How do you do an engine reverse flush?

I found numerous advice on the forum about the need to do an engine reverse flush, but nothing on how to do it.

Thanks.

I assume you're referring to the cooling system. Basically, you have to run water through the engine in the opposite direction that it flows normally.
With our older A-body Mopars, they had a radiator with a top and bottom tank, and the design is referred to as "down flow". (Radiators with side tanks are "cross flow".) With our down flow radiators, the hot coolant comes in the top, gravity feeds down through the tubes, and gets sucked out the bottom by the water pump. So, in our case, what we need to do is force water down through the top hose, through the engine, and out the bottom hose. The problem is that the thermostat is in the way.
ALERT! DO THE FOLLOWING WITH A COLD ENGINE!
You'll need a new thermostat and gasket. Drain and catch the anti freeze out of your engine, and dispose of properly. Pull the thermo housing and remove the thermo. Reinstall the housing, (not worrying if the gasket seals), disconnect the top radiator hose from the radiator, and pull the bottom hose off the radiator, leaving it attached to the water pump. Start running your garden hose in through the top radiator hose, and through the engine. (I think you can get some plug type adapters to "close" the system up temporarily.) Let it run until you get clean, clear water out the bottom. (You are going to get your feet wet, so wear your old shoes.) Shut off the garden hose and detach. Let the remaining water drain out the bottom hose, pull the thermo housing, clean it up for that new gasket, install the new thermo and gasket, reattach your top hose to the radiator. Reattach the bottom hose, and refill the system with proper, 50/50 mix of coolant. Start and run the engine, paying particular attention to the possibility of an air lock, that will show up as overheating, and no coolant flow through the radiator. (If the engine starts smelling excessively hot, and you can't see any coolant flow with the radiator cap off, then you need to worry.) If you don't have any difficulties, then you're done. Close it up the rest of the way and go get some ice cream.

Roger

Thanks for your prompt reply - and yes I was referring to the cooling system on my slant 6.

Your comment - (If the engine starts smelling excessively hot, and you can't see any coolant flow with the radiator cap off, then you need to worry.) What would be a cause if you can't see any coolant flow with the radiator cap off?

Thanks

I have found it easiest to fill the cooling system up to the thermostat housing level before installing the thermostat, or at least make sure you have a small hole drilled in the outer area of the thermostat to aid in getting the air bubbles out of the cooling system.

There are a number of threads here which detail how large a hole and where to orient it.

In response to your question about the coolant flow, it would be caused by an air pocket surrounding the thermostat, which is keeping hot coolant from contacting the spring to open the thermostat.

~THOR~

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