Distant intermittent whine

Hey there, I have a 97 2.5 GT wagon and there is a distant intermittent whine, usually only after periods of highway driving (the speed limit here in Switzerland is about 76mph), but once it starts it doesn't end until the car cools off. It always stops below 10-15mph and is never present at idle and does not seem related to RPMs (revving the engine does not elicit it). It doesn't stop all at once, as the car slows it slowly stops like if one turned off a creaking/whining fan.

 

My best guess is the radiator fan as the whine is "distant" in the passenger cabin, but as I understand it, it doesn't come on unless the coolant reaches a certain temperature? The temp gauge is normal (around 25-40%) and the coolant was replaced a few months ago. The alternator was just replaced and the belt is about a year old so I don't think it is that? Turning on the AC and turning up the HVAC fan does not affect the issue. Annoyingly, I lent my code reader to a friend and I cannot retrieve it until the COVID-19 restrictions are over. There are no CELs and everything else seems normal.

 

I live in Switzerland (it is a US-model car) and a lot of our driving is going to/from high altitude.

 

Any thoughts?

Edited April 13, 2020 by 97gter

The cooling fans will spin in the wind at those speeds, but any slower and they won't. Between that and the A/C not affecting it, I would say the fans are probably not it.

 

It might not work with the language difference, but are we talking about a whine, a groan, a whir, a screech, a hum? Are you pretty sure it's coming from the front of the car?

Thank you for the reply! I'm actually American - just working in Switzerland and have our car with us. I can walk to work so we only use it for errands and excursions. So it is closest to a whine, although at times I suppose it can be a whir or squeaking. I think it is from the front of the car, although at times I am not certain. When slowing to 10-15mph it winds-down (ha!), and is loudest at around 20-25mph. At highway speed it sounds like a distant whine, but doesn't change sound, for example, if I accelerate from 50 to 70mph.

 

If I drive down a narrow street with cars parked on both sides and the windows down, it is rather loud in echo. I guess it could be one of the belt pulleys? There is no visible wear on the belts themselves. The timing belt was replaced in 2012, but it has been driven maybe only 30k miles since then. It has 168k and is bone stock except for the alarm is disabled and it has NGK plugs/wiring. It doesn't really have any creaks/groans otherwise so any new thing is very noticeable.

 

Naturally, sometimes it doesn't do it at all. It for sure is not doing it at idle, no matter how much I rev the engine and if I pop the hood while it is idling, nothing sounds or looks amiss.

Edited April 14, 2020 by 97gter

It seems to not be related to the engine if you can only reproduce when moving but not revving.

 

Driving next to walls on one side then the other if possible can help find noises. Best to have an assistant to drive while you listen so you can move around to facilitate the listening.

 

If you had a mechanic stethoscope it would be useful, but mostly in order to go forward you need enough cement blocks or jack stands to get all four wheels off the ground so you can try 'driving' it in the air where you can move around it and listen.

 

That is a fair amount of work and can be dangerous if you don't get everything securely lifted. The down side to this is the suspension will be unloaded and that can affect the results. And of course this won't show wind related noises.

My first thought would be check all fluids including front differential.

 

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If you have long screwdriver just put your ear on it like a seashell if you want to diag before you get the stethoscope.

It sounds like a bearing is going bad. Can you make the noise go away or change pitch by driving in a slalom?

All good suggestions, guys! So we've been driving it in the mountains to go hiking (which requires some highway driving between 70-80mph) and of course, now it is not making the sound. Twisty narrow roads and slaloming do not seem to elicit the noise. I will keep monitoring as I have no doubt it will return.