Hmmm....looks like my fan might be on the way out.

I've noticed recently when crawling that I could hear the fan at lower engine speeds but the sound goes away as the rpm increase. About what you would expect on a hot day, but more pronounced than I remember.

This weekend I noticed that on cold start up the fan seems very loud but as it warms up it becomes quieter. Not silent, but less loud. Again, this is more or less what you would expect from the thermo-clutch of the fan but it's more pronounced than in the past. It's pretty loud.

I've never actually had to work on a fan clutch before and I confess I haven't done any real diagnostics beyond 'hmmm....that seems louder than I remember'.

Any pointers for t/s'ing the fan? I'll be home again this weekend and should be able to take a look at it. I've got a week-long trip in the Sierras coming up soon, so I'm keeping an eye out for potential issues. The trip won't involve any serous wheeling, but a fan issue could be trouble regardless.

 

What kind of sound are you getting from the fan? In my experience, if it's just a roaring, like the fan is working extra hard, then it's typically been a coolant, thermostat, or temperature sensor issue for me. I would look at checking/troubleshooting those items first.

However, if it make a different sound (don't know what since I've never had the fan go bad), the I suppose the fan could be to blame. I don't know how to troubleshoot it, but replacement is about a 10 minute job assuming you have the right tools - 36mm fan wrench (I think) and the pulley holder. If you don't have those, I've had great luck using an air hammer on the side of the nut that would cause it to loosen.

 

It sounds like your typical 'whirring' of a fan working too much. I suppose it could be a bearing going bad making that noise but the fact it seems to go away as the engine warms made me think fan. When I get home again on the weekend maybe I'll try to take a video w/sound but I travel for work so I won't see the truck again for a few days.

I actually ordered the fan tools and belts/tensioner last night as I figured if I was going to be in there I might as well do that stuff as well. I did a quick search and found the fan was $300 (!) which shocked me. I might be inclined to pick one up from British Recyclers if they have one as I don't think I've heard of many people having problems with them.

As far as testing, I'm wondering how 'stiff' the clutch on the fan is. i.e. can I hold the fan still while the engine runs. That would certainly tell me if the fan was making the noise. Like I said though, I haven't opened anything up to look at it yet.

 

I might add, that sometimes the fan just "does its own thing" on the LR3. There have been many times that the fan just starts working, seemingly extra hard, and then just stops whenever it wants to. This usually happens when I've been driving at slow speeds for a long time, especially with some idling mixed in (think driving on a trail, waiting for others, then driving slowly again, etc).

There were various posts about it, after which I determined that it was just a characteristic of this engine. I stopped worrying about it.

 

Since the fan is a electronic clutch, the ECM will control when the fan turns on and off. The ECM will also montior coolant temp, fan speed and engine rpm to calculate the correct engagement of the fan. The ECM will store a p0480 Fan error if the computer sees a problem. Take note of when the A/C is on. You don't have a condenser fan. When the A/C is on, this fan is required to run more frequently to cool the condenser.

Autologic and SDD has self test for the fan.

Old fashion test of a fan- cover the front of the grill will a blanket or fender cover to restrict the air flow. This will cause the engine coolant to raise in temperature. Monitor your coolant temp on the dash and remove the blanket when you notice an up tick in the gauge. You should hear the fan engage if the clutch is working correctly

 

Most belt driven fans are fairly loud on cold start. I'm not sure exactly why, but they do roar a bit during the first acceleration. Something I had to get used to coming from cars with transverse engines and electric cooling fans.

The ECM also has a lot of control over when and how hard the fan comes on as mentioned, so if it was exceptionally hot or there was a lot of stress on the engine, the fan will engage more, creating more noise. It's not just an off or on (or low and high for that matter).

I wouldn't worry too much about it unless you start to notice overheating.

 

This ^

I would be more worried about the idler pulley, etc.

 

I'm not overly worried, but it does seem to be louder and more frequent than in the past. Then again maybe I'm just being overly sensitive to it now. No real overheating problems, though I did see 240 on the GAP tool while slowly climbing trail to 10,000'. Also had a vapor lock (?) at that time that caused the truck to die but it re-started after cooling for 10-15 minutes. I think the relatively rapid climb from about 7000 to 10,000 in hot conditions caused that a couple weeks ago and I've been paying closer attention to the cooling system since.

BTW, I'm hardly the first to see the 'vapor lock' thing. I know several of the SoCal guys have had it happen in similar circumstances. I'm calling it vapor lock, though I don't actually know what it is. It self-clears and doesn't throw any codes, so not a huge worry. It's only happened to me the once.

Also of note, even when I was showing 240 on the GAP tool the dash gauge was right in the middle. Super-accurate there.

 

Yeah most temperature gauges on modern cars will not move from normal until the coolant temp is well outside of normal ranges. It's really just to tell you when the engine is cold, warmed up, or when it is about to blow a head gasket.

 

Did it die while under load? Or were you idling and/or braking?