Looking for opinions

[BloKKem]

(edit, had cylinder number mislabeled.)

I have always had what I would consider a repetitive ticking sound in my G8. It's never been anything like lifter tick from what I hear in the youtube videos but I have a sound nonetheless.

We recently did the VMS head and cam swap and noticed the #5 cylinder was black BLACK compared to all the rest. When I was stock, this was always the vicinity of where the sound appeared to be coming from when standing in front of the engine. I always thought it could be the fuel injector making the sound and considered the possibility of it being DOD lifter tick but I was never sure.

Post-head/cam install, the sound is back. That pretty much cancels out lifter noise since all new lifters have been installed but the sound is definitely coming from the same area. I'll try to explain when the sound is most prevalent: When I first start the car, everything sounds fine. There is typical valvetrain noise but it sounds good and healthy. Once I let the car warm up and start stepping on it 3-5k RPM, the ticking starts and it is very loud in the cabin of the car and underneath if I drop down and listen. It can be heard standing over the engine bay but a combination of all the other engine noises makes it a pain to focus on it.

Here is where it gets very difficult though, if I put it in PARK and step out with my stethoscope, I can't find where the sound is coming from. AND, if I take too long, it fades as the car idles. From my understanding, if it were lifter tick, it would be present at idle and be easily identifiable. So, I started thinking that maybe it was exhaust leak from the header. A trip to Jiffy Lube to get fuel injectors cleaned pretty much negated that theory since the smoke created from the process would have appeared in any leaks, and it did not come out anywhere other than my exhaust tips.

So now, I am out of ideas. I keep going back to that black #6 cylinder and trying to figure out why it was like that. New lifters, cam, pushrods, rocker arm trunnions, and spark plugs have been installed as of a few days ago so it has to be something that is still present in the system that was there before my recent install.

Looking for ANY help or ideas, I'm out there all evening with the car running, trying to figure it out. Perhaps this picture will help show that when I say black #6, I mean BLACK.



VIDEOS added:

Car warming up, sound is what is to be expected with the valvetrain. The tick is barely audible in this clip, as it always is, but it is not prevalent yet since I haven't revved the engine yet.


This is a 5 minute video but if you have the time, list to it to hear the transition of when the tick occurs from the beginning when I am simply revving the engine to when it begins afterwards:


This is the cammed exhaust note. It's sexy, but you can still hear that tick coming from the engine bay even from behind the car. This ticking sound is one of those sounds that almost appears to get louder the further you are away from it.

[Crazy Paul]

A couple simple things you could do to narrow down the suspects.
1) Compression Leak Down test. See if #6 is holding pressure as well as all the others.
2) Swap #6 injector for one on the other bank. See if noises and blackness swap sides.

[BloKKem]

A couple simple things you could do to narrow down the suspects.
1) Compression Leak Down test. See if #6 is holding pressure as well as all the others.
2) Swap #6 injector for one on the other bank. See if noises and blackness swap sides.

Accomplished both of these today. Cylinders were all very, very close to each other (within 4-5%).

I'm going to bring it in today and have Meineke put it on their lift and check all of my torca clamps and bolts on my Corsa to see if exhaust is leaking somewhere at higher RPM's. Another thought that has been thrown around is that the stock torque converter may be causing the sound. It's frustrating because I have my stethoscope on every part of the engine and exhaust and I can't find this loud ticking that is in front of me.

The car is still running amazing even with my crappy initial head/cam tune from VMS that is getting me 12 MPG (Down from 18 MPG I was averaging pre-head/cam VMS tune).

[BloKKem]

Just got back from the mechanic, who I was going to see if they could diagnose a potential exhaust leak. As soon as I started the car he tells me that 100% it's not an exhaust leak and that I have a misfire. I guess that would explain both the charred cylinder head pictured above and the sound. I guess the sound is there at idle, it's just very hard to distinguish (and I think I've had it a long, long time so I'm used to it). So it actually has nothing to do with the RPM's other than the fact that it just becomes more pronounced.

Time to find out what the next step is.

[vert]

The car is still running amazing even with my crappy initial head/cam tune from VMS that is getting me 12 MPG (Down from 18 MPG I was averaging pre-head/cam VMS tune).

OUCH... Maybe if you do have a misfire that would account for part of the bad MPG. Kind of odd though if the car is running well to be a misfire.

[BloKKem]

Videos added. Listen to 3:20-3:40 of second video is you want the down and dirty sound without all the preface getting there.

[BloKKem]

Since my last post I have changed I changed back to stock pushrods with the theory that 7.400" were too long and not allowing the valve to close all the way. Also, did a compression test on cylinder #5 & #7 with a 110psi result on each.

On Sunday, we're doing a compression test on all 8 cylinders and then replacing the O-ring on the oil pickup tube. If this doesn't work, we'll have to look even deeper, maybe a possible lifter problem or worse. I'm not blaming the lifters themselves yet, but looking more at the possibility that aerated oil is preventing the lifters from functioning correctly due to pinched/damaged pickup tube O-ring.

[BloKKem]

(This same thread topic on the other board has all of the "in-between" that occurred since my last post and now. I'm not going to bring it all over but I wanted to share the resolution.)

PROBLEM SOLVED! Thank you everyone for providing support and suggestions on how to tackle what was going on. I only hope that my experience can help someone from having to go through the same thing.

So today we dropped the oil pan back off with the suspicion that the oil pick up tube with the new o-ring attached didn't get properly seated to the oil pump yesterday.

We unbolted the bolt that attached to the oil pump and the two bolts that hold the pick up tube to the windage tray and then braced the tube while we felt the tube as we removed it from the pump to see how much resistance, if any, was there. It dropped right out. Bad sign overall, but a good sign to us since it proved that we didn't push the tube into the pump good enough.

It was a tricky situation (unless you already knew all of this) during our install yesterday because that bolt is torqued to 106 in-lbs and if it doesn't go in all the way, that bolt will torque to 106 in-lbs still. 106 in-lbs is not enough force to pop that pick up tube o-ring into place and mate it properly with the tube. Today when we pushed the o-ring portion into place, we used a breaker bar and pushed up, HARD, and eventually you get a nice "thwoomp". O-ring seated properly!

Buttoned the car back up, turned the starter a few times with the spark plug wires removed, then turned the car on....INSTANT 3.5-4BAR (measurement, not graphic) oil pressure, running 10W-30 right now so it leveled off to a constant 3BAR during idle and 4BAR during load. It never drops below 2.5-3BAR now and the TICK IS GONE.

Car is running amazing. The valvetrains sound perfect. The lifters sound like normal lifters.

.....A $4.00 O-ring.....amazing.

(I can take that oil pan off completely in 30-45 minutes now and I learned in incredible amount about that engine bay. Guess those are up side...)

Here is the mutilated o-ring. Don't REUSE your stock one!!!! It was so brittle. Replacement o-ring is GM PN 12584922. Their computer system says it's red, but the o-ring is actually orange.



Here are a couple shots of the oil pump and pick up tube before and after being seated properly to the oil pump:

[STL_G8GT]

Im glad you found this, but I hate reading things like this... makes me rethink my cam swap, and if I paid enough attention when this reconnected!

[vert]

This is the one area I will keep a close eye on when I do my cam swap in a few weeks.