Losing Coolant

It appears I may be losing coolant and I need help help troubleshooting.

Back in March I marked the reservoir with a green line after replacing the radiator and flushing the coolant.

The longer red line is where the coolant sat(cold) last Saturday. It's now dropped a little more.

• No signs of visible leaks though I'm not entirely positive where to check.
• Checked tranmission fluid to see if I'm losing coolant via "pink milkshake". Looks fine to me but both the coolant and ATF are red/pink so I don't know how obvious this would be.

• Worst case scenario. Potential head gasket failure. Looked under oil cap, no milky residue. I do have some condensation at start up from my exhaust but it doesn't look like white smoke. I've seen brand new vehicles at stop lights have the same thing I'm seeing.
• Water pump was replaced with timing belt just 22k miles ago.
• Vehicle has never ran hot or overheated. No bubbling coolant into reservoir.

I just bought a gallon of Zerex. My plan was to fill to the full line on the reservoir and keep an eye on it. What else should I check?

I know Blackstone Labs tests for coolant in the oil. I thought about sending them a sample but I'm not sure how valuable that would be.

Is it normal for levels on the reservoir to fluctuate over 6 months like this?

 

Doesn’t seem to be using too much which is good. There is a test some shops can do with a sniffer to sniff out any exhaust gases coming out of the coolant reservoir which would point to head gasket failure.

My old Tahoe used about that same amount but no signs of where it was going. I just kept her topped off and didn’t worry about it.

 

Is that a pressure test or different?

Yes, whatever is happening appears to be very slow which is good.

 

I would top it off and see what it does. With no visible signs of any other problems I think it's an air pocket burbing out from your last repair work. I've had the same thing happen in other vehicles and after topping off the fluid level stayed fine and I just attribute it to not intially getting all the air out.

That's basically the closed system doing it's job.

 

It’s literally just a sniffer test. I’ll see if I can find it online.

Block Tester BT-500 Combustion Leak Test Kit - Made in USA

$38 Block Tester BT-500 Head Gasket Combustion Leak Test Kit - Made in USA

https://www.amazon.com/dp/B06VVBSFTF/ref=cm_sw_r_cp_api_i_h20VDb7XCATJJ

 

I had that problem you can borrow a pressure tester from Autozone. My radiator had a crack and would only leak under pressure found it quick under pressure.

 

My radiator is only 7 months old but I suppose anything is possible. I'll look into this.

 

a pressure test will tell you if you have a leak. kinda doubt its headgasket.. not very common on these.

 

It’s uncommon unless he over heat the engine, Japanese engine can’t take that much heat. Cast iron block and aluminum head expands and contract at different rates.

 

any modern engine overheated these days your pretty screwed. but according to him its never been overheated

 

Then I think just a air pocket, unless he know how to bleed the cooling system, that’s a big chance there is a air pocket in the system

 

To be clear, it hasn't overheated since I've owned it. I don't know what happened in the first 14 years. I let it cool down last night and topped off the reservoir. I'll keep an eye on it and see what happens.

 

Likely an air pocket., they pop up from time to time. Especially when people start using their heater cores in the cold weather

 

Check the rear water bypass joint gaskets as well for coolant leaks, there is one on each side of the head at the back of the motor. My sequoia has a leak from the passenger gasket that I need to fix and it took me a while to figure out where it was coming from. If you go under the truck look at the area above the front O2 sensors and that is where you will see the leak. I found the pink crust all over my passenger 02 sensor. You have to pull the intake mainfold for access. Here is a youtube video of their location.

https://www.youtube.com/watch?v=KfLpcsX5ajg

 

I'm experiencing the same thing. Fill up to the line, after a drive, it's low again. Not overheating, no white smoke. Don't see any leaks under the vehicle. Hoping it's not the head gaskets...

 

I’d recommend measuring the coolant level after the engine has been brought up to full operating temp and use that measurement.

Reason being is that the colder winter atmosphere can effect that cold reading line and make it seem lower (due to the cold weather). Summer vs. Winter lines can read differently even with the exact same fluid contents read at cold.

Heating up that engine will give a truer reading.

 

I concur good sir.

 

Parked in a garage you think the cold temp will still fluctuate? I deleted cold vs hot measurement.

 

Can’t hurt if you didn’t try it. Fill it to F after the engine is up to temp. Thats your new reference line. This will eliminate the air bubble theory and temp theory.

Rad leaks can be difficult due to the fan blowing the slight leak drops away.

 

@FirstGenVol Did you every figure out what was your cause of coolant lose? I am having the same symptoms and wanted to see if you where able to identify the final root cause of this problem.. TIA.

 

Negative. I've only lost a little more since it happened last time so I haven't worried about it. I haven't even lost enough to top it off again.

 

03 Toyota tundra

Reservoir always near or empty. Went on for years. Never over heated. Replaced the radiator when there was a leak and it still measures low after filing to the F on a cold engine. I will try measures on a hot engine and see if there's a difference

 

This happened to me about a year and a half ago. Durning an oil change the mechanic noticed a pink crusty material all around the bottom of my engine when he pulled the stock skid plate to do an oil change. I kept my eye on it and sure enough it was loosing coolant, I had them replace my water pump and problem solved. Now every week I will check the oil level and coolant. My coolant will fluculate about 2.5 inchs from day to day driving.

 

Do this. Take a flashlight and look in the valley by the start. If you have any coolant in there it’s likely the o-ring on the coolant pipes. There is a weep hole under the starter which drains the valley to the rear. Next check the joints at 2 gaskets each on the rear and front coolant crossover pipes. These will weep coolant very slowly and are easy to replace but you have to remove manifold for rear ones. They will drip onto bellhousing. Look for pink crusty at the joint. Next look under the water pump pulley - there is a weephole and any coolant crust means it’s time to replace water pump. Only use AISIN or OEM. When was last time timing belt was done? Usually recommend doing both every 90K. Finally get under truck remove skid plate and look at radiator particularly lower tank crimp line for leaks. Also look where trans cooler bungs are threaded in for cracks or leaks.

 

Go to this thread and search for the phrase coolant leaks: https://www.tundras.com/threads/so-you-wanna-buy-just-bought-a-1st-gen-tundra-eh.115928/

There is a laundry list of things to check, with links to threads that have ample pics. Weeping at the front of the block is normal, there are provisions to allow it, but chances are it's the t-stat housing gaskets or water pump. Given you need to change the timing belt every 90-100k and 9/10 years per Toyota, and you should change water pump, tensioner and pulleys at the same time, maybe you're due anyway to have all this done. Don't discount your radiator though; some members have found theirs had a pinhole leak but it only actively leaked water while under the pressure of 2000+ RPM. Any discoloration of the caps should be taken as a sign of plastic fatigue, and warrant proactive replacement so you don't kill your transmission (pink milkshake).