Confused about the tapping sound

[motojeff]

I have read several threads on lifter tapping, piston slapping, tensioner pumping, and valve clearance. I understand this tapping noise is hard to identify sometimes.

 

My 2000 OBW limited with an EJ25 engine is making the tapping noise. It was making a slight tapping noise before I changed the timing belt. No, I did not change out the tensioner, or idler pulley's, but I did check them very carefully. The car is in Georgia so there is not salt damage anywhere on the car, always garaged, very clean all over, inside and out. After changing the timing belt the tapping noise was about the same except now a couple of weeks later it is becoming more prominent.

 

Here is the scenario;

• When not under a load the car runs as smooth as a sewing machine.
  
• When under a load it starts tapping (lifters? tap in cadence with the rpms).
  
• If I increase the load (step on it) the tapping goes away.
  
• This is happening both, when the car is cold or warmed up.
  
• The tapping seems to appear more in the area where the car is in between the idol and hard acceleration.

I recently changed the oil using 10w-30. The car has 110,000 miles. The weird thing is the tapping used to occur only when turing toward the right on a sweeping curve and accelerating. I recently changed out both CV half shafts to eliminate CV's. Now it is happening even while going straight down the road.

 

This Subaru has been a constant challenge for me to solve issues. The only way I could have come this far is with the help of this board. Thanks for your help.

 

I have several things in mind to try, but do not have a firm grip on the problem. My thoughts are to change the oil after using an additive and use a thicker oil.

 

Any help with this problem will be much appreciated.

 

Jeff

[Legacy777]

It's possible the oil pump may need some attention. There are screws on the backing plate that some times come loose, as well as an o-ring between the pump and block (however they don't usually fail).

 

I'd suspect a screw on the backing plate.

 

Here are some pics of my timing belt change which have some pictures of the oil pump and screws.

http://www.main.experiencetherave.com:8080/subaru/images/timingbelt

 

Have you tried changing oil viscosity higher or lower to see if that changes anything?

 

Josh

[idosubaru]

i would inspect the oil pump as well. the oring and screws.

 

also, the newer EJ's with adjustable valves have a 100,000 mile valve adjustment recommendation. i'm not familiar with what they sound like or do when they are in need of adjustment though, maybe someone who has experienced that can chime in for you?

[motojeff]

It's possible the oil pump may need some attention. There are screws on the backing plate that some times come loose, as well as an o-ring between the pump and block (however they don't usually fail).

 

I'd suspect a screw on the backing plate.

 

Here are some pics of my timing belt change which have some pictures of the oil pump and screws.

http://www.main.experiencetherave.com:8080/subaru/images/timingbelt

 

Have you tried changing oil viscosity higher or lower to see if that changes anything?

 

Josh

 

I have not tried thicker oil yet. I recently changed the timing belt, but I did not change the oring on the oil pump. I was hoping I would not have to take it apart again, but I will do what it takes. How much of a priority is this? Does it demand immediate attention or do I have a few miles?

[motojeff]

Today my check engine light came on. I have not checked the code yet. I wonder if it is related.

[idosubaru]

any autozone or advanced auto parts will read the codes for free. or go to Subaru and pay $80. i think it's a toss up if it's related or not. but i'd surely get it checked ASAP and find out, oil supply is nothing to mess with if that's what it is.

[motojeff]

I found a vac hose loose and put it back on, this fixed my CEL.

 

I have ruled out lifter, timing tensioner, pulleys, and slap. The engine purrs like a kitten sitting still, even when I rev it up.

 

The knocking starts at 30 mph with load applied. It is in cadence with the rotation of the drivetrain.

 

The autozone guys think it is wheel bearings. I thought wheel bearings are more grinding or rumbling. I have knocking.

 

I checked the rotors all the way around. They look good since I did not see any noticeable warpage. However, I did see wear and maybe a little uneven wear on the drivers side rotor. I went ahead and purchased two new rotors to put on tomorrow. I still have the same rotors with 110k on them. I suppose it would not hurt to put some new ones on. I have had slight vibration in the steering wheel and this may help that.

 

Still searching for the knock. I will post the answer someday, hopefully.

[hankosolder2]

I found a vac hose loose and put it back on, this fixed my CEL.

 

I have ruled out lifter, timing tensioner, pulleys, and slap. The engine purrs like a kitten sitting still, even when I rev it up.

 

The knocking starts at 30 mph with load applied. It is in cadence with the rotation of the drivetrain.

 

The autozone guys think it is wheel bearings. I thought wheel bearings are more grinding or rumbling. I have knocking.

 

I checked the rotors all the way around. They look good since I did not see any noticeable warpage. However, I did see wear and maybe a little uneven wear on the drivers side rotor. I went ahead and purchased two new rotors to put on tomorrow. I still have the same rotors with 110k on them. I suppose it would not hurt to put some new ones on. I have had slight vibration in the steering wheel and this may help that.

 

Still searching for the knock. I will post the answer someday, hopefully.

 

It sounds like you're really considering several different angles.

Have you tried holding the car in a different gear at 30 mph? If the pitch of the noise stays the same, it isn't the engine making the knocking! Good luck tracking it down.

EDIT: "Pitch" isn't really the correct term... what I am trying to convey is "does the pace of the knock change with road speed or engine RPM?"

 

Nathan

[motojeff]

It sounds like you're really considering several different angles.

Have you tried holding the car in a different gear at 30 mph? If the pitch of the noise stays the same, it isn't the engine making the knocking! Good luck tracking it down.

EDIT: "Pitch" isn't really the correct term... what I am trying to convey is "does the pace of the knock change with road speed or engine RPM?"

 

Nathan

 

Yep, the knock changes speed with the speed of the car. What makes this harder to identify if that the knock is intermitent and seems to wander from left to right to rear and back to left front. I believe it is sound being transferred through the metal of the car. I have several considerations for cause;

 

drive shaft out of balance

rotors slightly out of shape, moving the pads

trans diff problems

transmission problems

[Legacy777]

I have not tried thicker oil yet. I recently changed the timing belt, but I did not change the oring on the oil pump. I was hoping I would not have to take it apart again, but I will do what it takes. How much of a priority is this? Does it demand immediate attention or do I have a few miles?

 

If the sound is speed related, rather then engine related, then I would probably not suspect the oil pump or the related issues I mentioned above.

[mnwolftrack]

does the noise occur while revving the engine while not moving? Piston slap likes to make it's noise during the fast RPM changes, although I'm sure other noises like to do this too.

 

If it's something like a wheel bearing, it can definately become louder/quieter depending on which way you are turning vs. going straight. Wheel bearings do usally growl and howl though. I can't say I've heard one that taps. If you are in an area where you can weave a little bit back and forth while driving, just enough to make the car rock a little as the weight shifts, you might be able to decipher if it's a wheel bearing or not. Or, just find a curvy road. Generally, the wheel bearing will be on the opposite side of the car you are turning in the direction of when you weave. As the car body rolls ever so slightly, it places more weight on one side of the car (and those two wheels). Bad bearing noises will typically get louder with more weight on them. If you turn to the right, and the noise gets louder, the bad bearing should be on the left side, and vice versa.

[Aspen]

My MY99 recently developed rod bearing knock, so naturally, I think you may have too. These motors are pretty weak.

I notice mine at start up, when under heavy load and if I rev it up to 3000 rpm with my head under the hood.

[motojeff]

Well, I was going to put two front disc rotors on last night, but I noticed the new rotors were 10 inches and my exsisting rotors are 10.5. So, I took the new ones back for a refund and swaped the rotors left goes to right and the right goes to left. When I drove it the tapping was significantly reduced (almost un-audible). I am about to conclude the noice is in the disc rotors somehow. I will not be 100 percent sure until I have them turned and then take another test drive.

 

The thing that has made this difficult, concerning the rotors, is that I layed a straight edge across the rotors in several places and have not seen any warpage. However, swapping sides with the rotors made a huge difference. I will post the results after getting them turned. The 10.5 inch rotors are about 81.00 each. I have 16 inch wheels on this car.

 

I appreciate the input on this mystery.

[Hodaka Rider]

If the anti-rattle clips in the calipers are not all there, or are bent out of shape, you can get strange tapping noises from the pads. Swapping the rotors around could cause the pads to drag on ridges on the rotors slightly, reducing the noise. (I've had this happen before)

[motojeff]

If the anti-rattle clips in the calipers are not all there, or are bent out of shape, you can get strange tapping noises from the pads. Swapping the rotors around could cause the pads to drag on ridges on the rotors slightly, reducing the noise. (I've had this happen before)

 

Very interesting! I will have to check the clips. Can you get just the clips without buying another set of pads?

 

I am pulling the rotors friday night and having them turned saturday morning. I will know how it works by saturday afternoon.

[uniberp]

Is there still a vibration in the steering wheel? You may simply have had a tire out of balance.

 

When you swapped the rotors, the wheels were probably bolted back on in a different position.

 

Very interesting! I will have to check the clips. Can you get just the clips without buying another set of pads?

 

I am pulling the rotors friday night and having them turned saturday morning. I will know how it works by saturday afternoon.

[motojeff]

Is there still a vibration in the steering wheel? You may simply have had a tire out of balance.

 

When you swapped the rotors, the wheels were probably bolted back on in a different position.

 

I had the rotors turned. This eliminated the slight vibration I had in the steering wheel. The rotors were a little warped and turning them fixed this part.

 

I still have the knocking in the drive train somewhere, which appears when I am applying the gas. It seems to be in the front half of the vehicle. I fear it is in the transfer case. I looked under the car with both front wheels in the air and checked the CV joints (both are new). I noticed slack in the transfer case where it is connected to the cv half shaft (axle). Turning the tires did not produce any noise at all.

 

I believe I have decided to just keep driving it until it gets worse. I have one last theory. The CV half shafts I put on the car were fron Autozone. They were the "made in China" type parts. When I was putting the one on the left side it would not go on because the shaft was machined wrong. I took it back and got another, which fit perfectly. So, I have deduced that the other CV half shaft could possibly have gone bad due to it's cheap manufacturing (it only has about 1200 miles on it). It would not be unheard of for it to be a bad part (I have learned this the hard way). I will keep driving it and see if it gets bad enough to identify it as the culprit.

[motojeff]

I just wanted to follow up on this thread to let everyone know I found the problem and learned a few lessons.

 

The tapping sound was in the passenger side front CV joint.

 

Why did I not know this before?

 

I replaced the front passenger side CV half shaft six months ago after the OEM shaft boot split and slung grease everywhere. About three months later the CV joints apparently were starting to make noise. Not thinking it could possibly be the CV half shaft I just replaced, I proceeded to replace the drivers side CV half shaft. Purchasing the shaft at Auto Z.., because the part was less expensive than the OEM part, I could not install the drivers side CV shaft becuase the cheap chinese part was machined wrong and would not fit into the splines of the hub. I took it back, got another and it slipped right in. Test drove it and the tapping sound was still there. I had my rotors tunred thinking it was in the rotors. Once turned, my braking and balance had improved but still had the tapping. This made me start to think about things in chronological order. 1) The tapping did not start until after I had replaced the passenger side CV shaft. 2) The first cheap chinese CV shaft was defective. 3) If one of the brand new CV shafts I bought was defective it would stand to reason the other part, which I used for only three months, could be defective also. Since Auto Z... has a lifetime warranty on these parts it did not cost anything to replace it, except for my time and labor. I replaced the passenger side CV shaft and PRESTO! the noise is gone.

 

Lessons learned:

 

1) Just because a part is new doesn't mean it will last or fit properly.

2) Sound travels through metal making it hard to pin point the source.

3) Perseverance pays off.

4) This forum is priceless.