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Discussion Starter · #1 ·
So my father and I have been trying to figure out why my beetle has been over heating so much after we have replaced the:
1) water pump
2) temperature sensor
3) fixed the fans
the only thing we have not done is check the cylinder head gaskets. I've filled it up with coolant every time I go to drive it but after 12-15 minutes of driving it the dang thing is saying its over heating again. When I fill it up with coolant and I leave it running in the yard for an hr or so its fine. It doesn't leak anywhere that I can see and I never see any steam coming from the engine itself.
 

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I see, some possible issues; here are some questions:

1. did you replace the thermostat?
2. did you flush the cooling system?
3. what color was the old coolant, was it vw spec or green and was there red sludge or gunk in it, in the coolant bottle?
4. is the coolant, flowing back into the coolant bottle; when the engine is running?
5. are the coolant fans; kicking on and is the thermostat opening?
6. is the coolant temp sensor reading normally?
7. did you remove the air from the cooling system and "burp" it or fill with a vacuum filling tool?

For the gasoline engines: it is very common, to have a air pocket in the block and some are tough to "burp", to get the air out of the system and this, can cause a overheating issue (I would assume; there are similar issues with the TDI's).

Give us more info about your new beetle mechanical history and some details of the overheating issue, how long this has been going on, plus... any repairs or diagnositics you have attempted to resolve the problem.

Please, comment, on the above questions and we can discuss, more possible testing and things to try, to resolve the overheating problem. Thanks.
 

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Discussion Starter · #3 ·
We did replace the thermostat, we did flush the system, the old coolant was a brownish color but no gunk that I could see, I'm not sure if it is flowing back into the bottle, the fans are kicking on, I don't have a temp gauge to see when it is getting close to heating or not (sadly), and we did remove the air. It is a 2002 TDI 1.9 diesel.

I drove it from my parents house to mine which is 21 miles one way and to the store 5 miles away from my house a few times and had no issues with it at all. The coolant stayed at steady level and it ran fine. But on the way to work today it started over heating which is 13.5 miles away.

When it started over heating we replaced the water pump and it was fine for a few months. Shortly after the fans went out and we got that fixed as well. Now its over heating and we can't figure out why.
 

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Replacing the water pump involves disconnecting the timing belt. Hopefully you locked everything at TDC with the proper tools? Did you put an amazon/eBay/elcheapo/chinese water pump with a plastic impeller in the engine? Or was it a graf or hepu?

The tdi engine is not as prone to an air pocket as the gas engines are, but it can still happen.

The thermostat replacement, again cheap chinesium or a quality part?

These Diesel engines don’t make a lot of waste heat like a gas engine does, they rarely over heat, but a clogged radiator, or engine block from running the wrong coolant will do the trick. A water pump with an impeller that does not spin. You can check that by pulling the filler cap on the bulb and see if coolant is coming into the bulb from that little hose near the top of the bulb. A dead thermostat will also make for an over heat.

Hook up a vcds or some type of blue tooth reader that will monitor coolant temp, so you can find out exactly what the temp is. Often a tdi will not over heat just idling but needs to be put under load. You may just need to replace the temp sensor.

If all that checks out you’ll need to do a compression test, a blown head gasket can also be at fault. Changing a head gasket on one of these engines is not a bad job, and also a good time to replace the entire timing belt system not just the water pump.


Here is what a quality kit from a reputable vendor looks like with everything needed to keep you tdi running in tip top shape.



Let us know what you find.
 
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