Noise when turning... Hmm?

[Jayce]

I just acquired a 2005 Saturn Relay 3 AWD. This is one of those crossover vans that has some SUV-like capability while being in the shell of a minivan. So far, I'm really digging the ride. I have had a great experience with it so far. Tonight was the first night I've had it since it was raining. Coincidence? Perhaps. But I noticed when in hard cornering in parking lots I hear a groaning sound. I did a quick Google search on my phone at a wifi hotspot during dinner and some people said it sounds like it's a loose power steering belt. Okay, fine. Later when I got home I went to the parking lot across the street and put the window down. I stuck my head as far out of the window as possible while still having my foot at the pedal. It sounds to me that the groaning sound isn't from the front. It sounds like it's from the underside of the car right around the middle.

Could this be something with the differential? After all, it's AWD, so it should be interchangeably using all 4 wheels with appropriate torque applications as it needs. I've never had a vehicle that wasn't a small front wheel drive car so I can't say I've seen this before. I did however notice in my parents Kia Sorento that if I'm in 4WD and I go into a sharp turn, the front wheels sound similar (yet still slightly different) when in slow, yet hard cornering.

Can anybody chime in with some ideas on the table? Perhaps things to check or should it be okay as is? Thanks!

 

[C0RR0SIVE]

Does this happen when moving, or sitting still? If both, it's just your power steering pump under stress trying to pump more hydraulic fluid than can fit into the space.

If it's only when moving, and in SHARP turns, i would think bearing, but you said it comes from the middle which could be where the thing splits power between front and rear, guess you can call that a differential.

 

[Jayce]

I don't hear it when sitting still. I only hear it when moving and making sharp turns slow turns. Like I said, my parents SUV in 4WD does something similar, but I'm not sure how comparable 4WD is vs AWD. After all, 4WD makes all tires spin at the same speed, while AWD is computer controlled and allows each wheel to spin at independent speeds. I wonder if the wet roads were causing a little slip at the tires that I couldn't detect and it was the differential somehow engaging in a way it doesn't when it's dry out? I see it's supposed to be dry and sunny tomorrow, so I'll do the same thing again in the same parking lot tomorrow when it's dry and compare...

If it's supposed to be like that, I'm fine with it. I just don't want it to be a warning sign that it's about to drop the transmission on the ground or anything like that. I didn't notice it the previous 2 days I had it when it was dry out, so I have to wonder. I've only had it for 3 days, but like I said, 2 of those 3 days were absolutely fine. The third day (today) = rain. Hmm... I wonder?

EDIT - Man I love IRC. I found myself in an automotive chat room and fired away. Straight away a user said "I have the same thing in my Buick Rendezvous. He informed me he had the dealership look at it while it was under warranty. The dealership notified him if often happens with vehicles that have certain rear differentials, and even notated the Corvette has been a bit noisy in that regard with its own differential. He said they drove the vehicle in reverse for about a half hour in tight turns and it made the noise go away for a while. I have no idea why or what this did but he said it temporarily helped for quite a while. The biggest suggestion to me was to check the rear differential fluid, and that there should be a drain plug and fill cap underneath the vehicle where the rear differential resides (not underneath the hood like most fluids). I'll check my owner's manual tomorrow to see exactly what kind of fluid it needs, then I'll poke around and see if it happens to be low or something like that. Who knows, but it's at least a lead. The overall consensus was "It's not life threatening to the vehicle, but it's something worth looking into to make sure." I'll report back with findings...

 

[C0RR0SIVE]

AWD is basically the same as 4x4, but as you said, slightly different, it's not fully controlled by the computer, what you will typically have is TWO differentials, you have one for rear one for front normally inside the transmission. Your transmission on the back end has an output shaft that goes to your drive shaft, that goes to your differential. On that output shaft, inside the transmission you normally have a set of very heavy duty chains going to a shaft that moves power to the front end differential. The differentials are almost always going to allow "slip" that's what enables you to turn a car sharp enough, and allows all tires to spin at different speeds, thus eliminating skipping.

Typcial differentials use a HEAVY oil, something like 80-90w gear lube, some that do have electronics use special fluids, the stuff STINKS, is VERY thick, and rarely leaks out or runs "low" due to how thick it is, even when hot it is very thick stuff. I remember driving a Ford that had AWD support, was computer controlled, and would do funky things at times in turns, would also get strange noises, was just because of how it worked in the end. The only reason I think throwing it into reverse and going through things is because the gears are not properly seated or something, thus causing them to wear down a bit and sort of "set" into each other slightly differently eliminating the noise.

 

[Jayce]

Thanks for the detailed response. I'm starting to see the whole picture now behind this. Based on what you said about your Ford, I'm beginning to wonder if it's just the nature of the beast when you have an AWD vehicle that sometimes noises are just part of the way it's made. Is that what you are suggesting? Considering the vehicle's age/mileage, I kind of doubt anything serious is going on (2005, 53k, and very babied from original purchase), but I suppose anything can happen.

I'm wondering about that last line you fired out about the gears wearing. Is this to suggest that the gears are physically wearing down into a certain pattern? Similar to how brake pads on a bike wear down lopsided if you put them in offset? Is the life span of AWD transmissions any different from other automatic/4WD vehicles? Some reading I was doing suggested if anything, AWD was, by design, "supposed" to give you the best chances of a reliable transmission since the independent operation of each wheel would allow everything to work smoother, whereas 4WD would be a little more stressful on the overall transmission. Any opinion of that?

If you were in my shoes, what would you be doing? Checking the differential level just for the sake of making sure it's good to go would be my first thing... but if that's good... do I just ignore it? Or is there more troubleshooting I can do?

Just to recap, I'm fine with it if it's designed to be like this. I just want to make sure this isn't a warning sign for bad things coming.

 

[C0RR0SIVE]

I would drain the differential fluid and put fresh in, I have no opinion on AWD transmissions vs 4x4. And yes, the gears get worn just like your brakes and rotors do, they wear together, and usually this means a stronger connection, but in some designs can mean a noisier system. As long as you don't have metal chunks in your fluids, you are fine, there will always be a very fine metal coating on the inside of differentials from wear and tear and it's normal.

The reason I have no opinion on AWD vs 4x4 systems is because I have rarely drove such cars/trucks/suvs, as I have no need for them.

I think the noise your hearing, is a differential trying to allow the "slip" and it's having difficulties doing so. It would be worth checking, I am unsure of your vehicle, but most all cars/trucks that are rear wheel drive, don't have just a drain plug and a fill plug, they have a full sized opening allowing FULL access to gears, this is the only way on most to drain them, is poping that cover off, let the fluid drain out, locate the fill port, open that, put your cover back on with the proper gasket or sealant, and fill back with gear lube. I have only serviced two differentials, they are easy to do, but the stuff is just THICK and stinky, the fluid doesn't really wear out over time from what I notice, though it does get nasty and full of that fine metal from the individual gears seating together over time.


BTW, there may be more trouble shooting you can do, but where you are AWD, your going to have multiples of different systems (such as 2 differentials), and I am not really familiar with them as I have never worked on them, just going on what I know from 2x4 and 4x4 systems on a few cars. It might be worth it to pick up a Haynes or Chiltons (Both are owned by the same company, Haynes is now superior with pictures ) and see how you go about changing differential fluid and such on your car, and when it should be serviced if at all.

EDIT: I wanna make sure of something, earlier I asked if this happened when sitting still, or only when moving and such. Can you confirm this DOESN'T happen when turning hard left or hard right, while sitting still, just moving your wheels? If you get the SAME noise, it's your power steering pump.

BTW3.0: I honestly think, if your turns are hard ENOUGH, that a differential may not fully stop one wheel from spinning, and having the outside wheels spin fast enough, causing the noise as it's having difficulty doing that. The noise could also be gears rubbing together getting seated since you sad this thing has been babied. (Babying a car is in some ways BAD at times)

 

[Jayce]

Well, I meant babied from the fact it was serviced at proper intervals and wasn't drag raced by a 16 year old. The car was owned by an older man, who's son in law is a mechanic of 32 years or so, and he's the one who serviced the vehicle. Since I know this mechanic (good friend of my dad) I feel confident when he says the thing is in tip top shape. But again, it's still a car with a thousand moving parts - anything is possible I suppose.

The vehicle does NOT do this noise when I am sitting still and turning.
The vehicle only exhibits this noise in very tight turns when the wheel is literally 97-100% as far as it can go to either the left or right. As a result, the only time I notice this noise is when I am in a parking lot of some sort. Otherwise I'm never in a situation where I'm turning steep enough to cause the noise.
The noise from the vehicle is coming from the center-ish of the vehicle on the underside. By popping my head as far out of the window as possible while still being able to control the gas/brake, I was able to tell with a rather obvious determination that the noise is not coming from the front and it is indeed "behind" me from where I was sitting in the driver's seat.

When I drove the vehicle today, it made no noises whatsoever at first. It was still damp out as if it had rained recently, but the van's exterior was bone dry to the touch. I did a couple circles in a bank parking lot and noticed no issues, whether I crept around tight turns or gave it a little extra gas. Eventually I began to hear the sound somewhat there, but not nearly as loud as yesterday. At this point the van would have been warming up a bit. Whether it's related or not, I'm not sure. Just posting observations. Even still, these were tight turns pushing the very end of the turning radius as I was turning left or right.

I also made it a point to note the feel of the steering wheel. I didn't feel any jerking, hesitation, or anything like that as I went through tight figure 8's in the parking lot. On my other car, if I do a figure 8 quickly enough, when I am returning from the wheel being one direction and quickly try to turn it the other direction, I feel a second's worth of hesitation until the power steering pump "catches up" with me (that's what it feels like at least). But this van was very smooth, shifts smooth, turns smooth, etc. It's literally JUST the noise.

 

[C0RR0SIVE]

Honestly, I think it's just noise, it's gear related most surely, as they do get pretty hot after a bit, but only due to spinning so fast in the differential. I honestly don't think it's a major issue, I took note on a town car that has a very large differential, and it makes some very strange noises at times, I inspected it and it was perfectly fine, just normal wear on the gears, and some really old nasty fluid. Maybe a fluid change can get rid of it if your differential requires a special type of additive that wears down as it ages. Most differentials use like 2 of the large bottles of gear lube, but, with out me having a book on your car, I can't really tell ya.

Now that I typed that all, and re-read your last post, you noticed this again, after a little while of driving, with it getting warmed up, sounds like the gears are getting hot and the fluid may not be doing its job at lubricating and helping cool the gears some? I would call up that one guy, and see what he thinks, I mean, a gear lube change is cheap, about $20 for lube, $3 for sealant, and if it uses an additive maybe 5-10 bucks, I ain't no certified mechanic, nor have I worked around differentials/transmissions much, but I have some know how around them to kinda guess out.

 

[Jayce]

I have read that the vehicle has a self AWD turn-off feature with the differential if the differential lube overheats. I have seen no indication that the system is overheating. The trial this morning was done from a cold start. The vehicle sat turned on as I threw two bags in the back and then drove a half mile to the bank where I began doing turns. The vehicle was not turned on long at all, but I did several figure 8's with no sound, then I began to hear a distant reminder of the sound surfacing again. It never got as worse as yesterday, but considering I knew what I was listening for, I picked up on it. Had I never heard that noise yesterday and did this trial today, I probably wouldn't have ever second guessed it.

I'm going to look into doing a fluid change, or at the very least learning more about it from a dealership that may have some know-how about this particular vehicle. Nonetheless, curiosity was sparked and here we are. The vehicle is new to me and has a ton of potential as it has extra room and seats for kids that may be here before we know it. I'd much rather have kids in the Relay than my Elantra, so it'll be a nice addition that I want to keep running in great shape.

I'll post back with any info I receive. Your help and insight is greatly appreciated.

EDIT - I just called a local dealership and gave them the run down of what I was experiencing. He said it indeed sounds like it needs to have the fluid changed. He said on average, they see 50k mile lifespans of the fluid. He said this prior to me telling him I have 53k on it now, which meshed up to that comment. He said it'll get worse over time and I'll begin to notice it happening all of the time instead of just the rare times in the parking lot when I make tight turns. He said the sharper you turn, the more pressure the internal clutches are under, which is where you see issues forming first before they trickle down accordingly to all-of-the-time general purpose driving. He said cost for parts and labor to get the fluid flushed is approximately 200, with the fluid being 4 bottles worth @ 30 per bottle.

One thing I found strange that he said is there are times where a 2nd flush is necessary immediately following the 1st. He said there have been times where they've done a flush and driven the vehicle in numerous figure 8's and it make no difference, only to follow it up immediately with another flush and it work fine. He said after the 2nd flush if the problem continues, it's likely that there's internal issues with the gearing. He said considering the age of the vehicle (and mileage since I then told him) he thinks it's just part of the normal wear and tear. This was a generic dealership that specializes in an array of GM brands, and said he's seen identical results in the Pontiac Montana as well as a Buick van (but the name slips my mind), all 3 of which utilize the exact same differential design.

He commented on the design saying it's very robust, but like oil to a car, it just needs proper maintenance to ensure longevity. Considering the van is a 2nd vehicle, I'll likely tinker around online in the next 2 or 3 weeks to find more information about fixing it on my own. Difficulty wise he suggested that it's in the area of an oil change and that someone with basic expertise can handle the task fine. The only advisement he warned of is just like oil, it needs the proper amount. Not too little or too much... but the proper amount. He also mentioned I might need to invest in a tool to syphon some of the fluid out that might be laying in the bottom of the pan.

Nonetheless, even if I get a dealership to fix it, the labor isn't exponentially higher to warrant doing it myself anyway, so it might not be a bad gig to get it done there. I'm glad I took the time to Google around, ask here, and call the dealership though.

Sorry about the book report of a response, but I wanted to notate everything I experienced since I noticed this thread is one of the top hits on Google when I search for this problem. That way if anybody else stumbles across it, a book report is available for review to the user.

 

[C0RR0SIVE]

Interesting info, I wonder if he is talking of your transmission fluid though... As you don't normally flush a differential, at all, ever. 50k miles is right for transmission fluid.... I should pick a book up on this particular car. I would probably go ahead with an actual flush right now if I was you, a LOT of people are AGAINST flushing any system that deals with transmissions/differentials due to how sensitive they are, but the old wives tales are being proved false, mostly. A transmission that has never been serviced, might benefit from fluid swaps, but would be destroyed with a flush, but a transmission that has always been flushed at PROPER intervals, and filters changed will normally handle a good flush at any other point in its life as long as it's done on time.

Still, strange to hear 4 bottles of gear lube @ 30 bucks a bottle is a bit steep, for any gear lube, even with additives. But that's a dealerships price, and I am sure if anything bad happens then they can't play the blame game on using inferior fluid.

Honestly, if ya buy one of them haynes books, they list the exact fluid your van (what do you really call those things these days?) would take, how much, and exactly how to go about servicing it your self. The more I read that post though, the more I feel he is talking about flushing the transmission.... Because differentials don't have a pan, but when filling them, you do need a tube to help get the fluid inside them. And it is just like motor oil, too little and it over heats the gearing or can foam up, too much and it foams up really bad, and no longer does its job.