Rad fan question

[Tinman]

In another thread, I mentioned my rad fan doesn't work.

On my last trip out, the selenoid melted and the rad fuse melted slowly, causing the rad fan wire behind the fuse to overheat.

Pulling out the wire (light blue/red) it's the same wire that works its way to the fan motor. I can connect it to the positive terminal on the battery and the fan works fine.

Here's the issue - replaced the fuse and selenoid and the fuse popped. I'm guessing a short somewhere, but I can't find it. Here's what I did:

I pulled the harness line all the way to the fuse box. This harness includes:

fuel pump wiring,

oil pressure sending unit

Ground

water temp gauge

rad fan

I continuity checked all these lines and cross checked them, seeing if continuity leaked somewhere else. No continuity leak anywhere.

and a separate line branches out, which I can discount for a short for this reason:.

I disconnected everything on the main line and connected everything but the pump one by one. The fuse never blows when turning ignition on except when the rad fan is connected.

As you know, the plastic hose wrap is one piece, so to visibly check the wires is difficult, but I'm guessing there's a short in the rad fan motor. However, the rad fan works when connected directly. This leaves me stumped. Should I get a new ebay fan?

[Guest Lenny]

Disconnect the fan wire at the fan and at its other end. Now check for shorting to ground on the wire. If you undo part of the wire harnes, when putting things backtogether, don't tape the plastic loom arpund the wires and do'nt tape any junctions. Instead, use tywraps. That is the way mine is. When I need to get at wires, I just snipp tyraps. Much easier to work on. I also ran a 1-1/2" piece of PVC pipe from the front to the rear making adding wires or working on those wires much easier too. Sounds like your fan is ok. Maybe just run a new wire to the fan and forget the old one.

Lenny

[nocturnalsixer]

If you have a multimeter u could turn it to ohms (omega symbol) and then put lead on one end of wire then put the other lead on the other side of the same wire and if 0 come up on multimeter the wire is excellent and if there's numbers the bigger number the worse, ol or error mean short or open in the wire

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[Tinman]

Thanks Lenny, you pull through as always.

Actually, I think I found the issue, and it was after I checked against grounding as you suggested. It's dark now, so I'll work on this tomorrow.

My new replacement bosch relay has 86 and 30 switched compared to the old relay. I plugged in the wires thinking I'd put them in the same spot without actually checking the pin numbers. I had no idea these can be different from relay to relay. In fact, while searching bosch relays on the web, every example I found has the pin numbers the same as the old joyner relay. My new bosch relay is def different...

[Tinman]

If you have a multimeter u could turn it to ohms (omega symbol) and then put lead on one end of wire then put the other lead on the other side of the same wire and if 0 come up on multimeter the wire is excellent and if there's numbers the bigger number the worse, ol or error mean short or open in the wire

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Ahhhhhh... I'll check that too come tomorrow...

[Tinman]

Is the stock rad fan known to fail?

Trying to decide if I should replace. Everything is working now, but the fuse did blow...and relay...(likely water entering - won't happen again)

[nocturnalsixer]

I'm not sure if stock fan fail often,

Once i had a fan fuse blow on me, and also had my ecm fuse blow on me 4-5 times after long drive and the trooper get really hot.

I still don't know why it happened.

I haven't gotten to looking around i just replace fuse as needed I'm lazy but i plan on getting down to the bottom of it

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[nocturnalsixer]

Is the stock rad fan known to fail?

Trying to decide if I should replace. Everything is working now, but the fuse did blow...and relay...(likely water entering - won't happen again)

Did your relay have some rust or copper rust (green stuff) inside the relay? That would indicate it got wet

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[Tinman]

Near as I can tell, both the fan and fuel pump wires get too hot inside the fusebox. The new fan relay feels hotter than the other relays too, but it could simply be the fan pulling more amps. Things have gotten hot enough to damage some wiring and fuse connectors, which in turn heat things up even more. I'm adding external fuse holders to see how things turn out.

I'm suspicious that the fan is pulling too many amps, possibly from some internal short, but I can't be sure.

Just in case, I'm ordering this:

http://www.ffdynamics.com/FFD14B.html

QUESTION: When i start my engine, my fan turns on and stays on, which is weird. When a water temp sensor fails, the fan usually stays off until the engine overheats.

[Tinman]

No green on the terminals, and other than burned wires, nothing seems to indicate water...

[nocturnalsixer]

QUESTION: When i start my engine, my fan turns on and stays on, which is weird. When a water temp sensor fails, the fan usually stays off until the engine overheats.

On my trooper, any time the key is in on position my fan runs at all time

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[Tinman]

Huh. k. $100 plus shipping for new fan... makes me think. Might try a longer ride tomorrow to see if anything goes funny...

[Guest Lenny]

Here is what I went with. http://www.ebay.com/itm/16-Street-Rod-Radiator-Electric-3000-CFM-Fan-Reversible-Heavy-Duty-NEW-250-W-/270996600203?pt=Motors_Car_Truck_Parts_Accessories&hash=item3f18a7f58b&vxp=mtr

The bigger diameter giver better spread over radiatior and only $50

Lenny.

[Tinman]

Lenny,

does the fan motor you purchased on ebay tell you the amps it draws?

[Guest Lenny]

I can't remember but I really didn't give it much concern. I currently run two fans, one for the radiator and one for the aftercooler. I also run two fuel pumps, one for prepressuring the system and the main fuel pump. Both fans and fuelpumps run all thye time. I still have the stock alternator but I do run an optima marine battery so I keep plenty of reserve. The battery never runs down from normal use. My air compressor which draws about 10 amps runs every hour or so when on the trails because of a small leak I have in the system which I havn't fixed yet. I maintain aprox. 150 psi air pressure in a 3 gallon air tank. The only reason I use the Optima battery is so I have the extra security of always having starting juice when out in the middle of nowhere. I'm not convinced that the extra current draw of a bigger fan is an issue.

Lenny

[Tinman]

I've double checked everything I can think of, and can't find the reason for the fuse to keep melting, except for the fact that all I can buy here are cheap chinese fuses. It could simply be this. The fan motor was very hot after about 10 minutes of use. This might be normal, or not. I have nothing to gauge it against. It was uncomfortable to hold, but not impossible (I have thick calluses).

To date:

Replaced burnt ends,

moved one fuse out of fuse box (damaged box)

Tightened fuse clips

upgraded fan fuse to 30A (still really hot)

New fan relay (bosch), also gets hot

checked wiring to fan - nothing

Have purchased:

New fan

new fuse box

will be purchasing decent relays and moving relays and fuses over to new box / setup

[Tinman]

I can't remember but I really didn't give it much concern. I currently run two fans, one for the radiator and one for the aftercooler. I also run two fuel pumps, one for prepressuring the system and the main fuel pump. Both fans and fuelpumps run all thye time. I still have the stock alternator but I do run an optima marine battery so I keep plenty of reserve. The battery never runs down from normal use. My air compressor which draws about 10 amps runs every hour or so when on the trails because of a small leak I have in the system which I havn't fixed yet. I maintain aprox. 150 psi air pressure in a 3 gallon air tank. The only reason I use the Optima battery is so I have the extra security of always having starting juice when out in the middle of nowhere. I'm not convinced that the extra current draw of a bigger fan is an issue.

Lenny

How do you run the fans - as a pusher and puller on each side of the rad?

[nocturnalsixer]

I've double checked everything I can think of, and can't find the reason for the fuse to keep melting, except for the fact that all I can buy here are cheap chinese fuses. It could simply be this. The fan motor was very hot after about 10 minutes of use. This might be normal, or not. I have nothing to gauge it against. It was uncomfortable to hold, but not impossible (I have thick calluses).

To date:

Replaced burnt ends,

moved one fuse out of fuse box (damaged box)

Tightened fuse clips

upgraded fan fuse to 30A (still really hot)

New fan relay (bosch), also gets hot

checked wiring to fan - nothing

Have purchased:

New fan

new fuse box

will be purchasing decent relays and moving relays and fuses over to new box / setup

How thick are the electrical wires for the fan? Stock gauge? If so u should see if the wires itself get hot,

I plan on redoing my rad fan wiring with 10ga wires and the hot lead will come from alternator post to supply 14 volts instead of 12 volts to fans and use a 30 amp relay per fan as well when i get a new radiator

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[Tinman]

Huh. Never thought of that. I'll check wiring tomorrow when I use it again...

[Guest Lenny]

How do you run the fans - as a pusher and puller on each side of the rad?

The fans are both pushing. The rad fan, only one, is inbetween the engine and the rad. The intercooler with fan is mounted sidewise inbetween the intake manifold and the left rear shock. Pushing the air thru the rad is always better.

Lenny

[Tinman]

So that means you got rid of the aluminum shroud that the old fan was bolted to... Did you see an improvement with the new fan w/o the shroud?

You mentioned intercooler. Are you running a turbo? Ir is this an oil cooler?

[nocturnalsixer]

Lenny is running a roots style supercharger Aftercooler is for that..i believe

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[Guest Lenny]

Yes, as nocturnalsixer said, I run a supercharger. I eliminated the original rad shroud and built a new one when I went to a bigger rad.

http://good-times.webshots.com/photo/2529612320104928832zFKacA

Lenny

[Tinman]

Lenny, you DAWG! That thing must fly! Did you change the gearing on the tranny to compensate for extra boost at your low end, or is the gearing stock?

[Guest Lenny]

I went to Renegade differential gearing which is about 7% lower for more low end torque in the rocks. I do however run 31" tires so I'm actualy overall geared a bit higher then stock. I didn't gear down for more power but to be able to go slower thru the nasty stuff and at low rpms. I also have the torque cam from SilverBullet. Wished I had a low range for the rock crawling stuff.

Lenny

[Tinman]

For those replacing the water temp gauge with an aftermarket, the sending unit for the dash gauge is at the rad, lower right. The one at the head must be for the ECM...

This is not ideal as the coolant has already been cooled, but hey.

[Guest Lenny]

There is room on the front of the head to add a second temp sensor. You have to drill and tap for it. You can see where it will work by taking the existing sensor out to see what and where inside stuff is. I did this on mine when I switched to the megasquirt ECM.

Lenny

[Tinman]

The front of the head is so much better, with a more accurate reading. The sensor is on the left of the head. Did you put yours on the right?

[Guest Lenny]

Don't know which one I added anymore but one is above the other. The upper one is about 1/8" to the right from straight above.

Lenny

[Tinman]

Ahhh. My new gauge has a 1/8 TP fitting, so it's nice and small. I've got it on the rad, but I'll move it after my trip home. I can bring tools and all my taps, an issue that has been driving me batty.