My daughter just called me on the way from from college and said she
was having a problem with her car. She said that as she is driving
the temperature will sudden rise to just below the max, then just as
quickly return to the normal position.
Does anybody have any ideas as to what the problem could be?
It's a 1995 Jetta III with auto transmission.
Thanks in advance for any and all help.
Depends. When has the antifreeze last been changed? If it is more than
three years, not much of a pain at all as you are dumping the system
anyway. The stat itself is a few bucks.
Do a flush to get any sludge out of the system, use VW - approved anti-
freeze, and take your time.
There are sources on the net for How-To tutorials - for example, here
is one for an '03 Jetta:
I linked you to the housing in case it gets bunged in the process -
they are brittle if abused.
You could also pay your local mechanic or draft the boyfriend to do it
if you are uncomfortable with it. It is maybe 2 hours' work with the
draining, purging and filling. When you refill, remember not to forget
to "BURP" the system or you will have no heat - much has been written
here on VW engines needing burping for proper refilling.
Melrose Park, PA
I could NEVER get even most of the air out with squeezing hoses, etc,
etc. I just ran it 5-10 minutes, shut it off and let it cool, filled
the ball to MAX, drove around (like to work), stopped, let cool, topped
off, etc. Would take 3-5 heat cycles to get it stable.
I guess it depends on what "sudden rise" actually means.
A short in the wiring or a defective coolant temperature sensor could cause
fluctuations with the gauge.
BTW Is this a 4 cylinder gas engine?
A new thermostat is probably a good idea but make sure that a good brand is
I just talked to someone that installed a new thermostat ( I don't know the
brand he used) and it lasted about a month before it did not function
correctly. It was stuck in the closed position and the heater core had to
do the work of cooling the coolant. Well the car was driven too fast and
the heater core blew causing an accident with his 1997 Jetta 2.0. Car is
totalled but he is fine.
Agreed with the group. Sticky thermostat.
I'll assume the 2.0l engine.
I forget (sold the '95), is the thermostat up in the head under that
plastic goose neck? If so, replace that too. ~Cheap. They crack at
the mounting holes and cause a leak, then you gotta dump the coolant
again. If it's where I remember (see above) you're gonna be moving it
around, retorquing, etc, so I'd think if it were gonna crack, it'd be a
month after doin' the thermostat.
If the hoses are the least bit suspect, I'd do those too. Not so cheap,
and that oil cooler plumbing (just above the oil filter mount) is a PITA
to deal with. Look at the mass of hose in the area and you'll get the
idea. Did mine with the front bumper off (rad fan and fan belt R&R -
yep, it's got a fan belt) and it was still a PITA.
If you do the hoses, get that orange plastic dip stick tube too. You'll
prolly break it yanking around (or trying to take it off so you don't),
and it's cheap just to have in case.
'95 Jetta GLS (sold)
'08 Jetta SEL
If the wire connecting to the coolant temperature sensor gets grounded
believe this would cause the temperature gauge to go to maximum. There
could be a momentary ground short in that wire circuit. rich
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