I am having a very unusual problem with my cooling system. My radiator keeps ending up with unusually large amounts of air. I mean something like 8-12 oz of water required to top it off. The only reason I am noticing is its dropping below the temp sensor in the block and screwing up the cold start fuel mixture on the EFI controller.

I drove for an hour today after topping it off. The overflow bottle filled up there was air in the radiator. I let the car cool down and the overflow bottle was not drawn back into the radiator.

My cap and thermostat were both replaced in june.

I was thinking maybe I lost part of the head gasket in one of the cylinders, but the oil appears fine and there aren't any of the other bad headgasket signs. The cap does feel a little on the loose side and you can squeeze the upper hose and get flow through the overflow hose. Which seems a little odd to me. But the cap does hold pressure and there aren't any visible coolant leaks.

Am I missing something simple here?

 

Well you're losing fluid somewhere.

You're really not seeing any leaks at all?

 

what year / make and engine

 

its a 94, F22B2 motor.

As near as I can tell the fluid is ending up in the overflow bottle.
But as for leaks there are none that are obvious enough to account for the bubble thats ending up in there. Its not overheating either.

 

You have either a bad cap; allowing coolant to boil off, or a coolant leak at the same general level as that you are finding in the radiator.
Carefully check between the radiator and the condenser, you may have a pinhole that developed in the fin area.

Check the water pump area (under the car b4 you first start it in the morning). Water pumps start leaking from the shaft seal. Because of how the seals are oriented, they will leak once the engine cools off and the pressure subsides. I've seen them loose several quarts a night.
There is a weep hole at the engine block's driver's rear corner from which this errant coolant leaks from.
The water pump failure is often marked with a green stain left by the leaking coolant.

P

 

Water pump was done with the timing belt and engine swap the previous owner did around 7000 miles ago. I got the paperwork for it. I'll check it. A pinhole would account for the lack of vacuum to draw from overflow bottle. It would have to be very small though because like I said the radiator is holding pressure.

 

Update. The radiator boiled over yeasterday. Something is causeing the coolant to boil.
I replaced all of the hoses/clamps and this did not seem to solve anything. When the car runs with the cap off after a while a white vapor bubbles out of the radiator cap. more of the vapor comes out when I pull on the throttle cable.

 

That is so strange? I could only guess the thermostat or one of the sensors. If there was a hole that would introduce air at some point I would think it would leak from it as well. Sounds like an inspection is due. Follow the intake and coolant passages. You'll find it, look for a leak or vacuum point of entry

 

I'm gonna bring it in and have the do a block and compression test. This has me stumped. It started overheating as well. So whatver it is it's getting worse. Would't suprise me if it was one of those cars that got stop-leaked to fix a blown HG long enough to sell.

 

haha that would of sucked if you got one of those but those addictives dont really work...i heard they *** up your motors too...

 

dam i had air in my radiator as well but that doens't lead to major damages like your having . all i did was burp my system and properly drained the old anti freeze at the same time refilling it with new anti freeze then start the car radiator cap off set the heat a/c controller to col max then your car will burp up the air left in it when you see bubbles they last for like 5 minutes then they stop and your done no air .

 

It's not leftover air in the system. I've bled and burped and driven for twenty minutes with the heater valve wide open. Air in the rad wouldn't cause a continuous stream of air to come out of the overflow. Something is introducing pressurized gas into the sys on a continuous basis

 

Could be a bad head gasket allowing exhaust into coolant

 

thats what I was afraid of, and thats what it is. can't be anything else. small leak, but a leak nonetheless. to the shop. I don't have the facilities for a teardown of my heads

 

did you open the bleeder screw, when you filled the coolant.

 

of course, and I ran it with the heater valve wide open, for ten miles on the high way. It's not leftover air. compression leak into cooling sys. You can see the motor jump when whatever cylinder it is misfire.

 

I have a device that you put on the radiator opening and hook to an shop air and it causes a vacuum to the entire system and they you pull in the coolant and water with the vacuum that you created and it fill all voids. Has worked on the last few cars i have used it on. Ed not cheap though about $150 I got mine at the swap meet new for $7.00 though.

 

blown head?