az4x4runner

So my 4Runner (95, 3VZE) has had a small miss on startup for a couple weeks now. I've tested the O2 sensor, ECT sensor, checked plugs, cap/rotor, timing, vacuum leaks, anything in the general maintenance category I could think of, but everything checked out fine.

Last night I started it up and the miss was much worse and didn't clear up in a few seconds like it usually does. Then the white smoke started pouring out the exhaust with drips of coolant. My first thought was head gasket. I checked the oil, looks ok on the dipstick, then I looked under the oil cap which had some white gunk, which also led me to believe head gasket. The coolant appears to be ok in the radiator. I called it a night assuming I had a head gasket repair in my future.

This morning, I decided to pull the cold air intake hose off the throttle body and this is what I found: https://i.imgur.com/gOhjNuG.jpg

Now I am wondering if somehow the coolant bypass in the throttle body IAC is leaking and therefore coolant is being pulled into my intake from the TB. Has anybody seen this happen? If the head gasket blew, how would coolant get that high? I plan to pull and inspect the TB on my next days off work, but just wanted to get some input here as well. Maybe the white sludge under the oil cap is just from condensation of coolant entering through the TB and the fact I have only really driven the truck short distances lately so it's never at operating temp very long?

wyoming9

iTrader: (1)

Borrow/Rent if you don`t own a cooling system Pressure tester .

See if your system holds pressure

So it was coolant coming out the Exhaust it was the color you use Red or Green

Lots of Condensation ??

Head gaskets tend to be impressive with White Smoke but it is unpredictable

Is the Idle working like it should High till coolant temp comes up then drops to normal.

az4x4runner

Thanks for the reply.

I plan to pressure test it with the no. 4 and 5 coolant bypass hoses connected to the TB, then again with them connected together (bypassing the TB) to verify my suspicion of failed IAC leaking into the TB.

There was coolant dripping from the exhaust (green).

Also plan on pulling the plugs to see if all 6 cylinders got wet, as would be expected if the water was coming from the IAC.

The high idle has not been functioning properly part of the time leading up to this. I depended on how long the truck sat, if started without sitting too long, things seem normal, after sitting overnight or any extended period I would have a misfire and little to no high idle on start up (coolant leaked into cylinders?).

I will be digging into this on Tuesday and report back my findings.

az4x4runner

I guess I am not 100% familiar with how the IAC valve on a 3VZE is designed. I know some of the other model TBs have a gasket that can be changed, which does not seem to be the case with the 3VZE. Is there a component in there that can fail and allow coolant and air to mix? Not repairable as far as I know, a new TB would be the only option?

I'm hoping this is it, rather than head gasket. It sure seems like it to me, but I've never experienced it happen before.

az4x4runner

I pumped it up with a pressure tester, I hear air and gurgling in the plenum. It will not hold pressure at all, if I pump enough, coolant runs out the plenum then out of the throttle body. It is certainly not the IAC coolant lines leaking.

Any where else this coolant could be coming from, or pretty much would have to be head gasket?

Lrader7

Have you found the issue yet? I'm also have a leak problem... Had an overheating issue when I got it a couple days ago so I got a new radiator cap, put in some prestone flush cleaner, and burped it. Ran it for about an hour and it didn't overheat and then it started raining. Went to go finish the flush today and when I removed the radiator cap, coolant started spraying from the right side of the engine. Put the cap back on and it stops. Weirdest thing I have ever seen...

az4x4runner

Mine was head gasket for sure. Your issue certainly is strange. What part of the engine is the coolant coming from?

Due to mileage and engine condition, I am in the process of locating a remaned or used low mileage long block. Any recommendations?