[sdspeed]

Saw that a lot working in a radiator shop. The dirt, debri ,rust etc. settles into the low spots and gets caked in with the regular temp changes. We used to pull the thermostats out and open all the heater control valves and flush them until they ran clean. The heaters in all cars are notorious for holding muck in them. Problem is if you get to aggressive, i.e high water pressure or adding air during a flush Murphy's Law says if you end up with a leak it will be in the heater core.
If it really bothers you, you could get super pre-emptive and put a new Denso radiator, radiator, heater hoses, new stat and cap. Barely over $100 bucks worth of parts. Only leaves the heater core and block that might have some residual gunk in them.
Sounds like it runs good and the compression numbers are excellent.

 

[75aces]

This is a first for me. Not sure why the coolant is getting dirty in the first place. Though, I must ask you op.

Since the service performed by the mechanic recommended to you, was the coolant ever changed before this? Chances are it wasn't.

There's a good chance that a stop leak was used to seal the radiator and what you're seeing is the stop leak breaking down? Most likely it's going to continue. Do a pressure leak check on the radiator to make sure it's not the source of the issues. If the heater core was in fact leaking, the passenger side floor would be damp and smell sweet inside.

My instincts tells me, that the radiator does have a leak, but something added to seal the leak. On my Mazda, I just dealt with a leaking radiator that started to leak with 7 psi.

Hope it helps.

 

[Teton77]

This is a first for me. Not sure why the coolant is getting dirty in the first place. Though, I must ask you op.

Since the service performed by the mechanic recommended to you, was the coolant ever changed before this? Chances are it wasn't.

There's a good chance that a stop leak was used to seal the radiator and what you're seeing is the stop leak breaking down? Most likely it's going to continue. Do a pressure leak check on the radiator to make sure it's not the source of the issues. If the heater core was in fact leaking, the passenger side floor would be damp and smell sweet inside.

My instincts tells me, that the radiator does have a leak, but something added to seal the leak. On my Mazda, I just dealt with a leaking radiator that started to leak with 7 psi.

Hope it helps.

Last time the coolant was serviced was in 2015 a while before I owned it (2018) and at a Toyota dealership. But thank you and noted I will try a pressure leak test.

 

[Teton77]

This is a first for me. Not sure why the coolant is getting dirty in the first place. Though, I must ask you op.

Since the service performed by the mechanic recommended to you, was the coolant ever changed before this? Chances are it wasn't.

There's a good chance that a stop leak was used to seal the radiator and what you're seeing is the stop leak breaking down? Most likely it's going to continue. Do a pressure leak check on the radiator to make sure it's not the source of the issues. If the heater core was in fact leaking, the passenger side floor would be damp and smell sweet inside.

My instincts tells me, that the radiator does have a leak, but something added to seal the leak. On my Mazda, I just dealt with a leaking radiator that started to leak with 7 psi.

Hope it helps.

No leaking on the inside that I can see nor sweet smell. So may be ok there.

 

[TedL]

I believe the factory coolant was rated for 10 yr/100k miles, so the change in '15 should have been close to spec. Subsequent are , I believe, 5 yr, 50 k, so again, not abusive neglect.

Any chance there's ATF getting in there?

 

[Teton77]

I believe the factory coolant was rated for 10 yr/100k miles, so the change in '15 should have been close to spec. Subsequent are , I believe, 5 yr, 50 k, so again, not abusive neglect.

Any chance there's ATF getting in there?

I was thinking that could be a reason why but supposedly it would still come out milky and look like a strawberry milkshake? Which it definitely doesn't look like. I have some of the old coolant in a old water bottle and let it sit for a few days to see if the oil or whatever seperates and it hasn't at all still looks like the day i poured it in the bottle

 

[75aces]

It sounds like the sediment is loose and floating through your cooling system. Is it possible the cooling flush loosened the sediment or the previous owner used the wrong coolant.

 

[rhoderage]

Any chance you have a receipt or service record from the previous fluid change which may note what exactly was put back in the system? As 75 said, perhaps it was the incorrect coolant, perhaps incompatible?

 

[Teton77]

Any chance you have a receipt or service record from the previous fluid change which may note what exactly was put back in the system? As 75 said, perhaps it was the incorrect coolant, perhaps incompatible?

No receipt just CarFax showing that it was changed around 100,800mi in 2015 at a Toyota dealership. But I did buy it off of a weird private seller/car sales place so who knows if they have done anything to it

 

[rumrunn6]

had this on a 4Runner many years ago. it was engine oil finding it's way in. at first we thought it needed an engine overhaul. but turned out to be a gasket for the timning belt housing I think.

 

[Teton77]

had this on a 4Runner many years ago. it was engine oil finding it's way in. at first we thought it needed an engine overhaul. but turned out to be a gasket for the timning belt housing I think.

How were you able to tell it was oil besides the color of the coolant? Any other symptoms?

 

[rumrunn6]

How were you able to tell it was oil besides the color of the coolant? Any other symptoms?

oh boy this was a long time ago. it was an '85 4Runner that might have had 100K or more miles on it. I think the oil had a (sweet) coolant smell to it. but maybe I'm just incorporating what I read above into an old memory? see now maybe I'm confused & it was the oil that had coolant in it! agh! sorry

 

[Mgeorge]

Maybe you could send that antifreeze out for analysis to find out what's in it. Would cost around $75 probably. I changed my antifreeze at over 150,000 miles for the first time and it still looked fine. As a matter of fact, I can't think where any sediment can be coming from. Isn't the cooling system comprised of just aluminum, plastic and rubber? No rust there.

 

[75aces]

If the wrong coolant was used by the dealer that the op purchased from is probable. It wouldn't take long for it to break down.

I've never seen this condition before. The coolant becoming something else is odd to begin with. No idea where this is coming from.

It does seem like it's a stop leak? Maybe the head gasket was leaking at one point and didn't get repaired? This would be cooling issues, not coolant changing conditions.

 

[Teton77]

If the wrong coolant was used by the dealer that the op purchased from is probable. It wouldn't take long for it to break down.

I've never seen this condition before. The coolant becoming something else is odd to begin with. No idea where this is coming from.

It does seem like it's a stop leak? Maybe the head gasket was leaking at one point and didn't get repaired? This would be cooling issues, not coolant changing conditions.

How can you tell if a stop leak was used?

 

[75aces]

Pressure test for leaks on the radiator.

 

[75aces]

How can you tell if a stop leak was used?

I showed your images to a buddy of mine. Someone at some point used a different coolant at some point. Do a flush again. The flush that your mechanic did pushed more of the blue coolant through and mixed with the red coolant. It'll be a full flush of the cooling system to get the rest of the other coolant.