I have been driving the car for a while like this but after a recent autox event it has begun to worry me. Basically the car makes a ticking noise when it warms up, and it gets worse when cornering hard. This noise has been driving me insane, but I have a couple ideas of what it could be and hopefully some of you guys could shed some light on this.

about 2 to 3 years ago I swapped in a 228/230 .571/.573 on 112° comp cam and had the heads ported by TEA stage 2. Springs are PSI 1511ML and LS7 Lifters. I also went with a melling 10295 oil pump.

Now I am hoping that the ticking noise is lifters. I can rule out exhaust leak since at a recent autox event, the ticking got louder when I took a hard left turn. The ticking seems to be coming from the driver side, so there might be a connection there.

Right now I have 3 theories: First, I went with too much lifter preload. I chose 7.350" pushrods after measureing with the pushrod length tool. After my measurments that comes to .088" preload. After doing this I later learned that .060" is recommended for LS7 lifters and aftermarket cams. But I am not sure if going roughly .025" less is going to make a difference or prevent the lifters from collapsing.

Theory 2: I could have pinched the oring on the oil pump and that is causing oil airation. I've seen this cause the symptom that I am seeing where the engine starts ticking after getting warmed up. However, my oil pressure is roughly 60psi at startup and when its completely warm I get 42-44psi. I would think that it should be less if this were the case.

Theory 3: i just have a bad set of lifters, but I would think that they would be tapping all the time instead of once the engine is warm.

Now I am hoping its not something worse like rod knock, but it does not get louder with more revs and it does not go away if I start shutting down cylinders so there is still hope in that regard. If you read this far then thanks. Hopefully some of you guys can give me some ideas on getting this solved.

 

Nobody can shed some light on this?

 

I vote for theory 3, but you should recheck pushrod length/preload.

 

!st thing I would do is check the oil hot for small air bubbles. If bubbles are seen carefully replace the oring. Just run the engine until its good and hot and tapping. Shut it off and pull the dipstick, look for a lot of small air bubbles mixed in with the oil.

 

Not sure what kind of car this is, but the C5 requires an additional quart of oil be added for these types of events. Once done and on the street, oil is then drained. Pump can put oil up top and drain back is not fast enough. Is this a recent issue or something that has been ongoing since the cam swap. Is the Melling a high volume pump?

 

Its a melling high pressure 10295. The sound has been going on since the cam swap. This is a C5 Z06 and I do usually run 7 quarts which is about half a quart more than normal and I do not drain it out after an autox.

 

I did this the other day and I did see some really small bubbles. They were about 1mm diameter roughly if i had to guess. The engine was running when I did this though. Ill try it again with it off.

 

Double check for an exhaust leak especially the header gaskets. I thought the same thing as you and it ended up being the the header gasket underneath where you can't see. I thought for sure i had a lifter tick or a pinched o-ring but my oil pressure was always good like yours.

 

It can't be this since the sound changes while turning hard which implies oil is moving around and making it worse.

 

The oil pressure won't be low if the oring is leaking air into oil. I had full oil pressure but the oring was leaking air into the oil, air gets pushed into the lifters and they start collapsing.

 

If this has been going on since the swap I think it may not be draining back fast enough to feed that pump. Not sure if you used the stock spring or the other spring in the Melling pump but it may be putting too much oil on the top of the heads and during turns is causing an issue. I run 7 quarts in my C5 and that is just to bring it to full on the dipstick. I don't AUTOX my car, but I have read some who have used pushrods with smaller holes to limit the amount of oil getting to the top of the heads at high RPM. Might want to discuss with others that AUTOX. One person I know overcame this with an accusump so that while cornering there is extra oil to feed the motor during cornering and then the accusump recharges while in the straight. Here is a thread that might help. Note that "Eric D" is a GM engineer------>Thread

Hope this helps and you get it sorted out.

 

Had a similar issue. Was a lifter bleeding down at high rpm

 

Did you replace the oring with another blue/black oring? Im starting to think this is my problem. I really dont think backing out the pushrods by .025" is going to make all the difference. Currently running .088" preload on the LS7 lifters with 7.350" pushrods.

 

Use the blue oring. I had full oil pressure and the lifter were LOUD. With the engine hot the oil was full of tiny little air bubbles if you look close. Cold the oil will have some bubbles but once the oil heats up you should see NONE. Another thing I noticed If I ran the engine steady with a load on it like going up a long steep grade at the top the lifters would tap like hell then after it idled for a few mins it would quiet back down.

 

this is almost exactly what I am seeing. if you hold it right about 1700-2000 rpm its the loudest. I guess ill check the oring on the pump then. Thanks for the help. Ill be back with an update when I change it.

 

I don't think most people understand what happens when the oring is damaged-worn. It doesn't leak oil, it actually allows air to enter the oil as the oil is entering the pump. The oring is there to seal AIR OUT. This causes the oil to aerate badly and if the oring fails completely it will cause loss of oil pressure.

Engine oil can only enter the pickup tube-oil pump- engine gallery because of Atmospheric pressure. The oil in the pan is at Atmospheric pressure, the oil pump creates a low pressure area and the oil moves because Atmospheric pressure pushes it to the pumps low pressure area. If the oring is not sealing the low pressure area Atmospheric pressure also pushes air past the oring into the low pressure area. Because there is more area in the pan acting on the oil than at the oring , the oil continues to move up the pickup tube and into the pump. BUT some air still enters at the oring because there is a low pressure are at that very point. I hope this makes some sense to you, It dam near drove me nuts till I stopped listening to everyone and investigated myself.

A slightly damaged or old(more than 5 years 50k miles will just eff with you. Every time I had a bad oring if you held the rpm steady at 2000 rpm it would just clatter and come and go. It just makes you wonder what the hell is going on because you have full oil pressure. After replacing the oring I only saw a very slight increase in oil pressure, but all the bs was gone completely quiet. What really made me crazy is all the dealers were trying to pass it off as "PISTON SLAP" freakin morons. The oil was FULL of tiny bubbles!

 

Thought I would post an update. I replaced the oring and the one that came out of it looked slightly bent but no signs of an acute pinch. Just not perfectly flat. Anyways I got the car back toghether but it still taps. At idle it seems to be a bit better but if I hold the rpms at around 1900 it taps just like before. Do you guys think it could be the preload on the ls7 lifters? With the pushrods I went with I should have .088" preload based on my pushrod length tool. I could go .025 shorter and end up at .063" but I am not sure if this will make a difference.

 

Does it sound like all the lifters? I check for bubbles again to be sure you sealed it up. Is it possible you are hearing rod noise? Worn rod bearings in these engines can sound like lifters. If you think its certain cylinder you can try pulling the injector plug off to unload the cylinder and see if the noise changes. If it does you may have bearing troubles. Can you make video? Does this sound ever go away completely?

 

I've tried pulling injectors off individually to see if the noise changes and it doesn't as far as i can tell. Also its been doing this for a while and I drive it pretty hard and would like to think if it were a rod bearing it would have died a while a go.

Another note i should say is that if i turn hard towards the left, the tapping gets louder, which is why i think its driver side lifters as when turning hard maybe they are allowed to collapse easier. I checked for bubbles and saw a few small ones but not as much as others suggested it would be.

 

Try overfilling the oil by a quart and see if it helps. Almost sounds like a small hole in the pickup tube above the inlet screen on the left hand side. When you turn hard left, all the oil goes to the right.