-2014, 04:50 PM	#10
SS Tim Registered User Join Date: Aug 2010 Location: Edwards, CA Posts: 7,503	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 Attached Images __________________ 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.

04-26-2014, 04:58 PM	#11
trevarthan Registered User Join Date: Mar 2014 Location: Chattanooga TN Posts: 121	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?

04-26-2014, 05:23 PM	#12
SS Tim Registered User Join Date: Aug 2010 Location: Edwards, CA Posts: 7,503	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. __________________ 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

04-26-2014, 05:53 PM	#13
litew8 Registered User Join Date: Jul 2011 Location: Des Moines, Iowa Posts: 3,016	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. __________________ project: "my happy mess"

04-26-2014, 06:45 PM	#14
jabborabbo Senior Member Join Date: Apr 2013 Location: Podunk, Texas Posts: 754	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!

04-26-2014, 08:27 PM	#15
litew8 Registered User Join Date: Jul 2011 Location: Des Moines, Iowa Posts: 3,016	Re: 1971 chevy c10 custom I6 overflows coolant after each trip ^ So you're saying your radiator went bad. __________________ project: "my happy mess"



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04-27-2014, 04:52 PM	#17
trevarthan Registered User Join Date: Mar 2014 Location: Chattanooga TN Posts: 121	Re: 1971 chevy c10 custom I6 overflows coolant after each trip I checked my receipts. Autozone sold me a 7616 rad cap: http://www.autozone.com/autozone/par...fier=4437_0_0_ Instead of the 7016: http://www.autozone.com/autozone/par...6_177823_2695_ One says 16V on top, the other says 16. Otherwise they appear identical. I have no idea if that was a problem, but I'll drive it some more with the correct cap (7016) and see if that helps.

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