Black coolant

I don't know-Mine was black and I wanted to have it changed.they guy said it was ok... but I am old school and put in new stuff anyway...but not the expensive antifreeze-the cheap prestone they sell at stores.

Coolant contamination first comes to mind. But some Camrys seem to have this problem even when maintained by the dealer. I'd seen one myself. This is not the floating engine oil stain type of black right? It's almost like having black coffee in there.

If you have no engine oil, head gasket or ATF cooler leaks, then you may want to check acidic coolant and a bad case of corrosion. Particularly if you observe powdery deposits at the bottom of the coolant reservoir tank.

If the coolant (and nothing else) is the problem, don't just drain and refill. Get a complete power flush and refill with distilled water diluted coolant mix of 50-50%.

The old Prestone gold has silicates in it. The silicates will grind up the rubber o-ring pump seal of these imports. The US domestics use carbide seals and have no problems with silicates.

However, the new Prestone "All-Makes" is a variant of the GM-Dexcool type coolant. I don't think these have silicates. But it's always a good idea to use distilled water with any coolant concentrate.

If the corrosion is caused by electrolysis, which can eat the hoses inside out, then make sure to also check all the ground straps and even check cooling system stray voltage.

I would hesitate to power flush the cooling system on an older car because it will remove a lot of corrosion that is helping seal the rad and other parts of the cooling system .

I did that one time and had nothing but trouble in an older car .Been there done that~!!

I would respectfully suggest flushing , if neccesary ,with fresh water only , no pressure flush and then refill with silicate free anti- freeze and distilled water .

The use of distilled water is Very important ~!!!! it contains no minerals which can precipitate on the inner worlkings of a cooling system

The price of silicate free antifreeze is comparably the same as the the regular anti freeze at Walmart and you can get distilled water from a home de-humidifier or buy it at Walmart as well for a little over a dollar a gallon. Ed

This is what I use and have had no problems since I started on this cooling system program ..... Ed

This is interesting to me, as I dont really remember seeing coolant turn black. Metals in fine particulate form can appear black, as can some metallic salts. If hoses deteriorate internally, rubber particles could give a similar appearance. Carbon from a head gasket leak or crack might even be possible.....or the use of "stop leak" compounds.

I would want to know what is causing the problem before I went too much further. One year's service on coolant is not very long.

Sure, you can flush the system and refill with new coolant, but if you find the real cause, I hope you will post it.

I am not a fan of DexCool, since it does not contain silicates and does not, IMO, give the protection to aluminum alloys that the older silicated technology or the newer HOAT compositions provide.

The suggestion that you use distilled water in your refill is a good one, although not needed in some locations where the potable water is very low in minerals. It is very cheap insurance.

You're right there. I've been against power-flushing transmissions for exactly the same reason. Dohhh. Guess I was just passing along info from Modine warranty requirement mixed with Penray bulletin 99.014 without thinking there.

And if the hoses decay because of electrolysis corrosion with 1 year old coolant then the source of the problem should be identified and corrected.

But this could be one of many things at this point I guess.

Electrolysis does not eat hoses, John. Electrolysis is strictly a metal destroyer.

grounding, lead to the condition of electrolysis. This attacks the metals and turn the cooling system basically into a battery (Trouble Shooter. Motor Magazine, May 2001). The galvanic cell action, which Gates calls it "electrochemical degradation" or ECD, eats the new EPDM coolant hoses inside out while the hoses look good on the outside

But electrolysis is the reason for the electrochemical degradation of modern ethylene propylene diene monomer (EPDM) coolant hoses. Isn't it?

Coolant contamination first comes to mind. But some Camrys seem to have this problem even when maintained by the dealer. I'd seen one myself. This is not the floating engine oil stain type of black right? It's almost like having black coffee in there.

If you have no engine oil, head gasket or ATF cooler leaks, then you may want to check acidic coolant and a bad case of corrosion. Particularly if you observe powdery deposits at the bottom of the coolant reservoir tank.

If the coolant (and nothing else) is the problem, don't just drain and refill. Get a complete power flush and refill with distilled water diluted coolant mix of 50-50%.

Maybe I spoke out of turn, but I have never heard of electrolysis being involved with decomposition of elastomers. Elastomers such as the ones used in hoses, seals, etc are nonconductive and electrolysis has little meaning in such a context. There is no galvanic action in a nonconductive polymer.

I'll take a look and see whether I have to revise my technology;>)

Have looked at this brochure, John. Hoses can degrade due to chemical interaction, certainly, but I feel they are pushing the limit here. They could have, as easily and as accurately, said that the material was found to degrade prematurely in these coolant systems without trying to alibi some unusual electrochemical galvanic process.

I still dont buy the galvanic process, and feel they are playing with semantics.

That's an external leak, probably from the valve cover gasket (~$13 per set including spark plug tube seals) that happens every ~50K miles. Less than 30 minutes to fix.

Some simple quick checks:

- Is the engine using oil?

- Does the oil dip stick or drained oil have milky traces in it?

- Does the engine use coolant and is the radiator itself always full (check only when cold)?

There are cooling system/head gasket pressure tests that can be performed. But the cheapest is to make sure somebody didn't simply put a different brand (like green Prestone) into your system and mixed with the Toyota Red (or the less preferred Toyota Pink).

You should probably have a mechanically inclined friend or a trusted mechanic check the cooling system and even do a voltage test to see if your cooling system has turn into a corrosive battery cell.

Well yeah, a number of different publications are now indicating electro-chemical degradation being the primary mode of failure of the modern EPDM rubber. I'm sure Dayco, GoodYear, and other web sites will also show that. I just used the layman's term of electrolysis.

But for me I'm just sticking with the plain 1-1.5yr coolant changes with distilled water and Gates coolant hoses every 100,000 miles no questions asked.

Erhan wrote:

== Here's my first best guess. For some reason I don't understand, seems like people are reluctant to stay with genuine Toyota parts. If you mix Totyota's red coolant with Prestone green, you'll get brown color. I imagine if you leave it unchanged for a while, it wouldn't be too hard to imagine it turning black. Lots of people seems to neglect fluids and they turn dark (power steering, brake, transmission). I'm very fussy about only using Toyota genuine coolant and distilled water for the Camry. My "test bed" is a 1977 Toyota pick up truck, still running great, which I recently converted over to the Toyota red and distilled after changing water pumps and radiators three times, plus having a slowly progressing problem with a crusty grunge growing around the thermostatic choke coil. Now even the choke is working again. Just buy two bottles of Toyota red coolant and enough distilled water to change the coolant three times or so. Drain, fill, bring to operating temperature (let cool) and drain again, then repeat. This way you are adding nothing to the system apart from the correct concentration of proper fluids. Haven't seen this anywhere else, but the Toyota factory service manual states to use more than 50% but less than 70% ethylene glycol coolant so I measure out 60% and the cooling system stays absolutely pristine and perfect. This may actually help performance also. RedLine makes a "water wetter" product for racing so racers can run a higher concentration of water for improved cooling around combustion chambers. Presumably if the heads run cooler the ignition timing can be advanced, or at least not retarded by the knock sensor. The Toyota is tuned for reliability, so the added coolant may add lubrication for the water pump and increased corrosion protection for the aluminum radiator, head, and in some cases engine cylinder block. If my coolant were black, I'd also be changing the thermostat and radiator cap as inexpensive preventative maintenance items. I have an arrangement with the local Toyota parts manager where he gives me improved pricing on parts. The list price on the Toyota coolant is high, but somehow I get it for around half that. Initially, I just talked to him one day about how their pricing just seemed so much higher than the exact same parts available online. He replied that it depends on volume and he knows of one person buying parts from them and reselling for a profit on eBay. Told me to just ask for him in the future and that's what I've been doing. Have purchased, axles, ball joints. control arms, idle valve etc., and they've actually put me on "employee pricing." Doesn't hurt to be friendly. Nothing to lose. Discovered this with a Mercedes. Their special rear axle limited slip lubricant was so expensive I just stood there looking at the parts guy, finally said, something about price, and he was able to help me out, so I discovered those prices are necessarily fixed and one can always ask, especially if you ask the right person with the right attitude.

I've personally seen one case of a Camry maintained by the dealer using Toyota Red with the coolant turned black. So that's no sure cure if head gasket/oil/ATF leaks or electrolysis (or rather electro- chemical degradation) of modern Ethylene Propylene Diene Monomer (EPDM) rubber hoses were the problem.

Best to identify the source of the problem. Google "coolant analysis"

One reason might be that not all authorized Toyota dealers use the red coolant. One of the biggest Toyota dealership chains in my area has routinely replaced my '99 V6 Camry coolant with "green" since the first coolant change and flush required at about 30,000 miles. I'm not knocking the red, just curious about how common it is for warranty dealers to do that.