i cant keep coolant in this truck. Its not overheating, and it doesnt happen over night, but i keep losing all the coolant in my overflow and very slowly in the rad. Now before everyone screams head gasket at me, its not the head gasket . it was replaced less than 20K miles ago, holds pressure perfectly, no burning, no coolant in oil. now that thats out of the way. Whats left to check? could a bad cap cause it? i dont notice any seeping out of the neck or anything. thoughts?

 

Probably the water pump. They can seep slowly and it can burn off before it hits the ground. That's about the only other place it could be if you're not seeing any coolant trails or wet carpet from a heater core. Any idling issues? Do you smell coolant when you're in the cab?

 

How fast are you losing it?

 

Waterpump is less than 6 months old, no problems there. Idle is fine. Only place I notice any weaping is by the bottom of the intake manafold. But I don't know if it's coolant or not. No coolant smell in the cab or wet carpet.
It takes at least a month to go from full overflow to an inch under the cap but it doesn't seem to go under that point.

 

you can pressurized the system and you can determine how fast the pressure drops.....there is a special light you could use to find where it leaks, cause this light makes the coolant eluminate when that light hits it....or improper torque value or sequence on the water pump, which causes it not seat evenly, inturn leaks

 

Where towards the bottom of the intake? There are two hoses under the manifold that flow coolant through the Throttle body.....but i bet you they didnt seal the pipe correctly that runs under the intake manifold and between the two two heads.....do you know the one i am talking about?

1. Check lines to the Throttle body--see if they are leaking

2. inspect the water pump like a Mo-fo seriously--look for pink crust (?? hmmm and the hoses.....check radiator for pin leaks and etc.....take off the fan shroud and check that also like a Mo-FO

3. Yank the lowe intake manifold and check that pipe for leaks....i cant think of any other way to check it without pulling the lower intake manifold??

 

Coolant runs through part of the intake and could be crossing over into your runners or on the ground.... thus coolant buring. Check all coolant lines bellow your throttle body check closely. Even a spray of a leak can leak a gallon out in a week. Compression check? Check all hoses. Just cause you peep your head in there and don't see water gushing everywhere does not mean it ain't leaking. Turn the truck on get a flash light and look around. Get on your back and look. LOOK LOOK LOOK LOOK! Does it only leak at certain times.

 

Yep...check the rubber hoses that go into the radiator, they could be slightly cracked or not sealed properly

 

I think Kiroshu is on the right track. Had an S10 with the same problem once. No leaks around the motor and no sign of it being burned through exhaust (smell or smoke). Had a small leak in the lower intake gasket. It was being burned up over time.

 

It could also be a bad radiator cap.

 

I had a BMW once that had a pinhole in the return line to the overflow jug. It was the one line I didn't check carefully. It only leaked at max temp and away from the garage. That would also explain why it stops leaking when the rad has some room room to absorb expansion. Any other line will just keep leaking until the pump gets air.

 

he says it doesn't look like stains around the cap...but mabye it could be leaking anyway

 

When they wear out it can leak but it generally causes over heating as well, just though I would throw it out there.

 

Please clarify this. Does this mean that you are filling the overflow reservoir to the top?

 

check your heater hoses in the back of the engine

 

Good point

 

I have a 99 4Runner and it has always leaked a little right out of the top radiator hose going into the top of the engine. I have changed the clamp and the hose Occasionally I see a puddle on the engine cover. Not a big deal I just keep track of it and fill it when it needs more. I also keep the hose clamp really tight on top.

 

Hello All,

I just bought a 97 4Runner and noticed it was runnung hot. I filled it with about a gallon of fluid and a few hours of driving noticed that it was low again.

While under the truck I noticed 2 lines on the passenger side that were rotted and wet. After following them, I noticed that they were the coolant lines to the rear heater. This appears to be a common problem. Hopefully, if your vehicle is equipped with this, you should check it out and see if this is where you are loosing fluid. You can easily bypass the 2 lines and stop leak as I have. You just won't have heat from the rear heater.

My quest is to find the best price on replacement lines. Some forums quote 80 to 100 dollars and beware of the dealerships. Good luck and hopefully this helps.

 

sorry for the delayed response to questions, ive been out of town. No im not filling the overflow to the top, just filling it to "Cold" mark while the coolant is cold.

Ill check the heater core hoses, but ive tried to foil under the truck to see if anything is dripping, no luck. I have had the system pressure check, and no leaks found which is why im a little dumbfounded, but im getting ready to just start replacing hoses and see if that helps.

 

Chek the lower manifold it could b puddling around your knock sensor from gasket leak n youd never know.