Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Radiator Flush

I own a 2003 Grand Caravan SE and I wanto to drain and flush the radiator. What is the proper way to flush and fill with 50/50 mix and will it help the heater work? The heater is not warming up.

This time, I think you need a mechanic to do it for you. There may be something else wrong with the heater, such as blower, door, door control, etc.

The trick is to figure out how much coolant your cooling system holds.

First, buy a flush and fill kit. You also might consider a chemical flush. With either one, follow the directions carefully and the flush and fill kit will help you get the chemical flush out of the system.

Once the system is flushed and has been drained as much as possible (some water will still be in the system), this is when knowing your cooling system’s capacity will help. Add enough coolant to fill it half way and fill the rest with water.

I really can’t tell you if this will fix your heater problem. You really should get a professional diagnosis from a trustworthy mechanic. If one mechanic can’t figure it out, ask for your diagnostic fee back (if you paid it) and go to another mechanic.

Lastly, flushing might not help if the cooling system has been neglected. If the small passages inside the radiator and heater core are too clogged, you might need to replace them.

While a flush may be a good idea and there is a chance it may correct the problem, there are many other possibilities, including an air pocket.

Since your vehicle is only 5 years old, I would strongly discourage you from doing a flush, especially with any of those flush chemicals like “Superflush” etc. You could do more harm than good. You don’t need it anyway, even if the original coolant is still in there.

What you will need is a new thermostat and gasket when you purchase the coolant. I would recommend that you get one of the new HOAT antifreezes. They are the “Long Life” “mixes with all colors/types” or words to that effect. Also get some distilled or purified water, don’t use tap water.

Drain the radiator and drain the block. You will need to find the drain plug for the block. You might try and look for the repair guides, it may show you a picture. If you are buying at an Autozone, they will look it up for you and print out a picture. You could also buy a repair manual for your vehicle, I find they are well worth the money.

After you drain everything, replace the thermostat and refill the system. Don’t run tap water through there from your garden hose. What little remaining old coolant is in there won’t hurt anything where the garden hose will introduce minerals that could cause harm later. Its best to not contaminate the system. I would also suggest that you consider increasing the antifreeze to water ratio up to 65/35 ratio. The extra antifreeze will provide you with more corrosion inhibitors, lower freeze point and higher boiling point.