HELP!!! Coolant issue

I have a 05 Tacoma Prerunner v6 4.0 rwd and I’m having a coolant issue. There’s about 150k on the truck. About a month ago I looked under the hood to see that my coolant reservoir liquid was super low, almost none. So, I added some to the fill (full line). I thought nothing of it. Well, then I Pulled a trailer about 180 miles and something told me to check my reservoir again. Come to find out, it’s about to overflow. It was at the top. So, I let it cool down and I check it several hours later. It went back down to where I first filled it up, so I thought nothing of it and thought it was from pulling the trailer. It’s been going on for a couple weeks now of when it runs the coolant level in the reservoir rises until it cools down. So, I took it to my local shop and they did numerous tests for pressure, replaced the cap, block test. And, they came back with nothing. They’re unsure of any other issues to rule it’s a head gasket issue. I’m about out of options and next step is to take to dealership. I’ve checked the oil to see if it was milky, and it’s perfectly fine oil. When the engine is turned off, there’s slight bubbling, maybe 1-2 every 10-15 seconds. The picture is after I arrived at my location after pulling the trailer. Please if there’s anyone out there that encountered the same issue help me resolve this. Anything helps! Have a great day.

 

Are your cooling fans operating properly?

 

Welcome to TW!

 

If truck is cold, fill to add/ low line.
If truck is at operating temp after warm up light driving, low-mid.
If truck is hot off the highway, full line.

As truck gets hot, coolant cap lets coolant release to reservoir, as it cools it goes back into cooling system.

 

Yup, what he said ∆
Welcome to TacomaWorld

 

Yes everything is working as it should. Thank you for the warm welcomes. I have spent the past hour watching and reading more information and I believe I found the issue. This YouTube video and the descriptions of the customers complaints is almost mine to the T so I believe this is it.

https://youtu.be/mlOc7Xd25n4

 

Don't go off the deep end yet..

I'm a previous Toyota tech of 7 years.

When truck is cold, pull hose off bottom of reservoir to drain coolant down to add/ low line. leave it here when truck is cold.

With truck off, open rad cap and lower coolant level down so that it will not overflow but you can still see coolant.
Start engine and let run. If you see consistent bubbling... possible head gasket.
Snap-on(blue-point) and others actually have head gasket leak detector tools than use a color changing fluid that turns when exhaust gas is detected in coolant.

edit: adding pressure to cooling system will not always show a head gasket leak. sometimes after engine cooling down from hot it will draw in coolant to cylinder. Checking if this is happening is removing spark plugs when engine cold and seeing if coolant in cylinders. also can smell sweet/ coolant from exhaust.

 

Awesome. Thank you sir, I’ll keep updated.

 

For everyone that’s following this, I did a pressure test. I put it on the radiator cap and pumped to 15ft. I also removed one of the spark plugs, where I got a check engine light code from (I previously replaced all spark plugs because f this). In the process of this, I checked to see if the plug smelt like coolant, it did not smelt like gas. That’s a good thing. So after I pumped it to 15, I waited for about 1.5hrs and then I did exactly what the video did. I tried to start the truck with a piece of paper covering the open cylinder so I could smell it. Good news again, the paper smelt like gas. Now, I’m baffled… I have no idea what it could be now. It’s never ran hot. The coolant was trained back to normal, and the exhaust only has a gas smell. Next thing may be wondering is if the water pump is bad. Any comments? Thanks.

 

Welcome to the forum

1) Water expands about 4% when heated, this increases its volume: a cold gallon becomes more than a gallon (+4%) when heated, when cooled down you again have a gallon.

As the engine comes up to operating temperature the coolant expands and the level in the reservoir rises, this is normal.

The reservoir should be marked:

FULL HOT______
and below that
FULL COLD_____

From what you have described it sounds like you initially filled it to the FULL HOT line when cold.

Do you have any operating issues other than the level in the reservoir?

At normal operating temperature (after 20 minutes of driving) the hand on the temperature gauge should always point to the same place and it should not drift around. Is the hand pointing to the expected place on the gauge and not drifting?

PS: Never take a 15 year old truck to the dealer.

 

Thank you for the comments sir! Here is how the coolant reservoir looks as of after it was drained and filled properly. The needle for my temperature gauge has not moved ever even when the coolant was super high, never has been of worry because of the gauge. Hopefully the issue is fixed now that the coolant is back where it should be. Should I be concerned that when it was filled up really full about the slight bubbles I was seeing. 1-2 bubbles every 10 seconds?

 

If the truck is running fine, the temperature hand is acting as expected and it is not losing coolant I would just keep an eye on it.

The key to spotting trouble is regular observation, choose a day each week that you give the vehicle a good full attention look over.
This should only take around 5 minutes:

check all the under hood fluids
check condition of belts and hoses
do a walk around and check all the lights
check the tire condition and pressure
check the wiper blade condition -- I like to clean the windshield too

You can make a checklist if it helps you, after doing this awhile you will develop a routine to do this both efficiently and thorough.

The point is if you can't remember the last time you checked something how do you establish "normal"?

After you do your routine awhile you will know exactly what you expect to find when you pull the dipstick for example. Then on the day you pull the stick and find it half a quart low or a different color than normal (last week) the new condition stands out like a red flag and you can investigate further.

The weekly 5 minute inspection doesn't require much time, tools, money or even mechanical aptitude -- just a bit of effort and a rag. It will help you spot problems when they are small reducing repair costs and possibly saving major breakdowns.

 

Okay. Perfect. Thank you.

 

Leave everything where it is. If temp goes above half way you have an issue, if not your fine.
bubbles in reservoir mean nothing. Slight bubbles in radiator when filling is normal.

 

Thanks to everyone that has commented and gave their sense to my concerns. I believe I should be okay now that the level is back to where it should be. I was out all day today mowing yards and when I got home I checked the fluid and it was perfectly in the middle in the reservoir. As for now, I’m leaving it and just going to keep an eye on a couple numerous things. If anyone has any other comments, that would be awesome. Thanks so much again guys.

 

Hi. I have the same issue. How has it been since last Oct?