Why's my coolant brown?

1969mach1351 · Dec 9, 2005

Last time I changed my coolant was a one year ago and now it is brown. The engine has less than 20,000 miles on it and about 3.5 years. I put in about 30-40% coolant and two bottles of Water Wetter. It seems there might be some corrosion going on inside. My chrome plated thermostat housing (water neck) has corrosion on the inside on the bottom. It's at least an 1/8 inch deep where it is corroding. When I changed it last I back flushed it so there isn’t much chance that there is much left over stuff from anything previous.

SuperDave · Dec 9, 2005

Brown is NOT BEAUTIFUL

Brown (or rusty) coolant indicates corrosion. If you recently "flushed" the system, I would wonder how and how well. Regardless, I would again THOUGHLY flush the sysytem even if it means having it done professionally. Flushing a badly corroded system often take several attempts to get the system clean. Remember to keep the heater on during the flushing operation. Gunk can build up in the heater core as well as the radiator and the block. Running corroded coolant also endangers the expansion (freeze) plugs in the engine block.

mikec35 · Dec 10, 2005

Less coolant and more water will cause corrosion. It is best to run atleast 50% coolant and water. Like SuperDave said, I would flush and flush again until you see clear water coming out and then put the proper mix of coolant in.. Good luck...

1969mach1351 · Dec 10, 2005

I agree that more coolant would help. The thing is that I know multiple people who only run 20% or less coolant with Water Wetter and don’t have problems. Water Wetter alone helps protect against corrosion. I feel that I had plenty of protection but I guess not? Anyone here have problems with Water Wetter or Prestone coolant? I have a tee in the heater hose where you screw in the hose and then it pees out the top of the rad; yes I know to turn the heater on. I ran it for about 15-20 minutes and then a few more after the water was coming out clear. This time I'll do that and then actually drive it and do it again.

SuperDave · Dec 10, 2005

Why only 20%?

Prestone recommends a 50/50 mix. Water wetter only reduces the surface tension of water allowing it to flow with less resistance ergo better cooling. A THROUGH flush involving serveral cycles of fresh water followed by a period of warming up are often necessary. A sticking theromstat restricts water flow and will inhbit a good flush. A replacement t'stat might be a good idea.If the system was extremely dirty repetition of the flush routine are advised.

I use a "Flushing T" as well but I remove it after flushing completed. "Flushing T's often develop leaks" and are a PITA unless removed after you're done flushing. A power flush might be indicated especially if you don't know the vehicle's maintence history.

1969mach1351 · Dec 10, 2005

The thermostat is new and if it was sticking then it would have overheated long ago. The reason why the people I know who only run 20% is because they race and only use the antifreeze for corrosion protection and very slight freezing protection (doesn’t get cold). When they use a 50/50 mixture they were running too hot. With 20% or less and Water Wetter they run just fine on the track and on the street come no where near to overheating with the fans only running about 50%. The radiator and heater core I put in 5 years ago. After the first 2.5 years of the current engine and less than 20,000 miles the coolant was dirty (running 50/50 mix), that's the reason why I flushed it in the first place. I have already used a 50/50 mix and that didn’t seem to work, is there something else that I'm missing?
BTW I've never had a problem with the dozen or so flushing T's I've used

12sec67 · Dec 10, 2005

besides the mix set up - it would be best to change coolant more often.

i change mine once a year.

mustangdave · Dec 10, 2005

Even with a freshly hot-tanked block, you can stick a finger in and pull out gobs of casting flash(brown sand-colored crap). Go to your local Jiffy Lube or whatever it is called in you area and have them filter your coolant(flush). Don't be surprised if your wimpy heater core gives out shortly there after.

Why's my coolant brown?

1969mach1351

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Why's my coolant brown?

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