V6 Head Gasket?

So my Tacoma with ~320K miles keeps filling up its coolant overflow tank. After cooling down I find about 1” of air in top of radiator and top hose. I top off radiator but coolant tank overflows after a few drives, and air space reappears. Also when opening heater valve I hear gushing air for a couple seconds(after engine warms up post top off).

Previous owner had head gaskets done about 60K miles ago but I have doubts about the skill level of the shop after seeing other stuff they glazed over. Trying to figure out where to start with troubleshooting here...

One data point- about 600 miles ago I stripped top of engine down to pulling intake manifold for new(reman) injectors, new knock sensors, etc. noticed a large amount of staining from coolant in valley of engine (seems to be originating from head gasket area). Hard to determine if this is new or old, and with intake manifold removed you can’t do a pressure test to check.

Let me know where you think I should start. Never done head gaskets on these trucks but willing to learn if need be! I mean if I got the intake manifold off we are like 2/3 or the way there, right? A little scared that exhaust manifold studs are seized up and will break off. I hate working on old stuff but truck is otherwise a great reliable 4x4 with TRD locker, Corbeau seats, etc so seems like it’s worth some sweat equity.
Thanks for the help!

 

Leave the exhaust manifolds on if you're worried. Disconnect it from the back. Then attack them on the bench.

It sounds like a failed gasket to me, I'd buy a kit and start the tear down.

 

So take out the 3 studs/bolts on the manifold flange that ties it to the crossover pipe? Didn’t think of that approach. Worth buying all new exhaust studs given the miles?

 

^^^ Yep. I did an engine swap with exhaust manifolds attached and the cross-pipe removed.

I'm sure you know to have the engine set on TDC before you start?




If you don't have a tool for timing pulleys, I had good luck with the tool in this video. I used the one tool for all pulleys.

https://youtu.be/j_TfAACwJac

https://youtu.be/voLBRDZL9fE

I'm not sure why he removed the exhaust manifolds at this point.

https://youtu.be/in4VdfnHdI0

https://youtu.be/yTsocmNdBpQ

https://youtu.be/nFYEoWTX0YU

https://youtu.be/iQ7-wmjo6PE

https://youtu.be/5ysgDyea1GU



Buffed down the larger heavier pins to use on the crankshaft pulley.

 

$30 OEMTOOLS 27145 Combustion Leak Detector, Plastic and Rubber Tester for Engine Block Leaks, Automotive Blown Head Gasket Test

https://www.amazon.com/dp/B004FELK6A/ref=cm_sw_r_cp_awdb_t1_MZs3DbX8AV9TH
Combustion leak detector might help you feel better about opening up the heads by confirming that exhaust gasses are in there. I think I'd be pretty convinced already based on what and how you describe the symptoms (and that you say a shop has been in there, I'm sorry for a shop touching your stuff, unless it's the shop Bishop84 works at then it's a good thing)I'd be convinced somethings up and to open it up, it's likely head gaskets but you want to make sure the heads also don't have any cracks and make sure they're flat and true

 

I've used one of those before. It worked.

 

If you need head gaskets I'd just buy a lower mileage take out engine www.car-part.com

 

I wanna get one, keep waiting for my first need for one. Is it as simple as it looks? Just draw some fluid out of system and the color of it tells you right then and there?

 

I bought mine at NAPA. I still have it. Its been almost 10 years ago. Here's a vid on how it works.

https://youtu.be/ArG9Ve3bRjU

 

Oh you can use same tool to sniff the exhaust gas for coolant as well? That's cool, I always thought it was a different or separate tool for that

 

One last question, when you had the intake manifold off, did you have any pitting around the coolant ports that could be leaking now?

 

I think he sniffed the exhaust gas to show how the fluid changes color with the presence of exhaust gasses.

 

Oh oh, I see makes sense. I was watching with volume off and I see now, just wanted to show the reaction. Gotcha, thanks for clarifying...... Coulda led to a 'funny' data point I might've offered in future

 

Haven't had the issue on my Tacoma but on my LC when my reservoir was filling up and then not backflowing into the radiator as it cooled down I bought a new one of these. System needs to be airtight to work properly I believe, if not it will suck air in before sucking the coolant back out of the reservoir. I figured for the money it was worth a shot before getting elbow deep. Seems to be working so far.

 

All-
Thank you for all the replies! Giving me a lot to think about. Just ordered the Carbon monoxide tester and the new overflow cap/hose kit. Hope the $7 part fixes it but I know it's a longshot!

CS_AR: My coolant ports were not THAT pitted but I don't recall them being perfect. Might be worth another teardown to check. I did use new OEM gaskets there as I had some suspicions. Not sure how forgiving those gaskets are but the old ones were definitely a problem and had been re-used. Any ideas on fixing those if needed? Belzona and a good polish afterwards?

My plan this weekend, assuming parts/tools get here in time, is to start with the gas sniffer and then pull intake manifold to see how things look.

Thanks as always to the brain trust that is Tacoma World!

 

If yours aren't too bad, I doubt that's the problem. Check your other head gasket and coolant items first. I've dealt with pitted coolant ports on other aluminum head engines over the years.

I polish then the best way that I can with a Dremel tool brush. I've had good luck with a gasket that uses a silicone seal for imperfect mating surfaces.

Its the same surface seal concept as the new and improved OEM water pump gaskets.