blb

The engine is a '94 22RE with 134,000 miles. It runs great and there is no coolant mixed with the oil in the crankcase, and no oil mixed with the coolant in the cooling system. The symptom is that the coolant expansion tank gets fuller when the system gets hot (as it should), but the coolant does not go back into the radiator when it cools down. If I remove the radiator cap, there is no coolant visible, so I siphon the excess coolant from the expansion tank into the radiator, and the process starts all over again. I just replaced the radiator cap with a new one from the dealer, but no change in symptoms. Is there anything other than a bad headgasket letting the exhaust pressurize the cooling system that could be causing this?

kyle_22r

does your coolant smell like exhaust? when i blew a head gasket on a 22R, it cracked the #4 fire ring and was sending exhaust into the coolant, causing it to bubble out of the reservoir. fortunately i didn't get any coolant into the oil, since i wouldn't have figured it out until my engine blew(it was running fine).

the coolant was also brown. are there bubbles coming out of your radiator line? also, check your oil for the telltale milkshake of coolant mixing into it.

if things otherwise seem normal, i'd replace the radiator cap. often the seal will swell up and cause it to not allow coolant to flow back into the radiator from the overflow when the engine cools off.

Rick F.

When the engine cools down, the pressure in the cooling system should drop and pull a vacuum on the expansion tank. Since the tank is taking on coolant when the engine is hot, it doesn't sound like you have a clogged hose. However, I've seen where either the hose would collapse when the engine would cool and pull a vacuum on the tank or where some foreign material in the hose acted like a check valve and only allowed flow into the tank. One other thought is the system is pulling air in from somewhere else instead of pulling a vac on the tank, but that would probably show up as a coolant leak when the engine was hot and pressurized.

Glina

Try getting new radiator cap.

Rick F.

That was on my mind during my previous response but I suffer from CRS (Can't Remember ˟˟˟˟˟) and forgot.

blb

Thanks for the ideas. I'll check the hose form the radiator to the tank more closely. I didn't detect the smell of exhaust in the coolant, but I'll also check it more closely. As I stated in my original message, I purchased a new radiator cap from the dealer and installed it but there is no change in the symptoms. Thanks again for the responses and please feel free to offer any additional ideas you may have.