Help Needed

My 2007 I4 4x4 started overheating, I changed the thermostat but it pushed coolant out of the radiator and into the jug/ overflowed out. I thought it was the thermostat but I tested it, then I leaned towards head gasket. I did a radiator air pressure test and it was negative(I have also burped the lines multiple times). So I continued with a combustion leak detector kit and it was negative. Could one of my tests have been faulty? Is there air in the lines I can’t get out? I’m sorry for creating a new thread, I only made an account to try and solve this issue, I can’t afford to hire a professional, any help is much appreciated.

 

Digging deeper into what you’ve already done. When you replaced the thermostat, where did you clock the juggler? I’ve heard different options, but I put it on top or 12 o’clock.

Air pressure test, guessing pressure tested the cooling system. It held pressure with the needle not creeping down?

Combustion leak test, done at the radiator fill neck?

You could also try a leak down test.

Grab the water pump pulley, pull in out up down side to side. Does it feel loose? If yes, remove the belt, give it a spin. It should spin somewhat freely, no notchy spots, not wobbly.

Forgive me for asking silly questions. There’s many skill levels, I don’t know yours. No disrespect intended.

 

If you didn't see any leaks with your pressure test it's probably air in the system, a clog somewhere, or possibly a faulty radiator fan or water pump. If you haven't flushed the system in more than 5 years I'd probably try that first. Prestone makes a flush solution.

$5 Prestone AS105 Total Cooling Syststem Cleaner for Radiator, Heater Core, and Hoses, 22 oz., 1 pack , (Packaging May vary)

https://www.amazon.com/Prestone-AS1...gid=pla-524366749162&ref=&adgrpid=96944448874

$19 PEAK OET Extended Life Red/Pink 50/50 Prediluted Antifreeze/Coolant for Asian Vehicles, 1 Gal.

https://www.amazon.com/PEAK-Extende...yota+coolant&qid=1637873484&sr=8-1-spons&th=1

Here's what I do:

1. Drain the system then add your flush solution and water. Put the radiator cap back on and run the vehicle for 10-15 minutes or until it's fully warmed up and leave the heater on full blast in the truck while flushing so the coolant circulates through the heater core. It may need to run longer if you have sludge in the system or need to be flushed more than once.

2. Let the system cool completely then drain it. Fill the system back up with plain water. Repeat the flushing procedure above then let it cool completely again before draining.

3. Now you can add fresh coolant. A 2 liter soda bottle can be cut and turned upside down for a funnel. With the radiator cap off and using your funnel pour your fresh coolant mixture into the radiator until it appears full. Then start the engine and run it with the heater on full blast while the engine reaches operating temp. As the coolant gets sucked into the system carefully add more in your funnel each time. You should notice that bubbles are burping up through the funnel. It should do this several times (maybe 3-5) before it's full.

4. Let the system cool completely and check the coolant level one last time before installing your radiator cap. Check the coolant level again in the morning and bring some extra when you go on a drive just in case it was slightly low.

If that doesn't stop the overheating you've got another issue of some kind possibly a faulty thermostat, water pump, or radiator fan or other.

Good Luck!

 

@Waasheem since I have to return the air pressure tester to auto zone I thought I’d double check and it actually did creep down VERY little. From 15 1/2 to 15. I did the combustion test at the radiator fill neck I was wondering though, since the pressure test did creep down does that prove to be lines or radiator or could it still be the gasket/head and just not be enough fumes to register on the combustion test? No disrespect taken! Please correct my foolishness I am here to learn. One other thing, I’m still getting air out of the lines and everything just seems to lead in a circle on one of three issues

 

That doesn't sound like enough of a drop for a leak. I'll bet it's air in the system.

 

Could the needle on the pressure test falling be caused because of air in the lines or is the air in the lines because of a hole, and the gauge falling be proof of this.

 

I suspect it's air in the system. Do you see any leaks visible in the hoses or elsewhere when pressure testing?

 

@MGMDesertTaco ill try flushing the system I’ve only owned the taco for about 3 years and have not so it’s a good place to go from here. I sincerely appreciate all the help.

 

Could it be the water pump without the water pump leaking or showing visible symptoms?

 

Pressure testing, I’ve seen many get tricked, including myself. If you dribble any coolant anywhere. Opened the radiator cap, 15 drops dribbled down the side of the radiator. Removed the funnel, 5 drops dripped on the engine. It’s best for the entire engine, hoses, radiator to be completely dry. If you managed to test dry like that and found no leaks anywhere, it is possible it’s leaking into the combustion chamber.

I’ve never done this, if you pull the spark plugs, look inside the plug hole, you might see coolant seeping in. Or one cylinder looks much cleaner than the rest.

I’d rule out trapped air first. Usually if you fill the radiator to the top, and add just a bit to the reservoir, a few warm up cool down cycles should get the remaining air out. When filling the radiator, fill to almost the top, leave it for a few minutes. The level should drop. Squeeze and release the lower hose a bunch of times. That helps release air trapped in the radiator passages. Top it off, drive to bring to temperature, turn on the heater to get coolant flowing through the heater core. After it cools off fully, check the radiator again, top off if needed. One or two more heat up cool down cycles, then top off the reservoir, you should be good.

 

If you want to do a quick and easy check for a Head Gasket issue. Take off the radiator cap. Start the truck. Look into the radiator and watch for bubbles. They might be pretty small so watch close. Watch for at least 5 minutes. If you see bubbles you have an issue.

 

When did you change the Thermostat?
Before or after the overheating issue?

When you refilled the coolant, did you start the truck with the cap off, let the truck run until the coolant dropped and then add a bit more?

It sounds like you had air in the system.

As for the slow leak down. I usually like to inspect the cooling lines when under pressure.
The 2.7 had a plastic coolant line that likes to leak after awhile. They updated it on later year truck.
I’d take a good look around that.

 

Water pumps do go bad without showing visible symptoms and this can prevent coolant from circulating through the system properly. Sometimes they leak a tiny bit or a lot from a weep hole or make whirring noises like a bad bearing. So, yes it could be the water pump even if it's not showing any leaks.

Since you mentioned leaks weren't visible with your pressure test I suggested flushing and bleeding the system first. That way you can rule out air pockets in the system or potential blockages.

I don't think it's the thermostat as you just replaced it. Plus if the system continues to suck in new coolant during your refill procedure you can rule out a faulty thermostat as it would have to open and close once it reaches temperature to suck down coolant.

Start with a flush, refill, and proper bleed first.

 

@MARSHBUSTER it would do this same thing if it was air trapped in the line right? Just trying to rule out the cheaper fixes first.

 

@TnShooter i changed the thermostat after the initial overheating issue, and I’ve taken measures to get out the air. I’m leaning towards head gasket since I’m not sure how reliable the combustion test was, but I’ll be flushing the system tomorrow with the help of my dad.

 

I think if air was escaping you would get bigger bubbles then you will get from the head gasket.