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Coolant Disappears in Volkswagen Jetta 2003

My coolant in Jetta disappears very fast, no puddles, no smell, exhaust looks good, floor boards are not wet, oil is clean. What could it be?

Check the transmission fluid if its an automatic, as there’s a fault-path from the cooling system to the transmission fluid. If the transmission fluid is way too much, stop driving and tow it to a mechanic. More likely you’ve sprung a small leak in the head gasket and it’s going out the tailpipe a little at a time as you drive. Has the vehicle’s engine ever overheated, even just once?

Tranny and head gasket are excellent possibilities. Good roads to go down in the search for the cause.

Another path through which coolant sometimes leaks… but only when the engine is running… is via the water pump. The pump’s shaft seal can wear and begin to leak, but often only when the shaft is spinning. This means the leak occurs when you’re driving, but not when you’re parked, and leaks more when the engine is running at higher rpms… and much less at idle. This too is worth checking out.

Get under the water pump and look up at the weep hole, if the inside of the weep hole is the same color as the coolant, you have probably found your leak.

Never passed 190, it would disappear but not completely, after i got to college i checked tank it was below minimum, drove around when got to pepboys it was above minimum

Im pretty sure coolant disappears only while im driving

How much coolant do you add each day?

it happened recently, so far i added once in a week, i checked today in the morning after getting to college it was under minimum, after getting home it was above minimum, and light didnt pop up ever since, hopefully its just false alarm

Be advised that when the coolant level drops below the temp sensor due to loss of coolant, the temperature gage no longer reflects the actual engine temperature. Elevated engine temps do not show reliably on the gage.

If you believe that the coolant is been lost “very fast”, have your car inspected for leaks.

If you have only added coolant once in recent years it may have just become low over time and you may not have filled it completely on the first attempt.

puddle right under the engine, can’t lift my car cuz dont have jacks, any idea where it could be leaking from?All hoses that I was able to see looked good.

there is definitely a leak, I found a puddle right below the engine, but I don’t have jacks to lift my car, any ideas where it could be leaking from? I checked all the hoses that I was able to see but they looked good.

Under the engine is where a water pump leak would present its puddle. Under the front end of the engine to be specific.

Look, you’re going to have to buy some ramps (or jacks and jackstands… NEVER get under a car that’s only on jacks) and get under the car, or pay a mechanic to do so, to find where it’s leaking. There’s no other way.


The places I’ve experienced cooling leaks are the radiator, the water pump, hose fittings, and where the coolant return pipe connects up with the water pump. The radiator leak is usually pretty easy to spot b/c there will be coolant on the radiator’s bottom tray area. No need to lift the car to see that, just pop the hood and use a flashlight. Sometime you can also see a stain where the leak has moved beyond that, like on the under engine protector.

once im under the car do I change whole water pump or just a leaking hose or water pump is the issue?

If it’s just a leaky hose, just change the hose… and the other hose 'cause that one will be just as tired… and drain and refresh the coolant.

If it’s the pump, the job’s bigger. Unless I miss my guess, this engine has a timing belt that drives the water pump. It my guess is correct, you’ll need to change the belt as well as the pump. If you can swing it financially, you may want to change the belt tensioner too while you’re there. It’s been there for a while. And you should check for front crankshaft seal leakage while you’re there.

Get under there with a good worklight, see where the evidence leads you, and post back.
And PLEASE be sure the car is safely supported before getting underneath. I like molded ramps the best. When I use jacks, I put good jackstands under them and leave the jacks there as backups. And always on a flat, solid, level surface. If the car falls on you, you’ll suffocate. You cannot breath with a car on your chest.

thank you, Ive worked on cars many times before. Wasnt just familiar with cooling system