1994 Jetta Overheating

I keep having overheating issues in my 94 Jetta 2.0 litre USA market
automatic.

It heats up normally, but keeps going until it the gauge is pegged.

The fans don't engage. I replaced the thermoswitch twice with OEM Behr
units.

if I shove a paperclip into the plug, I can get the fans running on a
speed, perhaps high speed or low. I cannot get the "other" speed to
engage. There are three contacts, so only if I bridge two of them will
it run, if I do any other two combination I get nothing. Unless "high"
speed is all three jumpered, haven't tried that.

If I drive the car around 50 mi/h or 80km/h indicated in 3rd gear of
the autobox it usually won't overheat. But go less and heats up quick.

If I jumper the fans to low speed when I first start the car cold, and
drive around, it usually will overheat as well, just I can drive much
further before that happens. It hasn't gone significantly beyond 1/2
way point just because I don't want to risk that.

The car also appears to have a slight leakage of water, but can't
pinpoint it.

Once after driving, the coolant temp slightly higher than normal, I had
a weird milky substance visible on the dipstick. My heart sank as I
thought headgasket. But the oil looks nice and squeaky clean when it is
cold, just after I drove it that one time it looked weird...

In article . com>,
says...
> I keep having overheating issues in my 94 Jetta 2.0 litre USA market
> automatic.
>
> It heats up normally, but keeps going until it the gauge is pegged.
>
> The fans don't engage. I replaced the thermoswitch twice with OEM Behr
> units.

Did the coolant get changed just before this started happening? If so,
perhaps burping the system will help. I typically do this by squeezing
the upper hose and the hose leading back to the reservoir to get that
much air out. Then I run it for about 5 minutes, sitting still. Shut
it down and let it cool a little. The coolant ball should have a MUCH
lower level in it. Fill with more mixed coolant (you should have lots
left before this point if you bought the spec'd amount). Run it again,
maybe a short errand (15min runtime or so). Fill 'er up again. After a
coolant change I typically carry a jug of premixed coolant in the trunk,
just for makeup. It takes awhile to purge it all.

BTW, that first time, it won't register on the temp gage, and the fan
won't come on. Don't wait for it, just warm it a bit and shut it down.

It looks kinda like the coolant leak you mentioned below, but just until
you get it all filled up.

> if I shove a paperclip into the plug, I can get the fans running on a
> speed, perhaps high speed or low.

I'll look this up after we get the preliminaries out of the way

> If I drive the car around 50 mi/h or 80km/h indicated in 3rd gear of
> the autobox it usually won't overheat. But go less and heats up quick.
>
> If I jumper the fans to low speed when I first start the car cold, and
> drive around, it usually will overheat as well, just I can drive much
> further before that happens. It hasn't gone significantly beyond 1/2
> way point just because I don't want to risk that.
>
> The car also appears to have a slight leakage of water, but can't
> pinpoint it.

A common point is the goose neck on the driver's side of the head. It
cracks at the seal to the head. Replace it if necessary.

Another perhaps not common point is the oil cooler. It's a block just
above the oil filter. It's basically a spot for the oil to come in
contact with the coolant for cooling. Sometimes it springs a leak and
you get oil & water trying to mix. That might explain...

> Once after driving, the coolant temp slightly higher than normal, I had
> a weird milky substance visible on the dipstick. My heart sank as I
> thought headgasket. But the oil looks nice and squeaky clean when it is
> cold, just after I drove it that one time it looked weird...

If it's sat for awhile, or hasn't been well warmed for quite some time,
sometimes that happens.

Do both fans spin when the one is on? The other is connected to the
motor driven one with a belt.

Mark
'95 Jetta GLS

wrote:

>I keep having overheating issues in my 94 Jetta 2.0 litre USA market
>automatic.
>
>It heats up normally, but keeps going until it the gauge is pegged.
>
>The fans don't engage. I replaced the thermoswitch twice with OEM Behr
>units.
>
>if I shove a paperclip into the plug, I can get the fans running on a
>speed, perhaps high speed or low. I cannot get the "other" speed to
>engage. There are three contacts, so only if I bridge two of them will
>it run, if I do any other two combination I get nothing. Unless "high"
>speed is all three jumpered, haven't tried that.

I had the same problem with my 94 Jetta.
Turns out that the fan assembly had rusted so badly that the plug on
the fan itself that it could not get the "message" from the sending
unit to turn on.

Just a thought but it happened to me. so just check the connection.

wrote:
> I keep having overheating issues in my 94 Jetta 2.0 litre USA market
> automatic.
>
> It heats up normally, but keeps going until it the gauge is pegged.
>
> The fans don't engage. I replaced the thermoswitch twice with OEM Behr
> units.

Have you checked the _lower_ pipe to the cooler (radiator matrix)? Does
it gets hot when you car starts overheating? Does the cooler itself
gets hot?