Got some eng rust treatment stuff I want to run thru my raw water cooled BBC's. Instructions say to "drive car around" for a couple of days with this stuff in the cooling sys. Want to simulate a closed loop cooling system so the treatment goes thru a few heat cycles and circulates all around.

Looking at my orig (1990) thermostat housing, looks like I can connect both right/left side exhaust nipples together (4 total) with some 1" ID hose.

Remove raw water pump belt. Disconnect water inlet from oil cooler at thermostat housing and install a temp 1.25" hose from that nipple pointed straight up a couple of feet then be open.This will be how I introduce the treatment into the eng.

I'll connect the water hose from the house to the exhaust nipples on the manifolds/risers so they stay cool with eng running.

Idea is to run eng just long enough for thermostat to open, then shut it off till the next day then repeat the process for a couple of days, then drain and put everything back to normal for a good long idle flush.

Seems like it should work. Am I overlooking anything??

Maybe doing a set up like this that many of us do to run antifreeze thru motor for winter storage. Here’s mine on a neighbors boat.

Yup, I have a pretty much identical set-up that I use to get the pink anti-freeze into the eng. Looking for method that will allow the treatment to remain inside the eng thru a few heat cycles so it has a chance to work. Something more like what a car (or any closed loop sys) would experience since the stuff is really made for cars/trucks.

I've seen large inexpensive buckets/ watering troughs and Tractor Supply. Maybe lower the drive into it? If you have thru-hull exhaust, you can get some cheap hose.

I actually have a 110 gal horse watering "bucket" and I once used it to run a single Alpha drive boat. It does work but takes a lot of water to fill it up to a height above the water intake.

The eng flush concentrate comes in a 1 qt bottle and only makes abt 3 gals of treatment max.

Also, from what I've seen on videos, when the treatment comes out, it's pretty nasty looking. Wouldn't want to suck that stuff back into the cooling sys.

So are we talking time and temp or just temp ?

They say if there's lots of rust, keep it in the sys longer (3-4 days). I'm not sure if it needs temp or not. Would think circulation would be good though. Just trying to duplicate what the treatment would experience in a car engine.

This maybe too simplistic but what about removing the t-stat housing, dumping in the treatment and using a power drill to spin the water pump pulley? Keep pouring it in till the block is full?

Remove the block drains after treatment and flush with fresh water.

After a bit more reading, I'm seeing claims that the treatment will work w/o heat but works better/faster with heat. Still waiting on the 1 1/4" inlet hose to arrive.

The recirc water pump gets supplied via the thermostat housing, so need the housing installed to pump water/treatment around.

Block drains will be open for sure. One is draining much better than the other. Hopefully that too gets addressed with the rust removal treatment.

Block drains can be rodded out with a piece of stiff wire.