What’s this crud in my coolant tank/radiator?

Hey guys,

Purchased my 2002 Tacoma DC prerunner a few months ago and absolutely love the thing. I have Fox 2.5/2.0s, Alcan springs and an ARB bumper already on the way. Yesterday I checked my coolant tank to a nasty surprise and the same in my radiator. It doesn’t appear to be the dreaded “chocolate shake” but more of a rubbery/sawdust texture. My first thoughts were wither head gasket failure or transmission problems since it’s an automatic. I’ve also read that this could actually be a sign of two coolants being mixed together and will need to replace the radiator along with a flush. Any experienced advice is welcome! Thank you.

 

Looks like sand....

 

Probably no telling what is is but i’d do a full flush and refill sooner than later. The coolant color looks good so I dont suspect a bad gasket or cracked head that would allow oil intrusion.

Flush process in a nut shell:

Get eight 1 gallons of distilled water and do a thorough flush. Drain, fill with distilled water, run engine up to operating temp so the thermostat opens and circulates the fluid, drain, let engine cool before refilling with the colder distilled water, repeat until it comes out clear, drain and fill with OEM Toyota coolant(1 gallon concentrate), check coolant temp rating with antifreeze tester to make sure you are good for the possible lowest temp you could encounter.

 

rub it between your fingers and see if it feels gritty. since she is new to you you don’t know the history. my first though is grit from a sand blaster when/if the heads were redone. my second thought is casting sand from when they poured the block… seems kind of odd that it shows up 20 years later.

 

Months ago?

Man, fluids should've been checked/done immediately after purchase.

That stuff looks like some kind of stop-leak stuff people pour to hide a leak or worse.

Do the above and flush your whole system yourself.

 

looks like poor cooling system maintenance or none at all.

Over time if you mix coolant with Engine Oil you get something just like that in the coolant. A small leak over years will do that.

Do you have an oil cooler ??

 

Ahh, that too.

I've only seen stuff gummed up like that when those stop fixes build up and solidify in an attempt to block a leak.

Not all of it (or any of it) makes it to the leak and at some point, begins to form within the coolant itself.

Seen it in other vehicles prone to running hot(ter) than usual, specifically reverse cooled LT1/4 engines.