Moms car: 2004 VW Passat with 1.8turbo engine.

History: Car ran low on coolant twice. She stopped refilled, then got a coolant flush a week later. During the flush it was noted that her overflow tank had a crack in it. Her coolant system is the pressure type, where the overflow tank is pressurized.

I replaced the tank with a new one. Car starts and idles fine. When I drive the car it starts to over heat and the coolant fills up beyond the full mark and gurgles. I dont think its boiling. It looks like air is getting into the system and expanding causing the fluid to over fill.

I have ran the car with the overflow cap off hoping to bleed out any air, but more air seems to get in. I am guessing her headgasket is gone. At idle under vacuum its fine, but when I drive and the turbo builds boost, its pressurizing the coolant system thru a leak in the head gasket??

What you think?

9/8/2011 5:44:56 PM

At the very least sounds like a blown head gasket, PM beethead he is the VW guy.

9/8/2011 6:26:52 PM

blown head gasket on a 1.8t is pretty rare, but i wouldn't rule it out completely

is there oil in the coolant? i've seen a busted oil cooler cause this sort of issue.

edit:
on some of the longitudinal 1.8ts there was a bleeder screw on the hard coolant pipe that runs over the intake manifold.. not sure about an 04 right off hand.

[Edited on September 8, 2011 at 7:28 PM. Reason : edit]

edit2:
is it still losing coolant or are you just worried about it being overfull?
how many miles?
was the timing belt done?
typically when we see overheating it is a water pump or thermostat

[Edited on September 8, 2011 at 7:32 PM. Reason : edit2]

9/8/2011 7:21:56 PM

Did you properly bleed the coolant (some cars it is a pretty elaborate step)? If you are really lucky it just hasn't properly been bled and is getting airlocked causing your coolant to boil and expand.

9/8/2011 8:01:33 PM

^

Also, if the cooling system loses it pressure through any cracks the coolant will boil. If you don't have the right mixture of antifreeze(vw's use G12, remember), the coolant will boil.

The metal pipes on the heater core of passats like to crack. Take the plastic cover off underneath the windshield. The heater core will be in the center. Crank the car and let it get up to temperature. Look for evidence of leaks. One of the rubber hoses will have a small hole in it. Then loosen that hose and slide it back until the small hole is exposed to let air bleed out of the system. This only works once the thermostat is open.

If it is the heater core you can just bypass it temporarily. If you want to actually replace it, may god have mercy on your soul.

A leakdown tester is always nice to trace this sort of thing, but good luck finding one that will fit on those bastards.


[Edited on September 8, 2011 at 8:25 PM. Reason : .]

9/8/2011 8:21:35 PM

104k miles. Timing belt and water pump have not been changed.

Car is not loosing coolant. The level is correct. No leaks on the ground.

9/8/2011 9:08:08 PM

oil and coolant are not mixing

9/8/2011 9:18:31 PM

how can I tell if its the water pump or thermostat?

9/8/2011 9:19:29 PM

water pump should have a weep hole (unless VW is weird or something). so it will be dripping out of there. To check the thermostat you need to remove it and place it in a pot of water on a stove. turn the burner on high and stick a meat thermometer in there or some other thermometer. The valve should begin to lift at whatever the spec is, so say it opens at 180F, and then it will be fully open at whatever temperature. If it's bad it won't open.

I recommend you rent a pressure tester from an auto parts store and hook that up with the engine cold. as you pump up the tester it will force coolant out of any leaks.

[Edited on September 9, 2011 at 1:45 AM. Reason : could also be a bad radiator cap]

9/9/2011 1:45:02 AM

at 104k you should replace the timing belt and water pump regardless.

most likely problem is the impeller on the water pump. almost every timing belt/water pump job we do has a damaged impeller on the water pump. the original ones were plastic. the updated ones are metal.

9/9/2011 8:14:57 AM

trying to get my mother to maintain her car is hard. She is the drive and worry later type person. I told her months ago she would need a timing belt and water pump.

I have no clue on how to work on this complicated german turbo 4. Estimated cost for Tbelt and water pump job?

9/9/2011 8:21:33 AM

pm me your email and info and i will put together an estimate for you.

9/9/2011 8:24:50 AM