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I don't think this has been asked explicitly, so I wanted to start a new thread. Apologies if it has been asked, but my search-fu is weak.

There is a black tarry substance in my coolant reservoir. And I don't know what it is. Anyone ever come across this as well?

I had an epic thread with ezone (imagine that, I think all of this threads are epic if the op can keep up with him) and we touched on it lightly. We passed over it as this was not likely part of my main issue (see here) I just think it is a-typical. I have no basis for this, it just doesn't *feel* right.

It is not oil. I do not have milkshake-y coolant or oil. Cleaning the tank was a lesson in futility, so I replaced the coolant reservoir and the tar substance came back quickly.

So what say you. Eroded hoses? (Not sure when or if the hoses have been replaced) Oil in the coolant? Combustion gasses in coolant? At work now, can post pictures later.

Edit: found this: http://honda-tech.com/showthread.php?t=2700298

 
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not sure either but i recently cleaned out mine too and found all sorts of blackish stuff and some was stuck to the plastic inside and wouldnt come out. i think the issue is this coolant is not really circulated so it has a chance to grow stuff, have oily film buildup, and other things. should be changing the tank coolant every couple yrs when you do the regular coolant flush. im thinking some nasty buildup in there is normal. i think most comes from the rubber coolant hoses. when i had the res off, i decided to change the lil breather hose from the res to radiator and when i stuck my finger in, black stuff started coming off.

 
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I don't like the post you picked out of that thread LOL. I prefer this one.

https://www.civicforums.com/forums/3...ml#post4581739

Quote
"In short: If there was not a thick layer of oil sitting on top of the coolant in the reservoir, then the residue stuck to the sides of the bottle is pretty average.
It happens with age and miles.
Yes, it coats the bottle and makes it hard to see through.
I have ideas of what it really is, but never have heard a solid explanation of it.
But it happens to many/most of the cars in time.
Oil would float on top of the coolant. It should have been obvious if it was there. If it was there long enough, it would be thick like gear lube, and probably dark brown or black.

Good luck cleaning that crap out, let me know if you find something that works. (I think the residue may be the sealant that was put in at the factory.) "

No updates that I know of since that thread.

Not sure I buy into the hose theory either.
Especially since hoses can last the life of the car now, they have improved tremendously over the years.

Still no definite answer though.

 
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It might have something to do with climate condition as well. I live in Hawaii and my 2002 civic EX is 10 years old and I've changed the timing belt once which involved changing the water pump, which basically meant a fluid flush as I drained the radiator as well.

I put the newer blue extended life anti-freeze from Honda in after that and have absolutely zero discoloration and no black "tar" whatsoever in the overflow. The overflow is as clean as the day I bought the car.

 
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mine has 104k miles and all original hoses, only used honda coolant. the hoses can still work without failing, but over time the coolant tends to loosen some rubber from the inside. if you dont believe it, take a heater hose off and wipe inside it with a shop towel. it will be completely black.

 
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Chances are someone used "radiator stop leak" inside the system. Its a bitch to get out.

If it loosk like black jelly then chances are thats what it is.

I flushed out a friends radiator about 10 times and there were still traces of the stuff..
Its REALLY REALLY hard to get it all out.

This is why "radiator stop leak" of any brand should be avoided at all cost.

 
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That doesn't explain why so many have the residue, yet some don't.

Few real customers would ever use such a product. Most can't even open the hood LOL.

But the factory may have put some in there *citation needed*. Many manufacturers do.

 
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The factory puts it in the system? What does it look like?

I have drained my system and a few other Hondas never seen that stuff.

 
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I don't know for sure whether Honda does or not. That's why I stuck that *citation needed* clause in.

Many others do at the factory though, as an extra precaution against seepage. Not all sealants look like rat pellets.


I actually have no problem using GMs seal tabs for their aluminum engines for some types of coolant leaks in other cars.






I should start making a list of questions to ask the next time I visit a training center.

 
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Sorry guys, been super busy.

That's the stuff. It literally coats the inside of the tank.(pics of old tank here and here) Definitely not oil or floating. Makes me think it liquefies, or is at least becomes mobile, when hot then get tacky and sticks once it cools down. Which is good I suppose if it is accumulating in the overflow tank. Easy to change and a cheap part, I suppose. I have not seen any degradation in the hoses. They *seem* nice and thick with little to no inside wear. (Coming from an untrained eye.)

lol. Selective memory! Plus that is a marathon thread and who wants to re-read all of that

Yep, your quoted post here is spot on, still. Cleaning it was impossible, so I just replaced the tank.

Even if the hoses degrade or erode just slightly, could that still be the culprit? Or perhaps it is one or more specific hoses. For example, the small throttle body coolant lines may be susceptible to erosion. This is just speculation of course.

Did you have any BEFORE this work/fluid was done?

Nope quite certain none was ever used. This is my wife's car she bought brand new that I have "inherited". I was dating her the day she bought it, so I roughly know the history. Her father took care of the all the maintenance for years but claims there was never any work done more than brakes, tires and oil changes.

Hopefully I'm sweating it for no reason. I have some time tomorrow, maybe I'll go thru all the coolant hoses and check inner diameters. It's due for timing belt service. I'll likely take it somewhere as time is supper short these days and the service would be pushing my mechanical abilities. I have a good mechanic close by I'll throw the question too as well.

Thanks guys.

 
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I'll speculate an answer to that-- "Sure it could."
Does it really though---hellifiknow.


You won't find anything.




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This probably has nothing to do with the "tar" questions:
Hoses that have survived a serious overheat (the kind that warps the head) do usually show obvious signs of deterioration, they crackle when you squeeze them; the inner layers became brittle with the excess heat and break those layers as you stress them with the squeeze.

Would this apply to normal temperatures encountered in everyday driving? Doubt it.

 
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Yeah, a rhetorical question, I know.

Good, then I'll stop worrying about it.


Good to know. Never had an overheat to my knowledge. Next oil change I'll give all the hoses a good squeeze.

Thanks for your time. Have a good weekend.

 
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Im curious now, can you take a picture of the gunk?

 
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Nope. Never had any before I changed either. It was the original factory green coolant before I changed the timing belt and associated stuff.

About a month later, I found my radiator fan wasn't coming on like it was supposed too. I determined it was a bad fan motor. So when I swapped out the fan I decided to replace both the upper and lower main radiator hoses, clamps and the thermostat and gasket. All were OEM parts with the exception of the radiator fan. I got that from Amazon.

I kind of fired the parts cannon for preventative maintenance purposes there with exception of the bad radiator fan. I may get a scolding from ezone.

 
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Still at work. Will try to grab one tonight or tomorrow.

Did you see these?

 
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Nah. I'd post that helpful pic though.

Firing the parts cannon is for when you are trying to fix a real problem, but you just don't have a (F'n) clue.....as the caption on one of those pics says.

Most people that have to fire that cannon try to make themselves feel better about it by saying that "it probably needed all those parts anyway".
Certain subpar shops will tell their "customers" the same thing after they fire the same cannon. (In this case, P.T. Barnum may have said "There's a "customer" born every minute".)

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Excess maintenance is almost completely different.

The biggest problem is when people remove perfectly good factory parts (in the name of maintenance!), and replace them with cheapazz aftermarket parts that aren't going to last half as long as the original parts would have lasted.
Or they can't believe that a new part is bad, so they keep replacing other crap, going in circles.

Example (based on 100% actual experience): Original part lasted 150k. Replacement part (cheapazz, price is half of OE) only lasted 30k. Or less. Now you have to replace it on a regular basis.
Math this out and explain to everyone where the value is.


AutoZone: Turning your Honda into a Daewoo, one part at a time.

 
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^ LOLZA!
not that i agree that all OEM parts are actually that good

 
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General FYI...

I just found this recently on my 1997 Satrun SW2 with 157,000 miles. I changed the coolant about 3 years ago when I installed a new radiator. I have owned the car since it was new and never added or needed to add stop leak.

Stats:
All hoses changed as of ~ 2008 - except the ~ 1/4" ID little hose that runs from the reservoir to by the throttle body is original and I have never changed it.

Car has NEVER overheated, fan is original and still works well.
Car is MANUAL - so no A/T oil circulating in radiator.
For about the last 8 years or so I add about 6 OZ of coolant / year.
Water pump has never been changed - I'm getting ready to do it soon.
This problem happened within the past 1/2 to 1 year.
There is no oil in the coolant and no coolant in the oil. I change oil every 3K.
I normally run standard 50/50 coolant / distilled water.
I did go for about 5 years with mainly water - when I changed the coolant about 8 years ago it felt like water - was not slippery at all and smelled like water.
I drive real easy, 75% highway.
Car has been in San Diego since 2000.

 
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Just an update: I had the same issue in my 1997 Saturn SW2 owned since new and still own and drive. Solution: changed the head gasket and got head resurfaced and pressure tested for cracks. No problems since and it has been around 7 years.

Best thing to do is get the coolant tested with a test kit or go to Autozone or other place like that offers the test which will turn a certain color if exhaust / hydro carbons are detected in the coolant indicating a blown / leaking head gasket.