hi,
im on my first LS install of a 2005 Tahoe 5.3 into my 1940 Mercury coupe.

Ive read multiple posts about steam vent options, but drilling and tapping the water pump at this point would be a nightmare. Also, with so many curves in my upper radiator hose, adding a T seems counter productive (I'm trying to keep ithe engine bay as clean as possible)

i probably know the answer to this, but if I don't add a radiator overflow tank, could I attach the steam tube to the port pictured , or is that only for overflow? Aka exit only. Also, could I run a hose with a T to my overflow and connect my steam tube as well?

Thank you

 

Anyone?

 

Basically the steam venting must enter the cooling system BELOW the cap (pressure side). It has to see system pressure, NOT vent to the atmosphere.
BTW, you should run an overflow can or coolant recovery system unless you want coolant pissing all over that nice radiator

 

Thank you for the reply. I plan on adding an overflow tank, just haven't installed it yet.

Looks like some of the other steam vent methods are going to have to work. I'll post pics of what I come up with.

 

Take the radiator and have a nipple welded into the tank, might be a pain but would be
the best fix for now and for ease in the future.

 

I would use an OEM LS6 style which exits pointing straight forward from the driver side head or a late 4.8/5.3/6.0 Truck Style which exits straight up from the passenger head with the rears blocked off, and run it into the radiator below the highest point in the system like mentioned. I would put a fitting on the metal radiator hose portion and connect it there. You can not connect it to the overflow nipple on the radiator, it wont work that way since that is only open at higher temps/pressures. I would also run an overflow tank to be on the safe side, if something does happen it will **** a lot of your coolant on the ground and fill the radiator with air. Buy a cheap universal or get fancy with it and make one.

You can also hit up the junkyard and look for an OEM 4-Corner Style Steam Tube setup from an LS1 (98-02 Camaro and 1997-2004 Corvette) or a 1999-2002 LM4-4.8/LM7-5.3 from a 1500 and 1999-2002 LQ4-6.0 from a 2500 Silverado. I think those were the only Vehicles/Engines available with the OEM 4-Corner Steam Vent Setup.

There is also aftermarket 4-Corner systems, such as MotiveWorks V2 LS Flex Line Coolant Crossover Steam Kit for Low Profile Intake Manifolds (Such as your Gen3 Truck Manifold). This is probably the nicest 4-Corner kit you can buy in my opinion, but not the cheapest either. I have seen new kits on Ebay go for $160, retail $180.

For most applications, the front crossover is all you need, unless you are running boost or nitrous. Supposedly, GM started angling the engines downward a few more degree's in the back after 2002/2004 (depending on the engine) to help aid any air pockets towards the highest point in the head, which would be the front at this point, where the crossover and exit is.

 

I did a lot of research on this before my 5.3/4l80e/turbo swap.

The cleanest, cheapest ($=almost free) method was to drill and tap my upper radiator tank for a nipple which feeds to the 4-corner steam port solution.

also make sure you block (drill/tap/plug) the heater core in/outlets in the water pump if you are not using a heater.

 

40 Merc? Post pics of that sled!