[yrffej]

thanks for the replies, I couldn't be online for a couple of days...

205* is hot for my normal running temps, and clearly enough to fill the overflow higher than I've seen it before. 193* is the hottest i've ever seen it run during this same 200mi round trip i've made over a hundred times, over
summer or winter) the past 10 year

the bubble that I saw, were inside making me think the air leak was at the drain plug

I did drain and refill the radiator coolant before, somewhere near the 100,000 mi mark. since then I had the radiator replaced with an aftermarket one by a friend. shade-tree mechanic... and the radiator cap also...

I don't recall the mileages when these were done?
but it makes sense to next replace the cap this weekend, while I drain and inspect the overflow reservoir system...

 

[yrffej]

it is essentially still running hot... on my same 400mi loop, I drive every other week. 190* - 199* (it used to do this drive, staying under 190*) and I see it (scan-gauge) heat and cool with the up and down hills on the trip...

I did replace the radiator cap, and thought it helped? (more than a month ago)
last weekend I replaced the thermostat... and it, like the radiator cap... didn't really fix the world.


i'm beginning to believe that there is a pressure leak somewhere in the system (as BamZipPow suggested)

perhaps autozone has a pressure tester in their loan a tool program

 

[yrffej]

I did a coolant system pressure test today, and cant find any leak...

it held up to 20psi, for 15 minutes and only lost one psi...

I haven't a clue what to think of next.
I know hot engine coolant gets pushed under pressure into the reservoir but it doesn't flow back after cooling, and air takes its place in the radiator...

after running it today after the pressure test, I was able to siphon the coolant from the reservoir and pour it back into the radiator, and had no coolant loss? but in the past I have had coolant loss...

 

[yrffej]

update on today...
I used the coolant pressure tester, to also test the radiator cap I just bought a couple of weeks ago (autozone)


so... it horribly failed. holding pressure way above 25psi

it is marked on the top, with an #11. I assumed it means 11psi.

11.4psi is the absolute minimum opening pressure according to Tacoma tsm. with normal operating pressures being
13.5 - 17.8psi

wouldn't it be nice, if my original problem is a bad cap. that I replaced with a brand new, cheap bad cap?
the Toyota dealer said the oem cap will be in Friday...

I'm keeping my fingers crossed...
I was just about to purchase the gasoline mixed with coolant, chemical tester... thinking it may be a failed head gasket.


more later

 

[yrffej]

after my last, finding the new radiator cap being defective... I removed the drive belt, fan & shroud and looked around the water pump. weep hole was dry as if nothing ever came out of it, no stains... nothing. although the 240,000 mi serpentine belt, has some good cracks in it so I bought a new one to put in tomorrow... I had saved the original thermostat I took out 6 or 7 yrs ago... tested it in 180* - 205* water and it passed as it should according to what the tsm says it should do... so I removed the new ish thermostat I got from autozone (not a big fan of their parts, this week) and installed the old good Toyota thermostat...


tomorrow, its install the new belt, the new radiator cap, (from Toyota) bleed the system...
and see what I got?


it is still possible that there is blockage (reduced flow) in the radiator?
all the testing didn't address blockages (there are no leaks)…

more later

 

[yrffej]

plastic overflow which I first thought to be the problem, isn't...
the bubbles I saw and perceived to be a leak in the reservoir, was small amounts of air being pushed (under pressure) from the radiator...


but after checking the weep and air port at the water pump, after I had the belt and fan removed...
the water pump shaft isn't as free spinning as the tsm leads me to understand? not sure?
I can turn it easily, but with some minor resistance. I perceived the resistance to be the seal? rubber to the metal shaft... when I tried to spin it quickly as soon as I took my hand away, the shaft would halt. no continued spinning.
I don't know if this is normal?

and I don't know if its defective, could air be entering the system there?
pressure test, showed no leaks...
but still overflow fills, and coolant doesn't return to the radiator after cooling...

I have gotten a "loaner" block tester with the blue test fluid. drained the radiator half way...
gonna test it in an hour or so.
I really hope I pass this test...
i'd rather replace water pump and radiator, than have the dreaded blown head gasket.

more later

 

[yrffej]

So it's confirmed to be your radiator cap and not a gasket problem? That sucks, but it's not too bad.

thanks for the reply...
but nothing has been confirmed.
I did replace the cap, and replaced it again when the new cap failed the pressure test...
good thermostat at the same time as the good cap...
does now run in the 184*-190* range, where before it was 194*-200* range (cap and thermostat did that)

 

[yrffej]

seems as I have just failed the block chemical test...
turned from blue to green in less than 2 minutes, didn't go yellow... but still failed
(burned engine gas took the place of coolant in the cooling system)

looks like I'm gonna be pricing to have the head gaskets replaced. (it's not something i'd attempt to do myself)

any suggestions on who to look for?
i'm thinking a local repair place where i've seen some Toyota and Lexus parked in the lot...

does anyone here have a realistic price for having the work done on their own V6 truck?

 

[yrffej]

Sorry to hear about your car troubles. I too fear this will happen to me one day.

Same engine on the Rav4: How to fix

the Tacoma is the 1GR-FE, 4.0 V6