Radiator / Coolant overflow tank questions

[FJSleeves]

Hello

I am in the process of placing a GMC 5.3 V8 Vortex out of a 2002 Yukon into a 1971 Toyota FJ40 Landcruiser.

The FJ40 had an older Chevy 350 V8 with a custom horizontal flow aluminum radiator with a overflow tube at the radiator cap draining into an over flow tank. I would like to use this radiator with my new engine.

I believe the 1970 era 350 water pump delivered hot water to the lower right side radiator inlet and then cool water returned via the upper left radiator outlet. I also believe the newer 5.3 water flow is in the opposite direction with the hot water coming out left upper side and then returning from the right lower radiator to the motor. I am thinking, especially with the cross flow radiator, that it should not be an issue to merely hook the water hoses up and then have the water flow from the top left to bottom right of the radiator. Does anyone have any comments on this?

My other issue is the small hose coming off the top of the motor that I believe originally went to a pressurized coolant overflow tank. I believe the overflow tank then had a return to the radiator. My question is how to deal with this hose from the motor and hooking it up to a overflow tank. Do I need to place a pressurized overflow tank and then install a new vent tube in my radiator to communicate with the overflow tank? Where would be the best place to weld a tube to the radiator – upper or lower / left or right side? What do I do with the vent tube off the present radiator cap?

Does anyone have any recommendations on how to plumb a system that will work with my old radiator and new motor?

Thanks

[glennsexton]

The LT1 and LT4 are the only small blocks that use reverse coolant flow. If your engine is truly from a 2002 Yukon, you do not have an LT1 or an LT4. You have Vortec heads, and standard water pump. The reverse coolant pump would not even bolt up to your engine.

The LT1 debuted in 1992. The LT1 used a reverse-flow cooling system which cooled the cylinder heads first, maintaining lower cylinder temperatures and (in theory) allowed the engine to run at a higher compression than its immediate predecessors.
This LT1 engine was used in:
• 1992-1996 Corvette C4
• 1993-1997 Camaro Z28 and SS
• 1994-1996 Caprice (all including wagons and police)
• 1994-1996 Impala SS
• 1993-1997 Firebird Formula and Trans Am
• 1994-1996 Buick Roadmaster
• 1994-1996 Cadillac Fleetwood

There were several versions of the LT1. All had a cast iron block, with aluminum heads in the Corvette, Camaro and Firebirds, and cast iron heads in all others. Corvette blocks had four-bolt mains, while most of the other blocks were two-bolt mains. (special orders, etc..)

The 1997 model year Camaro and Firebird were the last year for this engine in a GM production car.

The LT4 was a special high-performance version of the LT1. With the addition of a slightly more aggressive camshaft profile, 1.6:1 roller aluminum rocker arms and better-flowing intake manifold (all were painted red) and cylinder heads, it was rated at 330 horsepower. It was introduced in the 1996 model year, for the last year of the C4 Corvette, and came standard on all manual transmission (ZF 6-speed equipped) C4 Corvettes. The engine was passed down to special versions of the Camaro and Firebird in 1997.

The LT4 was available on the following vehicles:
• 1996 Chevrolet Corvette when equipped with 6-speed manual transmission
• 1997 Chevrolet Camaro SLP/LT4 SS 6-speed –very limited production
• 1997 Pontiac Firebird SLP/LT4 Firehawk 6-speed - very rare, only 29 ever produced.

Long answer – but hope it helps.

Regards,
Glenn

[FJSleeves]

Thanks for the info!

I believe my motor is a Gen III LM7. I also believe the flow is the same as the LS1 and newer. I also believe the LS1 and newer all have the steam vent coming off the top of the motor.

Is this correct?

My real questions is where / how to connect the steam hose from the motor to my system? I am considering welding a vent into my radiator just below the radiator cap. That way steam from the motor should vent out to the overflow tank from the radiator cap vent. Any thoughts would be appreciated.

My other issue is that the "hot" water hose coming from the motor goes over my shroud to the top left of the radiator. This hose is now about 1 inch above the level of the radiator cap. Will this result in me not being able to fill the radiator or will any air in the system be forced out the radiator cap vent and be replaced with flud from the overflow tank? Will this "burp" itself or do I need to vent the air somehow? Any advice would be appreciated.

Thanks