Question about 2003 Volkswagen Passat

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Coolant leak near rear of engine.

I have a massive coolant leak from the rear of the engine. One mechanic told me it was caused by the Heating Valve. Is this hard/expense to replace?

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What is a heating valve please ,never heard of this terminology ,a heater take off yes but a valve ?well if does have one i have never seen one ,most common cause is a core plug or in american freeze plug but a heating valve ?? couid be a heater hose perished and split i agree but a heating valve the heat on these cars is shut off by closing a flap on the heater inside the heater unit so this repair if its just a heater hose shouldnt take long unless its a core plug in which it may involve a longer job

Posted on Nov 27, 2013


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Posted on Jan 02, 2017

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SOURCE: oil in water resovour vw 2002 passat

Could be just the OIL COOLER. VW IS CORRECT.
If the oil cooloer fails internely you will have a mix of coolant and oil. In the engine and in the Radiator,

But not to say the other guys were wrong...

Posted on Jun 18, 2009

  • 102 Answers

SOURCE: coolant leak from left side of engine block running down oil pan.

when you say left side are we talking passanger side or drivers side if drivers side which is my guess most likely your waterpump seal is leaking

Posted on Mar 22, 2009

  • 17 Answers

SOURCE: 1999 2.0L VW Jetta coolant leak behind crankshaft pulley

The MK3 VW's are prone to failure of the "coolant flange", which is located to the right of the valve cover, and will have 4-5 hoses and or sensors sprouting from it.

I'd be willing to bet that this is the source of your leak, not the cam pulley.

The part is inexpensive.

Posted on Mar 15, 2010

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Dip stick barrel

The dipstick tube can leak oil, and massive oil loss will damage the engine, causing it to overheat in the last few minues of its life.  
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Heating in my car

There is a valve that controls the hot water into the vehicle heat exchanger which is on the cab side of the firewall. The device is controlled mechanically with a push-pull cable , by vacuum control or electro-mechanically by a servo actuator.
There are most likely TWO pipes that come from the engine radiator and go through the firewall, rear wall of the engine compartment, into the passenger cab area. The Heat exchanger control valve is
mounted somewhere along the path of ONE of those pipes or tubes (the "input" tube).
There are many threads on the Internet on this vehicle and year, and so many concern heating/cooling.
I would suggest getting or borrowing a $20-25 manual on the car and going to the body section and
tracing either the vacuum diagram or the heating control section to find the valve and also the dash controls. Something is disconnected or broken with either one of the three methods described.

This assumes all else is OK and NO COOLANT leaked into the Oil (frothy Oil on dipstick)
and no Transmission Fluid is in the Coolant (oily color reddish in the Coolant with oil smell instead of sugary sweet smell) ; if the coolant system integrity is compromised in any way as described; stop -> go to a mechanic <-; increasing damage is imminent.

If its just a control issue, you can probably set the valve up at 1/2 open if its a mechanical type with push-pull cable; I have done this on several cars when the control cable rusts; disconnect the valve end and set it manually 1/2 or 3/4 for the winter


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