coolant circulation
Thread Starter
Joined: Sep 2007
Posts: 640
Likes: 3
From: Northern California
Car: 1985 California Iroc
Engine: HSR ZZ4 0411 swapped
Transmission: 4L60E
Axle/Gears: 3.23 posi
coolant circulation
imediatly after i start my car the coolant is circulating? stuck open thermostat? could this be part of my cooling issue?
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Posts: 998
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From: Bedford Tx
Car: 1991 Z28 1LE
Engine: 370CID GenIII
Transmission: 4l60e
Axle/Gears: 4.33 Moser 9inch
Re: coolant circulation
u ever notice that hole on the left side of the water pump beneath the lower bolt, thats the bypass hole its there to allow coolant to flow a lil constantly so that the pump doesnt just cavitate and just whip the water. if the thermostat is stuck open it should be takeing longer to warm up then normal. a thermostats job is to force an engine to get warm not to pop open and cool an engine like so many people think...
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Joined: Jan 2000
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From: Mercedes Norte, Heredia, Costa Rica
Car: 1984 Z28 Hardtop
Engine: 383 Carb
Transmission: 4L60
Axle/Gears: 3.54 Dana 44
Thread Starter
Joined: Sep 2007
Posts: 640
Likes: 3
From: Northern California
Car: 1985 California Iroc
Engine: HSR ZZ4 0411 swapped
Transmission: 4L60E
Axle/Gears: 3.23 posi
Re: coolant circulation
thanks, that answers my ?. my lower rad hose feels soft, might this be my cooling issue? it seems to cool at idle, but at 2000 rpms and up it seems to have a hard time cooling down. and my air dam is in place.
Moderator
Joined: Jan 2000
Posts: 20,981
Likes: 11
From: Mercedes Norte, Heredia, Costa Rica
Car: 1984 Z28 Hardtop
Engine: 383 Carb
Transmission: 4L60
Axle/Gears: 3.54 Dana 44
Re: coolant circulation
What fan setup do you have? What do you mean by "has a hard time cooling down"?
Thread Starter
Joined: Sep 2007
Posts: 640
Likes: 3
From: Northern California
Car: 1985 California Iroc
Engine: HSR ZZ4 0411 swapped
Transmission: 4L60E
Axle/Gears: 3.23 posi
Re: coolant circulation
i have my single fan wired through a relay to a toggle,at idle the fan will keep the coolant cool. but at cruisin speed (even with the fan on) the temp will keep rising, iv had it as warm as 250ish+ on the highway.
Last edited by vasquezmrysvll; Jul 9, 2008 at 08:20 PM.
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Senior Member
iTrader: (1)
Joined: Dec 2006
Posts: 998
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From: Bedford Tx
Car: 1991 Z28 1LE
Engine: 370CID GenIII
Transmission: 4l60e
Axle/Gears: 4.33 Moser 9inch
Re: coolant circulation
with the engine running and in park with the parking brake on rev the motor from under the hood when its at full temp and watch the lower hose, it might be colapsing on itself. if so get the new hose with the coil in it so it cant colapse...
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From: San Antonio, Tx
Car: 86 Camaro Z28/ 87 Camaro IROC Z28
Engine: 5.0L TPI LB9 / 5.0 TPI LB9 w/cam
Transmission: Built 700R4 with Transgo shift kit
Axle/Gears: 3.27 9 bolt Posi/ 2.73 10 bolt Posi
Re: coolant circulation
Does it bubble over the overlow tank when you stop the engine?
I would replace the thermostat just in case, they are cheap and I have had a good run of them fail in the closed position. If its stuck closed or opens at a much higher temperature, its doing you no good. (If you want to double check for a bad t-stat, boil a pot of water and get some thongs and hold it in there with the thongs. You need a thermometer to check the temperature)
Also, if you have a thermometer, put it directly into the radiator to verify the temperature that the gauge is showing. I have also had cheap coolant temp senders show much higher temperatures than actual temps.
Check your engine bay for leaks, make sure that you dont have a leaking radiator, hose or intake gasket. When you turn the engine off listen for a hissing noise and look for coolant bubbling out. If its hitting the 245-250 range it will be bubbling over in the overflow tank.
I would replace the thermostat just in case, they are cheap and I have had a good run of them fail in the closed position. If its stuck closed or opens at a much higher temperature, its doing you no good. (If you want to double check for a bad t-stat, boil a pot of water and get some thongs and hold it in there with the thongs. You need a thermometer to check the temperature)
Also, if you have a thermometer, put it directly into the radiator to verify the temperature that the gauge is showing. I have also had cheap coolant temp senders show much higher temperatures than actual temps.
Check your engine bay for leaks, make sure that you dont have a leaking radiator, hose or intake gasket. When you turn the engine off listen for a hissing noise and look for coolant bubbling out. If its hitting the 245-250 range it will be bubbling over in the overflow tank.
Thread Starter
Joined: Sep 2007
Posts: 640
Likes: 3
From: Northern California
Car: 1985 California Iroc
Engine: HSR ZZ4 0411 swapped
Transmission: 4L60E
Axle/Gears: 3.23 posi
Re: coolant circulation
no coolant boiling over and no leaks, ill check the lower hose tomorrow(if its not too smokey outside)oh, by the way, california is on FIRE
Thread Starter
Joined: Sep 2007
Posts: 640
Likes: 3
From: Northern California
Car: 1985 California Iroc
Engine: HSR ZZ4 0411 swapped
Transmission: 4L60E
Axle/Gears: 3.23 posi
Re: coolant circulation
PROBLEM SOLVED! (well...one of them). i let my car get up to temp,revved the engine to 2000-2500 from under the hood, looked at the lower hose and it flattened like a cobra. i took the hose off installed a spring from a old hose i had lying around. took it for a test drive and the temp didnt get over 190. befor the spring it would climb to 240+.
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