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On my 72LS conversion, I need an expansion tank. I can't seem to find any good alternatives, but I've got a new idea.
Why not use my vacuum canister??
When I completed my conversion, I eliminated all vacuum requirements, but forgot to remove the big can on the drivers side. So my thought is to just use it as an overflow tank. It's got 2 nipples and I thought I would use the bottom as the line connected to the radiator and let the top be the overflow line.
Hi CW,
Merry Christmas!
Don't expansion tanks typically have a pressure cap on them?
I think overflow tanks are used on radiators that have the cap on the radiator and are really just 'catch' cans.
Are you thinking of using the vacuum tank in that way?
Regards,
Alan
Yes, that's what I meant. I've got a 16# pressure cap on my radiator, with no overflow tank. I'm fighting high temps on my LS3 and have been told I need to add an overflow tank. Maybe what I truly need is an expansion tank with a pressure cap. If so, then no way will the vacuum can work.
Yes, that's what I meant. I've got a 16# pressure cap on my radiator, with no overflow tank. I'm fighting high temps on my LS3 and have been told I need to add an overflow tank. Maybe what I truly need is an expansion tank with a pressure cap. If so, then no way will the vacuum can work.
Thoughts?
If you have a pressure cap on the radiator then the radiator is already designed to account for coolant expansion. An overflow tank simply catches excess coolant and returns it to the system - it's not going to cure your "high temp" issue. Your time and money would be better resolving the root cause of your "high temp" issue than adding an unnecessary overflow tank.
There was no overflow tank on my 70 when I got it, in fact even the little spigot for the hose on the radiator was missing. I fitted this and a hose that dropped down beneath the radiator but if you filled the radiator too much it would flow out the hose and the fan would pick it up and blow the coolant around the engine compartment making a mess. Besides coolant with antifreeze in it is toxic and I don't like the idea of some dripping on the ground and maybe one of our cats licking it.
So I fitted an aftermarket 1 litre bottle but this has proved to be slightly too small. I happened to call in at an out of town auto wrecker the other day and they had a three pint one off a chevy (I don't know what model) this one works like a champ and only cost $20.00
Overflow bottle on 70 vette. Not std but lots of things aren't on this car.
It is easy to be confused talking (internet - no pictures) because each type of tank can be called different names. There a 3 basic types: a catch for overflow from rad -no recycle, no pressure. A syphon resevoir - no pressure, coolant can move back and forth - needs proper rad cap. Pressure tank - usually high point of system, can have constant coolant circulation, or just a direct conection.
The LS has unique cooling requirments in that it has "steam vents" in the heads. It tends to generate steam/vapor and the factory vented this back to the cooling system. Most factory LS systems use a pressure circulation tank, you dont have to have it, but it works best.
Last edited by 74modified; Dec 25, 2015 at 08:32 AM.
The LS has unique cooling requirements in that it has "steam vents" in the heads. It tends to generate steam/vapor and the factory vented this back to the cooling system. Most factory LS systems use a pressure circulation tank, you dont have to have it, but it works best.
Exactly...
Chris- read through this- great read- has info on the steam ports-and everything you need to know about cooling-
The canister would make a poor recovery bottle because you can't easily fill it a little to ensure the radiator is always full. Isn't it also black so you can't tell if there is coolant so you know the radiator is OK? Your new tank looks good and should work fine as long as you have the correct radiator cap, it should have a little return valve in the middle of the part that actually seals inside the radiator neck.
Originally Posted by 74modified
The LS has unique cooling requirments in that it has "steam vents" in the heads. It tends to generate steam/vapor and the factory vented this back to the cooling system. Most factory LS systems use a pressure circulation tank, you dont have to have it, but it works best.
The expansion tank isn't because the engine is more prone to generating steam in the heads compared to other engines.
The LS engine water pump is on the front of the block and has both the in and out ports for the cooling system. This means the heads are higher than the return ports and any air in the engine coolant would simply gather in the heads above the return ports in the block. So, GM added the small vent ports as the highest point in the system to let any air out. The pump pushing coolant into the block means a little coolant is always flowing out of these vents and any air gets carried with it out of the engine.
The small-block and big-block engines have the coolant crossover on the intake at the highest point in the system so any air in the engine can easily escape by following the same path as the coolant. There is no need for extra vent tubes to let trapped air out of the heads.
The 90's LT1/LT4 engines have a front mounted water pump with both inlet and outlet ports on the block, similar to the LS engines. They also require similar steam vents as the LS engines.
The expansion tank isn't because the engine is more prone to generating steam in the heads compared to other engines.
The LS engine water pump is on the front of the block and has both the in and out ports for the cooling system. This means the heads are higher than the return ports and any air in the engine coolant would simply gather in the heads above the return ports in the block. So, GM added the small vent ports as the highest point in the system to let any air out. The pump pushing coolant into the block means a little coolant is always flowing out of these vents and any air gets carried with it out of the engine.
The small-block and big-block engines have the coolant crossover on the intake at the highest point in the system so any air in the engine can easily escape by following the same path as the coolant. There is no need for extra vent tubes to let trapped air out of the heads.
The 90's LT1/LT4 engines have a front mounted water pump with both inlet and outlet ports on the block, similar to the LS engines. They also require similar steam vents as the LS engines.
I did a bit of research on LS cooling before designing my system. Wether it generates more or less vapor than the SBC is not the issue. It is removing it from the system. Many race teams have reto-fitted the 4 corner steam vents instead of just using the fronts because it seems to generate around the rear exhaust valves. You dont have to use a pressure tank, you could even vent into the suction side of the water pump as they did on the Trailblazer SS. Can you get by without it? Sure, but a circulating pressure tank with a steam vent port is the most efficient way to continuously remove air, steam, vapor from the system. And, would GM add unnecessary cost and complication to a car if it wasnt a good idea?
Radiator expansion tank help needed.
DSCN5129 by Richard Hayes, on Flickr
DSCN5182 by Richard Hayes, on Flickr
