curious case of disappearing coolant

[96ExplorerSport]

Hi,

I've been trying to fix this problem for more than a year now. I have 96 X Sport, 4L OHV. Every 2-3 week of driving I have to add 1 quart of coolant. I cannot see any coolant leaking under the car, but I can definitely smell it when the engine is hot and running, like after a drive. I cannot smell any coolant in the cabin though. At first, I suspected radiator and it was indeed leaking a bit, so I replaced it with a new one, but I still have the leak. I inspected radiator hoses and I do not think they are leaking, since they are pretty new. I do not see any traces of leaks around water pump either. I suspected heater core for a while, but I do not smell coolant inside the truck. What do I have left? The leak has to be small. Can it be head gasket? Truck runs OK otherwise. What else can I check?

Thanks,
Sergey

 

[Bern]

Most likely a head gasket leak. Exact same thing happened to my '97.

 

[Cobraguy]

Crawl under the car with a flashlight and carefully check the parting line between the head and block. See if there aren't traces of coolant.

 

[bryanhbre]

I had the same problem with mine, I didn't see any obvious leaks until I looked a little deeper. Could also smell the coolant after driving, pretty strong too. It turned out to be a split water bypass hose on the water pump (90 degree hose) that was barely noticeable. It was taking quite a bit of coolant with it, although it wouldn't leak unless the car was running since it needed to be pressurized to leak. I think it was a $10 dollar part.

 

[budwich]

puts some dye in your rad and wait.... if there is any external leaks, they will become visible shortly thereafter.

 

[gtyates]

Another possibility is the heater control valve. This is the part near the firewall, passenger side. Look for evidence below the valve of a leak or residue from a leak. Mine was leaking and I would smell a sickly sweet coolant smell outsie the truck after running it for a while. I also did not smell it in the cabin.

 

[96ExplorerSport]

puts some dye in your rad and wait.... if there is any external leaks, they will become visible shortly thereafter.

thanks for the pointers guys, I'll try them all. Also, does the dye require UV light, or, will I able to see it with a naked eye? I just hope it's not a head gasket, I am not fixing that.

 

[budwich]

a UV light will help (some places will loan you one)... but usually the brightness of the coloring will be such that the "stain trace" will be obvious to the eye and will "glow" with a normal trouble light.

 

[lwrdxsport]

i just fixed a coolant leak and i replaced everything but the radiator and it ended up leaking from right behind the thermostat housing and was leaking on top of the motor it would evaporate before it dripped to the ground it was the thermostat housing a gasket that needed to be replaced i have the sohc but maybe it could be a similar issue

 

[96ExplorerSport]

If I have a head gasket problem, will there be traces of coolant in the engine oil? I can send my oil for analysis to check if there is any coolant in it.

 

[bryanhbre]

if there's coolant mixing with oil it should be fairly obvious (if there's enough coolant in the oil). could be milky-brown colored, should smell different than oil as well IIRC.

 

[96ExplorerSport]

if there's coolant mixing with oil it should be fairly obvious (if there's enough coolant in the oil). could be milky-brown colored, should smell different than oil as well IIRC.

I know that. My question is whether blown head gasket will introduce coolant to the oil.

 

[Cobraguy]

I know that. My question is whether blown head gasket will introduce coolant to the oil.

It most certainly can...but not necessarily so either. If the leak goes external, (look where I mentioned above) then you won't get coolant in the oil. But if it leaks to the intake valley or a combustion chamber, it certainly can. (leak past the rings when not running) Plus the combustion chamber leak should give you a sickly sweet white smoke exhaust.

 

[CHEESYPOOFS]

have u ever tried just using a bottle of stopleak? i used some a few years ago and havent had an issue since.

 

[96ExplorerSport]

It most certainly can...but not necessarily so either. If the leak goes external, (look where I mentioned above) then you won't get coolant in the oil. But if it leaks to the intake valley or a combustion chamber, it certainly can. (leak past the rings when not running) Plus the combustion chamber leak should give you a sickly sweet white smoke exhaust.

Thanks, it makes sense. I'll check the line.