A Definitive Answer on Flushing a Radiator

I am looking for a definitive answer on the advisability of flushing a radiator.

My 2002 Civic is in perfect working order. The car has 98,500 miles on it. I know the coolant was replaced w/o flushing at 60K. If the radiator has ever been flushed it would have been done by the original owner. I bought the car with 43k on it. My temptation is to change the coolant when the timing belt and water pump are replaced at approx. 100k. I am not looking for problems and I have heard that flushing will stir up sediment and possibly block the radiator. I would like to get at least 50 or 60k more miles out of the vehicle. Advice please.

You’ll find knowlegeable people on both sides. If it’s flushed long enough, the flush should work fine. You might ask to see the particles collected after the flush. This may help you determine if it works (for future reference). I suspect that flushing does work, because it mimics circulating coolant. The flush will remove anything that gets stirred up by circulating coolant.

I would replace the coolant when the timing belt and water pump are replaced and don’t worry about flushing.

You should be able to get much more than another 60K from this car if you follow the maintenance schedule.

I’ll bet the maintenance schedule says “replace engine coolant” not “flush radiator.”

Personally I manually flush mine when I change the fluid. I flush it well and use the water remaining as the dilution material to get the fluid at the correct strength. I have one advantage as the local water is naturally soft without hard minerals.

Flushes have become the THING and everyone seems to be selling them. They are not needed unless it is specified in the owner’s manual.

Good Luck

Other than the good advice you’ve already been given I will only add that I agree with mcparadise completely about the longevity of the car.

Change the oil regularly, do NOT continue driving the car if it ever overheats, and you should be able to easily get another 200k miles out of this car.

You might also check with the Honda dealer about any outstanding Recalls on this car, of which there are several I believe.
These are free of charge to you so take advantage of it and head off a potential problem before it occurs.

I don’t believe in chemical flushes for radiators. If there’s enough contamination in the core to warrant flushing, it’s time to change the radiator.

I do believe in disconnecting the lower hose and flushing the system good with plain garden hose water before putting in the new mix.

Yup, this is how I’ve always flushed out radiators and there’s never been an issue. Remove both hoses and run hose water through it until it runs clear. Doing the same through the engine is also a good idea.

“I don’t believe in chemical flushes for radiators.”

Did alvmitchel mean chemical flushes? I assumed that it was just a water flush. I don’t believe in chemical flushes, either.

I was not thinking of a chemical flush but rather a pressure flush.

Thanks to all of you who replied. If I did not live in an apartment this would be an easy do-it-yourself job for me.
As for the car lasting another 60k, I always follow the maintenance schedule to the letter. My last car was a 1994 Mazda. When I gave it to my son it had 230K. Clutch was replaced once at 140K.

I didn’t know. That’s why I clarified my answer.

I was getting ready to put my car on a machine this week and flush the block. I wonder if I should only flush the radiator first and see what that looks like. Today I drained some and it looked a rusty green color.

When you just flush the radiator like you said above with both hoses off - do you still put water in through the top and have the drain plug open at the bottom?

Does it come out both hose holes and the drain plug? Where can you put a pan to catch it all. I want to try it if I can figure out how without making a flood.

Thanks a lot.