Overheating 5.3l swap
10-02-2017, 12:36 AM
#1
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Overheating 5.3l swap I did a 5.3 swap into my 79 firebird and the temperature gauge is reading 230-240 degrees, the engine is out of a 2003 Surburban. I just ordered a 160 degree thermostat I'm hoping that will fix the problem, have anyone else had this problem with a LS swap?
10-02-2017, 02:33 PM
#4
TECH Addict
I'm betting air.. Did you fill with water or AF or a mix? I use a wetting agent (Redline/blue-Ice etc) in the cooling system of all my cars, I believe it helps bleed them better.. YMMV.
10-02-2017, 04:44 PM
#7
Loops contributes to over-heating (or rather, over-thermostating, or whatever its called when the inlet temp of the block is raised even though the original thermostat has not been changed).
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10-29-2017, 09:22 AM
#9
Rock auto says a 2003 suburban with a 5.3 has a 187 degree thermostat. If that is true than unless the stock unit is bad replacing it with a lower opening temp won't help.
LS motors are typically pretty easy to cool. If they overheat than the problem is typically air in the coolant or bad air flow through the radiator.
What radiator and fan set up do you have? Is it getting hot at idle or when moving?
LS motors are typically pretty easy to cool. If they overheat than the problem is typically air in the coolant or bad air flow through the radiator.
What radiator and fan set up do you have? Is it getting hot at idle or when moving?
10-29-2017, 10:02 AM
#10
Quit posting this as a fix because it's not the issue, Like I said when you gave this advice before, You do not need 4-corner steam vents and I have ran the heater outlets plugged and looped and through a heater core on different builds and none had a overheating issue. You keep giving advice like you have experience and from looking at your past posts you obviously DO NOT!
Last edited by LLLosingit; 10-29-2017 at 10:21 AM.
10-29-2017, 10:07 AM
#11
Agree 100% here, I will also add this, Try jacking the front of the car up while running to help get any trapped air out of the system, Camaro and Firebirds of that year were hard to get the air out with the stock engine, I don't see how the LS engine would be any easier.
10-29-2017, 03:28 PM
#12
Quit posting this as a fix because it's not the issue, Like I said when you gave this advice before, You do not need 4-corner steam vents and I have ran the heater outlets plugged and looped and through a heater core on different builds and none had a overheating issue. You keep giving advice like you have experience and from looking at your past posts you obviously DO NOT!
Try google there is an entire website dedicated to why you shouldn't loop the heater core lines.
And yes I do have experience, a friend's local 5.3 Was staying a little hot all the time, we blocked the heater core and removed the loop it dropped 20*F at the engine inlet. I never had this problem with my 5.3 because I never looped it. Thats two engines so far experience.
10-29-2017, 04:01 PM
#13
it isnt my advice. It is something I researched up online before doing the swap.
Try google there is an entire website dedicated to why you shouldn't loop the heater core lines.
And yes I do have experience, a friend's local 5.3 Was staying a little hot all the time, we blocked the heater core and removed the loop it dropped 20*F at the engine inlet. I never had this problem with my 5.3 because I never looped it. Thats two engines so far experience.
Try google there is an entire website dedicated to why you shouldn't loop the heater core lines.
And yes I do have experience, a friend's local 5.3 Was staying a little hot all the time, we blocked the heater core and removed the loop it dropped 20*F at the engine inlet. I never had this problem with my 5.3 because I never looped it. Thats two engines so far experience.
11-03-2017, 12:42 PM
#15
http://www.pirate4x4.com/tech/billavista/Cooling/
It seems pretty obvious the low pressure side of cooling system is tied with lower radiator hose. With a looped heater hose you pump hot-engine water into the radiator's low-pressure side, which is cooled water coming from the radiator. In the picture it looks like both are behind the thermostat but if that was true I don't see how the hose would have any differential for flow.
It seems pretty obvious the low pressure side of cooling system is tied with lower radiator hose. With a looped heater hose you pump hot-engine water into the radiator's low-pressure side, which is cooled water coming from the radiator. In the picture it looks like both are behind the thermostat but if that was true I don't see how the hose would have any differential for flow.
Last edited by kingtal0n; 11-03-2017 at 01:33 PM.
11-03-2017, 01:49 PM
#16
And yes I do have experience, a friend's local 5.3 Was staying a little hot all the time, we blocked the heater core and removed the loop it dropped 20*F at the engine inlet. I never had this problem with my 5.3 because I never looped it. Thats two engines so far experience.
The lines must be looped. I know from firsthand experience. I overheated the sht out of my car when I first swapped it. Went into limp mode, melted the seal on my brand new $170 2010 camaro water pump, the works. Did some research and found out there isn't a valve in the heater core lines like the german and japanese cars I was used to, water always flows through the heater core, even when the heat is off.
The heater core circuit for the LS is designed to keep coolant circulating throughout the engine at all times - even when the thermostat is closed - to keep the entire engine at the same temperature and prevent hot spots. If you block that circuit, you block a LARGE portion of that coolant and it will boil in those hotspots, especially if you're running a radiator that's on the small side like I am. Once that coolant starts to boil, it's a downward spiral trying to get it under control.
Coolant must flow at all times through them. They cannot be blocked.
11-03-2017, 05:17 PM
#17
The temperature of the water coming out of the radiator has nothing to do with the temperature of the engine. In fact, that cooler water in the radiator should have been a sign that less heat was being taken from the engine.
The lines must be looped. I know from firsthand experience. I overheated the sht out of my car when I first swapped it. Went into limp mode, melted the seal on my brand new $170 2010 camaro water pump, the works. Did some research and found out there isn't a valve in the heater core lines like the german and japanese cars I was used to, water always flows through the heater core, even when the heat is off.
The heater core circuit for the LS is designed to keep coolant circulating throughout the engine at all times - even when the thermostat is closed - to keep the entire engine at the same temperature and prevent hot spots. If you block that circuit, you block a LARGE portion of that coolant and it will boil in those hotspots, especially if you're running a radiator that's on the small side like I am. Once that coolant starts to boil, it's a downward spiral trying to get it under control.
Coolant must flow at all times through them. They cannot be blocked.
The lines must be looped. I know from firsthand experience. I overheated the sht out of my car when I first swapped it. Went into limp mode, melted the seal on my brand new $170 2010 camaro water pump, the works. Did some research and found out there isn't a valve in the heater core lines like the german and japanese cars I was used to, water always flows through the heater core, even when the heat is off.
The heater core circuit for the LS is designed to keep coolant circulating throughout the engine at all times - even when the thermostat is closed - to keep the entire engine at the same temperature and prevent hot spots. If you block that circuit, you block a LARGE portion of that coolant and it will boil in those hotspots, especially if you're running a radiator that's on the small side like I am. Once that coolant starts to boil, it's a downward spiral trying to get it under control.
Coolant must flow at all times through them. They cannot be blocked.
For the record, even GM blocks them on their COPO cars. So......
11-03-2017, 05:56 PM
#18
No men, world is flat. Don't you know we stone bitches that say otherwise? Better retract that scientific fact before Duke runs out of bubble gum.
And I like how he "swears" it cannot be done. Perfect example of how the state of things got to where it is.
And I like how he "swears" it cannot be done. Perfect example of how the state of things got to where it is.
11-03-2017, 08:44 PM
#19
http://www.pirate4x4.com/tech/billavista/Cooling/
It seems pretty obvious the low pressure side of cooling system is tied with lower radiator hose. With a looped heater hose you pump hot-engine water into the radiator's low-pressure side, which is cooled water coming from the radiator. In the picture it looks like both are behind the thermostat but if that was true I don't see how the hose would have any differential for flow.
It seems pretty obvious the low pressure side of cooling system is tied with lower radiator hose. With a looped heater hose you pump hot-engine water into the radiator's low-pressure side, which is cooled water coming from the radiator. In the picture it looks like both are behind the thermostat but if that was true I don't see how the hose would have any differential for flow.
Think of the heater core as a very small radiator (it is what it is) with a surface area that is probably less 10% of your total cooling capacity and with no air blowing on it 99% of the time (nobody I know runs the heat while driving on a hot day), Now given the small amount that is actually diverted to the heater core and what does is loosing very little heat how in the hell can you say that this is going to cause an engine to run hot?
Since the engine doesn't know the difference between the hoses being looped or running through the (longer loop)heater core = looping does not and will not cause a heating issue!
If this was the case just about every LS based engine on the road would overheat!
Like I've said several times now looping or blocking makes no difference, What does make a difference if having the proper cooling capacity for the amount of heat generated AKA Appropriate sized radiator and the ability to get air across said radiator. It's as simple as that!
If you think your engine is overheating because you did or didn't loop/block off the heater hose outlet/inlet on the pump then you have other issues to deal with because that's not the cause.
Last edited by LLLosingit; 11-03-2017 at 08:59 PM.
11-03-2017, 09:04 PM
#20
water always flows through the heater core, even when the heat is off.
The heater core circuit for the LS is designed to keep coolant circulating throughout the engine at all times - even when the thermostat is closed -
Coolant must flow at all times through them. They cannot be blocked.
The heater core circuit for the LS is designed to keep coolant circulating throughout the engine at all times - even when the thermostat is closed -
Coolant must flow at all times through them. They cannot be blocked.
Plus if your engine is overheating then the thermostat would be open correct? That would tell you right there that your theory doesn't work.