New Addition

[UpstateDieselGuy]

Well I am going to start going through my new to me 1991 Jetta 1.6L Diesel 5 Speed today and getting it ready for the road.  We're going to change out all fluids etc.  I am going to use a good dose of fuel conditioner etc to help clean it out.  Right now the fan is on a switch that is controlled manually.  I want to test the Coolant Temperature Sensor, if I can, and try to make my own circuit to control it.  I think if the Sensor works I can use it to signal a relay controlled power to the fan.  I know I need a battery, but when I start cold this thing is rough.  As it warms up it smooths right out.    I just think a lot of it has to do with sitting for a while.  There is a cold start handle and I can hear the sound change, but that's about it.  Sorry about the long post, just a little excited.  Chris

[chrissev]

Well I am going to start going through my new to me 1991 Jetta 1.6L Diesel 5 Speed today and getting it ready for the road.  We're going to change out all fluids etc.  I am going to use a good dose of fuel conditioner etc to help clean it out.  Right now the fan is on a switch that is controlled manually.  I want to test the Coolant Temperature Sensor, if I can, and try to make my own circuit to control it.  I think if the Sensor works I can use it to signal a relay controlled power to the fan.  I know I need a battery, but when I start cold this thing is rough.  As it warms up it smooths right out.    I just think a lot of it has to do with sitting for a while.  There is a cold start handle and I can hear the sound change, but that's about it.  Sorry about the long post, just a little excited.  Chris

Re: the fan is on a manual switch.  That must be annoying in summer stop and go city traffic.  The fan circuit on that car is ridiculously simple.  All you need to do to make it work is wire the negative from the fan to any ground you can find.  Then install a new thermal switch at the bottom of the radiator, wire the one side of the positive wire from the fan to the switch, and then wire the other side of the thermal switch through an external fuse to the battery.  The fan will then come on whenever the rad reaches a certain temperature.  No need to turn it on yourself.  The thermal switches cost maybe $10 at any VW dealership and they have plenty of them.  

With the cold start you start the car, then pull it out.  Then leave it out for a few minutes till the car warms up (you know you can put it in when if you do so the engine sound doesn't change, ie it doesn't start shaking - usually doesn't take that long).

[UpstateDieselGuy]

Cool.  I didn't think it would be too bad, but someone did a job on this thing.  I have completed all of the servicing and just need to start driving it.  The Temperature Guage for the Coolant works, I'm guessing that it uses the sensor in the Radiator?  I pulled the connector off of the Sensor and there are three prongs on it in a line horizontally.  If the guage works off of this temperature sensor then it would appear to be good.  If not I know I can get one at NAPA as the nearest VW Dealer is like an hour away.  What prong is for what? lol  I am good at wiring, if I have some decent guidelines.  I can tap what is there or bypass it as long as it keeps the Temperature Guage functional.  Thanks again and in advace, Chris

[UpstateDieselGuy]

There is a three prong connector there, but it doesn't match the the connector on the fan.  However they may have changed the fan when they changed the engine.  The original setup was replaced after it overheated and cracked the head.  I will look at it more tomorrow and try some things and get out the test lights.

[Black Smokin' Diesel]

You must have a one speed fan. The three prong connector is for a two speed fan. I don't really know how to make the two speed system work with the one speed system. You can always replace the fan with a two speed one but they are kinda expensive from the dealer or even parts store.

[UpstateDieselGuy]

I'll try to use the three prong temperature sensor and make it work.  I just wonder which prong is for what.  I like your suggestion and will try something.

[UpstateDieselGuy]

Just been thinking a little here.  How cold will these things start without Glow Plugs?  I am wondering if my Glow Plug Relay is bad and not cycling.  The car starts great when warm, but when cold she throughs fits.  It almost sounds like it's loading up when it's cold and takes a little to warm her up without wanting to stall.  I'm thinking I will use a test light to see if the GPR is sending power to the Glow Plugs.

[Black Smokin' Diesel]

That's a good question. In fact I have no idea. I'm the kind of guy who cycle them even during summer lol.

[chrissev]

Just been thinking a little here.  How cold will these things start without Glow Plugs?  I am wondering if my Glow Plug Relay is bad and not cycling.  The car starts great when warm, but when cold she throughs fits.  It almost sounds like it's loading up when it's cold and takes a little to warm her up without wanting to stall.  I'm thinking I will use a test light to see if the GPR is sending power to the Glow Plugs.

Hey:  like everyone else said, the three prong sensor on the rad is for the two speed fan.  The connectors are two positive and one negative.  If you only have a one speed fan, then you don't need a three prong sensor.  I think that you can screw a two prong in its place.  Either that or get a two speed fan.  

If the car is hard to start when cold the problem could be glow plugs.  There is a way to test them, that is in the bentley manual.  I haven't got it with me now but it involves testing the resistance with an ohm meter.  You can test for voltage when the plugs are on from the tip of the plug to anywhere that you can get a good ground on the engine.  You might also consider using your block heater.  Another reason why the car may be hard to start is the timing may be slightly retarded.  They tend to be very rough running when they are cold if this is the case.  

Chris

[UpstateDieselGuy]

Well it's on the road and seems pretty decent.  I'm going to keep doing the little things as I go.  I appreciate all the help along the way that you guys have given.  I will figure out the fan sometime, but it's getting cole enough that the guage stays down this time of year.  Thanks again, Chris