Toyota FJ Cruiser Forum banner
1 - 11 of 11 Posts

·
Registered
Joined
·
5 Posts
Discussion Starter · #1 ·
Desperate after spending over a thousand dollars with no solution to the following problem:
My FJ Cruiser is leaking cooling fluid at a rate of 0.25 liter per 100 miles. It seems that the fluid is leaking through the AC drain hose. The hose is dripping even though I never-ever use the AC unit. My assumption was that the heater core was leaking and the air blows the water up into the AC evaporator where it then drains out through the AC drain hose.

I had the cooling system pressure tested but no leaks showed up. I concluded that the Heater Core was leaking and I had it replaced (very expensive replacement).
The dealer filled the cooling system again with cooling fluid and over the first 100 miles, I detected no loss of fluid. It came back after that initial 100 miles and now leaks at the same rate. I am now running a test with the (new) heater core detached from the cooling circuit and the supply and return hoses plugged. If no loss is detected, the dealer must have xxxxx (fill in the blanks...). If fluid loss detected, I will try to get radioactive fluid to trace where it leaks...

Has anyone had a similar problem?

It's a 2005 FJ cruiser with 192,000 miles and has been a reliable vehicle for the past 14 years that I owned it.
 

·
Premium Member
Joined
·
3,815 Posts
A leaking heater core is pretty rare. If it is still leaking after replacing it, then it sounds like maybe the pipe to it has a leak, near the core and the dealer didn't properly diagnose the original issue?

Are you sure your FJ is an '05? They didn't start making them until '06.
 

·
Registered
Joined
·
6,341 Posts
Some of this just isn't making much sense ...

"I had the cooling system pressure tested but no leaks showed up. I concluded that the Heater Core was leaking and I had it replaced (very expensive replacement)."

I'm confused ... if a cooling system leak test showed no leakage, how did you conclude that the heater core must be leaking?

Did you not trust the test results?

Questions:
1. How and where are you checking coolant level? You should be checking at the coolant reservoir, with the engine at operating temperature.

2. Have you checked the coolant reservoir itself for any cracks that may allow a slow seepage of coolant? The reservoir is unpressurized, and a cooling system leak test would not detect a leak in the reservoir.

3. There is no such thing as engine coolant with a "radioactive" tracer for leak detection. Most standard coolants contain a fluorescent dye that glows brightly under UV light, which helps trace even small leaks.
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #4 ·
A leaking heater core is pretty rare. If it is still leaking after replacing it, then it sounds like maybe the pipe to it has a leak, near the core and the dealer didn't properly diagnose the original issue?

Are you sure your FJ is an '05? They didn't start making them until '06.
sorry, typo it's a 2007.
the problem was that the pressure test showed no visible leaks. The only part that is not visible is the heater core.
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #5 ·
Some of this just isn't making much sense ...

"I had the cooling system pressure tested but no leaks showed up. I concluded that the Heater Core was leaking and I had it replaced (very expensive replacement)."

I;m confused ... if a cooling system leak test showed no leakage, how did you conclude that the heater core must be leaking?

Did you not trust the test results?

Questions:
1. How and where are you checking coolant level? You should be checking at the coolant reservoir, wh=ith the engine at operating temperature.

2. Have you checked the coolant reservoir itself for any cracks that may allow a slow seepage of coolant? The reservoir is unpressurized, and a cooling system leak test would not detect a leak in the reservoir.

3. There is no such thing as engine coolant with a "radioactive" tracer for leak detection. Most standard coolants contain a fluorescent dye that glows brightly under UV light, which helps trace even small leaks.
it is confusing... the pressure test showed no visible results. Still, 0.25 liter per 100 miles is not a small leak. The heater core is the only part that is not visible.
1. The unpressurized reservoir shows loss of fluid at operating temperature: after filling it up it's again empty after driving 100 miles.
2. If I don't use the car there is no fluid loss. The reservoir should therefore be ok but, I will check again, maybe it only leaks with hot fluid in the reservoir.
3. I was joking about radioactive... but maybe the fluorescent dye works. The dealers (multiple) never suggested this.

I am serious about being desperate, the FJ has been in the garage 4 times with huge bills and no solution.
I very much appreciate your suggestions. I'm still driving with the heater core disconnected. I should know within 2 days if that part can be ruled out.
 

·
Registered
Joined
·
6,341 Posts
A couple of other thought here ...

1. Have you ABSOLUTELY CONFIRMED that the fluid leaking from your AC evaporator drain hose is actually engine coolant (glycol solution) and not pure distilled water?

You stated that you never use your AC, but if you have your HVAC control knob in the DEFROST position, the AC compressor is actually running (the AC light will NOT be illuminated), the AC evaporator will be very cold, and you WILL have constant condensation of distilled water dripping out the evaporator drain.

2. How frequently have you been changing out the engine coolant to refresh the corrosion inhibitors that prevent corrosion of the head gaskets?

3. On a cold start, do you ever see any white smoke out the exhaust for the first few seconds after engine start-up, or smell the 'sweet' odor of burning glycol?

The bottom line is that, if you are constantly losing coolant, it has to be going somewhere.

It is either an external leak, in the cooling system components OUTSIDE the engine block, or it is a head gasket leak, allowing coolant to seep into one or more of the engine cylinders, get burned during the combustion process, and finally exit the engine as vapor via the exhaust pipe.

Pull the front spark plug from Bank 1 (passenger side) and the rear spark plug from Bank 2 (driver's side, cylinder #6) and compare the deposits on the electrodes and insulator. Coolant contamination in a specific cylinder will leave a unique deposit on the plug that is distinctly different from the appearance from cylinders that have no coolant present.

Early 1GR-FE engines had a head gasket design that sometimes tended to develop a leak at cylinder #6, especially if the engine had ever overheated, or if the coolant wasn't changed at the appropriate intervals. First symptom of a failed head gasket is frequently a small but continuous loss of coolant.

Your engine's age and mileage put it in the range where head gasket failures are sometimes seen.
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #7 ·
1. I never knew that defrost turned on AC. I've always used the defrost setting because it prevents the air blasting into my face. Wow... 150,000 miles with AC running all the time. What a waste. I now have to assume that the AC drain was only draining condensation.
2. I always had it serviced by professionals. Maybe they never flushed the coolant? I really don't know.
3. No steam during startup.

There is actual coolant on the garage floor. Everything is wet and I can't pinpoint the source. I thought the AC drain was the source. As discussed before, the pressure test showed nothing. Anyway, the gasket is probably not the culprit.

in the mean time, with the heater core detached, the coolant reservoir remains at the same level over the past 150 miles. No coolant on the garage floor. Seems like the engine is all fine, right? The heater core is new. Need a ghost buster...

Today, I noticed that the hose of the heater core is actually above the filler cap of the radiator.
How is this as a theory: a little air gets trapped in this hose and as the engine heats up the air expands (much more than the coolant). Lots of coolant is pushed out and drains from the reservoir. The engine cools down and the contracting air bubble sucks in extra outside air. Next time, there is more air, expanding more and sucking in even more air. And so on.

Tomorrow, I'll reconnect the heater core, fill in coolant while the FJ is parked on a hill with the filler cap at the highest point. Run the engine with filler cap removed until it starts boiling. this should remove all, or most air.
I must say that it is really a design flaw that the filler cap is NOT the highest point.
I guess me developing wild theories just shows how desperate I am.
More as the mystery continues....
 

·
Registered
Joined
·
6,341 Posts
(big snip)
Today, I noticed that the hose of the heater core is actually above the filler cap of the radiator.
How is this as a theory: a little air gets trapped in this hose and as the engine heats up the air expands (much more than the coolant). Lots of coolant is pushed out and drains from the reservoir. The engine cools down and the contracting air bubble sucks in extra outside air. Next time, there is more air, expanding more and sucking in even more air. And so on.

Tomorrow, I'll reconnect the heater core, fill in coolant while the FJ is parked on a hill with the filler cap at the highest point. Run the engine with filler cap removed until it starts boiling. this should remove all, or most air.
I must say that it is really a design flaw that the filler cap is NOT the highest point.
I guess me developing wild theories just shows how desperate I am.
More as the mystery continues....
Sorry, your 'wild theory' about a Toyota design defect in the cooling system resulting in an ever-expanding pocket of air in the cooling system is incorrect.

The purpose of the coolant reservoir is to allow the coolant in the cooling system to expand as the engine heats up, and to capture the coolant that is displaced and gets forced past the 'pressure relief valve' built into the radiator cap.

After the engine is shut off and cools down, the coolant contracts and generates a negative pressure in the cooling system. The vacuum relief valve in the radiator cap opens, and allows coolant to be drawn from the reservoir back into the cooling system. This should keep the cooling system free from any air pockets.

The cooling system is designed to operate 100% filled with coolant, and with zero air entrapped. The normal expansion and contraction of fluid will generally purge the system of any small volume of air that is in the system. In some vehicles when the entire cooling system is completely drained there is difficulty in purging all the air out, but not the 1GR-FE engine in the FJ.

So, two things to check:
1. Make sure the rubber hose from the neck of the radiator to the reservoir cap is not split or cracked, and fits tightly on the hose fittings. Any defect here will allow coolant to leak out, and air to be drawn in.
2. Make sure the rubber dip tube inside the reservoir is not split, and is tightly connected to the fitting on the inside of the reservoir cap. Any defect here will allow air to be drawn into the cooling system.
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #9 ·
Mystery solved....
So, this is the history of the fools that lined up and end up costing me over $ 2,500:

Fool # 2: Four years ago, a respectable professional (fool #2) replaced my leaking radiator and I (fool # 1) went with his advice to also replace all hoses of the cooling system. This professional replaced the water hoses to and from the heater core with cheap, longer look-a-likes that were NOT approved for Toyota. In the process he swapped intake and outlet and mounted the hoses way to high. This made it more difficult to flush air out of the system. To make the top hose fit, he cut the hose and this cut is where he damaged the hose that over the past 3 years eventually failed. $$$

Fool # 3: One year ago the system needed replenishment of coolant every 100 miles. I had another respectable fool (#3) look at it and he replaced. He couldn't find it; "everything is wet and we cannot find the source". He pressurized the system and found nothing. Then he suggested to replace the hoses that feed the transmission " it seems that's the candidate". $$
Found that the system was still leaking and I went back. Wow...free service to top the coolant and no, not finding the leak. Then, I (the original fool) found that if I used the heating, there was coolant loss and if I didn't use the heating, there was no loss. Back to fool # 3 and asked them to test the system with the heating on. Pressure test: No leak found. $

Fool #4: Since multiple tests showed only leaks when the heater core was used, I thought the heater core needed replacement. I went with another respectable dealer (fool # 4) and payed $$$. I drove 200 miles; no leak (hurray!!). Then the leaks came back. I decided to disconnect the heater core to once and for all rule it out. First 150 miles: no leak (hurray!!). I reconnected the heater core hoses and LEAK! So, must be heater core, right? Fool # 1 was wrong. I finally broke down and went under the car, something I have done in the past way too many times. I owned, disassembled, replaced parts, assembled, and repeated that every week with two Lotus sportscars. I had decided that there were professionals that do this for a living with Toyotas.
Under the car, I stared at the trail of pink fluid. It simply led me to the leaking heater core hose. A total of 18 hours were spend by professionals. It took me a whole minute to find the problem.

Lessons?
1) Talk to the FJ forum (thank you for your help)
2) Use original Toyota parts
3) The biggest fool is me. The most professional fixer is me. Shame and Fame.
 

·
Registered
Joined
·
5,990 Posts
That is a bummer. I do think some people worship dealerships and the mechanics there like a false god. Patches on a shirt don't make a mechanic any more than a hat don't make a cowboy.
 

·
Registered
Joined
·
6,341 Posts
All that shows why it is highly recommended to stick with OEM Toyota parts, especially hoses that have molded-in bends, etc. that are required for proper fit and function. Additionally, many Toyota hoses are made from high-quality, long-life EPDM rubber that is extremely resistant to deterioration from high temperature, ozone, oil, hot glycol, etc.
 
1 - 11 of 11 Posts
Top