Excessive coolant consumption?

2003 3.4 V6. Over 200,000 miles.

I have had to add coolant twice in the last 6 months, roughly about a quart each time. I do live in a warm part of the country (100 degrees in the summer), but I am curious if this is normal. I cannot find any leaks, so I am a little concerned, especially since I have heard of multiple head gasket issues with the 3.4. I realize some of it will boil off. I have not pressure tested my cooling system, but I wonder if I need to.

This is one of the "newer" vehicles I have owned. I have had to add to all my previous vehicles because they all leaked, whether it be from radiators or loose hose clamps. I am just not sure if this is normal for a newer engine.

 

Could be the water pump seeping a bit. It would be hard to see without removing the timing cover. (That's what I call it).

 

I checked my timing belt cover. No leaks there. I replaced my water pump with my timing belt about 20,000 miles ago, so that should not be an issue, at least for a while.

 

Assuming you have a non-leaking fluid overflow at the radiator cap, I would say any loss of coolant is a sign of trouble. It is definitely not normal for the 3.4L to use up coolant.

FWIW, my water pump/timing combo belt is coming up on 80,000 miles with the same coolant. I have never had to add any.

Based on the info you have given, I would say you have a small leak between one cylinder and a coolant port in the block. Most likely at the head gasket. The coolant is going into the combustion chamber and out the exhaust in gaseous form. Eventually you will be able to smell it in the exhaust as the rate of leak increases. Kind of a sweet smell.

 

You may need a new radiator cap. I had a 98 Corolla that had mysterious coolant loss and it turned out to be evaporating through the radiator cap.

 

Certainly not what I wanted to hear, but I suspect you may be right. My overflow reservoir has never gained level, so my radiator cap is not relieving pressure. I guess I will pull my plugs and see if any of them are steam cleaned.

 

What is really a b1tch about this is my 2014 Tacoma has more issues than my 2003... My '03 has been my ace-in-the-hole.

 

Check your hoses for pin holes. They can leak a small amount that evaporates on something hot without dripping on the ground.

 

Another thing to check, is around your tranny. And back of motor. I have an internal leak under the manifold. Think it's the bypass tube. If there's a leak in there (could also be a freeze plug) it will pool up and seep out the back plate in back of engine. You will see signs of it leaking down the side and dripping off the tranny. that's what mine is doing anyways. To check even further, use an inspection mirror and go in from the passenger side of truck from the top or bottom and you should be able to find that plate. It's a hexagonal shape type plate that the heater bypass tube goes into. I go through coolant at about the same rate. Still trying to figure out what is entailed to fix it. And plan on tearing it down and doing a while top end rebuild anyways while I'm at it. But yeah, something to check into. I have some links bookmarked of a writeup regarding the process with pics if you do in fact discover you have this leak like mine. Take a look and let us know.

 

Is the Radiator original? Mine started leaking at about 185,000 and I couldn't tell because it was so small. the leak was on the drivers side lower corner of the radiator. It was like a hairline crack.

 

That is the next thing I will check. It has been muddy and wet in my area, so I am struggling to identify leaks at the moment. My radiator is original, and I have not really been diligent about changing out my coolant throughout the truck's life.

toendanger mentioned a bypass tube. I checked around my transmission where he thought it may leak, but did not really see any leakage there.

This is really bothering me because the last thing I want to do is start tearing into the top end to replace a gasket... So I hope it is just a leak that I am not seeing.

I appreciate everyone's input!

 

I've never heard of a head gasket blowing or even leaking on a 3.4l. I'd check the bottom of the radiator really good. Have you checked the oil for coolant?