[tibug]

I just fixed one bad knock in my engine which was the t-belt tensioner. Now I am noticing another knocking from the engine. It is a sort of subtle low frequency knock. It doesn't sound like rod knock to me but it very well could be because I haven't heard lots of rod knock in my years. It definitely doesn't sound like piston slap. I can barely hear the knocking in the car and I can only really hear it at idle. In this video, it's most noticeable when I put the camera under the car.

I have Delta 1500 reground cams in my car which make more valvetrain noise. The noise I am referring to is not a tick (which this engine has PLENTY of), it's a deep sort of drawn out and resonating "knock". Could this just be the camshafts "loping?" I can't say I've really noticed it before but I certainly could have missed it.

Thanks...

Here's a video of right after I put the cams in, and if the noise is there, it does not seemed to be as pronounced...

Thanks guys!

 

[ntippet]

Sounds like the cams/rockers/valves to me.
How did the valve lash adjustment go after installing the cams?
Are they all back to specified clearance?

Intake:
0.20±0.04 mm (0.0079±0.0016 in)
Exhaust:
0.25±0.04 mm (0.0098±0.0016 in)

 

[tibug]

I adjusted the valves twice now. The results of my first adjustment are reflected in the second video and the second adjustment is in the first (later) video. The first adjustment had the valves adjusted to .008/.010 and the second I adjusted them to 0.006/0.008. Perhaps that is too tight? That could make sense.

 

[tibug]

Post oil change video...

See my previous video for what the car sounded like before the oil change. Is it a bit better now or is it just me?

I had 5w30 Pennzoil High Mileage conventional oil in the car with an OEM blue Subaru filter. The oil had 3300 miles on it, almost 3000 of which were pure highway "cruise control" miles.

I just drained and refilled with 5w30 Valvoline NextGen conventional oil with a Purolator PureOne filter (which incidentally is a lot larger than the OEM blue...if that means anything, I don't know)

In person, I could just barely hear a muted version of the thump/knock that was present before the oil change (see my previous video). But the audio on the video actually picks up a bit more than I heard in person. So I think the "thumping" is picked up by the camera so it is obviously still there, but it does seem more subdued.

The video was taken with the same camera, settings unchanged, so the sound should be comparable.

 

[cardoc]

Its sounds like the lifters aren't getting oil.

 

[tibug]

Thanks! Could that be caused by the valve clearances set too tight? I haven't listened to carefully, but now that I think about it, the sound seems to be loudest when the engine is warmed. Perhaps the valves aren't closing enough? I'm pretty clueless.

 

[cardoc]

You are doing the adjusting with the engine cold, right?

 

[tibug]

Yes, with it cold. I've adjusted it twice now. And also, my engine doesn't have lifters haha. SOHC Ej25

 

[cardoc]

Its either adjusted wrong, on the wrong stroke, or its an oiling issue.

 

[lavarock]

What does it sound like at the exhaust pipe? My very first impression was a leaking exhaust manifold. By that I mean it sounded like exhaust. Go to the rear of the car and listen. That is how an old mechanic friend used to detect burnt exhaust valves years ago.

 

[tibug]

It doesn't really sound like exhaust leak to me. It did have an exhaust leak before so I think I know what it would sound like, though I imagine it could have different sounds. I replaced the header/midpipe gasket recently, and the header/block gaskets were replaced about 8k miles ago.

If the weather is decent tomorrow I will readjust the valves back to 8 thou/ 10 thou (edit: actually before I had it at 7/9 so that's where I'll go) and look for any signs of issues in the valvetrain...

Thank you very much.

 

[lavarock]

It doesn't really sound like exhaust leak to me. It did have an exhaust leak before so I think I know what it would sound like, though I imagine it could have different sounds. I replaced the header/midpipe gasket recently, and the header/block gaskets were replaced about 8k miles ago.

If the weather is decent tomorrow I will readjust the valves back to 8 thou/ 10 thou (edit: actually before I had it at 7/9 so that's where I'll go) and look for any signs of issues in the valvetrain...

Thank you very much.

How about the sound at the tail pipe?? Does it sound like all cylinders sound the same??

 

[tibug]

Well guys...adjusted the valves today. All went well. No effect on the noise. On startup I noticed a wisp of exhaust exit the joint between the midpipe and the header. :ucrazy: Yup, turns out you guys were right, one (or both) of the exhaust flanges are warped so that the gasket does not seal. I'm not sure how I didn't notice that before. I also managed to strip the threads in the block for the exhaust manifold bolts (the studs have long since seized to the nuts and become bolts). Perhaps now is the time to replace all of those rusted pieces of crap with new studs and nuts. It is only a matter of time before I strip out all of the threads out of the aluminum...

Thanks guys...

 

[signage]

If a stud come out with the nuts, this must be replaced. Reason is the threads of the studs into the block are course thread and the threads for the nuts are fine for torquing purposes. So if you try to torque the with the threads of the stud to the block you are not getting an even pull!

 

[tibug]

I actually didn't know that. Thank you. I've been reusing the studs as bolts. I think a lot of people do that especially in the rusty North. I know it's not a good idea...but I learn things the hard way, and stripping out the threads in the block is just what it took for me to come to my senses.

 

[signage]

You do know that Locktite makes a thread fixer that seems to work well if you can get the area clean of any oil.