Bleeding cooling system - The 1947 - Present Chevrolet & GMC Truck Message Board Network

C15_Sierra · 03-12-2012, 11:28 AM

I'm running a stock '80 cooling system in my 5.3 swap, and I'm thinking over my lack of coolant flow issue. I thought it might be a new water pump, but now I'm doubting that and thinking that it's air-locked somehow.

I used '00 Silverado radiator hoses (my 5.3 is from a '00 Silverado), and the upper radiator hose runs up and across to the radiator inlet on the drivers side. I moved it down since it was the highest point in the system, but I'm still not getting any flow. It does seem like there's any coolant in there, so how can I bleed that hose so I can figure out if its indeed my water pump.

Previously, I replaced the thermostat, so I know that's good. Any other tips?

SeventyOne · 03-12-2012, 02:32 PM

Did you run the engine w/o a thermostat and the radiator cap removed?

68gmsee · 03-12-2012, 05:32 PM

Is it running hot or above normal or you just can't feel water moving?

What I usually do is turn the heater to hot and run the vehicle with the cap off while I top off the radiator. Then I'll put the cap on, run it to operating temp (thermostat opens) and after it cools off check it and top it off again if it needs it and make sure the overflow container has coolant in it.

I'll say that in some vehicles you can't always feel water going through the upper hose. I guess I should say, I haven't always felt it but I know it's going through there cause it does get hot..

C15_Sierra · 03-12-2012, 06:12 PM

Couldn't run w/o a thermostat because it's built into the water pump inlet housing, low in the system (so replacing it would defeat the purpose)

I didn't feel any heat in the heater hose or in the upper radiator hose...that shoulda told me something

What I DID forget was to back-feed coolant into the block via the upper radiator hose. Did just that, and lo and behold, she ran a steady 197 degrees according to the scan tool. Heater hoses had heat and so did the upper rad hose

Thanks guys!

cableguy0 · 03-12-2012, 06:38 PM

The easiest way to bleed a cooling system is with a funnel like this one

Amazon.com: Lisle 24610 Spill-Free Funnel:... . It stops you from making a mess and having coolant blow all over the place from running the vehicle with the radiator cap off.

68gmsee · 03-12-2012, 08:48 PM

Quote:

Originally Posted by C15_Sierra

..... lo and behold, she ran a steady 197 degrees according to the scan tool. Heater hoses had heat and so did the upper rad hose
Thanks guys!

Great going!

Quote:

Originally Posted by cableguy0

The easiest way to bleed a cooling system is with a funnel like this one Amazon.com: Lisle 24610 Spill-Free Funnel: Automotive . It stops you from making a mess and having coolant blow all over the place from running the vehicle with the radiator cap off.

Good idea. I usually use a funnel but it never seems to want to stay in place. Might have to order one of these since my yearly coolant change is due on my vehicles... Thanks.

**truckdude239** · 03-12-2012, 10:10 PM

i got the same funnel at work not quite figured it out yet

cableguy0 · 03-12-2012, 10:40 PM

The trick is to not fill funnel to the top. The coolant needs room in the funnel to expand. Also when it first starts pushing the air out while its running it will push the coolant upward. I keep the funnel filled to about when it goes from the large cone to round area right on the line. That way it doesnt overflow.

fastwillie 696969 · 03-13-2012, 01:58 PM

have you tried to jack the rear of the truck up

03-12-2012, 11:28 AM	#1
C15_Sierra Registered User Join Date: Apr 2011 Location: Hartford CT Posts: 223	Bleeding cooling system I'm running a stock '80 cooling system in my 5.3 swap, and I'm thinking over my lack of coolant flow issue. I thought it might be a new water pump, but now I'm doubting that and thinking that it's air-locked somehow. I used '00 Silverado radiator hoses (my 5.3 is from a '00 Silverado), and the upper radiator hose runs up and across to the radiator inlet on the drivers side. I moved it down since it was the highest point in the system, but I'm still not getting any flow. It does seem like there's any coolant in there, so how can I bleed that hose so I can figure out if its indeed my water pump. Previously, I replaced the thermostat, so I know that's good. Any other tips? __________________ -Steve 1980 GMC C15 Sierra LWB Dark Carmine Red/Carmine Int Was: 250/3spd (1980-88), then a 305/TH350 (1988-2011) Now: 5.3/4L60E, 2.73 12-bolt open rear

03-12-2012, 02:32 PM	#2
SeventyOne Registered User Join Date: Mar 2007 Location: Oakland, Ca Posts: 1,362	Re: Bleeding cooling system Did you run the engine w/o a thermostat and the radiator cap removed?

03-12-2012, 05:32 PM	#3
68gmsee Active Member Join Date: Jul 2007 Location: Centrally located between Houston, Austin and Waco. BCS area. Posts: 7,947	Re: Bleeding cooling system Is it running hot or above normal or you just can't feel water moving? What I usually do is turn the heater to hot and run the vehicle with the cap off while I top off the radiator. Then I'll put the cap on, run it to operating temp (thermostat opens) and after it cools off check it and top it off again if it needs it and make sure the overflow container has coolant in it. I'll say that in some vehicles you can't always feel water going through the upper hose. I guess I should say, I haven't always felt it but I know it's going through there cause it does get hot..

03-12-2012, 06:12 PM	#4
C15_Sierra Registered User Join Date: Apr 2011 Location: Hartford CT Posts: 223	Re: Bleeding cooling system Couldn't run w/o a thermostat because it's built into the water pump inlet housing, low in the system (so replacing it would defeat the purpose) I didn't feel any heat in the heater hose or in the upper radiator hose...that shoulda told me something What I DID forget was to back-feed coolant into the block via the upper radiator hose. Did just that, and lo and behold, she ran a steady 197 degrees according to the scan tool. Heater hoses had heat and so did the upper rad hose Thanks guys! __________________ -Steve 1980 GMC C15 Sierra LWB Dark Carmine Red/Carmine Int Was: 250/3spd (1980-88), then a 305/TH350 (1988-2011) Now: 5.3/4L60E, 2.73 12-bolt open rear

03-12-2012, 06:38 PM	#5
cableguy0 Senior Member Join Date: Apr 2000 Location: Delta,Pa Posts: 14,950	Re: Bleeding cooling system The easiest way to bleed a cooling system is with a funnel like this one Amazon.com: Lisle 24610 Spill-Free Funnel:... . It stops you from making a mess and having coolant blow all over the place from running the vehicle with the radiator cap off. __________________ Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member.

03-12-2012, 10:10 PM	#7
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,217	Re: Bleeding cooling system i got the same funnel at work not quite figured it out yet __________________ David fuller Ase Certified Mechanic Click here to help support our board!! 1971 Chevy c-10 under going a 4.8l LSx swap Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305 2007 Honda Accord my daily 145kmiles 2002 Honda Accord 4 door With 330k(sisters car) 2005 toyota Avalon 228k( brothers car) 2002 Sububran 5.3 245k 2000 Tahoe 5.3l 378 General manager for Marco's Carwash & lube

03-12-2012, 10:40 PM	#8
cableguy0 Senior Member Join Date: Apr 2000 Location: Delta,Pa Posts: 14,950	Re: Bleeding cooling system The trick is to not fill funnel to the top. The coolant needs room in the funnel to expand. Also when it first starts pushing the air out while its running it will push the coolant upward. I keep the funnel filled to about when it goes from the large cone to round area right on the line. That way it doesnt overflow. __________________ Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member.

03-13-2012, 01:58 PM	#9
fastwillie 696969 ~Rest In Peace~ Join Date: May 2005 Location: CALIFORNIA NOR CAL Posts: 9,707	Re: Bleeding cooling system have you tried to jack the rear of the truck up __________________ is it fast ? it has a lighting bolt donut? B___H please, I can remove 90% of your so called "beauty" with a kleenex



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