Just wondering as to what may be that "brown stuff" sitting at the bottom of the overflow tank..the previous owner had the coolant changed at 30k mi at the subi dealer and I don't know if at this time the over flow tank was cleaned ... and even though the car has 80k mi on it now...the coolant has been changed twice since then but also without cleaning the over flow tank...(this time the tank has been scrubed out)

The tanks are never cleaned. I would just clean the tank (good luck on that, I did it and it was a PITA due to its shape), and not worry about it.

 

The brown stuff can be anything from age, dirt, results of road grime, coolant additive.

 

 

nipper

The tanks are never cleaned. nipper

 

 

I wish you would stop making that generalization every time someone mentions an overflow tank, nipper. Mine is so clean you could drink out of it.

 

To clean the tank, remove it from the car and partially fill with warm water and detergent, stuff a small piece of rag in it and shake vigorously. Then take a length of coathanger wire, form a small hook on the end and use it to push the rag into the corners to scrub with.

 

Hey, stop by for a drink sometime!

I use gravel. Small pieces, larger pieces, etc. with the cleaner of your choice. A handful or two. Don't forget there is a pinhole when you're shaking it.

 

Learned this method from coating gas tanks on old cars - before I started having someone else do them.

 

Soaking is your friend too.

 

I try and keep a few pre-cleaned ones around.

I tend to see things from a shops point of view, and a coolant flush on the shop level is a money maker for them, and they never clean out the tanks, since time is money.

 

Thats why i say they are never cleaned.

 

 

nipper

I agree with Nipper on this.

 

It's amazing the Subaru's that I see that have HG jobs that often they don't even bother cleaning the radiator, let alone the overflow.

 

I haven't seen a clean overflow on a Subaru other than one I've done, or a new one.

 

I'm usually dealing with broken cars (HG's and such) but often folks have just tried rad caps, waterpumps, T-stats, rad flush, etc. All the usual stuff but don't touch the overflow.

 

Those 2 little bolts stop them from doing a thorough job. Yea - it's a little bit of a PITA but makes for a thorough job. And when they do the flush they are more concerned with turnaround.

 

I'm sure there are exceptions - but they are very rare in my experience.

Gentlemen, I don't disagree with you at all. But vast overgeneralizations like "never" just ruffle my feathers!

What is a pain in the rump roast about the overflow?? With my 93-94 legacy's simply pull out the pipe going to the rad cap, and remove one bolt and the tank lifts RIGHT out. In the process of cleaning mine right now btw

What is a pain in the rump roast about the overflow?? With my 93-94 legacy's simply pull out the pipe going to the rad cap, and remove one bolt and the tank lifts RIGHT out. In the process of cleaning mine right now btw

 

Removing it is easy, cleaning it is tough, though i do need to remeber the pebble trick.

 

nipper

i know there are a ton of cleaning products out there and a lot for specific auto items, but one that most of us already have at home, is powdered dishwashing detergent. it has a degreaser built in. a little power, some hot water, shake and soak. add pebbles as needed.

Edited March 10, 200917 yr by johnceggleston

Hey - liquid Cascade is one of the best coolant system flushes you'll ever use.

 

Even does a good job on the ceramic shower stall (recommended by a tenant of mine).

 

I have a locally mixed excellent environmentally friendly cleaner. Best degreaser I've ever used. It does suck all the moisture out of your hands is you use it straight(there is a warning on the label). Throw it in a foamy sprayer, get to the carwash, spray down the engine compartment and hose it down. But it works excellent in the overflow's with the pebbles. I've got 2 soaking right now in the spare side of the laundry tub.

Mine has a bit of grime at the bottom as well, good tip about the gravel + cleaner, I'll do that today

Is there any other place this "brown" stuff can be lurking around in...maybe inside the rad??...I still fail to understand why this Brown gunk was so heavily accumulated in the reservior tank, especially when the coolant was from subaru and changed out slightly more often then recommended

I noticed the last few inches of coolant in my overflow tank has turned an orange / brown. Just did radiator and hoses this winter. All new green coolant at that time. Didn't actually flush the system but the coolant I drained was in good shape (nice solid green, no orange/brown, no oil, etc).

 

I cleaned out the overflow tank at that time as well. It was pretty dirty in there. While I didn't scrub it I certainly cleaned it up to a point much better than it was.

 

Think my water pump is on it's way out. Noticing a bit of coolant dripping down along the thermostat housing (and on to the exhuast, yuck!) Aquiring parts now for timing belt and water pump replacement. Just wondering what the heck is causing this.

Think my water pump is on it's way out. Noticing a bit of coolant dripping down along the thermostat housing (and on to the exhuast, yuck!) Aquiring parts now for timing belt and water pump replacement. Just wondering what the heck is causing this.

 

Check to see if water is oily. If not its your dying water pump and not dying a full flush that is doing it. Aleays replace a waterpump, idlers tensioner and timing belt together, otherwise Mr Murphy shows up.

 

nipper

The brown sludgy stuff is just that. Brown sludgy stuff. It's dropout. There's really no way to prevent it, it just happens with age. It's caused by a reaction with air. Only the coolant in the reservoir is exposed to air. A small amount is purged as the engine warms and gets sucked back into the engine as it cools. So eventually it will build up in the engine and radiator, but it will generally be only a small amount.

I used one of those cylindrically shaped bottle-brushes to clean inside my coolant overflow tank.

 

It did the trick nicely. Now I can actually see the coolant level through the plastic.

The brown sludgy stuff is just that. Brown sludgy stuff. It's dropout. There's really no way to prevent it, it just happens with age. It's caused by a reaction with air. Only the coolant in the reservoir is exposed to air. A small amount is purged as the engine warms and gets sucked back into the engine as it cools. So eventually it will build up in the engine and radiator, but it will generally be only a small amount.

 

I agree with this answer and add I think the cooling system conditioner leaves a brown residue as well.

Just a dirty tank =/

 

I drained it lastnight into a container and it looked fine. Poured in fresh new mixed coolant. Shown a light behind the tank and bam; it looked orange/brown again! Moving the light around some more I could get it to change all kinds of colors based on what ugly spots the light was shining through =P There's just some weird discolorations to the tank which makes the lowest portion of the coolant *look* brown but it's actually not.

 

Glad to find out it was nothing to be concerned about.