Last year I noticed that my Jeep would only blow out hot air if the RPM’s were up above 3k. If I came to a stop it would blow out cold air. I took it to a local shop and they said my radiator was leaking and I would have to replace it…and they said I would have to change the transmission fluid since it was being contaminated. I got a second opinion from a guy I had recently became acquanted with who owns a garage. He put a pressure cap thing on the radiator and said there was absolutely no leak. He put some anti-freeze in it and it worked great. Well this year comes along and same problem. I bring it back to this guy I know and he adds more anti-freeze and the heat works great…so do I have a leak that this guy isn’t noticing? Does anit-freeze need to be refilled every once and a while? Someone told me it could be a problem with the thermostat…? I just want to make sure I don’t do any harm to the engine or transmission.
The problem maybe in two places. Your coolant should not need a fill if you do not have a leak. The heater should work if you do have low coolant. You might have a vacuum leak affecting the heater door that moves the hot air. The coolant may be leaking slowly, too slowly to see it in a quick pressure test. You need an overnite pressure test. In this test pressure is maintained for a long period showing leaks that are not easily detected. My treatment of these leaks is a common copper based additive to the coolant. You need to check your coolant every gas fill or at least every month to catch problems like this.
It could be a clogged heater core or a worn water pump impeller.
I Would Get The Cooling System Pressure Teated To Determine Where The Coolant Is Going. You Could Have An External Or Internal Leak.
With an internal leak, coolant can be consumed by the engine and will not be noticed until the coolant level drops.
I repectfully disagree with advice given pertaining to heater output. Low coolant is one of the first things to check when a heater starts blowing cold. You have experienced this situation yourself, twice.
CSA
I’m pretty car dumb…are coolant and anit-freeze different? When I go back to the mechanic, should I ask for an overnight pressure test, or would I need to go to some kind of specialist. He owns a pretty small garage. If it is a small leak, is it doing serious damage to the car?
Would any garage be able to do a cooling system pressure test? If it is a leak, is it doing serious damage? If it is a leak, what is the fix…I guess it would depend on where it is?
Coolant = Antifreeze. A Shop With A Cooling System Pressure Tester Can Do It. Most Shops Should Have One. They Are Relatively Inexpensive.
The shop attaches a little pump to your cooling system and pumps it up to the pressure that cooling system is designed to operate under. A gauge will indicate that the system can hold pressure over time. A drop in pressure indicates a leak and often makes the location of the leak obvious.
Water pumps, pressure caps, freeze plugs, radiators, hoses, heater cores, and gaskets are some of the places coolant can leak. Some leaks are inexpensive to fix and some not. Somes leaks are external and drip on the floor. Some leaks are inside the engine, often caused by faulty intake manifold or cylinder head gaskets.
This does need to be taken care of before damage results. A small leak can turn into a big leak without warning and the posssibility of overheating or contaminated engine fluids exists.
CSA