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Discussion Starter #1
I'm the type of guy who keeps meticulous records on the vehicles I own. One thing I've noticed in my records is that the coolant level has gone down some in the reservoir tank (located at upper RH corner of the radiator) since I've owned my 2005 Taco.

Here's the summary. All level checks done cold in level garage. Distance between ADD and FULL line on the reservoir tank = 60 mm.

1,100 miles (near new), level = 35 mm above ADD mark (slightly over ½ full between marks)
8,150 miles, level = 23 mm above ADD mark.
12,000 miles, level = 15 mm above ADD mark.

So the level has gone down about 10 mm (0.4 inch) over about 1.5 years and 11,000 miles.
Update - the level has actually gone down about 20 mm (0.8 inch), not 10 mm (math error). More details in Post #8 in this thread. The coolant tank is wedge shaped on one side, which throws a spin on the measurements.


I have looked for any signs of slight leakage and can't find anything visible. No signs anywhere of coolant being leaked inside or outside the engine. However, I do smell coolant vapors sometimes in the area of the coolant reservoir tank, but others have mentioned this too. See this related thread.

http://www.tundrasolutions.com/forums/tacoma/66542-anti-freeze-smell-2005-tacoma-normal/

I'm wondering if the vapors I smell is just normal slight evaporation of the coolant in the reservoir tank, and with mileage (like I've shown above) the level will drop slightly?

Has anyone else monitored the coolant reservoir tank carefully and noticed a slight drop in level like me? Just wondering if this is normal behavior or not. Maybe the location of the tank causes this since it’s always pretty hot being right on the radiator and vented to atmoshere (i.e., not under pressure).

I found this article, and they quote:
"Most vehicles will lose a little coolant over time due to evaporation from the reservoir. But a significant loss of coolant in a relatively short period of time usually signals a leak, a radiator cap that isn’t holding pressure or a cooling system that’s running too hot."

Radiator and Coolant (Antifreeze) Service Article

Thanks!
 

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^ I don't think a .4 of an inch over a 1.5 years isn't anything to worry about. If it was leaking.. I think you would be able to tell visually through the oil or on the ground. It's certainly normal to lose some through evaporation based on operating temps. However; if it leaks out, lets say a garage floor, it will stay around much longer(less evaporation) for you to noticed it. Have you monitored the temp gage and noticed any increase or decrease in temp? I would think if the cap wasn't holding pressure you would notice fluctuations on the gage. Once again, the loss of.4 of an inch over 1.5 years seems normal and appears to be within the normal range of evaporation. However, if your smelling coolant on the inside or outside of the coolant reservoir.. thats a sure sign of a leak either through the heater core or somewhere within the coolant system itself.
 

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I have had a couple of vehicles that when pulling into the garage I can smell the coolant due to it sloshing around in tank, then the cooling fan spreads the smell. No noticeable loss of actual coolant.
 

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Discussion Starter #4
Have you monitored the temp gage and noticed any increase or decrease in temp? I would think if the cap wasn't holding pressure you would notice fluctuations on the gage. Once again, the loss of.4 of an inch over 1.5 years seems normal and appears to be within the normal range of evaporation.
Yes, I watch the temp gage often and it never moves from just below the half way point which is normal based on what other owners here have reported with their 2005+ Tacomas. The truck is only 1.5 years old, but I guess the radiator cap could be going bad and not holding lots of pressure. The radiator hoses feel pretty hard when the engine is hot, so I know the cap is holding what seems to be normal pressure. I make it a habit to squeeze the hoses now and then when the engine is fully hot just to confirm they are under lots of pressure. 12 or 14 psi should make the hose feel pretty firm if squeezed hard by hand.

I'm thinking that losing a slight amount over 1.5 years and 12,000 miles is probably normal with this truck based on the design of the coolant reservoir tank (vented to atmosphere) and it's hot location.

However, if your smelling coolant on the inside or outside of the coolant reservoir.. that’s a sure sign of a leak either through the heater core or somewhere within the coolant system itself.
I have never smelled coolant inside the truck, but I have on occasion smelled a weak coolant scent near the reservoir tank - if you can smell vapors the it must be evaporating to some degree I would think. Others here have reported smelling coolant under the hood or near the front right wheel well on their Tacomas (i.e., link in my first post).

Again, the reservoir tank's cap is vented directly to the atmosphere, and the tank is mounted right up against the radiator which keeps the tank pretty warm while driving and probably near radiator temps in stop/go driving. Since the coolant in the tank is not under pressure like the coolant in the radiator, it is surely going to evaporate to some degree over repeated hot cycles. If the small loss I saw was due to a leak, it would have to be so small that it would probably never be able to be found.

It would be nice if someone else with a 2005+ Tacoma has noticed a slight drop in coolant tank level over a long period of time to confirm that this is probably normal. Anyone track their coolant level closely?

I think I'll call a couple of Toyota dealers tomorrow to see what they think. Maybe it's something they see all the time and can confirm. I'll let you all know what I find out with the dealers.
 

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I have exactly the same situation with my '05. There has been a slow but steady drop in the reserve tank since day one, and I have smelled coolant when I walked past the front of the truck on a hot day, but not on a consistent basis. When I look under the hood there aren't any signs of an actual leak, so I have no idea where it is coming from. My truck is coming up on 2 years old, and it is just getting to the point where I need to add a little coolant, since it is just a bit below the low line.

I do not consider this normal. I have never had to add any coolant to any of the other Toyota's that I have owned (8, including my Tacoma), and I have never smelled any coolant under the hood before either. I'm not sure what to do about though - unless the coolant was gushing out through the grill, the dealer would just tell me that there wasn't a problem, so I haven't bothered to even mention it to them.
 

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SuperBusa,

If your still worried about disappearing coolant, here is some similar info that we used at our service center where I worked. After inspecting and working on several hundreds of various vehicles in the past, I still think .4(10mm) loss over 1.5 years is not uncommon. However, you may find this info helpful, keep me posted...

Coolant Loss: How to Diagnose? Further information: See Head Gasket Failure. [Query:] My Buick is losing coolant; is it the head gasket? How do I tell? How do I pull the head? [Response: Don Foster] Pulling the head is not a casual or inexpensive job. You might even cause more problems than you now have. First, look long and hard for the leak.
[FONT=Arial,Helvetica]If it were my car and I was worried about disappearing antifreeze, I'd carefully crack the oil drain plug, let the first few tablespoons drip into a bowl, and examine it carefully for antifreeze. It'll sink to the bottom, so should be the first out. Do this with a stone-cold engine (not run for several days). If the antifreeze has mixed with the oil in a running engine, it'll form a "dispersion" and the oil will take on a grayish, cloudy characteristic.[/FONT]
[FONT=Arial,Helvetica]Next, I'd pull each sparkplug and look for evidence of coolant in the cylinders. An engine leaking coolant into a combustion chamber will have an unusual amount of white exhaust smoke, particluarly on a cold day (steam). More typical, however, is that the combustion gasses are forced into the cooling system -- and can be detected with a simple instrument.ELD..electronic leak detector. Every garage should have one. I do.[/FONT]
[FONT=Arial,Helvetica]Much more likely is a hidden leak elsewhere in the cooling system. First, look very carefully around the water pump. When the seal starts to leak, often antifreeze can "sneak" unseen down to the splash pan -- and if it's a slowish leak, you might not see a puddle 'til the leak gets worse. The antifreeze will escape only when you're driving.[/FONT]
[FONT=Arial,Helvetica]Another "invisible" (but problematic) leak might be the heater core. Or even the heater control valve. If you find something around the heater (and fix it) don't forget to get the coolant out from under the carpets -- they really should be pulled. Otherwise you'll be facing rusted floors in a year, or so.[/FONT]
[FONT=Arial,Helvetica]If you're really determined (and have some equipment available), get an old radiator cap and mount a barb fitting in it. Then hook a compressed air supply to the cooling system through a regulator -- you shouldn't use more than about 10 psi pressure -- 12 max. This way you can accelerate any leak for you inspection without running the engine. [Editor's note: see Headgasket Failure for procedures on a cooling system pressure test: highly recommended that you have the correct equipment for this.][/FONT]
 

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Discussion Starter #7
I have exactly the same situation with my '05. There has been a slow but steady drop in the reserve tank since day one, and I have smelled coolant when I walked past the front of the truck on a hot day, but not on a consistent basis. When I look under the hood there aren't any signs of an actual leak, so I have no idea where it is coming from. My truck is coming up on 2 years old, and it is just getting to the point where I need to add a little coolant, since it is just a bit below the low line.

I do not consider this normal. I have never had to add any coolant to any of the other Toyota's that I have owned (8, including my Tacoma), and I have never smelled any coolant under the hood before either. I'm not sure what to do about though - unless the coolant was gushing out through the grill, the dealer would just tell me that there wasn't a problem, so I haven't bothered to even mention it to them.
So about how much has the level dropped in the time you've had the truck, and over how many miles?
 

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Discussion Starter #8
SuperBusa,

If your still worried about disappearing coolant, here is some similar info that we used at our service center where I worked. After inspecting and working on several hundreds of various vehicles in the past, I still think .4 (10mm) loss over 1.5 years is not uncommon. However, you may find this info helpful, keep me posted...

Thanks for the info flyman. I noticed in my first post that I made a mistake on my calculation. I said the level went down 10 mm when checked cold ... but it's actually 20 mm. (35 -15 ... can't subtract, LOL).

Anyway, I was looking today at the shape of the tank and noticed it's wedge shaped on one side which will give different deltas depending if the level is checked hot or cold. I checked it hot today and discovered this after thinking about it ... see below.

Cold checks: Level went from 35 mm at to 15 mm above ADD mark in 12,000 miles/1.5 yrs. (20 mm difference)

Hot checks: Level went from 50 mm to 40 mm above the ADD mark in 12,000miles/1.5 yrs. (10 mm difference)

So what this means is the same volume removed will make the delta different depending if its checked cold or hot due to the wedge on the left side of the tank. I don't know how much volume this equates to, but I'd think a 10 mm delta at the hot level would probably be around 3 to 5 oz. If I add some coolant I will be able to get a good measurement.

Didn't have a chance to call the dealers yet, but will. At this point I'm not convinced it's a real problem, and if it was I'd suspect the radiator cap first since I can't see any other signs of leakage. Maybe the radiator cap doesn't hold pressure perfectly all the time and causes some coolant to evaporate over time ... hence the faint coolant smell now and then on hot summer days near the reservoir tank.

Also, I'm wondering if driving it hard sometimes might cause coolant to cavitate/evaporate and escape as gas out the radiator cap to the tank and be lost as vapors (again you'd smell that). Not sure if that's possible, but maybe. I drive my truck pretty hard now and then.
 

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So about how much has the level dropped in the time you've had the truck, and over how many miles?
The level dropped from around the top mark to just below the low mark in 22,000 miles - about 22 months. I also drive my truck pretty hard at times, but I had a Supra and 2 MR2's that I also drove pretty hard and non of them lost any coolant over time. As I said, I don't think it is normal, but it is way to subtle for my dealer to ever find or fix.
 

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When parked in the garage on a warm day I too can smell, on occasion, the odor of coolant. I ran my '06 DBL Cab PreRunner in to my shop and placed on the lift to investigate.
I found this.. On the right side of the block is a handy drain petcock. It is damp around the o-ring that seats the valve against the block. It is so minor I haven't bothered to take it to Toyota yet. I will but haven't had time.
Yes, I have seen some "loss" in the reservoir too. But I'll attribute that to the new coolant formula that most manufacturers are using now. Gone is the "Prestone" and the new long life coolant has more of a tendency to evaporate.
It's a good thing. I'll take the time to top off versus a coolant that has phosphates in it that will pit the engine liners and head over time.
 

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Discussion Starter #11
When parked in the garage on a warm day I too can smell, on occasion, the odor of coolant. I ran my '06 DBL Cab PreRunner in to my shop and placed on the lift to investigate.
I found this.. On the right side of the block is a handy drain petcock. It is damp around the o-ring that seats the valve against the block. It is so minor I haven't bothered to take it to Toyota yet. I will but haven't had time.
Thanks for the input. I'll have to crawl under my truck and inspect the block drain too.

I was looking around tonight and did notice some pinkish powder residue around the base of the hose that runs between the catch tank and the radiator pressure cap neck. It looks like it has seeped a small amount of coolant in the past. I'm wondering if maybe that's where I've lost some, and if it was also the source of the coolant smell at times. Like some others here, I have smelled coolant near the front, right of the truck, but it doesn't do it all the time. Maybe this hose was seeping on/off at times over the last 1.5 years. I'm going to watch it for signs of new leakage if I ever smell vapors again. Maybe the dried crud has sealed it up again. This hose in not under pressure, so it seems it would be hard for it to leak unless there's some kind of flaw on the tank nipple where the hose attaches. Might pull it off and inspect if it shows more signs of leakage.

Anyone else who's seen the coolant level drop in the catch tank should check this hose for signs of leakage (pink powder residue).

Yes, I have seen some "loss" in the reservoir too. But I'll attribute that to the new coolant formula that most manufacturers are using now. Gone is the "Prestone" and the new long life coolant has more of a tendency to evaporate.
It's a good thing. I'll take the time to top off versus a coolant that has phosphates in it that will pit the engine liners and head over time.
I didn't realize that the long life coolant is more prone to evaporation.
 

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I was looking around tonight and did notice some pinkish powder residue around the base of the hose that runs between the catch tank and the radiator pressure cap neck. It looks like it has seeped a small amount of coolant in the past. I'm wondering if maybe that's where I've lost some, and if it was also the source of the coolant smell at times. Like some others here, I have smelled coolant near the front, right of the truck, but it doesn't do it all the time. Maybe this hose was seeping on/off at times over the last 1.5 years. I'm going to watch it for signs of new leakage if I ever smell vapors again. Maybe the dried crud has sealed it up again. This hose in not under pressure, so it seems it would be hard for it to leak unless there's some kind of flaw on the tank nipple where the hose attaches. Might pull it off and inspect if it shows more signs of leakage.

Anyone else who's seen the coolant level drop in the catch tank should check this hose for signs of leakage (pink powder residue).
SuperBusa,

I have noticed the exact same issue on my truck. The hose leading from the radiator to the catch tank is leaking a small amount of coolant. It also had some dried coolant crust on it. I recently topped the coolant off, and noticed it was dropping slowly again. I think it must be the hose leading into the catch tank causing this issue.

Did you ever get it resolved or let the dealer look at it? I would like to have this fixed if possible. It should not be leaking.
 
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