1989 Diesel radiator fan not working

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Canadark
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1989 Diesel radiator fan not working

Post by Canadark »

1989 Syncro Tristar with a 1.9TD AAZ engine with JX bits, no A/C.

Having some issues with overheating. Not boiling over, but running hot.
The radiator fan is not coming on.
I have replaced the thermo switch which threads into the radiator.
Radiator is getting hot (also new water pump and thermostat) System throughly bled.
I have jumped the pins at the switch connector and the fan comes on regular and full speed.
The Aux water pump and turbo cooling fan comes on after truck is hot, but the front fan is still not coming on.

So, besides the thermo switch that threads into the radiator are there any other relays I need to check?
Last edited by Canadark on 17 Jul 2014, 19:28, edited 1 time in total.

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marlinowner
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Re: 1989 Diesel radiator not working

Post by marlinowner »

When you jumper the pins you are mimicking the switch action, if the fan then works correctly than the circuitry is all OK. So either the switch is faulty, there is a bad connection at the switch, or the switch hasn't reached operating temperature - does the temp warning light come on?
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lloydy
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Re: 1989 Diesel radiator not working

Post by lloydy »

I know you don't get a lot of AAZ's out there.. So do you know they run very hot? Mine was like it was on a knife edge! A 25 row oil cooler works well in keeping temps more reasonable. Are you able to measure the temp of the rad? This will let you know if the switch is meant to be kicking the fan in.
As you have the turbo fan and aux pump coming on (when engine turned off) this means the engine is REALLY hot. Mine only ever came on once.
To keep mine cool, i fitted---- oil cooler, new rad, removed cat from exhaust (last one made a massive difference)
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max and caddy
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Re: 1989 Diesel radiator not working

Post by max and caddy »

I have a 84 degree stat fitted to mine and it runs too cool! Assuming your rad is in good condition and not gunged up with rust or missing its fins I suspect your fan switch may be kaput..if its actually seeing the heat at all.

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bigherb
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Re: 1989 Diesel radiator not working

Post by bigherb »

As Lloydy said you need to measure the temp at the rad and and the thermostat housing. Diesel engines are thermally efficient engines, the slower the revs the more efficient they are. It could just be that the engine can lose enough heat by radiation particularly if the ambient air temperature is low and does not need the fan.
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dave friday
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Re: 1989 Diesel radiator not working

Post by dave friday »

Stick the rad thermo switch in some boiling water with[ an ohm meter connected] you should see zero ish ohms on both tags...if its ok,then your rad is gunged up!!
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Canadark
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Re: 1989 Diesel radiator not working

Post by Canadark »

Thanks for the replies guys.
I need to buy one of those thermo readers, seems like they might have enough uses to justify the price.

I'm thinking maybe it's time for a new rad. I did pull it and throughly flushed, it seemed to flow nicely. I even tried putting a rad from a low milage 90 Westy in there, but it had a small leak so I replaced the original back in.
The radiator does get hot although it seems to take awhile. The gauge is reading 3/4 to 7/8 but the light has not come on yet. If the engine is getting hot enough for the turbo fan and aux pump to run shouldn't the radiator fan come on!
It has a brand new thermo switch from VanCafe. I guess it could be bad out of the box. I'll try the boiling trick. (where I live it's hard to boil water over 95 degrees)((high altitude))

So jumping the pins activates the relay? I should also check the grounds I guess.

I'm trying hard to get this truck on the road and have already spent a fair amount of time and money. An oil cooler setup is more of the same!
(and then there's the boost gauge, EGT gauge, intercooler, rev counter,etc!)

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marlinowner
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Re: 1989 Diesel radiator not working

Post by marlinowner »

Jumping the pins is doing what the switch should do when it gets hot, if the radiator fan runs when the switch is jumpered then fan, relays, earths etc are fine. Testing the switch in boiling water is the first move.
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Re: 1989 Diesel radiator not working

Post by dave friday »

Are sure that the water pump is turning the correct way?
You can use oil to test the rad switch [boiling oil anyone?!!]
Does the heater work well?
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AdrianC
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Re: 1989 Diesel radiator not working

Post by AdrianC »

Canadark wrote:I need to buy one of those thermo readers, seems like they might have enough uses to justify the price.

I'm thinking maybe it's time for a new rad.

A £10 IR thermometer is definitely a wiser buy than a £100+ radiator that might not be needed...

Get it hot. Make sure that the coolant in the engine bay is hot before the 'stat opens. Then make sure there's hot water flowing to the rad. Make sure the rad gets up to temp and is evenly hot all over. THEN keep it warming up until you're seeing switch-opening-temp at that corner of the rad. If the rad is uneven temp, or that corner is cooler than the rest, you need a rad. If the rad starts to get warm as soon as the engine does, or if the pipes to the rad don't get hot, you need a stat.

If it just sits at a nice even temp BELOW the switch temp, then you've got a diesel so efficient it doesn't need the fan in your kind of ambient temps at idle.

So jumping the pins activates the relay? I should also check the grounds I guess.

If the fan comes on, the earths are good. All that the switch does is connect the two wires together when it's hot enough. No more, no less.
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Canadark
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Re: 1989 Diesel radiator not working

Post by Canadark »

Water pump and thermostat are new. The pump is a Saleri and is a clockwise rotation for the V belts I have. I boiled the thermostat before installation, it opened.

Pipes to the front are hot. Like I said, the radiator does get hot but takes awhile. I can follow the heating with my hand. Gets hot enough to burn!
The cabin heating system works perfect, loads of heat. In fact I need a new shutoff valve as the front heat exchanger never quits.

I should have thought of boiling oil! Thanks, I'll give that a try. I'm assuming that cooking oil will work fine?

I have no idea if the overheating warning light works, it has never come on. Good way to test?

Thanks for the confirmation about pin test!

That's whats bothering me, everything seems to be working, but the rad fan never comes on and I know the engine is getting hotter than it should.
I'm wondering if maybe there is a blockage coming from the engine? Maybe the hose from the head has blockage? The main pipes to the front are both good, I have wet vac'ed the coolant through them and have had all those hoses off and replaced most of them.

Here's a pic

http://images.thesamba.com/vw/gallery/pix/1229339.jpg" onclick="window.open(this.href);return false;
http://images.thesamba.com/vw/gallery/pix/1229338.jpg" onclick="window.open(this.href);return false;

dave friday
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Re: 1989 Diesel radiator not working

Post by dave friday »

Try another rad flush,make sure that water comes out of the rad switch hole...ask me how I know!
Bung one of the rad pipes up!
Good luck.
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Canadark
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Re: 1989 Diesel radiator not working

Post by Canadark »

While reviewing older posts and the archives I came across the Aux water pump wiring diagram from Syncrosport:
http://www.syncrosport.com/wiring_diagr ... ntpump.pdf" onclick="window.open(this.href);return false;

Very helpful, but I'm wondering what is N43 (electro-magnetic cut off)? Is that the fuel cut off solenoid on the I.P.?

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Hacksawbob
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Re: 1989 Diesel radiator not working

Post by Hacksawbob »

yes it is
member 1168

dave friday
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Re: 1989 Diesel radiator not working

Post by dave friday »

Yes I can't think of any other electro mag shut off valve, shame they didn't say where it was on the van!!
Oh! and have a look at the "Wiki" it has a Diesel circuit diagram/wiring diagram.
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