Jump to content
Sign in to follow this  
Gaurav

Pajero coolant expansion bottle turn brown

Recommended Posts

I have been using original Mitsubishi coolant in the radiator and in the expansion bottle always. To top after some time I use ENOC green coolant occasionally. Just now open the coolant expansion bottle as it was low, and noticed that green coolant has turned brown, literally rust or sand color brown. Opened the radiator cap to inspect and coolant was full with bright green color.

Wondering, what can cause coolant in expansion bottle to turn brown?

  • Like 1

Share this post


Link to post
Share on other sites

Take out and wash the bottle thoroughly and dump the old coolant. Also not all coolants are compatible with each other. 

So better flush out the old stuff and refill with fresh new coolant. Coolant should be replaced every two years anyways. 

  • Like 1
  • Thanks 1
  • Totally Agree 1

Share this post


Link to post
Share on other sites

I will def clean the bottle and coolant is less than a year old.

Any clue why expansion bottle turned brown...?

  • Like 1

Share this post


Link to post
Share on other sites

Coolant in the bottle specially in a system that has a radiator cap doesnt cycle as much or as vigorously as it does in the radiator so think of it as a catch can or filter all the heavier dirt and rusts from the cooling system settles in it.

Like the Range L322. It has a flawed radiator design with the lower hose 8 rows above the bottom. So all the gunk settles in those last 8 rows as watee doesnt cycle as much through the bottom rows. Unfortunately those last 8 rows are also used for ATF cooling. While the engine is sufficiently cooled but the Trans oil cooler gets cooled in turn cooking the transmission too. 

  • Like 2
  • Thanks 2

Share this post


Link to post
Share on other sites

If you clean the bottle, it will just turn brown again. You need to do a full coolant system flush with a proper flushing agent then rinse all the flush out with clean water, bottom to top. Dishwasher tablets are great for this. If you rinse tip to bottom, the water doesn’t get into all the galleries and you miss some. Bottom to top means the whole system is filled and all the crap gets washed out. 

Be 100% sure the coolant you’re putting in is the proper stuff. Don’t listen to the parts shop monkeys, they  will tell you this colour is better than that colour when colour has nothing to do with it. 

You can get extra corrosion inhibitors like Fleetguard DCA4 to add to the system. They don’t sell them in normal car part stores but a decent truck and plant parts store should have them. 

Personally, I would just switch to a waterless coolant like Evans. The engine runs a few degrees hotter but it will never overheat and you won’t have any more corrosion problems because there’s no water in the system to boil and no water to cause oxidisation.

  • Like 4
  • Thanks 1
  • Haha 1

Share this post


Link to post
Share on other sites

Another issue with coolants is that different brands/formulations have different densities, so apart from anything else, if you mix coolants it can happen that the lightest coolant floats on top of the more denser coolant when the engine does not run. 

This is very likely the reason why you are seeing green coolant when you open the radiator cap, but if you should drain the radiator from the bottom hose, you will almost certainly see another color coolant coming out first. 

Moreover, since not all coolants are compatible, mixing coolants can destroy the rust protection function of all the coolant formulations in the mix, which is the origin of the corrosion-colored coolant in the expansion tank. 

Edited by treks
  • Like 1
  • Thanks 1

Share this post


Link to post
Share on other sites

Thanks, guys for valuable advises, I have cleaned the bottle and touch that brown sedimentation part and it was confirmed as sand and not rust. Later I recall that this happen in the past too and I just rinse the bottle and top it up with the coolant, without bothering asking this question.

Now, my question is how sand is getting inside the coolant system and expansion bottle working as a catch-can to hold the sand at the base and only allowing coolant to recirculate as its suction pipe is a bit shorter than the height of the expansion bottle.

  • Like 1

Share this post


Link to post
Share on other sites

Sand most probably enters from the overflow pipe of the expansion bottle as they have one incase you overfill or coolant expands too much the overflow is dumped out. Hence if you notice even if you fill the bottle till the brim, after a drive or too the coolant is back to its normal level. 

Since you go to the desert alot and kick up a lot of sand, some probably enters through that pipe.

This is just a theory, since I can't see another open to air access in an otherwise closed system.

  • Like 1
  • Thanks 1

Share this post


Link to post
Share on other sites

Better to flush completely and start using Toyota pink coolent as it has better rust protection and has property's to seal minor leak's too... 

  • Like 1

Share this post


Link to post
Share on other sites
19 hours ago, Gaurav said:

Thanks, guys for valuable advises, I have cleaned the bottle and touch that brown sedimentation part and it was confirmed as sand and not rust. Later I recall that this happen in the past too and I just rinse the bottle and top it up with the coolant, without bothering asking this question.

Now, my question is how sand is getting inside the coolant system and expansion bottle working as a catch-can to hold the sand at the base and only allowing coolant to recirculate as its suction pipe is a bit shorter than the height of the expansion bottle.

Not wanting to start an argument here, but did you actually rinse the sediment under clean water, and found grains of desert sand? Or did you just squeeze the sediment between your fingers and found the sediment to be granular? 

This is an important point since pure silica (sand) will not discolor the coolant, so unless you have been kicking up sand that contains clay particles (that would certainly have discolored the coolant), the coolant should have remained clear.

But, @desertdude makes a good point. If there was a lot of sand flying around the engine bay just at the point when the cooling system sucked in coolant from the expansion tank, some sand could conceivably have entered the tank through the overflow tube. 

In my experience however,  granular material in expansion tanks sometimes sticks to a magnet, in which case it is rust. If it does not stick, it is obviously not rust, and likely to be the result of chemical interactions between different types of coolant in the water, and/or reactions between coolant mixes and some metals in the cooling system- most notably, some aluminium alloys in some radiators.  

@Barry, also makes a good point- waterless coolants eliminate all of these issues, and although it is more expensive than regular coolants, their overall performance and protection levels are miles ahead of anything you can mix with water. 

  • Like 2
  • WOW 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×
×
  • Create New...

Important Information

Terms of use