Cooling system issue

Hey people, new to Tacoma World. I’m a newbie again!
Anyway, maybe some of you can help with my new conundrum.
04 V6 Tacoma, 114,000. New water pump and timing belt at about 65,000.
Issue is coolant reservoir is slowing running down. Sometimes I can smell coolant. Last trip I noticed temp gage move to just above 1/2 way then move down to middle after about 45 of freeway driving. Any thoughts?

Thanks!!!

 

maybe check oil see if coolant is getting in oil, check coolant see if oil in coolant, look for white smoke comming out of tail pipe after truck has warmed up any of these would point towards a head gasket. go to auto zone, orielys use a block tester to verify.

you say you smell coolant feel around the carpet under the dash on either side of the radio/hvac if its wet and smells like coolant it might be a leaking heater core or line most likely hope this helps

 

What flyck4 said.

Question for you OP, is your radiator an original one?

Look at the plastic expansion tank; the plastic becomes brittle over time and I actually had to replace my radiator due to a leak from a hairline crack.







Mine was a dead giveaway considering there was dry coolant on my shroud.

 

Thanks for reply’s fellas. I already checked for milky motor and tranny oil. Nothing there.
Hairline crack on radiator has me intrigued.
Could it be a failing fan clutch?
Thanks again fellas.
Have a good Memorial Day!!

 

Smelling coolant is different than overheating so I wouldn't suspect a fan clutch at all; easy to check and easy to replace though if you're considering general maintenance.

 

I would replace the radiator, mine has similar symptoms and with no evidence of big leaks or coolant in oil/tranny fluid. I'm guessing that it is just being slowly clogged internally just from age/mileage (193k) and just not flowing/cooling as efficient as it used to. Coolant does evaporate over time, especially in these hotter months.

Worst case scenario is you have a brand new radiator, which are fairly easy to swap and not too $. The expansion tanks are plastic, which gets brittle over time so chances are it probably is due or close to being due after 15 years

Another really cheap potential fix could be if your rad cap is not holding pressure. My gf's 98 4runner had a bad cap on a parts store radiator the previous owner had installed. Put a new cap on and it was running great up to when we sold it

 

When was the thermostat replaced? And a new radiator will help with cooling. If it's original it probably don't have much time left until that plastic starts leaking if it not leaking already so not much of a waste to replace it now.

I'd be more worried if you are losing a lot of coolant from the radiator, not just the coolant reservoir.

 

I would put a new pressure cap on the radiator, not too expensive and cheap insurance. If the system does not hold pressure the boiling point of the coolant is reduced and the proper operation of the overflow bottle is eliminated. While driving down the road the coolant gets hot and it expands and pressurizes the system. When the pressure exceeds the caps ability to hold pressure any excess gets pushed into the overflow bottle, when it gets full, it pushes coolant out on the road. When the cooling system cools off, coolant is sucked back into the motor. Whatever spilled out on the road now shows up as a coolant loss.

I am not saying that this internet diagnosis is "it", it is just one possibility. You could actually have a seepage.

Common areas for the 3.4 are the small coolant hoses off the IAC block and the thermostat bypass tube in the "V" of the engine. I mention these specifically because you cant really "see" them, you have to know that they are there and not being easy to see, they get over looked.

 

All good areas to look at. Thermostat was replaced with the water pump and timing chain about 40,000 miles ago. I removed the rad cap and took a look, it looked clean, and the springs worked, I'll pick up a new stant tomorrow. Coolant tubing under the intake is a possibility, maybe new valve cover gaskets is the next job, this way I can have a look at that hidden coolant tubing.
Thanks Fellas!!!

 

There's also the issue of the thermostat jiggle valve that comes up here all the time. The Toyota repair manual says to install the thermostat on the V6 with the jiggle valve at the 6 o'clock position, while most other engines have it installed at 12 o'clock. Owners that have had it at 12 o'clock say it runs 10 degrees hotter and after switching it to 6 o'clock it runs cooler.

If you use a scan gauge on the OBD2 port you can get a more accurate coolant temperature reading than the dashboard gauge.

 

Update!!
Refilled reservoir and removed radiator cap to inspect. Cap looked ok but I rinsed it and worked the springs by hand, then re-installed.
No issues now, no coolant odor either.
Go figure!!

 

I would lean towards the radiator. Plastic reservoirs can develop cracks and leak. Other culprits could be hoses and or heater hoses and cracked overflow tank.

 

if you're smelling coolant in the cab, could the heatercore be leaking?