flushing coolant system

[BOL]

can somebody walk me through flushing my coolant system 1991 ranger 4.0

 

[Earl43P]

Buy some Prestone Super Flush and a flush kit.

The flush kit will instruct you to cut one (or two) heater hose and install two fittings that let you hook a garden hose to them.

I don't do it that way. I drain it by loosening the lower radiator hose. I also remove the thermostat (and later replace it with a new one) and put its housing back together. Reinstall lower hose, fill it with Flush and water, run it IAW the flush directions (heater on hot/hi), drain it again from the lower hose while keeping the radiator full with the garden hose, engine running. Then, after it runs out clear water, shut it off and let it drain empty again. Reconnect the hose, intall T-stat, fill it with 50/50 Antifreeze and DISTILLED WATER, burp the air from the loosened top hose while filling, check coolant level after each drive cycle for a few days and call it good.

You can also disconnect one heater hose at the firewall, the other heater hose at the shut-off valve (if it has one, not all years do) and flush the heater core seperately. I do that if it was full of crud.

You can also do any/all of the above and skip the flush agent (just use water). Some say it'll create leaks by its corrosive cleaning.