Running Hot - The 1947 - Present Chevrolet & GMC Truck Message Board Network

theslawdawg · 10-12-2010, 07:47 PM

Hello all,

Here's my situation: I previously had a two core radiator that I switched out with a nice three core radiator. Prior to this switch, my temp level was fine. I made the switch only because I am moving to a way hotter climate and just planning ahead. Now, my temp level is much higher. It is not necessarily overheating, just well past the line I'm normally used to (so it is running hotter). Any thoughts?

Also, If it is the thermostat, and the thermostat is bad, wouldn't you know it pretty quick or is it a very slow gradual process?

**truckdude239** · 10-12-2010, 07:55 PM

sounds more like an air pocket

theslawdawg · 10-12-2010, 08:46 PM

Sorry for my ignorance, what is an air pocket and what does it cause, and how do you eliminate it?

Shyguy · 10-12-2010, 09:34 PM

An air pocket in the coolant system can happen when the system is drained and refilled. The water pumps will not pump air, only water. If hot water does not get to the thermostat it will not open allowing coolant flow.

Normally the system will burp after the thermostat opens, but not always. On some cars there is a plug on the thermostat housing to allow for venting air out.

I am sure others will chime in.

Camper Power · 10-12-2010, 09:50 PM

definatly sounds like an air pocket. i find running the engine with the rad cap off is the best way to get rid of them. just start it when its cold and let it warm up to operating temp with the cap off so the air can escape. and have some coolant on hand to gradually fill it up while its running

theslawdawg · 10-12-2010, 10:09 PM

It really is weird. On my two core, the temp needle never went past the first tick. Now, it goes slightly (but noticeably) past the first tick after about thirty minutes of driving. So basically, it is slowly overheating while trying (but failing) to keep things cool.

Thanks for the advice. I'll try this in the morning and see if it solves anything.

theslawdawg · 10-12-2010, 11:21 PM

Okay,

I ran the engine at idle, with the cap off for probably 15 minutes. The temp needle maintained at a good level when it got warm. I noticed the coolant level getting a little higher (the reservoir took care of the excess) and then it settled. I then turned the truck off and screwed the cap back on. I didn't have to add anymore coolant though.

I will say that even though the engine got to normal operating temperature with the needle at a good level, it gets hotter throughout the driving day (which is usually about 30-45 minutes of driving for me). Hopefully I "burped" it right.

mrein3 · 10-13-2010, 07:32 AM

Here is how I burp a coolant system.

Engine cold, off. Open the radiator and set the cap aside. Place a catch pan under the open radiator.

Start the vehicle. Have 50-50 ready to add to the system. As the vehicle warms up you will notice the level in the open radiator go up and down. Some will spill.

Wait until you notice a good flow coming out of the fins of the radiator. The upper radiator hose should be warm now. Fill the radiator to the top and screw the cap back on. You're done.

68Stepbed · 10-13-2010, 08:18 AM

Something else to consider is the type of thermostat. I had almost the same issue with mine for the past 3 years. Mine never actually overheated, it just ran about 200 deg. with a Stant 160 therm. I changed to a Mr. Gasket(Robert Shaw style) therm and it now maintains a consistent 180 deg. It does tend to rise to about 210 in traffic, but that may be due to having just an elec. fan with no shroud.

Blazer1970 · 10-13-2010, 05:41 PM

Was it a new radiator that you installed?

Longhorn Man · 10-13-2010, 06:09 PM

it's getting to the second mark on the temp guage?
Sorry... I don't see a problem here.

theslawdawg · 10-14-2010, 01:31 AM

It is a brand new radiator (3 core).

This is more of a curiousity for me right now. I know that the even though the needle is higher, it still bugs me to see it considerably higher now than when I had my beat up 2 core in it.

Longhorn Man · 10-14-2010, 04:54 PM

flushing the old coolant may have rinsed some crap off the temp guage sender maybe.
I think I'd be happy that is up in the normal range now.

10-12-2010, 07:47 PM	#1
theslawdawg Registered User Join Date: Dec 2009 Location: VA Beach, VA Posts: 67	Running Hot Hello all, Here's my situation: I previously had a two core radiator that I switched out with a nice three core radiator. Prior to this switch, my temp level was fine. I made the switch only because I am moving to a way hotter climate and just planning ahead. Now, my temp level is much higher. It is not necessarily overheating, just well past the line I'm normally used to (so it is running hotter). Any thoughts? Also, If it is the thermostat, and the thermostat is bad, wouldn't you know it pretty quick or is it a very slow gradual process? __________________ 1972 Chevy C10

10-12-2010, 07:55 PM	#2
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,230	Re: Running Hot sounds more like an air pocket __________________ 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

10-12-2010, 08:46 PM	#3
theslawdawg Registered User Join Date: Dec 2009 Location: VA Beach, VA Posts: 67	Re: Running Hot Sorry for my ignorance, what is an air pocket and what does it cause, and how do you eliminate it? __________________ 1972 Chevy C10

10-12-2010, 09:34 PM	#4
Shyguy Junior Member Join Date: Dec 2006 Location: Southeast Missouri Posts: 2,436	Re: Running Hot An air pocket in the coolant system can happen when the system is drained and refilled. The water pumps will not pump air, only water. If hot water does not get to the thermostat it will not open allowing coolant flow. Normally the system will burp after the thermostat opens, but not always. On some cars there is a plug on the thermostat housing to allow for venting air out. I am sure others will chime in. __________________ '67 Chevy C-20 short stepper - build complete, 454/SM-465. '75 C-30 Single Cab DRW-350 small block/NP-435. '77 GMC-6500 Dump Truck, 427 Tall Deck. '92 GMC K-3500 Duallie, 454/4L80E.

10-12-2010, 09:50 PM	#5
Camper Power Registered User Join Date: Feb 2008 Location: Grande Prairie Alberta Posts: 261	Re: Running Hot definatly sounds like an air pocket. i find running the engine with the rad cap off is the best way to get rid of them. just start it when its cold and let it warm up to operating temp with the cap off so the air can escape. and have some coolant on hand to gradually fill it up while its running __________________ eh 1970 Chevy C20 daily driver 1975 GMC Jimmy 4x4 project 1966 GMC C10 Dad's project

10-12-2010, 10:09 PM	#6
theslawdawg Registered User Join Date: Dec 2009 Location: VA Beach, VA Posts: 67	Re: Running Hot It really is weird. On my two core, the temp needle never went past the first tick. Now, it goes slightly (but noticeably) past the first tick after about thirty minutes of driving. So basically, it is slowly overheating while trying (but failing) to keep things cool. Thanks for the advice. I'll try this in the morning and see if it solves anything. __________________ 1972 Chevy C10

10-12-2010, 11:21 PM	#7
theslawdawg Registered User Join Date: Dec 2009 Location: VA Beach, VA Posts: 67	Re: Running Hot Okay, I ran the engine at idle, with the cap off for probably 15 minutes. The temp needle maintained at a good level when it got warm. I noticed the coolant level getting a little higher (the reservoir took care of the excess) and then it settled. I then turned the truck off and screwed the cap back on. I didn't have to add anymore coolant though. I will say that even though the engine got to normal operating temperature with the needle at a good level, it gets hotter throughout the driving day (which is usually about 30-45 minutes of driving for me). Hopefully I "burped" it right. __________________ 1972 Chevy C10

10-13-2010, 07:32 AM	#8
mrein3 Registered User Join Date: Feb 2000 Location: Center City, MN, USA Posts: 3,253	Re: Running Hot Here is how I burp a coolant system. Engine cold, off. Open the radiator and set the cap aside. Place a catch pan under the open radiator. Start the vehicle. Have 50-50 ready to add to the system. As the vehicle warms up you will notice the level in the open radiator go up and down. Some will spill. Wait until you notice a good flow coming out of the fins of the radiator. The upper radiator hose should be warm now. Fill the radiator to the top and screw the cap back on. You're done. __________________ '70 cab, '71 chassis, 383, TH350, NP205. '71 Malibu convertible '72 Malibu hard top Center City, MN

10-13-2010, 08:18 AM	#9
68Stepbed Registered User Join Date: Mar 2005 Location: 10-Uh-See Posts: 5,609	Re: Running Hot Something else to consider is the type of thermostat. I had almost the same issue with mine for the past 3 years. Mine never actually overheated, it just ran about 200 deg. with a Stant 160 therm. I changed to a Mr. Gasket(Robert Shaw style) therm and it now maintains a consistent 180 deg. It does tend to rise to about 210 in traffic, but that may be due to having just an elec. fan with no shroud. __________________ Matt 68 C10 stepside, LS1/700R4, TCI Engineering suspension system

10-13-2010, 05:41 PM	#10
Blazer1970 Registered User Join Date: Dec 1999 Location: Old Mission, MI, USA Posts: 2,510	Re: Running Hot Was it a new radiator that you installed? __________________ Tim

10-13-2010, 06:09 PM	#11
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: Running Hot it's getting to the second mark on the temp guage? Sorry... I don't see a problem here.

10-14-2010, 01:31 AM	#12
theslawdawg Registered User Join Date: Dec 2009 Location: VA Beach, VA Posts: 67	Re: Running Hot It is a brand new radiator (3 core). This is more of a curiousity for me right now. I know that the even though the needle is higher, it still bugs me to see it considerably higher now than when I had my beat up 2 core in it. __________________ 1972 Chevy C10

10-14-2010, 04:54 PM	#13
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: Running Hot flushing the old coolant may have rinsed some crap off the temp guage sender maybe. I think I'd be happy that is up in the normal range now.



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