yellow Lava looking stuff

[NeverGiveUpYota]

Does you noticing this correlate with the overheating? With overheating comes pressure.....possible freeze plug.
I'm not 100% sure but I think there's a freeze plug in the back of the block in that vicinity. I'll verify when I get home
this evening.

Added a pic of the full rear side. Larger freeze plug not installed here. Smaller one at mid left corner has a hex plug. And course the big one behind the head.

 

[Seth S]

I google searched your problem and came across other forums with similar issues for other cars. No one seemed to know for sure the cause but the leading theory was buildup due to a leak but also because of two incompatible coolants mixing together. One forum referred to flushing the whole system with water multiple times and then refilling with proper coolant.

 

[greg85fj60]

After poking around with a mirror and a camera, I still have no clue what the yellow stuff is. I cleaned it off and it turned into the same orange nasty looking stuff that came out of the old radiator. I just don't know how it got there. Someone earlier mentioned the same... but I am leaning towards it coming from the firewall drain port for the heater.? I was over heating on last cruise so I turned on the heater to bring engine temp down...maybe the yellow goo was in there and excess heat pushed it out. I have a few more things to do before I can run it again, but I will give an update. Thanks to all

 

[Spike Strip]

I would get one of those cheap Prestone flush kits and remove the lower Rad hose and flush the snot out of the heaters and block. If you can do it when the thermostat is removed, even better.

Refill with mineral-free Green (or Toyota Red) Coolant.

 

[greg85fj60]

Added a pic of the full rear side. Larger freeze plug not installed here. Smaller one at mid left corner has a hex plug. And course the big one behind the head.

View attachment 2389114

Using the above pic (thanks), I drew in yellow where my leak Is. Today after it warmed up i Saw it coming from there and I almost certain It is the rear freeze plug. So I guess dropping the trans and bell is what I need to do. Am I correct in assuming it’s that Rear freeze plug? since I saw it coming from that spot I feel I can eliminate it being a hose or heater overflow.

 

[chbrow10]

I am on the "wrong coolant mix" bandwagon, especially since you've had an overheating event recently. I concur with a complete system flush via the lower rad hose and some kind of flushing kit now that you have the rad out. maybe rig up a garden hose driven system or something to take the place of the rad.

 

[NeverGiveUpYota]

Using the above pic (thanks), I drew in yellow where my leak Is. Today after it warmed up i Saw it coming from there and I almost certain It is the rear freeze plug. So I guess dropping the trans and bell is what I need to do. Am I correct in assuming it’s that Rear freeze plug? since I saw it coming from that spot I feel I can eliminate it being a hose or heater overflow. View attachment 2410801

Before you start pulling things get a pressure tester and try it. You can squeeze a mirror behind there and maybe get a better idea too while doing the test. Would seem tho that if it’s pooling liquid along the edges of the bellhousing then your prob right.
while your in there... RMS, clutch kit, the list begins!