Advice on flush in a bottle products

Joined
Nov 30, 2005
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620
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Texas
I did a search, nothing really came up. I am currently flushing my fathers old honda accord. To make life easier, we are simply doing the drain, refil, run, drain, and so on method. I removed the thermostat to make things a bit faster, and the heater is always on high. My question is, whats a good flush product? I have used the prestone flush in the past, and we have a bottle of Zerex Rad cleaner thats in there now. Unfortunately, this cooling system is NASTY...and the water is still draining out brown even after 7 drain and fills, with varying degrees of run time in between (sometimes a drive around the block, others a couple minutes of idling). The zerex stuff is in there now, and it says to accumilate about 3-6 hours of run time before draining. After this stuff is out of there, I am looking to try something else. Car is a 89 Accord, with about 163k. Just did a complete service on the thing, replacing the major cooling system hoses, thermostat, new gaskets, plugs, wires, cap/rotor, etc. Its running 10x better than it was, but the cooling system still looks like [censored]. Once its flushed, will be filling with G-05...as I have tons of it laying around. I would like to get this cooling system as clean as possible before filling, so any help will be greatly appreciated.
 

pzev

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Joined
Nov 30, 2005
Messages
620
Location
Texas
Cleaner is in the tank as we speak...I'll try and find the fuel filter, as thats not a bad idea.
 
Joined
Mar 17, 2008
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Michigan
Any product for that purpose will work well. I think the problem is you are not running it long enough to get nice and hot and to let it work. (Prestone says to run it 3-6 hours) Taking out the thermostat may have slowed not sped up the process.
 
Joined
Sep 19, 2008
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Pennsylvania
Many of these cleaners contain oxalic acid to break loose and complex rust. They need some time and heat to really work. Also, make sure that you get ALL of it out of there with full flushes of water. If you leave any in the cooling system, you leave behind a strong acid.
 

pzev

Thread starter
Joined
Nov 30, 2005
Messages
620
Location
Texas
The only flushes that have been short have been pure water. So far, I have only used the prestone flush, and I followed the instructions to the T...same with the Zerex, which is still in the engine. I took out the thermo so it would be easier to remove the flush products...as I don't have to wait for the thermo to open for the clean water to circulate. This engine easily reaches operating temp without the thermo, especially when parked after a quick drive. I'll just go ahead and let the zerex run it's course. Hopefully it does the trick. I may pick up some RMI-25 to run with the first fill of coolant, then drain and flush it again after a few weeks of normal driving. Thanks for the tips guys. The moral of the story is my father should have changed his coolant on time! Its only been changed twice in 20 years, and each time I don't think it was a complete flush...just a refil of what was lost while doing some other repairs.
 
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