Help! Radiator fluid does not return from recovery tank

[air1jpg]

Radiator fluid does not return from recovery tank after engine cools down after engine shutdown. I have replaced the radiator cap, what else could cause this? :confused Eventully, the low coolant light will come on after a few days.

 

[Hib Halverson]

When the low coolant light comes on is the overflow bottle full?

If not, the engine is using coolant. If there are no leaks, test the engine for a blown head gasket.

 

[air1jpg]

When the low coolant light comes on is the overflow bottle full?

If not, the engine is using coolant. If there are no leaks, test the engine for a blown head gasket.

The overflow bottle is full. I also have not noticed any abnormal white exhaust.

 

[boomdriver]

The overflow bottle is full. I also have not noticed any abnormal white exhaust.

There is an air leak somewhere...or water leak.

The radiator as it cools creates a vacume inside that draws water from the recovery tank back into the radiator...as it should work.

If that vac (which is small) is not there, coolant cannot make the return trip and it will keep escaping under pressure...which suggest, under normal conditions there should NOT be much, if ANY coolant going into the tank. Thats there for boil-over capture or very hot days. The only other way it can push coolant out of the radiator and into the recovery tankwhen its not extremely hot, is by pressurizing the radiator with exhaust or compression from a blown head gasket.

When its stone cold, start the car and go remove the radiator cap. if there is pressure in there, you have problems.:ugh If there are bubbles in there, same problem just more evidence now.:ugh:ugh

 

[John Robinson]

Besides the head gasket theory you could also have a leaking water pump which would have the same results as a leaking head gasket or a very small pin hole in one of the radiator hoses. You don't say but when you run the heater do the windows inside the car fog up (if so bad heater core) All of which would do what a blown head gasket would do. You could take the car to some place like Advance Auto Parts and have them do a pressure check on the system which would include pressure checking the new radiator cap to be sure it is good. What you are looking for is evidence of were the hole is so do a visual inspection around all of the hoses etc for the tell tale stain antifreeze leaves when it leaks out.

 

[Hib Halverson]

The overflow bottle is full. I also have not noticed any abnormal white exhaust.

Sorry. I asked the wrong question.

Is the overflow bottle at the "full" mark or is it full to overflowing out its vent?

If the bottle is truly overflowing, then the coolant is not being taken back into the system after expansion forces it out. If the bottle is simply "full" but the coolant light comes on periodically, then the engine is using coolant and I'd take John Robinson's advice and have the system tested.

 

[tmkassin]

It is possible that the recovery tank is dirty and plugging the return line. When the car has cooled down remove the tank and wash it out with mild detergent.

 

[air1jpg]

Sorry. I asked the wrong question.

Is the overflow bottle at the "full" mark or is it full to overflowing out its vent?

If the bottle is truly overflowing, then the coolant is not being taken back into the system after expansion forces it out. If the bottle is simply "full" but the coolant light comes on periodically, then the engine is using coolant and I'd take John Robinson's advice and have the system tested.

Before I replaced the radiator cap, it was full too the top of the tank. The last time I checked, it was full to close to the top of the tank. I am going to have the system pressure checked here soon after I get my truck back from Ford.

 

[air1jpg]

The heater works good and I have no fog on the windows. The engine idles and runs good with no white exhaust from the tail pipe.

 

[gmjunkie]

The heater works good and I have no fog on the windows. The engine idles and runs good with no white exhaust from the tail pipe.

Check the hose and aluminum line that go's from expansion tank to reservoir, It's got a crack sucking air!~!!(Probly where it's attached to the Expansion Tank!~!!)

 

[Hib Halverson]

Before I replaced the radiator cap, it was full too the top of the tank. The last time I checked, it was full to close to the top of the tank. I am going to have the system pressure checked here soon after I get my truck back from Ford.

We're having a nomenclature problem here...happens sometimes with diagnosis via Internet.

I was asking about the overflow bottle not the high-fill bottle. The overflow bottle is up in front of the right front tire. The high-fill bottle is to the right-rear of the engine and has the radiator cap.

Let us know what the pressure check reveals.

If the cap is defective, the overflow bottle may fill up and eventually overflow because the system is venting coolant into the overflow but not taking it back in.

 

[KANE]

Jon-

What about the cap- are you losing pressure due to a bad radiator cap?

EDIT- I just saw that you replaced the cap. Hmmm...

Is your temp sensor bad on your water pump? If yes- it could be running hotter than you think it is and therefore not showing on your gauge. I had to replace the sensor on my LT1 a few weeks ago. My tank was getting filled as well- due to running hotter than showing.

 

[air1jpg]

Jon-

What about the cap- are you losing pressure due to a bad radiator cap?

EDIT- I just saw that you replaced the cap. Hmmm...

Is your temp sensor bad on your water pump? If yes- it could be running hotter than you think it is and therefore not showing on your gauge. I had to replace the sensor on my LT1 a few weeks ago. My tank was getting filled as well- due to running hotter than showing.

Turns out, that the generic replacement radiator cap I bought from Advanced auto was a crap. I bought a OEM cap from a Chevy dealer and it made a world of difference. The fluid level in the recovery bottle is now constant. But now I think I have a new problem. I now occasionally have a strong antifreeze odor inside the car and can see vapor comming out of the vents. I think my heater core is going out, does this sound right? Could some anti-freeze be entering the vents due to a worn heater core, but not be bad enough to allow fluid to dump onto the floorboard? :ugh

 

[John Robinson]

I think you already know what is going on with the new problem. Sometimes with closed high pressure systems when you fix one thing it forces the pressure to the next weak spot. So be prepared to not only replace the heater core but the next thing to go could be a hose or the radiator. I certainly hope that is not what happens to you but it has been my experience in the past.

 

[air1jpg]

I think you already know what is going on with the new problem. Sometimes with closed high pressure systems when you fix one thing it forces the pressure to the next weak spot. So be prepared to not only replace the heater core but the next thing to go could be a hose or the radiator. I certainly hope that is not what happens to you but it has been my experience in the past.

Thank you for your input. My upper and lower radiator hoses are soft so they will be replaced soon after the core is replaced.