1979 C3 383 running hot
11-15-2018, 12:20 AM
#1
1979 C3 383 running hot
Replaced my 350 with a 383 stroker and its running at 230° installed 4 core aluminum radiator, dual electric fans, high volume water pump. Still not running at normal operating temps need help with this one... thanks
11-15-2018, 10:37 AM
#2
With all the upgrades you have done to your cooling system it is definitely sufficient to cool your engine. This is likely a timing or fuel issue.
What is your timing curve like?
Initial/base timing
Mechanical advance
Vacuum advance
Total timing
Second thing to consider is fuel
Have you checked your spark plugs since installing the 383? They should give you an idea of if you are running super rich or lean.
Are the exhaust fumes burning your eyes?
What is your timing curve like?
Initial/base timing
Mechanical advance
Vacuum advance
Total timing
Second thing to consider is fuel
Have you checked your spark plugs since installing the 383? They should give you an idea of if you are running super rich or lean.
Are the exhaust fumes burning your eyes?
11-15-2018, 11:14 AM
#3
Melting Slicks
Guage? Sending unit? If these are still the original pieces it may be a simple indication error. I have a new 434 sbc in mine, during the cooler weather it's running around 180. During our hot summer where it was over 100', it was around 210 at the warmest part of the day, in traffic, a/c running. I have 2 sources that pull water temp. 1 off the cylinder head that sends info to my F.I. unit, I can see the temp thru the handheld controller. The other off the intake sensor. I am running an afternarket mechanical guage. You may want to consider an oil cooler as well. I did. Also, even though you are running a big radiator with dual cooling fans, is it shrouded? I hand built my cooling fan shroud to capture every bit of the core surface area, many of the aftermarket shrouds leave a lot of the radiator core hanging outside of the shroud. Frosty has some good items to check, timing can certainly influence temp. I had a 383 prior to the latest 434, it had an issue where it would blow a small amount of coolant out of the overflow after shutdown. I never saw water in the oil. Then one day, with less than 3000 miles on the engine, I noticed white smoke out the exhaust. That "little" nusance problem turned out to be a cracked cylinder wall. Could have been a few things, core shift, improper setup of the boring machine, but regardless the block was now a boat anchor. Im lucky it didnt break out the wall entirely. Anyway good luck.
11-15-2018, 06:49 PM
#4
Race Director
I agree with 'Sunstroked'. IF the sendling unit was changed out....it can and more than likely is INCORRECT. Install an aftermarket temp gauge that you know is a good one and check it off of that. I have a liquid filled AutoMeter gauge I use JUST for this same problem that I come across a temp problem on new engines.
DUB
DUB
11-15-2018, 08:46 PM
#5
Dr. Detroit
Member Since: Mar 2012
Location: New Braunfels Texas
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Yes......double check with another mechanical gauge screwed into the head.
Jebby
Jebby
11-16-2018, 09:52 AM
#6
and as I've been "getting acquainted" with my first Vette ... I've used a laser thermometer on the thermostat housing to verify the temp is matching the thermostat operation (was 195 ... I've since put 160 in it) ... the gauge now reads approximately 140 despite the sending unit's being on the driver side head (hotter) ... but it's a reference.
Also, the oil pressure isn't accurate, but will reveal lost oil pressure. (wandering, I know)
laser thermometer ... also check the return temp from the radiator that way, and the heater core (coil???) input/return.
Also, the oil pressure isn't accurate, but will reveal lost oil pressure. (wandering, I know)
laser thermometer ... also check the return temp from the radiator that way, and the heater core (coil???) input/return.
11-16-2018, 03:30 PM
#7
383 overheat temp guage bad?
I agree with 'Sunstroked'. IF the sendling unit was changed out....it can and more than likely is INCORRECT. Install an aftermarket temp gauge that you know is a good one and check it off of that. I have a liquid filled AutoMeter gauge I use JUST for this same problem that I come across a temp problem on new engines.
Last edited by rio9760; 11-16-2018 at 04:03 PM.
11-16-2018, 03:41 PM
#8
Guage? Sending unit? If these are still the original pieces it may be a simple indication error. I have a new 434 sbc in mine, during the cooler weather it's running around 180. During our hot summer where it was over 100', it was around 210 at the warmest part of the day, in traffic, a/c running. I have 2 sources that pull water temp. 1 off the cylinder head that sends info to my F.I. unit, I can see the temp thru the handheld controller. The other off the intake sensor. I am running an afternarket mechanical guage. You may want to consider an oil cooler as well. I did. Also, even though you are running a big radiator with dual cooling fans, is it shrouded? I hand built my cooling fan shroud to capture every bit of the core surface area, many of the aftermarket shrouds leave a lot of the radiator core hanging outside of the shroud. Frosty has some good items to check, timing can certainly influence temp. I had a 383 prior to the latest 434, it had an issue where it would blow a small amount of coolant out of the overflow after shutdown. I never saw water in the oil. Then one day, with less than 3000 miles on the engine, I noticed white smoke out the exhaust. That "little" nusance problem turned out to be a cracked cylinder wall. Could have been a few things, core shift, improper setup of the boring machine, but regardless the block was now a boat anchor. Im lucky it didnt break out the wall entirely. Anyway good luck.
Last edited by rio9760; 11-16-2018 at 03:44 PM.
11-16-2018, 03:47 PM
#9
Guage? Sending unit? If these are still the original pieces it may be a simple indication error. I have a new 434 sbc in mine, during the cooler weather it's running around 180. During our hot summer where it was over 100', it was around 210 at the warmest part of the day, in traffic, a/c running. I have 2 sources that pull water temp. 1 off the cylinder head that sends info to my F.I. unit, I can see the temp thru the handheld controller. The other off the intake sensor. I am running an afternarket mechanical guage. You may want to consider an oil cooler as well. I did. Also, even though you are running a big radiator with dual cooling fans, is it shrouded? I hand built my cooling fan shroud to capture every bit of the core surface area, many of the aftermarket shrouds leave a lot of the radiator core hanging outside of the shroud. Frosty has some good items to check, timing can certainly influence temp. I had a 383 prior to the latest 434, it had an issue where it would blow a small amount of coolant out of the overflow after shutdown. I never saw water in the oil. Then one day, with less than 3000 miles on the engine, I noticed white smoke out the exhaust. That "little" nusance problem turned out to be a cracked cylinder wall. Could have been a few things, core shift, improper setup of the boring machine, but regardless the block was now a boat anchor. Im lucky it didnt break out the wall entirely. Anyway good luck.
Last edited by rio9760; 11-16-2018 at 03:48 PM.
11-16-2018, 04:00 PM
#10
With all the upgrades you have done to your cooling system it is definitely sufficient to cool your engine. This is likely a timing or fuel issue.
What is your timing curve like?
Initial/base timing
Mechanical advance
Vacuum advance
Total timing
Second thing to consider is fuel
Have you checked your spark plugs since installing the 383? They should give you an idea of if you are running super rich or lean.
Are the exhaust fumes burning your eyes?
What is your timing curve like?
Initial/base timing
Mechanical advance
Vacuum advance
Total timing
Second thing to consider is fuel
Have you checked your spark plugs since installing the 383? They should give you an idea of if you are running super rich or lean.
Are the exhaust fumes burning your eyes?
11-16-2018, 06:50 PM
#11
I would examine if the dual fan setup and make they are drawing ample air through the rad. Heat is heat, the air removes the heat. If the shroud seals are open on the sides, the air movement from the fans is going around rather than through the rad. Its a simple heat exchanger, you are not moving enough air to remove the heat you are making.
On the stock shroud setup the seals are not optional, without them, the best parts will run hot.
On the stock shroud setup the seals are not optional, without them, the best parts will run hot.
11-17-2018, 07:10 PM
#12
Melting Slicks
Regarding stock exhaust, if its a 2" exhaust thru the original mufflers, at the minimum you are not taking advantage of that stroker. I ran into that situation with my new engine. I installed the corvette central 2.5" dual exhaust with the magna flow mufflers when I installed the 383. it actually necks down to 2" exits. That is a major log jam with the 434. It showed up on the dyno runs. Im about to order 3" exhaust tubing and mufflers, I have new 1 7/8" headers waiting to go on. Im told it will add significant power to the 455 rwhp on tap now. I can only guess that the engine may run cooler too.
11-17-2018, 09:46 PM
#13
Regarding stock exhaust, if its a 2" exhaust thru the original mufflers, at the minimum you are not taking advantage of that stroker. I ran into that situation with my new engine. I installed the corvette central 2.5" dual exhaust with the magna flow mufflers when I installed the 383. it actually necks down to 2" exits. That is a major log jam with the 434. It showed up on the dyno runs. Im about to order 3" exhaust tubing and mufflers, I have new 1 7/8" headers waiting to go on. Im told it will add significant power to the 455 rwhp on tap now. I can only guess that the engine may run cooler too.
11-17-2018, 09:48 PM
#14
I would examine if the dual fan setup and make they are drawing ample air through the rad. Heat is heat, the air removes the heat. If the shroud seals are open on the sides, the air movement from the fans is going around rather than through the rad. Its a simple heat exchanger, you are not moving enough air to remove the heat you are making.
On the stock shroud setup the seals are not optional, without them, the best parts will run hot.
On the stock shroud setup the seals are not optional, without them, the best parts will run hot.
11-17-2018, 09:51 PM
#15
11-18-2018, 11:37 AM
#16
Race Director
MORE information needed:
Are you sure the radiator cap is one for a CLOSED SYSTEM??? And it should be at least a 15 lb cap.
When the engine is running and getting hot.....when you squeeze on a radiator hose. Is it tight like it is under pressure???
You can use water with rust inhibitor in it if you live in an area of the world where it does not freeze.. Due to you have not basically filled out your Public Profile...we do not know basically where in the world you are at. Are you using a coolant/distilled water mix of at least 50/50???
Are your electric fans coming on at all???? You have not mentioned that at all.
Have you VERIFIED that the water pump is doing its job?? . Because the impeller on a water pump can be made to work in the opposite direction and that can be your problem. This is an easy test to verify.
Also are you 100% certain that the cooling system is SEALED UP by pressure testing it with a coolant system pressure tester and also that it is filled up.
The reason I say this is that is why I drill a small hole in the thermostat so when the engine is running and I am filling it up the rest of the way the air that would NORMALLY be trapped by the thermostat that is still in the top of the cylinder heads can get past it and into the radiator thus allowing me to fill it up all the way. as needed. I will rev the engine slightly ( 1500 rpms or so and hold it for a few seconds) to get the coolant moving really good to get the air bubbles out while filling it. But I do this when the level in the radiator is still down about 3 inches or so from the cap.
I agree that increasing the size of your exhaust can not hurt by any means but it alone may not be the smoking gun in this scenario on what is causing this problem.
IF you are having a problem in NOT getting the timing to advance...I would look a t your distributor and make sure that advance weights can move and the plate can rotate. Not knowing what you have for a distributor...it is hard to say nay more. Thus...more information needed. Incorrect springs on the advance weights can cause issues. A bad vacuum advance diaphragm can also cause problems also when setting the timing and seeing what your 'ALL IN: advance is set al.
DUB
Are you sure the radiator cap is one for a CLOSED SYSTEM??? And it should be at least a 15 lb cap.
When the engine is running and getting hot.....when you squeeze on a radiator hose. Is it tight like it is under pressure???
You can use water with rust inhibitor in it if you live in an area of the world where it does not freeze.. Due to you have not basically filled out your Public Profile...we do not know basically where in the world you are at. Are you using a coolant/distilled water mix of at least 50/50???
Are your electric fans coming on at all???? You have not mentioned that at all.
Have you VERIFIED that the water pump is doing its job?? . Because the impeller on a water pump can be made to work in the opposite direction and that can be your problem. This is an easy test to verify.
Also are you 100% certain that the cooling system is SEALED UP by pressure testing it with a coolant system pressure tester and also that it is filled up.
The reason I say this is that is why I drill a small hole in the thermostat so when the engine is running and I am filling it up the rest of the way the air that would NORMALLY be trapped by the thermostat that is still in the top of the cylinder heads can get past it and into the radiator thus allowing me to fill it up all the way. as needed. I will rev the engine slightly ( 1500 rpms or so and hold it for a few seconds) to get the coolant moving really good to get the air bubbles out while filling it. But I do this when the level in the radiator is still down about 3 inches or so from the cap.
I agree that increasing the size of your exhaust can not hurt by any means but it alone may not be the smoking gun in this scenario on what is causing this problem.
IF you are having a problem in NOT getting the timing to advance...I would look a t your distributor and make sure that advance weights can move and the plate can rotate. Not knowing what you have for a distributor...it is hard to say nay more. Thus...more information needed. Incorrect springs on the advance weights can cause issues. A bad vacuum advance diaphragm can also cause problems also when setting the timing and seeing what your 'ALL IN: advance is set al.
DUB
11-20-2018, 09:00 AM
#17
Racer
Member Since: Mar 2006
Posts: 349
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Make sure your dual electric fans are mounted correctly, some are meant for pushing some for pulling, even if you wired them to spin correctly the blades are curved differently.
ecklers has a Front spoiler extension for a 79(it will fit 68-79), It dropped my temperatures down to 190.
11-20-2018, 11:25 PM
#18
MORE information needed:
Are you sure the radiator cap is one for a CLOSED SYSTEM??? And it should be at least a 15 lb cap.
When the engine is running and getting hot.....when you squeeze on a radiator hose. Is it tight like it is under pressure???
You can use water with rust inhibitor in it if you live in an area of the world where it does not freeze.. Due to you have not basically filled out your Public Profile...we do not know basically where in the world you are at. Are you using a coolant/distilled water mix of at least 50/50???
Are your electric fans coming on at all???? You have not mentioned that at all.
Have you VERIFIED that the water pump is doing its job?? . Because the impeller on a water pump can be made to work in the opposite direction and that can be your problem. This is an easy test to verify.
Also are you 100% certain that the cooling system is SEALED UP by pressure testing it with a coolant system pressure tester and also that it is filled up.
The reason I say this is that is why I drill a small hole in the thermostat so when the engine is running and I am filling it up the rest of the way the air that would NORMALLY be trapped by the thermostat that is still in the top of the cylinder heads can get past it and into the radiator thus allowing me to fill it up all the way. as needed. I will rev the engine slightly ( 1500 rpms or so and hold it for a few seconds) to get the coolant moving really good to get the air bubbles out while filling it. But I do this when the level in the radiator is still down about 3 inches or so from the cap.
I agree that increasing the size of your exhaust can not hurt by any means but it alone may not be the smoking gun in this scenario on what is causing this problem.
IF you are having a problem in NOT getting the timing to advance...I would look a t your distributor and make sure that advance weights can move and the plate can rotate. Not knowing what you have for a distributor...it is hard to say nay more. Thus...more information needed. Incorrect springs on the advance weights can cause issues. A bad vacuum advance diaphragm can also cause problems also when setting the timing and seeing what your 'ALL IN: advance is set al.
DUB
Are you sure the radiator cap is one for a CLOSED SYSTEM??? And it should be at least a 15 lb cap.
When the engine is running and getting hot.....when you squeeze on a radiator hose. Is it tight like it is under pressure???
You can use water with rust inhibitor in it if you live in an area of the world where it does not freeze.. Due to you have not basically filled out your Public Profile...we do not know basically where in the world you are at. Are you using a coolant/distilled water mix of at least 50/50???
Are your electric fans coming on at all???? You have not mentioned that at all.
Have you VERIFIED that the water pump is doing its job?? . Because the impeller on a water pump can be made to work in the opposite direction and that can be your problem. This is an easy test to verify.
Also are you 100% certain that the cooling system is SEALED UP by pressure testing it with a coolant system pressure tester and also that it is filled up.
The reason I say this is that is why I drill a small hole in the thermostat so when the engine is running and I am filling it up the rest of the way the air that would NORMALLY be trapped by the thermostat that is still in the top of the cylinder heads can get past it and into the radiator thus allowing me to fill it up all the way. as needed. I will rev the engine slightly ( 1500 rpms or so and hold it for a few seconds) to get the coolant moving really good to get the air bubbles out while filling it. But I do this when the level in the radiator is still down about 3 inches or so from the cap.
I agree that increasing the size of your exhaust can not hurt by any means but it alone may not be the smoking gun in this scenario on what is causing this problem.
IF you are having a problem in NOT getting the timing to advance...I would look a t your distributor and make sure that advance weights can move and the plate can rotate. Not knowing what you have for a distributor...it is hard to say nay more. Thus...more information needed. Incorrect springs on the advance weights can cause issues. A bad vacuum advance diaphragm can also cause problems also when setting the timing and seeing what your 'ALL IN: advance is set al.
DUB
11-21-2018, 07:23 AM
#19
could also be cavitation in the pump, assuming the temp sensor is reading correct a high volume pump may be drawing enough coolant that air is coming in from the top of the rad, even a few bubbles slowly being introduced will cause cavitation which will self correct as the engine is burped after cooldown. I think this is where dub is heading in his earlier post about the air in the system.
Last edited by sambrand; 11-21-2018 at 07:27 AM.
11-21-2018, 12:13 PM
#20
I would examine if the dual fan setup and make they are drawing ample air through the rad. Heat is heat, the air removes the heat. If the shroud seals are open on the sides, the air movement from the fans is going around rather than through the rad. Its a simple heat exchanger, you are not moving enough air to remove the heat you are making.
On the stock shroud setup the seals are not optional, without them, the best parts will run hot.
On the stock shroud setup the seals are not optional, without them, the best parts will run hot.
