Reverse flushing cooling systems.

[roger97338]

What are your opinions and/or experiences with reverse flushing cooling systems. In the 1974 Chevrolet repair manual, it's mentioned as part of the routine cooling system maintenance procedures, and requires a "flushing gun."

In my many years as a casually-educated-ish shade tree mechanic, I've never reverse flushed a cooling system nor operated a flushing gun. Although, looking back on many projects, that would have been a marvelous idea.

I know there are some professional mechanics here, as well as some guys that must have engineering doctoral degrees. What are your professional opinions on this procedure?

And for those of you that have had your cooling systems reverse flushed by a friend, garage or dealership, was your experience a positive one? Or maybe not so much?

And since I've done it numerous times, if anyone wants to post something completely unrelated to the topic, you've my blessing. Cat pictures, incoherent ramblings, and even conspiracy theories will not only be tolerated, but enjoyed.

[zieg85]

Knowing what I do about the cooling system the only parts that would benefit from reverse flow would be the heater core and radiator.  I am sure others will chime in but if the coolant system is flushed with plenty of clean water through a heater hose flush adapter along with draining radiator and flushing by itself should be good enough.  I use the flushing additive from Prestone but this has been a long time ago.  In vehicles past a new waterpump was needed fairly soon after a flush.  This is an interesting post and I will look forward to what the experts have to say.

[LTZ C20]

Babble babble babble blah blah blah yak yak yak. Rubber ducky rubber ducky rubber ducky. (Physco random incoherent nonsense) hahaha.

Anyway, I have flushed and back flushed my cooling system a few times, did it about 4 times normal directional and 4 times reverse flush when I was prepping for my first new engine, think I did it again when I replaced the heater core. It did not have or present any negative affects.

Here at work, when we have cooling systems that are heavily contaminated or have transmission or oil mixed with the coolant, we will usually flush it out 2 or 3 times with a cleaning agent and 1 of those will usually be a reverse flush. I haven't seen or heard yet of it being an issue, the systems are just a continuous loop so unless you have some kind of valve in the system for whatever reason, back flushing shouldn't be a problem. And if you did have a valve, as long as it's open, that shouldn't be a problem either.

I know it didn't hurt my truck at all.

[Irish_Alley]

never felt the need to do a reverse flush, never felt the need to do a flush also lol. i really dont see what a reverse flush would do in something like an engine block cause the fluid doesnt have just path to go to and would go to the path of least resistance so even if you had a restricted passage it would go to another. thats just my opinion and others may not agree but all i usually do is drain fluid when i doing an engine change and add new fluid

[VileZambonie]

It's the only way to do it these days. I use BG products. Tee into the system, top it off with the cleaner, run it to operating temp, do the fluid exchange with mineral free coolant. Top it off with the conditioner.

[LTZ C20]

It's the only way to do it these days. I use BG products. Tee into the system, top it off with the cleaner, run it to operating temp, do the fluid exchange with mineral free coolant. Top it off with the conditioner.

BG is the same company we use for most of our service and maintenance chemicals. They make great stuff. We do the same thing for flushing.

[Dr_Snooz]

I'm a drain-and-fill guy too. I've done flushes, but they always leave a bunch of coolant all over the driveway and half-way down the street. Which never impresses the neighbors. The cooling system is very simple and there's no real need to overcomplicate things. Unless you have chunkies floating around in it, there's little reason to flush. Be sure to drain the block though.

[VileZambonie]

[pholliday1]

Why do we park in the driveway but drive on the parkway? Just saying.....

[LTZ C20]

Pholliday! Yes why?!