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HI. got 2016 L83 engine, obviously have aftermarket old style radiator what fits in my '57 chevy truck. Do i need coolant overflow tank or expansion tank ?
i have overflow outlet from the radiator and i have i believe a purge outlet right by the engine. where do hook up that purge outlet? Can anyone explain me what i need and how to hook it all up correctly.
thanks in advance
here are pics of outlets.
I would run an expansion tank, just as GM does.
-Run the small hose from the thermostat housing to the top of the expansion tank.
-Run the hose from the bottom of the expansion tank into the lower radiator hose or the heater core return hose.
-Make sure the cap on your radiator is rated at a higher pressure than the expansion tank cap.
-Cap off or plug the nipple under the radiator cap.
-Running a overflow tank off the expansion tank is optional, but is required to run at most track events.
It's the same principle as the LSx engines. Here's a good diagram to wrap your head around the concept.
thank you s14hunter. that makes sense. not going on the track, Los Angles weather tho.
can i run the line from radiator overflow to reserve overflow ? if not what go i do with expansion tank overflow nipple? does it matter how high the expansion tank is placed ?
thanks again. this seems so simple , but somehow I'm little baffled by it and want to make sure its right.
You don't really "need" either. It is pretty easy to add an overflow tank, just run a line off your current radiator overflow nipple into a bottle of some sort. The advantage of that is it keeps the radiator full by sucking coolant instead of air back in as the motor cools off. Can be done very cheaply, I made one out of a steel water bottle
The expansion tank does a better job of this and even allows air to be stripped out of the coolant as the engine runs. A lot more work and like said above you need to get it higher than the rest of the motor. I don't think any of my cars have ever had one.
...The advantage of that is it keeps the radiator full by sucking coolant instead of air back in as the motor cools off.
If the expansion tank is the highest point in the system (and the fill point), then the radiator will always be full. Some people like to do things right the first time, and some like to be cheap and cut corners.
You only need the pressurized expansion tank if the radiator cap is not the highest point in the system, to release air.
My LS 69 vette has a low radiator and needs an expansion tank (much like new LS vettes).
My 72 olds LS has a high radiator mount and a simple overflow tank works fine. Just the way 99% of cars and trucks are set up.
I'm guessing your radiator is fairly high and the cap is the highest point in the system. If that's the case, an expansion tank is pointless.
You only need the pressurized expansion tank if the radiator cap is not the highest point in the system, to release air.
My LS 69 vette has a low radiator and needs an expansion tank (much like new LS vettes).
My 72 olds LS has a high radiator mount and a simple overflow tank works fine. Just the way 99% of cars and trucks are set up.
I'm guessing your radiator is fairly high and the cap is the highest point in the system. If that's the case, an expansion tank is pointless.
If the expansion tank is the highest point in the system (and the fill point), then the radiator will always be full. Some people like to do things right the first time, and some like to be cheap and cut corners.
Have to laugh at that one. As the old saying goes better is the enemy of good enough.
If you REALLY want to do it right and not cut corners than install a deaerating expansion tank. Have it strip the air from the coolant to increase it's cooling capacity.
Like I said you don't really need either. Overflow bottles didn't show up until the 60's I believe. I'll stick with my handmade over flow bottle. Think I got the bottle free and the bracket metal was from a file cabinet at work. I might have 37 cents in the hardware
Last edited by Pop N Wood; Apr 7, 2017 at 06:26 AM.
at my local track you cant run unless you have a sealed catch. I have mine plumbed from the catch to the windshield squirter on the passenger side so if I'm lifting a head and pushing water it'll be really easy to see
thanks guys.
Shunter14 - my radiator is too high. i can't add expansion tank and have it higher than radiator.
For all you smart people : So if i go with overflow tank. where does the steam vent valve from the thermostat housing connect to? do i plug it? (it is plugged at the moment, you can see on 2nd picture i posted)
thank you all
Have to laugh at that one. As the old saying goes better is the enemy of good enough.
Your old sayings match your old tech mentality
Originally Posted by Pop N Wood
If you REALLY want to do it right and not cut corners than install a deaerating expansion tank. Have it strip the air from the coolant to increase it's cooling capacity.
You do realize that the main purpose of ANY expansion tank is to deaerate the coolant. That's my whole point.
Have a look at any LS GM truck and see that they run an expansion tank EVEN WITH the radiator being the highest point.
OP, to answer your question about the small hose on the thermostat housing, the ideal route would be to run it to the top outer corner of your radiator with a weld in bung. I'm sure these other guys will tell you to plug it. Have fun!
Last edited by s14hunter; Apr 7, 2017 at 02:00 PM.
Dammit, I spent $7 at autozone for a generic overflow tank. The cheap plastic hose kinked, mounting bracket cracked, and I like the look of yours more....
Originally Posted by Pop N Wood
Have to laugh at that one. As the old saying goes better is the enemy of good enough.
If you REALLY want to do it right and not cut corners than install a deaerating expansion tank. Have it strip the air from the coolant to increase it's cooling capacity.
Like I said you don't really need either. Overflow bottles didn't show up until the 60's I believe. I'll stick with my handmade over flow bottle. Think I got the bottle free and the bracket metal was from a file cabinet at work. I might have 37 cents in the hardware
if you dont want to weld in a bung, there are water tight bulkhead AN fittings available or you can use the upper radiator hose "tee" from jags that run . com.
at my local track you cant run unless you have a sealed catch. I have mine plumbed from the catch to the windshield squirter on the passenger side so if I'm lifting a head and pushing water it'll be really easy to see
thanks guys.
Shunter14 - my radiator is too high. i can't add expansion tank and have it higher than radiator.
For all you smart people : So if i go with overflow tank. where does the steam vent valve from the thermostat housing connect to? do i plug it? (it is plugged at the moment, you can see on 2nd picture i posted)
thank you all
On the Chevy Trailblazer the steam vent line attaches to the heater hose down by the water pump, that is how I routed mine and it is working fine. But, the steam line also goes through the throttle body. There is a line straight through the bottom of it (to warm it up in cold driving conditions). I guess you can ignore that one if only summer time driving is on schedule.
I have no expansion tank, either. The radiator sits high in an GM A-body, and I just leave some empty space (2 inches or so) in top of the rad (water level still higher than the engine) for expansion. Drove it all summer without the fans even kicking in. This is one cool running motor. But I live in Sweden and we have crappy summers
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Radiator Coolant overflow or expansion tank 
