Radiator fan won't turn on.

[86VaNa60N]

Hello everyone, I first want to say thank you so much for being a great resource for all of us. I appreciate you guys.

I just finished putting in an entire coolant system: radiator, pump, them., junction, pipes, hoses and sensors. I fired her up and she's running so I proceeded to follow the bleeding technique in the Bentley (no Libby bong). So far, I've added 4.5 gallons of Prestone phosphate free coolant. I read it takes 5 gallons. during this process, I have not heard the radiator fan turn on once. I did put in a new rad. Fan switch, resistor. Connections were sound last time I checked.

This is my question, would still having air in the system cause the fan to not turn on?

Thanks.

[greebly]

You can jump out the wiring to the switch, just unplug the harness and jump out two connections:
Cut and pasted from Ken Wilford cause it was easy:
w-to, very simply, trouble shoot the Radiator Fan system on 83.5-91 watercooled (non-diesel) Vanagons.

Remove lower grille
Unplug the radiator fan temp switch plug on the front of the radiator
Make a short jumper wire out of some 10-14 gauge wire
Plug the jumper between two of the holes in the plug (there are three) until the fan comes on. (I forget which holes but you can figure this out easy).
When the fan comes on, try swapping one end of the wire out into the other hole until you get the second speed working.
You should be able to have two speeds (low and high and you will be able to tell the difference as high is like huricane force).
If the two speeds are working then everything in the wiring is good (fan, relays, wires, plugs etc).
If only the high speed is working then your radiator fan resistor is bad and needs to be replaced. We have these in stock just give us a call.
Now run your van up to temperature.
Not far past the center on your coolant temp gauge (to the left of the LED) the fan should come on low.
If the fan comes on, then you should be OK. I don’t think you can get the van hot enough to check the higher speed just with the van idling.
If the fan doesn’t come on at all or only the high speed comes on at a higher temperature then your radiator fan sending unit is bad and must be replaced.

This is just a simple trouble shooting plan for this system but it works well and will tell you in a very short time exactly what your problem is and how to fix it.

Hope this helps,
Ken Wilford
John 3:16

[Tom Powell]

[davevickery]

I could be wrong, but I would say yes. When bleeding the system, the radiator fan turning on, is the indication that the system is 99% bled. It runs a little hot until the fan comes on, and the temps suddenly drops when it does. The next couple heat/cool cycles will burp a little more air and you can top off the tank and you should be good to go.

If the fan worked before, it is 99% chance it's fine and you just need to run the engine longer. Front end up on a slope or jacks, and around 2000 rpm has always worked for me.

[T3 Pilot]

bleeding cooling system can be so much simpler.....


http://www.thesamba.com/vw/forum/viewtopic.php?t=573302&start=0
_________________
1988 Vanagon

The most important part in every vehicle is the nut behind the wheel......

[86VaNa60N]

Greebly, Tom, Dave,

Thanks for the tips, I will jump the switch to confirm fan is operable. I'm hesitant to pull the new fan switch (GoWesty) since it's gonna be a mess but this may be necessary. Resistor is new as well (VanCafe). I'm hoping Dave is right and I just need to bleed the system more before it starts working.

Thanks guys.

[Tom Powell]

[86VaNa60N]

Update:
I happened to get about 5 gallons of coolant into the system after I filled the expansion tank to the max line. Fan still not turning on and the temperature on the dash gets up past the LED light pretty quick. I bled/burped several 4-5 times so I think I got it pretty good. So now I will start testing the fan components.

Side note on coolant used. Prestone - phosphate free
1. It has ethylene glycol
2. It was concentrate and recommended to dilute with water 50-70%. UUuuuuuuh I didn't do that... Not sure if this is the problem. I may have to remove some coolant now and dilute. I hate spacing out, it just creates more work.

Thanks Tom, I will be quick if I have to change out the "new" fan switch. I still have the old one too, however, there was no washer and it looks like someone used sealant on the threads.

[Tom Powell]

[86VaNa60N]

Thanks Tom, I was thinking the water probably activates something in the coolant. I better go buy some distilled water.

[Snort]

[Steve M.]

get yourself some fluid line clamps from harbor freight so you can squeeze the hoses closed so you don't loose coolant and generally make a mess, You can get the thermostat out easy enough without loosing much coolant. Same for the Rad. switch on the front, but you can also change that pretty quick just using your finger to block the hole. I have 2 sets of the hose clamps just to have the more of the large sizes for the bigger hoses.
http://www.harborfreight.com/automotive-motorcycle...65116.html

[86VaNa60N]

Hi guys,
This is what I did:
1. Drained off 1.3 gallons coolant, added. 1.5 gallon distilled water.
2. Drove to friends house (stopped 5x to kool engine). Engine heats up just below max line in 5 mins.

3. Noted pipes under van were cool while heater hoses were hot.
4. Bleeding is difficult since it overheats so quickly.
5. Tested fan posts - runs, ground reading was weak. (It was fine 1 month ago and this fan motoris 1 year old).
6. Jumped connector to therm switch - started fan - but it worked intermittently.
7. Jumped connecter to resister behind driver headlight - started fan 2 speeds
Again, it didn't work every time.

Conclusion:
1. Air trapped in all new hoses/pipes is inhibiting hot coolant to reach the radiator. Thus not triggering fan (pipes/hoses cold right off radiator).
2. Potential wiring issue off radiator harness or weak ground on radiator.

Next step:
1. Replace new therm switch with old one.
2. Possibly replace thermostat with old one.
3. Test new units in hot water.

Thanks for helping me along.
Noah

[atomatom]

i would suspect your thermostat - or, if serious engine work has been done, coolant hoses aren't on the correct pipes leading to radiator.

but... i would stop all this guessing and purchase an IR thermometer (as other tom suggested) and read the temp at (1) the radiator switch (which you have jumped to ensure the fan works - but... intermittently?!?), and (2) the waterpump/thermostat housing where the temperature your dash shows.

there are a lot of trees you can be barking up, but if it isn't actually hot enough to turn on, then you are trying to fix something that ain't broke. the main reason the temp gauge goes up is it needs more coolant or the coolant level sensor isn't connected properly... or you are on a hill trying to keep up with traffic.
_________________
84 Vanagon Westy, 1.9L, California raised but defected to Canada.

[86VaNa60N]

Hi Atom,
That's a good suggestion. I was wondering about the temp sensor.
That may be the 1st thing to test

If I'm getting a false high temp reading, that would send me on some wild diagnostics.

Thx Noah

[Tom Powell]

[pomfritz]

Check your ground. Mine was bad. Did a separate ground and has been working fine since.

Also make sure your system is fully bled, i.e. You get a steady stream of coolant out the bleed valve. Not just some bubbles and fluid.

Just speaking from past experiences.
_________________
83.5 233K. GW 2.3, SS exhaust, My German Frau named her Stefi

[atomatom]

the temperature gauge is used for two purposes. the temperature of the coolant at the engine (well duh!) and the coolant level. http://www.gowesty.com/tech-article-details.php?id=79

most times, if your temperature shoots up when you rev the engine or the engine isn't actually hot, then it is the coolant level in the pressurised tank (with blue cap). when you rev the engine, it sucks down the coolant level from that tank.

also, the coolant level sensor wire can become loose. when the wire isn't connected, the temp level shoots up and light blinks. this can be intermittent, but if you see the gauge rise quickly then pull over and check coolant level, if it looks ok and the engine isn't hot, then suspect the wiring.
_________________
84 Vanagon Westy, 1.9L, California raised but defected to Canada.

[86VaNa60N]

Alright everyone, I solved the overheating issues.

1. New Temperature sensor (GoWesty) was giving me a false high reading. Replaced this neatly with the old sensor and the readings are normal. I used an IR therm. Which was very nice.
2. Ground on the radiator fan was intermittently cutting out. Installed a large 2nd Ground large gauge which solved the fan issue.
3. Replaced the new thermostat with the old one as it seemed the pipes near the radiator weren't getting hot with the new thermostat.
4. Libby bong was applied and made refilling/bleeding soooooo much easier.

Now the van is running great with a low temp unless in traffic. Fan kicks in to cool down once the needle just passes the LED light.

As far as engine temps. Are concerned. I was taking measurements of 170-200 degrees F. At what temperature would you be concerned about melting the head gaskets? Just curious.

[Tom Powell]