Why Do LS Engines Have Steam Tubes?

Why LS Engines Have Steam Tubes And Why You Need Them!

Why do LS engines have steam tubes, do you need them, and do you need two or four-port versions? Before we get into all this, let’s take a step back a bit and look at why small-block and big-block engines don’t have them. 

Steam Tubes

On traditional SBC and BBC engines, coolant would flow through the engine before exiting the top of the engine through the thermostat. On LS engines, the thermostat is located much lower on the engine in the water pump housing. That means that any air that enters the cooling system can get trapped in the upper end of the engine. 

When air pockets occur, that means that heat isn’t being transferred out of the block and into the water to be cooled. This can cause overheating and other issues like detonation and pre-ignition. To eliminate this issue, GM added steam ports to the heads, two in the front and two in the back. 

Four Or Two LS Vent Steam Tubes?

Early LS engines generally had all four steam ports hooked up, while later ones have only two. How to determine if you need to hook up four or two ports, you need to look at how to level the engine is. If it’s level in your chassis or close to it, use all four steam ports. If the engine is tilted down in the rear, that will allow the steam to flow forward and out the front two ports. 

For peace of mind though, we would recommend hooking up all four. Better to be safe than sorry or overheat and ruin your engine. Once you have all four connected, you can run the steam line to your radiator, or in some cases the water pump. 

We sell LS swap radiators that already have the steam port bung welded in for easy installation, click here to see. If you have any other questions or need help determining what steam port kit your LS swapped ride needs, give our friendly techs a call at (203) 235-1200


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