1994 Nissan Sentra Coolant Loss

1994 NISSAN SENTRA
150,000 MILES • 4 CYL • FWD • AUTOMATIC
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WALTPALMER
  • MEMBER
  • 1 POST
Car runs well. Temp is normal. When idling or running, coolant overflow receptacle appears normal. As soon as engine is shut off, coolant overflow receptacle begins to bubble and overflow itself, spilling coolant. Up to 1-2 cups of coolant can leak out during this time. Engine temperature never changes. Coolant appears to be boiling, but it may be some sort of back-pressure getting into the system.

Any ideas? I haven't tried touching it while bubbling.
Oct 26, 2009 at 11:21 AM
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MHPAUTOS
  • ✓Experienced Mechanic
  • 31,937 POSTS
Hi there,

Thank you for the donation,

When you shut down the engine it becomes a big heat sink, that is it is still heating up as the circulation of coolant has stopped and in most cases the cooling fans aren't cutting in, (VW's for instance will turn on the fans if the car ids off and coolant temp goes above trigger point) my feeling is that the engine may be running a little warmer than normal and as the engine is shut down the heat sink effect is causing this increased temp and localized boiling, i would replace the thermostat, flush the coolant have the radiator professionally cleaned & flow tested and ensure that the fans are switching on at the correct temp,

start here.

Mark (mhpautos)
Oct 26, 2009 at 9:00 PM
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