Overcooling possibly???
02-13-2018, 11:43 AM
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Overcooling possibly??? Good morning all, I've searched through the forum trying to find any info pertaining to this but no luck. I have a LS6 spec iron block that was originally a 5.3 in a silverado (still in a silverado) with a whipple pushing 9 pounds of boost. I installed a 3 row aluminum radiator in tandem with electric fans as well to help with the heat since pushing the truck would warm up the factory radiator fairly easily and being iron it takes a while to come down. I am running the factory 186 thermostat but with the new radiator it seems to be overcooling the engine. At idle it comes up to temp no problem but when I get on the freeway the truck slowly goes all the way down to 160 
.
Things I've done so far
Temperature is being verified by EFI Live not the dummy gauge on the dash
I've removed the thermostat which is OEM and newer ( 2 years maybe) Boiled it and it opened right around 186 and full open around 195 then when cooled down back to 186 range the stat closed correctly
I've also verified that the e fans are not coming on as well (unplug)
Everything I've read leads my to believe the engine shouldn't cool down past the rated thermostat temp. I'm not sure if I'm missing something or I'm just ill informed.
Any help would be super appreciated
other details that help
ambient temp is 45 degrees
truck is kicking along at 65 turning 1700 rpm
I went with the larger radiator since we can see as high as 110 in the summer here and I like the idea of more heat capacity
.Things I've done so far
Temperature is being verified by EFI Live not the dummy gauge on the dash
I've removed the thermostat which is OEM and newer ( 2 years maybe) Boiled it and it opened right around 186 and full open around 195 then when cooled down back to 186 range the stat closed correctly
I've also verified that the e fans are not coming on as well (unplug)
Everything I've read leads my to believe the engine shouldn't cool down past the rated thermostat temp. I'm not sure if I'm missing something or I'm just ill informed.
Any help would be super appreciated
other details that help
ambient temp is 45 degrees
truck is kicking along at 65 turning 1700 rpm
I went with the larger radiator since we can see as high as 110 in the summer here and I like the idea of more heat capacity
02-13-2018, 01:31 PM
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It's possible for an engine to cool below it's rated t-stat temp, this usually requires lots of airflow in the engine bay, cold/cool ambient temps, and low engine speeds. Sounds like you have all the ingredients necessary for such.
I see the same thing happen on my '71. I've got lots of airflow through the engine bay (full sized grille, front wheel wells are not sealed, open cowl hood), so when the ambient temps get very cool on a spring or fall night, I sometimes see engine temp dip below the 180° rating of my t-stat during periods of steady cruising at low engine speeds (made worse by running the heater, since more heat is then lost via the heater core). As soon as engine speeds rise above a certain point, or vehicle speed slows below a certain point (thus reducing airflow), the coolant temps begin to rise. It's probably even more noticeable in your case since you have an OD trans and can maintain even lower engine speeds at even higher vehicle speeds.
Another example is my daily driver, a 2010 Malibu with a 2.4L I4. On a very cold day, I can prevent the engine from reaching operating temp seemingly indefinitely by sitting at idle with the heater on full blast. Airflow across the heater core is enough to keep that particular engine, in that particular configuration, cooler than it's rated t-stat temp at idle speeds in very cold ambient temps. But if airflow was reduced or engine speed was increased, more heat would be retained and/or generated.
So, if you want the engine to run hotter then you'd need to increase engine speed or reduce airflow. You could simply block a portion of the grille during the cold months as an easy fix for this. But, I guess the bigger question is, is 160° really problematically cold during periods of high speed steady cruise in cool outside temps? That's still warm enough to produce plenty of heat for the interior. I know there is great debate about ideal operating temps for any given engine, and I tend to be on the side of slightly warmer temps being preferred, but if this is only happening during steady expressway cruise in cold weather then it's probably not a huge concern (unless you only ever drive under these conditions).
I see the same thing happen on my '71. I've got lots of airflow through the engine bay (full sized grille, front wheel wells are not sealed, open cowl hood), so when the ambient temps get very cool on a spring or fall night, I sometimes see engine temp dip below the 180° rating of my t-stat during periods of steady cruising at low engine speeds (made worse by running the heater, since more heat is then lost via the heater core). As soon as engine speeds rise above a certain point, or vehicle speed slows below a certain point (thus reducing airflow), the coolant temps begin to rise. It's probably even more noticeable in your case since you have an OD trans and can maintain even lower engine speeds at even higher vehicle speeds.
Another example is my daily driver, a 2010 Malibu with a 2.4L I4. On a very cold day, I can prevent the engine from reaching operating temp seemingly indefinitely by sitting at idle with the heater on full blast. Airflow across the heater core is enough to keep that particular engine, in that particular configuration, cooler than it's rated t-stat temp at idle speeds in very cold ambient temps. But if airflow was reduced or engine speed was increased, more heat would be retained and/or generated.
So, if you want the engine to run hotter then you'd need to increase engine speed or reduce airflow. You could simply block a portion of the grille during the cold months as an easy fix for this. But, I guess the bigger question is, is 160° really problematically cold during periods of high speed steady cruise in cool outside temps? That's still warm enough to produce plenty of heat for the interior. I know there is great debate about ideal operating temps for any given engine, and I tend to be on the side of slightly warmer temps being preferred, but if this is only happening during steady expressway cruise in cold weather then it's probably not a huge concern (unless you only ever drive under these conditions).
02-13-2018, 01:40 PM
#3
I may have a solution for you. I battled this for FNG EVER on my Silverado until someone on here earned himself a six pack and a BJ.
The factory Silverado radiator has a restriction where the small hose (3/4" -ish???) connects to the radiator on the passenger side. The line that runs from the radiator to the overflow tank. A lot of aftermarket radiators DO NOT have this. The result is that you are constantly getting a decent amount of coolant flowing through your cooling system, bypassing the thermostat.
And it makes sense that it gets cooler on the highway. The waterpump is spinning faster and youve got more air moving over it. You're likely moving a lot of coolant despite your thermostat.
My fix was to find a piece of round metal stock that fit inside the factory hose. I cut a 1/2" long piece of it, then drilled a small hole through the middle then stuck it in the hose. Result? Boom - instant restriction, instant "normal" cooling again. Life saver. Check it out. See if you see a lot of coolant being squirted into your overflow tank while the truck is idling in your driveway. Rev it by hand, see more? Could be your problem.
The factory Silverado radiator has a restriction where the small hose (3/4" -ish???) connects to the radiator on the passenger side. The line that runs from the radiator to the overflow tank. A lot of aftermarket radiators DO NOT have this. The result is that you are constantly getting a decent amount of coolant flowing through your cooling system, bypassing the thermostat.
And it makes sense that it gets cooler on the highway. The waterpump is spinning faster and youve got more air moving over it. You're likely moving a lot of coolant despite your thermostat.
My fix was to find a piece of round metal stock that fit inside the factory hose. I cut a 1/2" long piece of it, then drilled a small hole through the middle then stuck it in the hose. Result? Boom - instant restriction, instant "normal" cooling again. Life saver. Check it out. See if you see a lot of coolant being squirted into your overflow tank while the truck is idling in your driveway. Rev it by hand, see more? Could be your problem.
02-13-2018, 01:55 PM
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I may have a solution for you. I battled this for FNG EVER on my Silverado until someone on here earned himself a six pack and a BJ.
The factory Silverado radiator has a restriction where the small hose (3/4" -ish???) connects to the radiator on the passenger side. The line that runs from the radiator to the overflow tank. A lot of aftermarket radiators DO NOT have this. The result is that you are constantly getting a decent amount of coolant flowing through your cooling system, bypassing the thermostat.
And it makes sense that it gets cooler on the highway. The waterpump is spinning faster and youve got more air moving over it. You're likely moving a lot of coolant despite your thermostat.
My fix was to find a piece of round metal stock that fit inside the factory hose. I cut a 1/2" long piece of it, then drilled a small hole through the middle then stuck it in the hose. Result? Boom - instant restriction, instant "normal" cooling again. Life saver. Check it out. See if you see a lot of coolant being squirted into your overflow tank while the truck is idling in your driveway. Rev it by hand, see more? Could be your problem.
The factory Silverado radiator has a restriction where the small hose (3/4" -ish???) connects to the radiator on the passenger side. The line that runs from the radiator to the overflow tank. A lot of aftermarket radiators DO NOT have this. The result is that you are constantly getting a decent amount of coolant flowing through your cooling system, bypassing the thermostat.
And it makes sense that it gets cooler on the highway. The waterpump is spinning faster and youve got more air moving over it. You're likely moving a lot of coolant despite your thermostat.
My fix was to find a piece of round metal stock that fit inside the factory hose. I cut a 1/2" long piece of it, then drilled a small hole through the middle then stuck it in the hose. Result? Boom - instant restriction, instant "normal" cooling again. Life saver. Check it out. See if you see a lot of coolant being squirted into your overflow tank while the truck is idling in your driveway. Rev it by hand, see more? Could be your problem.
That makes total sense!!!!! I noticed after I put that radiator in the hose going to the degas tank is blasting out coolant. I thought it was strange but never really paid attention to the degas bottle before.
I'm going to try that tonight
Last edited by nbs lq9; 02-13-2018 at 02:01 PM.
02-13-2018, 01:59 PM
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It's possible for an engine to cool below it's rated t-stat temp, this usually requires lots of airflow in the engine bay, cold/cool ambient temps, and low engine speeds. Sounds like you have all the ingredients necessary for such.
I see the same thing happen on my '71. I've got lots of airflow through the engine bay (full sized grille, front wheel wells are not sealed, open cowl hood), so when the ambient temps get very cool on a spring or fall night, I sometimes see engine temp dip below the 180° rating of my t-stat during periods of steady cruising at low engine speeds (made worse by running the heater, since more heat is then lost via the heater core). As soon as engine speeds rise above a certain point, or vehicle speed slows below a certain point (thus reducing airflow), the coolant temps begin to rise. It's probably even more noticeable in your case since you have an OD trans and can maintain even lower engine speeds at even higher vehicle speeds.
Another example is my daily driver, a 2010 Malibu with a 2.4L I4. On a very cold day, I can prevent the engine from reaching operating temp seemingly indefinitely by sitting at idle with the heater on full blast. Airflow across the heater core is enough to keep that particular engine, in that particular configuration, cooler than it's rated t-stat temp at idle speeds in very cold ambient temps. But if airflow was reduced or engine speed was increased, more heat would be retained and/or generated.
So, if you want the engine to run hotter then you'd need to increase engine speed or reduce airflow. You could simply block a portion of the grille during the cold months as an easy fix for this. But, I guess the bigger question is, is 160° really problematically cold during periods of high speed steady cruise in cool outside temps? That's still warm enough to produce plenty of heat for the interior. I know there is great debate about ideal operating temps for any given engine, and I tend to be on the side of slightly warmer temps being preferred, but if this is only happening during steady expressway cruise in cold weather then it's probably not a huge concern (unless you only ever drive under these conditions).
I see the same thing happen on my '71. I've got lots of airflow through the engine bay (full sized grille, front wheel wells are not sealed, open cowl hood), so when the ambient temps get very cool on a spring or fall night, I sometimes see engine temp dip below the 180° rating of my t-stat during periods of steady cruising at low engine speeds (made worse by running the heater, since more heat is then lost via the heater core). As soon as engine speeds rise above a certain point, or vehicle speed slows below a certain point (thus reducing airflow), the coolant temps begin to rise. It's probably even more noticeable in your case since you have an OD trans and can maintain even lower engine speeds at even higher vehicle speeds.
Another example is my daily driver, a 2010 Malibu with a 2.4L I4. On a very cold day, I can prevent the engine from reaching operating temp seemingly indefinitely by sitting at idle with the heater on full blast. Airflow across the heater core is enough to keep that particular engine, in that particular configuration, cooler than it's rated t-stat temp at idle speeds in very cold ambient temps. But if airflow was reduced or engine speed was increased, more heat would be retained and/or generated.
So, if you want the engine to run hotter then you'd need to increase engine speed or reduce airflow. You could simply block a portion of the grille during the cold months as an easy fix for this. But, I guess the bigger question is, is 160° really problematically cold during periods of high speed steady cruise in cool outside temps? That's still warm enough to produce plenty of heat for the interior. I know there is great debate about ideal operating temps for any given engine, and I tend to be on the side of slightly warmer temps being preferred, but if this is only happening during steady expressway cruise in cold weather then it's probably not a huge concern (unless you only ever drive under these conditions).
That kept it at 198 which is 8 degrees higher than the normal stock radiator so I've been working that program and as you mentioned I've got the perfect storm with a truck that was before the sealing the engine bay era so plenty of cool air to go around.
02-13-2018, 02:21 PM
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The factory Silverado radiator has a restriction where the small hose (3/4" -ish???) connects to the radiator on the passenger side. The line that runs from the radiator to the overflow tank. A lot of aftermarket radiators DO NOT have this. The result is that you are constantly getting a decent amount of coolant flowing through your cooling system, bypassing the thermostat.
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02-13-2018, 02:38 PM
#8
Lol at the painters tape over the grill. I created grill block offs out of cardboard one year, taped them on and basically made my grill air tight. Still no help.
Changed thermostat twice. Still no help.
Bought a new clutch fan thinking maybe the factory one was locked and over cooling. Still no help.
Put efans on with a fan thermostat. Still no help.
I lived this way for way over a year in my daily driver. I tried everything I could. I talked to every friend and relative about it. My best friend is a professional mechanic turned fabricator. Nothing. Then one tiny bit of knowledge and about 6 minutes worth of work and all was right again.
RPM - I don't know if it's specific to just trucks of that period or not, but I suspect that it is. Nobody knows or tells you about this stuff, lol.
Changed thermostat twice. Still no help.
Bought a new clutch fan thinking maybe the factory one was locked and over cooling. Still no help.
Put efans on with a fan thermostat. Still no help.
I lived this way for way over a year in my daily driver. I tried everything I could. I talked to every friend and relative about it. My best friend is a professional mechanic turned fabricator. Nothing. Then one tiny bit of knowledge and about 6 minutes worth of work and all was right again.
RPM - I don't know if it's specific to just trucks of that period or not, but I suspect that it is. Nobody knows or tells you about this stuff, lol.
02-13-2018, 03:25 PM
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However in this case, it sounds like you've perfectly nailed the OP's problem. I'm guessing that will be his fix as well.
02-13-2018, 04:36 PM
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Lol at the painters tape over the grill. I created grill block offs out of cardboard one year, taped them on and basically made my grill air tight. Still no help.
Changed thermostat twice. Still no help.
Bought a new clutch fan thinking maybe the factory one was locked and over cooling. Still no help.
Put efans on with a fan thermostat. Still no help.
I lived this way for way over a year in my daily driver. I tried everything I could. I talked to every friend and relative about it. My best friend is a professional mechanic turned fabricator. Nothing. Then one tiny bit of knowledge and about 6 minutes worth of work and all was right again.
RPM - I don't know if it's specific to just trucks of that period or not, but I suspect that it is. Nobody knows or tells you about this stuff, lol.
Changed thermostat twice. Still no help.
Bought a new clutch fan thinking maybe the factory one was locked and over cooling. Still no help.
Put efans on with a fan thermostat. Still no help.
I lived this way for way over a year in my daily driver. I tried everything I could. I talked to every friend and relative about it. My best friend is a professional mechanic turned fabricator. Nothing. Then one tiny bit of knowledge and about 6 minutes worth of work and all was right again.
RPM - I don't know if it's specific to just trucks of that period or not, but I suspect that it is. Nobody knows or tells you about this stuff, lol.
02-14-2018, 08:01 AM
#11
That's what had me worried, anytime I had a problem like this it usually involved throwing a decent amount of money at the problem until either its fixed or I go back to the previous setup. I was sitting this morning thinking about how I'm going to graft radiator shudders from a new truck onto mine but the more I thought about it, the worse the idea seemed since its like having 2 thermostats for a system that isn't in control so here I came. I will update with what I find tonight.
02-14-2018, 11:02 AM
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I hear ya. I spent a lot of time and money on mine. In the end the fix was literally free. Although I am glad I went to e-fans. I bought a used f-body fan/shroud set up. Fits pretty damn good. On a 90+ degree summer day the factory system couldn't keep up and the AC would cycle off and on. Meaning I'd eat my lunch sweating. Now it can be 100 degrees and AC blows great even if left idling forever. I suppose theoretically I gained some power as well. But a handful of ponies is hard to feel in a 5,500lb truck with 90lbs of wheel and tire at each corner. I want to put my new motor in so badly!
That LS6 is going to be a screamer when its in. hind site I wouldn't have supercharged mine and would have done NA. much less headache but it's nice to walk camaro ss on the freeway and the truck looks totally stock down to wheels and tires plus I can't be too obvious since they pull people over and pop hoods around here. Folks usually just pull up laughing afterwards since it's a full size ext. cab z71
02-14-2018, 11:32 AM
#13
Awesome man, glad to hear it. When I fixed mine I had my Bluetooth dongle plugged in and the torque app running so I could see the temp climb digitally on my phone. I can't tell you how exciting it was to see that temp climb. And then pause around 194 when the thermostat opened. It was like witnessing a miracle.
I'd love to supercharge mine, I think. I went with an LS6 because the price was right on a rebuilt motor. That Whipple has got to give you the instant torque you need in a big *** truck, no?
Glad I could help out with one of the tiniest, simplest, yet most difficult to diagnose problem I've ever come across.
I'd love to supercharge mine, I think. I went with an LS6 because the price was right on a rebuilt motor. That Whipple has got to give you the instant torque you need in a big *** truck, no?
Glad I could help out with one of the tiniest, simplest, yet most difficult to diagnose problem I've ever come across.
02-14-2018, 11:53 AM
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Awesome man, glad to hear it. When I fixed mine I had my Bluetooth dongle plugged in and the torque app running so I could see the temp climb digitally on my phone. I can't tell you how exciting it was to see that temp climb. And then pause around 194 when the thermostat opened. It was like witnessing a miracle.
I'd love to supercharge mine, I think. I went with an LS6 because the price was right on a rebuilt motor. That Whipple has got to give you the instant torque you need in a big *** truck, no?
Glad I could help out with one of the tiniest, simplest, yet most difficult to diagnose problem I've ever come across.
I'd love to supercharge mine, I think. I went with an LS6 because the price was right on a rebuilt motor. That Whipple has got to give you the instant torque you need in a big *** truck, no?
Glad I could help out with one of the tiniest, simplest, yet most difficult to diagnose problem I've ever come across.
the engine is right around 450 ftlb at 3200 and 560 at 4000 rpm so it does help but a little stall and a lighter truck would get the mail no problem.
The blower helps quite a bit, I went with a ZR1 cam for durability (gentle ramp rates) and so I wouldn't blow the tires off the truck when taking off since it bleeds a lot of compression off and I left the stock stall as well (towing) plus stealth idle due to wide LSA. The thing about that cam is the motor always wants to be in boost. I also went with 317 heads to lower the compression more so I'm at 8.26:1 DCR or about 9.2:1 static. That gives you an idea of how much that cam bleeds off.
I also had to switch to hydroboost braking since the truck only makes about 10 inch of vac at idle plus no vacuum coming off boost. My issue is when pulling the trailer I have to be careful and not sit at 7 pounds of boost since cylinder temps start to get high indicated by Knock. (motor always wants to be boosting when being worked at all)
The new radiator should hopefully fix the heat though, last night I was happy to see temps drop as I was pushing the motor so definitely worth it
Whipples are also somewhat noisy too, not the whine but gear-roll-over noise from the blower making you think its lunching itself but its normal at idle.
The price on the whipple was right and it was something I always wanted but after the fact its kinda meh, quicker but more to worry about. The one to have right now for twin screws seems to be Kenny Bell liquid cooled blower which eliminates heat soak plus intercooling as well = monster
I built the motor and looking back I could have built a pretty nasty 408 stroker with similar power figures for a little less money but I had a blower sitting on the bench staring at me and waiting to sing one of the sweetest songs I've ever heard in my life.
sorry about the long response, everyone I work around knows cars like I know fashion so I rarely get to talk about this stuff with folks
Last edited by nbs lq9; 02-14-2018 at 12:08 PM.