Engine Knocking

[Jerry1]

Asking car guys to listen to a video. There’s a knocking sound in my engine compartment. It’s a 6cyl and the sound goes away after it warms up. In the video there are 5 knocks. Doesn’t seem like a lifter or rod due to the pace of the knocking (about ever 2 seconds). I’m hoping for some ideas before I have to take it to the dealer.

Thanks.

https://youtu.be/_s6pDCU9hsI

 

[ExPatKiwi]

Asking car guys to listen to a video. There’s a knocking sound in my engine compartment. It’s a 6cyl and the sound goes away after it warms up. In the video there are 5 knocks. Doesn’t seem like a lifter or rod due to the pace of the knocking (about ever 2 seconds). I’m hoping for some ideas before I have to take it to the dealer.

Thanks.

https://youtu.be/_s6pDCU9hsI

Thermal expansion? Old cars with cast iron blocks and alloy heads made lots of expansion heating/cooling down noises.

 

[street]

^ this or

I'm no car guy but I would say it is something other then from the engine. It maybe something from air movement or a rub sound of some sort. Just my 2¢

 

[pb4uski]

How many miles on the engine?

I'd throw a can of STP in the crankcase and see if that helps at all.

If it goes away when it warms up then I probably wouldn't worry about it too much... over the years I've had cars that sound very different when first started than a couple minutes later.

 

[Jerry1]

This is a 2017 Equinox with a 6cyl with just over 23K miles. If it’s the engine, it’s still under warranty, but given the cadence of the knock, I’m not sure it’s in the engine.

 

[Sunset]

OP - how did you discover this sound ?

Wondering if a new situation let you notice it, or you listen to your engine regularly and this is new ?

 

[latexman]

Do this, get a "listening rod" -

A looong screw driver works too.

 

[ERD50]

I'd chalk it up to thermal expansion as well. Especially "goes away after it warms up". Exhaust systems go through a large thermal swing. You might want to give the whole exhaust system a good visual check, maybe something is coming loose, but probably not an issue at all. Just keep monitoring it for changes.

Related - in DD's home, there was an odd "click", very regular, once every 3 seconds or so, when the furnace ran. Nothing obvious. It bugged me, I finally tracked it down to the long PVC exhaust pipe. As it heated, it expanded. It was lying across a 2x4 at the top of the wall (forget the term for that piece), and as the tension built it, it would overcome the friction, and move a bit, making the clicking sound. Then repeat 3 seconds later. We slipped a bit of cardboard under the pipe at that point, and the sound went away.

-ERD50

 

[Jerry1]

I noticed it when DW was backing out of the garage while I was standing outside near the garage door. You don’t really hear it inside the vehicle.

 

[ERD50]

This is a 2017 Equinox with a 6cyl with just over 23K miles. If it’s the engine, it’s still under warranty, but given the cadence of the knock, I’m not sure it’s in the engine.

Right. Any engine drive train part would be repeating much faster than that. A 600 RPM idle is 10 x per second, a very fast repeat (like a card in a bike wheel), camshaft is half that rate, but still fast.

That's why I say thermal expansion.

-ERD50

 

[target2019]

At 2 second intervals I would think a compressor is discharging pressure. Or a pressure system doing its thing.
Those are my WAGs for the day.

 

[Sunset]

If you want to listen to various parts (areas) of the engine, this tool is cheap at ~ $5

https://www.harborfreight.com/mechanics-stethoscope-63691.html

 

[pb4uski]

This is a 2017 Equinox with a 6cyl with just over 23K miles. If it’s the engine, it’s still under warranty, but given the cadence of the knock, I’m not sure it’s in the engine.

How could a 2017 still be under warranty? An extended warranty?

If it is still under warranty, then I'd have it checked out the next time it is in for servicing.... unless it really bothers you or the next servicing is a real long ways off.

 

[Jerry1]

How could a 2017 still be under warranty? An extended warranty?

If it is still under warranty, then I'd have it checked out the next time it is in for servicing.... unless it really bothers you or the next servicing is a real long ways off.

The drivetrain has a 6yr/100K warranty. Any internal issues like a lifter . . . would be covered. I’m sure I’d have some out of pocket cost, but it would lower the hurt if it was internal to the engine. I’m sure I’d have to pay for the dealer to diagnose. So I’m trying to do some homework before I go there.

CORRECTION - The power train warranty is 5 years 60K. But, still under warranty for me through 12/2022.

 

[Bamaman]

I would assume this is the 3.6 liter GM engine used across the board in many of their car lines--FWD and RWD? The engine has been out for many, many years.

On paper and when running right, that V-6 is quite a performer. But in reality, it's been a very, very troublesome engine.

GM once had so many overhead valvetrain problems that they quietly dropped the 60K mile original warranty back to 36K miles. I really would have thought they solved those engine problems with so many on the road.

My step son has a Camaro with the V-6, and the timing chain, pulleys, tensioners and guides had to be replaced. The engine had to be about half disassembled to replace the parts, and it's more than a day's labor. He paid just under $3K to get it fixed. A couple of years later, the same thing happened again, and he bought a completely new crate engine with a 3 year, 36,000 mile warranty.

It sounds as if you've got some kind of ESP. By all means, take that car to the dealer and get it looked at. And don't accept that it's a normal wear issue. The dealer by now has seen so many V-6 engines in their shop that they probably can tell you what's wrong by listening to the engine running.

 

[ERD50]

I would assume this is the 3.6 liter GM engine used across the board in many of their car lines--FWD and RWD? The engine has been out for many, many years.

On paper and when running right, that V-6 is quite a performer. But in reality, it's been a very, very troublesome engine.

GM once had so many overhead valvetrain problems that they quietly dropped the 60K mile original warranty back to 36K miles. I really would have thought they solved those engine problems with so many on the road.

My step son has a Camaro with the V-6, and the timing chain, pulleys, tensioners and guides had to be replaced. The engine had to be about half disassembled to replace the parts, and it's more than a day's labor. He paid just under $3K to get it fixed. A couple of years later, the same thing happened again, and he bought a completely new crate engine with a 3 year, 36,000 mile warranty.

It sounds as if you've got some kind of ESP. By all means, take that car to the dealer and get it looked at. And don't accept that it's a normal wear issue. The dealer by now has seen so many V-6 engines in their shop that they probably can tell you what's wrong by listening to the engine running.

How could a valve-train issue create a 'tick' at regular intervals a few seconds apart like in the video?

Any valve train problems I've ever heard were at a speed related to engine RPM. Cam runs 1/2 speed, even an intermittently noisy lifter is going to be related to engine RPM (might skip a few beats, but it would still be kinda like Morse code, tik-tik.....tik-tik-tik....tik.....tik.... related to engine RPM).

OP, simple test - do that video again, but rev the engine a bit for some time. Does the tick noise change with RPM? I'd be surprised.

-ERD50

 

[NW-Bound]

I am at a total loss. The repetition rate is too slow to relate to the engine rpm. I cannot offer any theory or guess.

 

[Jerry1]

OP, simple test - do that video again, but rev the engine a bit for some time. Does the tick noise change with RPM? I'd be surprised.

-ERD50

I’ll try listening and changing the rpm and see what happens. I’ll also let it idle and see how long it takes for the noise to stop. I just know that after a short trip, when I got home, it was no longer making the noise. But, it did make the exact noise the next time (next day) I started it. I’ll do a couple simple things and see what I find out.

 

[Jerry1]

The dealer by now has seen so many V-6 engines in their shop that they probably can tell you what's wrong by listening to the engine running.

I was thinking of just taking the video to the dealer and see if they can do just that.

I’m not afraid to spend money on the car, but I’ve had enough intermittent issues with cars that I don’t want to waste money having the dealer pecking around at their hourly rate.

 

[Sunset]

I’ll try listening and changing the rpm and see what happens. I’ll also let it idle and see how long it takes for the noise to stop. I just know that after a short trip, when I got home, it was no longer making the noise. But, it did make the exact noise the next time (next day) I started it. I’ll do a couple simple things and see what I find out.

Next time you come back from a short trip, turn off the engine , wait 20 seconds and turn it back on to see if you hear it again.

If you do, it's related to the starting, but not thermal expansion.

 

[Jerry1]

Next time you come back from a short trip, turn off the engine , wait 20 seconds and turn it back on to see if you hear it again.

If you do, it's related to the starting, but not thermal expansion.

Okay. I’ll try that too.

 

[Telly]

If it was a 1970 car, I would suspect Dave Edmunds

I'll go with the exhaust system thermal expansion idea. When your DW backs out of the garage, slowly, try getting down on all fours to listen for sound emanating from underneath as it slowly goes by. Only if you can do it safely. If you look up, and see that she is holding a potato besides the steering wheel, make believe you are in the starting blocks for the 50 yard dash... and go!