Recently purchased Legacy has knocking sound when coasting and/or hitting bumps in road

[cgates30]

New to the board and tried the search, but my search terms might have been wrong.

Just bought this car for my daughter from the 2nd owner who kept the car for 15 years. Overall it's in good condition and had the timing belt and clutch changed about 50k miles ago (now at 200k). However, I have noticed a couple of issues during our first week of ownership. 

1) When driving over small bumps (think expansion joints in the road or 1-2" potholes) or coasting (in neutral or not under load) I notice a slight knocking sound coming from the right front of the car. I jacked the front of the car up and looked at the suspension and ball joints and I didn't notice anything obvious. There's no play in the wheel when lifted. The CV joints on the axles look to be in good condition, etc. The sound is somewhat faint inside the car, but with the window down it is more noticable. Is there a common problem that sounds like this description?

2) When the AC kicks in, sometimes I hear a loud screaching. During test drives, it didn't do it (of course), but the PO warned me that "sometimes" the belt whines. It doesn't sound like a whining belt to me, more like a screach. Is this a compressor issue?

3) On the way home... the CEL came on. Autozone was on my way home so I stopped in and got them to read the code. P0325 for the knock sensor. From what I've read, the knock sensors fail on these cars and a simple replacement solves this problem. Does the ECU use feedback from this sensor to adjust timing or something? I.e., is it a bad sensor or is it indicating something is wrong with the car that needs other attention? I already bought a sensor, so I'll find out soon enough.

 

Otherwise, I'm pretty happy with the car. I have a P-car with a flat 4 and am excited about the engine design combined with AWD.

[el_freddo]

1) needs new front struts. The old units are worn out and make that clunking sound over small ripples and bumps in the road.  Replace the struts, get a wheel alignment and you'll be sorted. 

2) inspect the AC belt for cracks etc and replace if necessary or just tension the belt up to reduce the initial slip that's causing the screeching. 

3) replace the knock sensor and reset the ECU either by the battery dance (disconnect the battery for at least half an hour), then warm the engine up without touching the throttle for five or so minutes. Then go for a drive. 

You may find that the oxygen sensor will need replacing too. 

That should solve your issues. I reckon they're pretty small overall. 

Cheers

Bennie

[cgates30]

Thanks for the hints! I really appreciate it!

[1 Lucky Texan]

details on car?

 

yeah, many folks have good luck with $10 ebay knock sensors - make note of which direction the cable comes off the old one, remove it, maybe wire-brush the mount are, mount the new one with the cable oriented the same  direction. Don't overtorque its bolt.

 

you might check the roll bar mounts and endlinks, also check the rear bushing of the front lower control arm - they could knock/thump.

 

if there is a lot of red dust under the hood and around the a/c compressor's area, it may not be the belt slipping, the clutch may be slipping. Some folks have adjusted their a/c clutches - others have found the a/c relay to be a problem. If the belt seems ok and tensioned properly, try the relay next(maybe swap with a headlight or other identical relay in the box), then perhaps pursue a compressor adjustment or get a used one from car-part.com.

Edited August 2, 2018 by 1 Lucky Texan

[wtdash]

Howdy,

HEADS UP on adjusting the Subie  accessory belts - P/S, Alt, AC - as they have another bolt that 'locks' them in place - common to break the actual adjuster bolt if the lock bolt is not loosened.

 

[cgates30]

The car is a Legacy and it's basically a base model. Manual window cranks and doors. The PO was in his mid 60s and owned it for 15 years, so from what I can tell and based on his descriptions it was pretty well maintained. However, he hauled his dogs around in it, so the interior is decent but not super. The body is straight and the engine compartment is clean, however, I can see some oil seepage around the oil pan.

I haven't noticed any red dust, so I'm hoping that's a good sign. I'll check the belt tension and locking bolt, etc.

[1 Lucky Texan]

year of car?

one uncommon failure is delamination of the crank pulley(it's 2-piece) - but I'd expect other problems like heavy steering during the 'screech' sound if that were the issue.

 

hoping a new or adjusted belt does the trick.

 

[wtdash]

+1 on Year/Trim - Subarus came w/different engines and some were more (in)famous then others. If yours has the EJ25D from the '96-'99 OB/GT you may have Head Gasket issues in your future. But sounds like yours is a Legacy Brighton w/the venerable 2.2/ EJ22E...the best engine, IMHO.

 

Edited August 2, 2018 by wtdash

[cgates30]

Yes, it's a '97 model Legacy. I believe it is the 2.2 and its a really basic car, so if the Brighton was the base model then that's what I think I have. No difference in the steering during the screech. There's some seepage on the top side, but really the top looks pretty good. While there's more seepage on the bottom side it isn't enough that I've noticed anything hitting the driveway after sitting overnight. 

I did get the $11 knock sensor from Amazon and the light hasn't been on since (replaced it during my lunch break and drove it about 30 minutes afterwards). Now I have to start looking at the belt tension and the other pointers mentioned above. 

Edited August 3, 2018 by cgates30

[cgates30]

One item on my to-do list is to replace the front struts. I found these are eBay. I don't usually buy things on eBay, but the price looks good ($135 including shipping for both fronts). Does anyone have any feedback on these? KYB 2 Excel-G Front Suspension Struts 

I'm guessing new strut top mounts and the boots with rubber stops should be replaced at the same time. Is there a DIY on doing this, maybe with suggestions of what all should be replaced at the same time?

[wtdash]

No issues buying on ebait if buying name-brand (AND Seller's feedback).  KYB is the best.

There are lots of online installs for these. Unless yours are clunking, the tophats (strut mounts) may be fine. 
 

Depending on your shopping skills (and patience) I recently bought all new for a different car. All KYB and found better prices shopping around on Amazon and Rockauto (RA). 

RA 5% code: 8605686777408527 and KYB's have a rebate per their site.

Edited August 3, 2018 by wtdash

[heartless]

personally, i have never bothered much with the boots, but that is personal preference.

Top mounts, most likely are needed if they have never been replaced.

Unfortunately there is only one way to really check them, and that is to take the assembly apart. I tend to be proactive on a "new to me" vehicle that has obviously worn suspension and will just order new front tophats, just because. They are a somewhat important part of the steering after all.

Also take a really good look at the springs - my 95 had a broken one when I got it.. it is not super common, but it does happen

[idosubaru]

1.  I would look at your control arm bushings first before assuming the struts are causing the bumps. 

3.  Knock sensors happen all the the. Replace with cheap eBay specials and done. 

Struts - KYB is commonly favored Subaru struts  others can be terrible and flaoting,bouncing feeling.

Strut mounts - absolutely avoid anything but Subaru.  I’d even keep the originals before even thinking about aftwrmarkets. I’ve put 250,000 miles on Subaru strut mounts plenty of times. They do fail, just check them but if they look fine you can run them too. 

But struts are time consuming to replace so good idea to replace mounts while it’s apart. Just don’t get aftermarkets. They deflect crazy train amounts and I’ve seen them fail in a week. 

[cgates30]

I'll definitely look at the control arm bushings before jumping into the struts/strut mounts. Strut mounts, being the mounting point visible at the top of the strut in the engine compartment? "avoid anything but Subaru" I take that means to avoid the KYB as well. Not a problem, but just wanted to be clear since I'm building my shopping cart, etc. 

What's the best way to inspect the strut mount? Just a visual from under the hood? They look good from the top. I've seen them on other cars where the bushing material was deteriorated, etc. 

[heartless]

53 minutes ago, idosubaru said:

1.  I would look at your control arm bushings first before assuming the struts are causing the bumps. 

3.  Knock sensors happen all the the. Replace with cheap eBay specials and done. 

Struts - KYB is commonly favored Subaru struts  others can be terrible and flaoting,bouncing feeling.

Strut mounts - absolutely avoid anything but Subaru.  I’d even keep the originals before even thinking about aftwrmarkets. I’ve put 250,000 miles on Subaru strut mounts plenty of times. They do fail, just check them but if they look fine you can run them too. 

But struts are time consuming to replace so good idea to replace mounts while it’s apart. Just don’t get aftermarkets. They deflect crazy train amounts and I’ve seen them fail in a week. 

the only other strut mounts I would consider are the KYB - put a set of those in the 95 Legacy I had and they were just fine. Car handled and rode great.

[john in KY]

My 95 wagon with 330k miles still has its original strut mounts. 

[cgates30]

I'm thinking mine look pretty good... Wow, 330K, that would never happen on my other car. I have a BMW 530i (e39) and at 150k miles they were pretty much shot. Of course, it's a much heavier car with a large engine sitting up front. 

[heartless]

LOL - you can not tell just by looking at them.. you need to disassemble and check the bearing itself

if it rotates smoothly with no binding, no slop, no crunchiness or notchy feeling then yeah, it is fine.

but if there is ANY slop, binding, or anything other than smooth movement it needs to be replaced.

As an example - the other half has a 2006 LL Bean Outback with around 180K that we just put new struts in... the top mounts "looked" fine, but once we had things apart it was VERY obvious the one was completely shot, there was a lot of slop in the bearing..

[idosubaru]

You have to remove it and check condition.

Ive never tried but you could try to jack the wheel off the ground and see if you can get any diagnosis by moving and loading the strut or even unbolt it from the knuckle and do the same   

It is unfortunate to not know until the strut us disassembled  

another option is to buy two struts mounts from somewhere that would let you return them if they’re not needed   Then you have them on hand but onky replace if needed    

 

 

[el_freddo]

KYB are the original factory equipment. The difference in sourcing them from anyone oter than Subaru is that oem KYBs are oil filled, aftermarket are gas filled. 

Both will be fine to use. 

Cheers

Bennie

[1 Lucky Texan]

mine on the WRX were bad at under 70K miles - take 'em off, spin them on a finger. I was shocked at how dry/crunchy mine were.  (WRX is only on surface roads and gets driven hard on occasion)

 

if anyone involved in changing struts out is a new to the process, there are a coupla 'gotchas'; the top spring mount has an orientation. There are a 3 holes and the center one faces to the fender. Or there's an arrow or something, it may vary by brand of strut. When you remove a stock assembly , look at the top spring mount.

and, there'sia a beveled/cone-shaped spacer that goes on the top of the top spring mount and the narrow side will be pressing on the underside of the strut mount's bearing - don't flip it over or the assembly will 'drag' when turned.

Edited August 4, 2018 by 1 Lucky Texan

[cgates30]

4 hours ago, heartless said:

LOL - you can not tell just by looking at them.. you need to disassemble and check the bearing itself

if it rotates smoothly with no binding, no slop, no crunchiness or notchy feeling then yeah, it is fine.

but if there is ANY slop, binding, or anything other than smooth movement it needs to be replaced.

1

That make sense, thanks for pointing that out.

[cgates30]

While taking a look at the suspension components, I got a better view of the front differential. Looks like it is leaking on both sides. In the records I have, it looks like they changed the gear oil ~50k miles ago. 

[idosubaru]

11 hours ago, cgates30 said:

While taking a look at the suspension components, I got a better view of the front differential. Looks like it is leaking on both sides. In the records I have, it looks like they changed the gear oil ~50k miles ago. 

 

You may have just captured your issue, that looks like an aftermarket axle, unless the grease covered inner joint is deceiving me. 
Aftermarket axles are notoriously problematic, I would replace them even if they are not making the noise.  They're not long time reliable components, they're risky trash for penny-wise-dollar-dumb time wasters and used car flippers. 

You could alternately pull the boots back and clean and regrease them.  More than likely they didnt' have enough grease or it's watery and degraded and knocking...or it's one of those and the joint is a trashed POS, that's no surprise either.  You would want to concentrate on the inner joints - they're the ones that have the exact symptoms you're describing when they lack (good) grease. But for my time and money I'd just throw those away and get Subaru OEM axles. 

$15-$35 all day long on car-part.com or local yards. buy one, clean it, reboot it.  i've rebooted open-boot, dirty as #(!)%* knocking, clicking Subaru axles and never had an issue, they've all quieted right up with no failures.  i've had multiple brand new aftermarket axles blow apart within 50 miles (one was less than 100 yards that was awesome) and have multiple other issues besides that.  which is funny because I spend way more time and miles with OEM so I should see more OEM failures...but nope, it's the aftermarkets blowing away the competition...quite literally. 

[idosubaru]

check your diff (and other) oils and make sure that's loosing fluid.  it does appear to be the case but other leaks can drip/blow back to that same rearward/central location so best to verify. 

1. be very careful changing those diff side seals - it's a very precise process and not getting it right will mean you need a new transmission.  the retaining rings has to be returned to the exact same number of turns and precise location it's currently installed or the bearing pre-load/ring and pinion backlash will be lost and you'll need a new transmission. 

2.  if you have issues present (thumping) after a significant job (strut replacement) - then more than likely the issue is due to the work done.  So those struts and the associated work done during that time needs backtracked and checked. 

3.  ***Can you tell which "side" is more prevalent?  Like is it more likely to do it on the left or right - when you hit a bump on the right (but not the left) or the left (but not hte right) - are the symptoms still identical no matter what?

4. *** Do the symptoms change at all if you encounter the same situation driving straight or while turning?  If it makes the noise in a certain situation - will it make that exact same noise under the exact same situation while turning left, driving straight, and turning right?