Depends on where the coolant landed. If it landed on top of the metal splash plate under the trans, there's a pad that is used probably for sound deadening. It also act like a sponge soaking up oil drips and perhaps in your case the coolant.

The 4.4 doesn't have the acoustic pads on the splash plate. I think a week is too long for it to be an old spill

Thanks for the input here. Hopefully others will chime in with their thoughts on running temp.

By electric fan, are you referring to the auxiliary fan?


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Yes, auxiliary electric fan. Most E53 X5 have a mechanically driven fan and the Aux electric fan. But, there is at least one variant with only the Aux electric fan.

If you are standing in front of the car, you should hear the aux fan if it turns on at high speed. It is crazy loud. Low speed is a little more subtle, but not silent.

I'm pretty sure mine isn't kicking on, I'm bringing it back to the mechanic tonight to have him replace that. This was already known, could be the main issue though.


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The aux fan should kick on when the air conditioning is turned on. The aux fan should also run a self test when the engine is first started so it runs for a short time then. You may have a clutch fan going bad. If the fan turns easily by hand when the engine is at operating temp it is an indication the clutch fan is dying. Now that the cluster is unlocked you can monitor temp easier and verify the gauge is accurate. The normal thermostat controlled operating temp is 225 degrees. That is not necessarily the optimum performance temp but what is needed to be in compliance with emission standards. Sometimes when an engine is marginally overheating you can smell coolant that is forced out at the weakest link (should be the cap) but it is a small amount that is not visually evident an takes a long time before it is obvious the coolant level is low. Before replacing the aux fan be sure the temp sensor is working. The fan can be fine, just not getting the message to get to work.

I know you've mentioned coolant smell....just a thought.......how's your engine oil?

It seems like all the usual suspects have been covered in this thread already. I would just like to add a couple of things. As far as the temperature reading goes, it's not too high but those temp senders are notoriously inaccurate. What's more important than the actual temperature reading is the fluctuation while driving. If it reaches operating temperature and plateaus then things are working correctly. Sudden spikes or uneven temperatures will indicate things are not working right in your cooling system.

A pressure test is good to find leaks, but occasionally leaks show up only when all the parts are hot. It's infrequent, but does happen. They are extremely hard to track down and not worth the effort. If you aren't losing much coolant and it's not over heating, I wouldn't worry about it. It will either get worse and show itself, or get fixed when you change a part during maintenance.

Valley pan gasket or gasket behind the bell housing? Those don't always show themselves leaking... but still smell obviously.