Engine overheated due to broken impeller. Repaired and no leaks found in head gasket by VW. 5 miles later Beetle overheated and towed back..

YOUR WATER PUMP IMPELLER IS PROBLEY DAMAGED .IT IS A COMMON THING IT IS A PLASTIC IMPELLER AND THEY COME LOOSE FROM THE SHAFT ALL THE TIME AND THAT MEANS THEIR IS NO WATER FLOW THRU THE HEATER CORE AND AS YOUR FANS GO IF THERE IS NO FLOW THRU COMPLETE SYSTEM (SUCH AS THERMOSTAT) THE ENGINE GETS HOT BUT THE RADIATOR DONT .THERES A SENSOR IN RADIATOR THAT TURNS ON THE FANS AT HIGH SPEED WHEN IN OVER HEAT MODE I KNOW IM A VW TECH

More than likely you need new head gaskets.

This has to be because of a mechanical problem in the engine. Possible sources are the timing belt is broken (one indication is the starter spins the engine faster than normal, because the camshaft that opens and closes valves is not turning with the crankshaft), or the head gasket has failed (from overheating as the most likely cause), or badly worn piston rings and/or valves not sealing well (common on high mileage engines).
Compression is built up in the upper part of the cylinder where combustion occurs, so leaks or lost compression are due to valves not sealing, or head gasket that seals the cylinder head to the engine block-sometimes the aluminum cylinder head can warp due to overheating, and the head gasket no longer can maintain a seal. Or also the piston rings are worn so bad that compression will leak past them into the crankcase. For valves or head gasket, the cylinder head has to be removed and repaired. For the rings, the engine has to be rebuilt entirely.
First check if the timing belt is still intact.
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No. Check if it is the head gasket or simply the rocker cover gasket that is leaking. The cylinder heads can be removed with the engine in place, if it is the head gasket.

The blown head gasket problem that you repaired may have damaged the O2 sensor. A 2004 probably needs one anyway

The problem sounds like your radiator its 12 years old clogged with sediment and losing pressure at the cap or
vapor loss right through the aluminum you can't see it .Its a mist at driving speeds not at ideal .
Do a pressure test on the system 14.6 lbs per sq " also check the heater core both in and out hoses should be hot and have good water flow .
The problem isn't your water pump .
Also look at your spark plugs take them out . If they are burn white the vehicle is not getting enough fuel .


















































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I don't know what the knocking sound is, or how serious it might be, but the fact that you are being given an explanation that is clearly untrue is worrisome. I would not buy this car unless first I took it to a VW mechanic and found out what the noise really is so I could evaluate the value of the car accordingly. Unfortunately, it may not be possible to diagnose the noise without tearing down the engine.

You may think you have a leak from topping off your reservoir three times. You can also have a leak but puddle not present under your car. Unless you have a leak a pressure test will not solve your problem, it will just tell you you don't have a leak. Either way you have a cooling problem.

Original VW water pumps has a plastic (composite) impeller to draw coolant from the reservoir and pressurize the cooling system. That impeller is attached to a shaft and the water pump pulley on the other end of it. When it cracks from the shaft connection it will spin slowly or not at all while the pulley is spinning together with the engine. In short.. it broke off and doesn't spin at all while the pulley is spinning. When that happens it doesn't pump coolant around the system and causes your engine to over heat. From over heating (coolant not flowing) comes evaporation of the coolant due to excessive heat, hence, the need to top off your reservoir again and again thinking you have a leak.

Solution:
Replace with aftermarket metal impeller water pump and have another VW independent shop to install it for you. It would also be a good time to have a timing belt service since this needs to be removed to get to the pump.

hi it mite be that the water pumps impeller is made of plastic on these models an they break up after time (very common on audis an vw same engines)and dont pump the water effectivley the car constantley over heat.the solution is to but a pump wid a metal impeller ive had the same problem on my audi a3 turbo..also changing the thermostat is an option...hope this helps

Sometimes, if the leak is small, when car is running and engine hot, you do not get dripping under the car because water is getting vapourized, before dripping down.

Check water level, if water level is going down, then there is either another leak, or the head gasket is going.

When head gasket starts to go , water is vapourized into the engine.

If car overheated after the radiator problem, it is not uncommon that this may had damaged the head gasket, go back to the dealer and complain, as after replacing radiator, the car should had been inspected properly for additional problems.