Brown radiator fluid

[TheOtherLeft]

Hiya gurus,

I've had a strange thing happen to my radiator fluid over the last few days.

I flushed my radiator a few months ago and all has been sweet. It hasn't overheated or used any water. I use Castrol concentrate at about 33%. Then a few days ago when the really hot weather started down here in Sydney the fluid in the overflow bottle has a brown tinge. I emptied the bottle 2 days ago and filled it with plain water as I was out of concentrate. I then checked this morning and the brown tinge is back so it looks like maybe the rest of the coolant is brown as well. The car still doesn't run hot. I checked the radiator cap and it still has green coloured fluid all around it

I haven't been in any mud and my last trip was at Stockton. The gearbox was a little overheated as some fluid had leaked out of the dipstick hole but it was still fine (the fluid was not burnt). Not sure how it could be related to the engine coolant though.

Any ideas? Rust maybe???

[bakerboy]

whats the history of the car? probably totally unrelated but i know when i used chemiweld in the old subi the coolant was brownish

[dank]

Have you run your heater since you flushed the cooling system?

When I was replacing my engine I shoved a hose onto the heater inlet into the firewall and flushed it out...water was pretty dirty, then I stuck the hose onto the outlet and back flushed it and a whole heap more dirty water came out.

Maybe you have run the heater a couple of times since the flush and it has contaminated your coolant again??

[TheOtherLeft]

The engine and cooling system has been 100%. I've never had a problem with it. When I flushed it a few months ago the old coolant was fine too with no rust or bits. I never used used chemiweld in it.

It's got me stumped why all of a sudden the coolant is brown.

[TheOtherLeft]

Have you run your heater since you flushed the cooling system?

When I was replacing my engine I shoved a hose onto the heater inlet into the firewall and flushed it out...water was pretty dirty, then I stuck the hose onto the outlet and back flushed it and a whole heap more dirty water came out.

Maybe you have run the heater a couple of times since the flush and it has contaminated your coolant again??

When i flushed it before I made sure the heater was set on high. I did run water through it a few times to make sure all of the old coolant was out as well.

[MICK77]

How old is the vehicle?
How often is the coolant changed?

It may be corrosion in part of the cooling system eg. Water pump impeller. engine block, cyl head, steel water pipes(if any) and as mentioned above the heater core etc.

When you flush the system, do you remove the drain plug in the block? This is assuming the vehicle has one.

Quite often people will only partially flush the system. This leaves old coolant still in the system which has little to no protection for your cooling system.

Cheers,

Micko

[alien]

mine goes brown from getting mud in the overflow tank... you can actually see the bits of crud floating in it - its gross.

but rust is another possibility for sure.

[Utemad]

When the coolant in Dad's ute went brown it was due to a blown headgasket. It had snapped a head bolt in half!

[TheOtherLeft]

It still the strangest thing.

There is no loss of power. No coolant loss. No over heating. The oil is fine (looks like oil not milky). There is no smoke from the exhaust and no coolant smell.

The only symptom of anything being wrong is the coolant in the overflow bottle has a brown tinge. Not a milky brown but more of clearish dirt-mixed-in-water kinda brown.

Maybe somehow dirt/fine sand was sucked in during my last Stockton trip?

[paulm958]

What year and model??? quite often if you use either the green pink or red coolants this is exactlly what happens as there not always compatible, we found green coolant in our hdt fte completely flushed the system 5/6 times added the pink coolant and after a couple of weeks turned a brown color,
it may pay to flush the system and try again

[TheOtherLeft]

The old coolant was green. The new coolant is green too. I flushed it about 6 months ago so not sure why the incompatibility would show up so late. Maybe I didn't flush it enough and there is brand incompatibility?

Seems like a reflush is on the cards.

My method of reflushing was:
- drain radiator tank from tap at bottom of radiator
- refill with water
- turn on heater to max and run engine until warm
- repeat until all coolant is flushed - fluid is now clear
- Refill with water and coolant concentrate
- bleed any air with rad cap off

Is this the correct method?

[TheOtherLeft]

It's a 2002 Suzuki Grand Vitara. There has never been any cooling issues, no leakages so there's been no signs in the past about problems.

[MICK77]

The old coolant was green. The new coolant is green too. I flushed it about 6 months ago so not sure why the incompatibility would show up so late. Maybe I didn't flush it enough and there is brand incompatibility?

Seems like a reflush is on the cards.

My method of reflushing was:
- drain radiator tank from tap at bottom of radiator
- refill with water
- turn on heater to max and run engine until warm
- repeat until all coolant is flushed - fluid is now clear
- Refill with water and coolant concentrate
- bleed any air with rad cap off

Is this the correct method?

Once you have drained the system, I would remove a heater hose, push the garden hose into it and flush until clean water flows from the fitting you removed the heater hose from. Try flushing in both directions as this gives you the best chance of removing any crud in the system.

Cheers,

Micko

[TheOtherLeft]

Could Algae be a problem too?

I used tap water, which maybe wasn't overly clean?

[MICK77]

Could Algae be a problem too?

I used tap water, which maybe wasn't overly clean?

I wouldn't think that would be an issue, unless you used stagnant tank water or similar.

Cheers,

Micko