1999 Volkswagen Passat Engine Coolant Sensor Pops Out

AUSTINMAXWELL

MEMBER
1999 VOLKSWAGEN PASSAT
4 CYL
FWD
AUTOMATIC
87,000 MILES

Sir:

I have a 1999 Passat in which the Engine Coolant Sensor "pops out". It has done this 3 times in the last week despite changing and putting in 2 new clips that hold it in place. The sensor is blue and inserts into a small coolant pipe towards the back of the engine. Firestone thinks that engine pressure is building up within the engine and looks to escape via the weakest point which is where the sensor is. What would be causing engine pressure to build up and if it is building up what is the likely fix. Firestone said they think a Gasket is going bad.

This vehicle has a rebuilt title on it and was previously rebuilt from a wreck.

3 Replies

MHPAUTOS

MECHANIC
31,937 POSTS

HI there,

Thank you for the donation,

The only thing that will build up that kind of pressure is a faulty radiator cap, it is designed to open at a given pressure and stay open if that pressure is maintained, replace the radiator cap.

Mark (mhpautos)

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Wednesday, July 15th, 2009 AT 5:40 AM

AUSTINMAXWELL

MEMBER
2 POSTS

OK. If a faulty radiator cap is NOT THE PROBLEM could the problem then be related to a head gasket going bad? That was one other potential reason that I was told.

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Thursday, July 16th, 2009 AT 10:27 AM

MHPAUTOS

MECHANIC
31,937 POSTS

HI there,

If the head gasket was faulty it would increase cooling system pressure, but you would still have the cap as a relief valve and if the head was that bad, you would have a bad miss fire and severe overheating problems with coolant loss.

Mark (mhpautos)

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Thursday, July 16th, 2009 AT 5:24 PM