Engine noise

[landon]

I am trying to determine the cause of an engine noise and of course would love to rule out a rod knock. Car is a daily driver except for winter. 

Engine has 225k miles and otherwise runs quite well. No misfires. decent power and good oil control for the mileage.

Noise has been around for a while... not sure how long but probably a couple of seasons. Just seems to be ringing in my ears louder now...

 

1. Valves are adjusted. I've done .006 and .007 adjustments with no difference in noise. Valvetrain sounds OK to me and nothing out of the ordinary under the valve cover.

2. I disconnected the AC belt to eliminate that pulley.

3. Using a stethoscope and my untrained ear, the noise "seems" loudest on the bottom end toward the back of the engine. 

4. I disconnected plug wires one at a time and the noise remains. No difference other than the rough running of 3 cylinders. I've done done this a few times and quite sure there is no difference in the knocking noise.

 

Noise is not apparent on start up and fast idle. It is there after warmup. 

You can hear it best on the low idle video - temp is coming up off the blue and choke is disengaged so idling at 700 rpm or so. Hard to hear on the fast idle video at startup. Ignore the loose alternator belt....

New engine is in the long term plans but I would love to drive this a while longer while I sort the logisitics of a swap. I just don't want a catastrophic failure on the road. 

 

Thanks for your thoughts. 

 

 

  

[tzei]

Rod bearing would be my guess.

 

Clutch engagement does not change the noise?

Edited March 18 by tzei

[Mike Self]

What weight oil are you running?  Do you have an oil pressure gauge?  If you're running the usual 20w-50, it's closer to 50 weight when cold, and could mask a loose bearing.  As the oil warms and the viscosity thins, that loose bearing is no longer cushioned by the thinning oil. Or...

 

You may have a worn oil pump that's OK when pumping thicker oil, but as the oil warms, the pressure gets lower at a given rpm.  A gauge would tell you that.

 

mike

[landon]

1 hour ago, tzei said:

Rod bearing would be my guess.

 

Clutch engagement does not change the noise?

I don't think so but I'll have another listen.

[landon]

15 minutes ago, Mike Self said:

What weight oil are you running?  Do you have an oil pressure gauge?  If you're running the usual 20w-50, it's closer to 50 weight when cold, and could mask a loose bearing.  As the oil warms and the viscosity thins, that loose bearing is no longer cushioned by the thinning oil. Or...

 

You may have a worn oil pump that's OK when pumping thicker oil, but as the oil warms, the pressure gets lower at a given rpm.  A gauge would tell you that.

 

mike

running 20w-50 VR1. No gauge other than dash light. Remote gauge may be next step. I'm sure the 225k oil pump is less than factory fresh but I'm not likely to replace one in this engine. Just wondering how a failure may come about - slow burn or sudden seizure?

[Son of Marty]

Loose oil pump chain is also in the mix.

[2002#3]

Just so I know...are we discussing the clicking noise audible only in the low idle video?

[TobyB]

I heard a sound on the internet...

 

I'm usually no good at those, but that has a double 'clack' to it that makes me think valvetrain.

As in, eccentrics with really flat spots, maybe?  Or plugged oil hole(s) in the rocker shaft(s)?

Exhaust gasket leaks are usually a 'snap', so that's prolly not it.

 

The 'unhook a spark plug' is usually really good at finding a bad rod bearing, too.

Rods sound more like someone hitting the block with a 32 oz hammer, once, and yours sounds like 

an 8 oz hammer, twice...

 

I'd lash rockers to zero clearance one at a time and see if that shuts anything up...

 

t

 

[landon]

22 hours ago, tzei said:

Rod bearing would be my guess.

 

Clutch engagement does not change the noise?

No change with clutch engagement...

[landon]

14 hours ago, 2002#3 said:

Just so I know...are we discussing the clicking noise audible only in the low idle video?

Yes, best heard on low idle. Sounds like a lower toned knock to me....

[landon]

13 hours ago, TobyB said:

I heard a sound on the internet...

 

I'm usually no good at those, but that has a double 'clack' to it that makes me think valvetrain.

As in, eccentrics with really flat spots, maybe?  Or plugged oil hole(s) in the rocker shaft(s)?

Exhaust gasket leaks are usually a 'snap', so that's prolly not it.

 

The 'unhook a spark plug' is usually really good at finding a bad rod bearing, too.

Rods sound more like someone hitting the block with a 32 oz hammer, once, and yours sounds like 

an 8 oz hammer, twice...

 

I'd lash rockers to zero clearance one at a time and see if that shuts anything up...

 

t

 

Understood these are hard to evaluate over the internet... but thanks for listening!

I was hopeful with the plug test but wasn't sure if that is 100%.

My untrained ear doesn't quite get the double clack but checking valvetrain again is worth doing.

I'm guessing I can tighten valves one at a time at operating temp for this? 

['76mintgrün'02]

My engine makes a similar noise, but not all the time.  It's been that way for as long as I've owned it (12 years).  In my case, I think it is the oil pump chain.  Here's a post where Paul shared photos that show where his chain was hitting.  (I miss Paul).

 

 

Here's another post he made on the topic, with similar photos.

 

One symptom of a (too) loose oil pump chain is a loud chain rattle.  It's loud because it is hitting the oil return pipe on the front of the oil pump. If you can push the chain over and touch the pipe it is definitely too loose.  The deflection is supposed to be +/- 5mm.

 

 

Tom

[jimk]

The first photo of the oil pump chains shows the chain is worn out.  Evidence is the oil scum is wiped away seen between the links.  As the links are gripped by the sprocket teeth, the chain links fit to the tooth pitch and when the link is somewhere off the sprocket the wear slop lets the links pull away and the clean area on the link is exposed.

[tzei]

Double ”clanks” makes me think chain tensioner…

[Son of Marty]

If your engine has a reground cam chances are it will have lash caps on top of the valve stem, is these can wear a dish in the center of them so when you set your valves the feeler bridges the dish so you think you've got it set right only for it to clatter when you start it.