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Subaru forester VISCOUS COUPLING (coupler) Manual transmission

i have a 2003 subaru forester 2.5x (the low end basic model) and recently it with make a horrible clicking noise when turning (more than a quarter turn of the steering wheel).

my initial though was a CV joint issue (having had this happen on an 87 subaru wagon) but it only happens after 20+ miles of traveling…so when it’s hot.

i brought it to my repair shop, they said it was probably the viscous coupling and not to worry about it.

well, it has been irking me.

first, should i worry?

second, any idea on the cost to have this fixed?

I am not a Subie guy but I know the viscous coupler is something to worry about. What have you found in regards to a service interval for the coupler?

there is no reference to the viscous coupling in the suggested service intervals i have seen.

maybe i can just replace the center differential?

Yes, you should worry, and you should find another repair shop, preferably one with more knowledge of Subaru drivetrains. Noises and/or binding indicate serious problems.

You didn’t tell us the mileage on this car, or whether it has an automatic or manual transmission. This is important information. Read your owner’s manual; you’ll see.

I suggest you have the transmission lube/fluid and the lube/fluid in both differentials replaced ASAP.

And as far as the cost goes, the longer you delay this the more it will cost.

i brought it to my subaru only repair shop.
any suggestions for one in the boston area (i’m willing to drive a distance if they are good).

sorry about the omission.
it has ~133,000 miles on it.
manual transmission.

i have had the fluids changed about 4000 miles ago.

Did the shop check the fluid level or condition in your rear differential? Changing rear diff(regular service item) it would be my first move if any noise is coming front in.

changing the rear differential is a regular service item?

i know changing the FLUID for the rear differential is a regular item and has been done a few times since i have owned the car.

I am having the same exact problem with my 2003 manual transmission Subaru Forester (2.5 model, as well). Oh, and it has 74,000 miles on it. I, too, thought it was the CV joints. It just started doing this two days ago.
I took it the the shop today and they couldn’t locate the problem just by lifting it and looking at it (so I am doubting the CV joints). They told me to drop it by tomorrow morning and they are going to really investigate it. The first thing he said they would look at is the rear differential fluid.
I started looking here to get more info and discovered this post. I am curious if you ever found out what the problem was and how much it cost?
Thanks very much, I appreciate it!

I have a feeling the “VISCOUS COUPLING” is what most people call the center differential. The weak knee of AWD vehicles…

i have yet to find a solution.

the last time i did have the rear differential ‘serviced’ was at a valvoline oil change place about a year ago.

i was going to poke around and see about changing the fluid myself. i hate those quick oil change places and have decied to do my best to avoid them.

logically, bear in mind i AM NOT A MOTORHEAD, it seems the fluid is fine at cold temps, then after warming up maybe it breaks down and no longer works as it should. sorta makes sense. gets cold and more viscous and the cycle continues.

a local VW specialty place said he’d take a look at it, but didn’t say a price. and neither did my regular subaru specialty place (neither one dealerships). but as i mentioned before my subaru place didn’t seem to want to fix it.
it sounds horrible. people look it’s so loud.

luckily i have not been driving it much as of late just due to biking more and having another car to use for two weeks.

please post what you discover!

probably true.

my friend’s astro van AWD has a similar problem. not sure if it’s exactly the same.

All of this leads to the inevitable questions:

Are all 4 tires of the same brand, the same size, and with the same number of miles of wear on them?

Were the tires rotated every 5k or every 7.5k?

If the answer to either question is a “no”, then you have the source of the problem.

Sorry you haven’t found a solution yet!

We live in Houston, Texas-it gets a little hotter than normal here :). So, the heat factor could make sense.

I am no motor head, either-by any means. I quit my job about a year ago and money is a little tighter, so it made me a better investigator. I no longer just drop it off at the shop with little to no idea what is wrong. I nudge around on the Internet until I, at the very least, have a better understanding of the problem (or the possible problem).

I’m dropping it off tomorrow at I place I trust (ie-they haven’t been dishonest yet), and I will let you know what they say (maybe it will help you figure out what you need to do for your Subaru).

I may try to get under the car tonight to see if I can see the rear differential, but all the diagram/photos I’ve seen so far-it doesn’t look like you can actually see the fluid-you have to unscrew some stuff and let it drain. So, I don’t know how to tell if the fluid is actually low or not? Back to the Internet!

Thanks for replying and I will let you know what I find out!

I don’t know about the OP (brandwashed), but my tires are all the same brand and were all replaced at the same time (I was told it is important to change all four tires at the same time due to the four wheel drive?). And, I rotate them religiously every other oil change (which was not even 3000 miles ago). Also, I checked the pressure and that wasn’t it, either-they all seem to be filled to the recommended PSI limit. I so wish it was the tires-that would be a nice, quick fix! :slight_smile: Thanks for the suggestion, though.

yeah, my tires are exact. now bridgestone potenza G009s.

it came from the dealer with four matching yokohamas and the spare was something else. but i’m reluctant to believe that my driving for 200 miles with one mismatched tire (of the same dimensions) would cause the issue especially since the issue didn’t start until years later. so if blow a tire you can’t use the spare because the width is slgihtly different due to one being new and the rest being worn? i find that hard to believe. if it were the case, those who are less apt to check tire pressure and tire wear as i would also have crippled subarus, and there would be a great many clunking on every hard turn.

i understand the logic behind the tires being the same (which they are in my case) but the treads wear at different rates and i have many friends who have foresters and do not have this clunking/clicking issue, despite their less than vigilant tire rotation and matching.

Yes, driving for 200 miles with a mismatched tire can cause this problem, even if the problem does not become apparent until sometime later. The temporal spare is only supposed to be used for a maximum of 50 miles, so it is not likely to be a source of this problem.

Yes, tire treads wear at different rates, but if the alignment is correct, and if the tires are regularly rotated at the same interval (5k or 7.5 k), the slightly uneven wear is “evened-out” sufficiently to avoid problems. Your friends may not have experienced problems yet, but they will.

i called local dealership.

they will replace the coupler for $1700-1800.
assuming that is the issue.
i have not shown them the car’s issue yet.

I just got my Subaru Forester 2003 (138K miles) back today after taking it in for this exact same issue. The diagnosis: viscous coupler/center differential. My symptoms matched yours to a tee. They charged me $1250 plus tax to repair it. I did the repair because I’m giving this car to my son in a few months after I get my new 2010 Forester. The dealer told me that this issue and the head gasket issue are the two biggies he sees on Foresters of that age/mileage. And since I just did the head gasket replacement about a month ago, I seem to have taken care of the major anticipated issues this car would be facing in its lifetime! So, hopefully all my son will have to worry about will be the “little stuff”.

Just wanted to chime in with an affirmative report on this issue, with a confirmed diagnosis from my dealer and the cost of repair in my area (Rochester, NY).