Stock BRZ Engine Knock Video

[humblebrz]

Background info on car: 2014 Brz 6MT. Stock with no aftermarket modifications. 20,000kms. Subaru oil changes and maintenance. After sitting in the cold Below 0 celsius for approx 4+ hours the start up results with what is heard in the video. The knocking noise sounds like it is coming from the passenger side.(this is where the video is taken) additionally the knocking isn't present until after the car is idling for 5+ minutes with the heat on, rear window defroster and heated seats turned on. If those accessories are turned off, no knocking noise is heard. The knocking noise is not present when the vehicle is stationary reved at any RPM or if it at normal operating temperature. I have tried to diagnose this without success. My local dealer just replaced the cooling fans because they said one was warped and hitting the shroud... needless to say the noise is still there.

[Ultramaroon]

Next time you have the noise step on the clutch. Does it go away?

[humblebrz]

Negative. Ive also tried to put load on the engine to replicate the sound when the interior items (blower motor, defrosters, heated seats are off) by putting the car in gear with the brake on and slowly releasing the clutch to the point where the vehicle almost stalls with zero noise heard.

[Tcoat]

Brake booster vacuum pump.


http://www.ft86club.com/forums/showt...=112137&page=2


EDIT: Wait. That is just for ATs! Nevermind.

[Ultramaroon]

Originally Posted by humblebrz

Negative. Ive also tried to put load on the engine to replicate the sound when the interior items (blower motor, defrosters, heated seats are off) by putting the car in gear with the brake on and slowly releasing the clutch to the point where the vehicle almost stalls with zero noise heard.

No not to load it. I mean while it's in neutral making the noise and you step on the clutch to disengage it, does the sound stop? Is it possibly coming from the transmission? Sorry, lazy short post from asking the same question many times.

[WorldRallyB]

Originally Posted by humblebrz

Background info on car: 2014 Brz 6MT. Stock with no aftermarket modifications. 20,000kms. Subaru oil changes and maintenance. After sitting in the cold Below 0 celsius for approx 4+ hours the start up results with what is heard in the video. The knocking noise sounds like it is coming from the passenger side.(this is where the video is taken) additionally the knocking isn't present until after the car is idling for 5+ minutes with the heat on, rear window defroster and heated seats turned on. If those accessories are turned off, no knocking noise is heard. The knocking noise is not present when the vehicle is stationary reved at any RPM or if it at normal operating temperature. I have tried to diagnose this without success. My local dealer just replaced the cooling fans because they said one was warped and hitting the shroud... needless to say the noise is still there.

I'm 90% sure this is belt "slap". My current 06 impreza does this and my previous '12 legacy did this on cold starts. Hard to tell through cell phone speakers but here is another good comparison video

Its just caused by your belt being stiff and the timing belt tensioner fluid being too viscous from the cold. If it goes away when it warms up, dont worry about it. If it gets louder or worse look into having your tensioner replaced

[humblebrz]

Originally Posted by Ultramaroon

No not to load it. I mean while it's in neutral making the noise and you step on the clutch to disengage it, does the sound stop? Is it possibly coming from the transmission? Sorry, lazy short post from asking the same question many times.

Yes sorry I knew what you were asking. NO the noise does not go away with the clutch pedal pushed in. Listening with a screw driver on the back of the engine casing I could hear the noise but its so close to the clutch that its hard to determine whether its engine or trans related. Vehicle was dropped off at dealership today at 1700hrs to try and get to the root cause. Had tech listen to phone video. Suggested it may be normal they are going to compare two brz's back to back...I advised that my 17 brz doesn't make this noise.

[humblebrz]

Originally Posted by WorldRallyB

I'm 90% sure this is belt "slap". My current 06 impreza does this and my previous '12 legacy did this on cold starts. Hard to tell through cell phone speakers but here is another good comparison video

Its just caused by your belt being stiff and the timing belt tensioner fluid being too viscous from the cold. If it goes away when it warms up, dont worry about it. If it gets louder or worse look into having your tensioner replaced

I appreciate the input. I did stumble across this video awhile back. My concern is that the video shows the knocking at various RPMS whereas in my case the knock is at 600-750 rpm (idle) and goes away once warmed up.

[humblebrz]

Video from today before taken to the dealer.


[ame="https://www.youtube.com/watch?v=rjwj6_ttRuI"]Brz Knock 2 - YouTube[/ame]

[WorldRallyB]

Originally Posted by humblebrz

I appreciate the input. I did stumble across this video awhile back. My concern is that the video shows the knocking at various RPMS whereas in my case the knock is at 600-750 rpm (idle) and goes away once warmed up.

Yes.. i know. His tensioner is completely shot, yours is just worn out a bit and its only apparent when your belt is stiff making it harder for your tensioner to compensate. I justed watched your most recent video. Definitely sounds less knocky and more belt. I'm sticking with my diagnosis. It would take you or a tech 30 seconds to check with the method in the video i posted..

[humblebrz]

Ive seen the tensioner move around a little bit when idling. Will for sure check it out when I get it back. Thank you

[ToySub1946]

Now that I've seen and heard the latest video, way more telling than the first video done poorly in the dark:

Looking at how dirty the car is under hood and in wheel wheels, I'd say most likely the real rattle is coming from the engine undercover or skid plate (aluminum) hitting part of the exhaust system. This happens after you run over things with the front of car...or if debris is within the skid plate.

This happened to me after I ran over a large rock on a remote dirt road. First I removed skid plate and straightened it, then later replaced the part (because it was actually torn open)...About $136. online. I have not done anything about the slight dent in my oil pan which is not bad enough to have damaged the oil pickup.

Back in the day, in cold country, with snow and ice, we wait till spring to deal with these things. First video appears there is possibly snow on undercarriage of the car. Second video shows dirt and mud on areas of the car.

Hopefully this trip to the Stealership, you'll get a tech who'll take the time to properly diagnose the problem. Unfortunately, If I'm correct, it ain't The manufacturer's fault, driver fault instead. We'll see...

For a tech to properly diagnose this problem... to actually hear it....car should be on an alignment type lift, running, with suspension compressed as it would be driving down the road. Heat shields on exhaust parts near engine can also get bent (they are extremely thin) and make noise as well. Best to listen for these noises after aluminum skid plate is removed...if it's already been determined that aluminum against these heat shields is not the sole noise problem.

Note: Attached image came from Google Images...

[Ultramaroon]

Originally Posted by humblebrz

Yes sorry I knew what you were asking. NO the noise does not go away with the clutch pedal pushed in. Listening with a screw driver on the back of the engine casing I could hear the noise but its so close to the clutch that its hard to determine whether its engine or trans related. Vehicle was dropped off at dealership today at 1700hrs to try and get to the root cause. Had tech listen to phone video. Suggested it may be normal they are going to compare two brz's back to back...I advised that my 17 brz doesn't make this noise.

Ok, well, it certainly isn't normal. Almost sounds like the water pump.

I've also had my bottom cover come loose. It doesn't sound deep like that but who knows?

[humblebrz]

Originally Posted by ToySub1946

Now that I've seen and heard the latest video, way more telling than the first video done poorly in the dark:

Looking at how dirty the car is under hood and in wheel wheels, I'd say most likely the real rattle is coming from the engine undercover or skid plate (aluminum) hitting part of the exhaust system. This happens after you run over things with the front of car.

This happened to me after I ran over a large rock on a remote dirt road. First I removed skid plate and straightened it, then later replaced the part (because it was actually torn open)...About $136. online. I have not done anything about the slight dent in my oil pan which is not bad enough to have damaged the oil pickup.

Back in the day, in cold country, with snow and ice, we wait till spring to deal with these things. First video appears there is possibly snow on undercarriage of the car. Second video shows dirt and mud on areas of the car.

Note: Attached image came from Google Images...

We've had 9.8 feet of snow this winter so for sure that is possible. There is no obvious damage underneath. We can drop the skid plate and see if the noise still exists.