Ticking noise after head swap
 

I am hearing a ticking noise from my ’08 Z that is driving me nuts and would value some input on possible causes. Here are a couple of videos.


It's louder when the engine is warm, and is loudest underneath the car. I can hear it in the cabin. Seems to go up to about 1600 rpm. I can hear a slight ticking noise with a stethoscope up to the valve covers on both sides of the motor, and it doesn’t get louder around any particular valve.

I recently did a head swap - AHP Stage 4, PM guides, resurfaced/minimal milling, reused stock pushrods (Kohle & team have been great BTW). I only had stock heads for a few weeks with little driving, but I seem to recall this sound before the swap – though it may be louder now. I also perceive more "sewing machine" noise. Of course, since the swap I have been hyper-sensitive to noises.

Exhaust leak and lifter tick come to mind. The car has 56k miles, has been gently driven and is stock except for the heads. I did not inspect lifters. I did not measure preload but have pulled the valve covers twice to verify rocker alignment & torque. I put on new manifold gaskets and can’t detect an exhaust leak, but I get an odor on cold starts for 10-20 seconds.

Any opinions? Is this "normal" or cause for concern?

you should have replaced the push rods !!!!

It sounds like an exhaust leak to me.

Not likely. The stock liftrers have a wide range of operation. He said minimal milling, I am guessing .010 or less, the stock PR's will work fine.

OP, if it's the noise i think you are conserned about, that does sound like a lifter. You wouldn't be the first one to experience this sort of issue. What to do about it, if anything? I've heard this on multiple motors, on both sides of the block (usually you hear it more from the block, around the fender area). It really depends on just how loud and consistent it is (consistent is better than intermittent), the threshold determining if it's "normal" or "a problem". :cheers:

and why exactly is that? :toetap:
if they simply decked his head surface (from what the OP stated), then stock length is fine. Granted, the OP should've checked preload, but as stated by Dan above, the lifters have a wide range of tolerance.

make sure your lash caps are on your intake valves!!!!

I am certain they are, I took tons of pictures of old and new heads just to give myself peace of mind on that, lol.

The noise is definitely loud by the fender. I have to think the noise is loud enough (since I can hear it in the cabin) that it should not be considered "normal."

Is there any additional diagnostic I can do before pulling the heads to verify a lifter issue?

I couldn't tell by your video, but lifter clicking will usually sound like it's coming from the intake, more like in between the two heads. If it sounds louder on the drivers side vs the passenger side, or the other way around, it's more likely an exhaust leak or rocker noise.

sounds like an exhaust leak to me seems like you can hear it under the car which tells me exhaust. Hard to tell for sure from video.:cheers:

my 2 cents: lifter noise

but hopefully exhaust leak you are smelling till heat expands and stops leak.

:cheers:
DH

What does AHP/Kohle have to say about it? Showed this to him?

Taking mine there in a couple months for the works :)

Yes I have been talking to Kohle and he has been very helpful in trying to diagnose remotely. Exhaust leak and lifters were his thoughts too. Videos are useful up to a point, it would be much easier to determine in person but there isn't a shop I know of to trust near me (Oklahoma). Also just to clarify I don't think at all this has anything to do with his product, I just mention the swap to provide more context around the issue. I think you'll be happy with the choice to work with AHP.

My car has ahp heads on it and its pretty loud. Im going to replace the comp trunnion bearings for bushings,check the pr length and c if that helps.

:lurk:
I'm in for either exhaust leak or cylinder misfire due to bad plug or plug wire

I got the package 4 heads and the C.H.E bushed rockers as well and the sewing machine sound is very present. i'm going to pull the rockers after 1k miles on the motor to check valve guide clearance. If guide clearance checks out I'm going to chalk it up to these motors sounding like this and not worry about it anymore.

Exhaust leak with factory Exhaust? I think not. Its the VALVE TRAIN

I think it is lifter noise.

improper torqueing or undertighening of header bolts could easily cause exhaust leak on all exhaust systems......
to me sounds like driver side lifter issue.

Remember that the LS engines are notorious for the sewing machine sound, that is normal. One of the things that can help reduce that noise is in an aftermarket camshaft with lobes specifically designed for LS engines; EPS's website describes it well, TSP & CamMotion also offer comparable camshaft lobes.

You might have a little more lifter preload than what you need, and perhaps that could equate to some of the excess sewing machine noise? I have a set of heads in the works from AHP as well, and this is as I learned. The OE PR length of 7.800" gives the OE LS7 lifters a preload of around .120, and they routinely reinstall on their builds a slightly shorter PR at 7.775" to both reduce some of this preload to around .100, but also I imagine to account for any slight reduction in the height of the heads, even if it was just minimally resurfaced. This also assumes you retained the OE head gaskets and their thickness.

Before you were to have to go back and remove the heads so that you could see if your lifters were alright, I would suggest that you take the rocker arms off and replace your PR's with new 7.775" PR's. While you had the rockers off, get yourself a CHE LS Trunnion kit (got mine from TSP for $200) and put those in for good measure; they are only going to help all around.

My theory and plan of attack on my head swap was to replace the plastic trays and inspect my OE LS7 lifters while I had my heads off. (BTR sells the OE trays in a four pack for like $26.) You most likely don't have to replace the lifters if you're not changing the cam (general rule: new cam = new lifters,) but it's good peace of mind to verify there are no abnormal wear patterns on either your lifter wheels or camshaft lobes, and you could also ensure that each lifter's plunger travel was still working correctly. Put them back in the new tray's and you have much more peace of mind of where your lifters are at.

Coming from Oklahoma there are multiple great places in the DFW area but if you're ever down to the North Austin area (Cedar Park), look up Aikman Performance and Jerry will get you taken care of.

Thanks all for the comments and suggestions.

My plan of attack is to start with the easiest/lowest risk item which is the exhaust. I've found a shop that will work with me this weekend on detecting any leak source(s). I properly torqued header bolts with the new GM gaskets so I don't think that's where a leak could be, but I still won't rule it out yet.

After that I'm interested in the shorter pushrods and possibly the trunion upgrade idea. Could just putting in shorter pushrods help? That's an easy test to try. Any other thoughts on this?

If that doesn't work then I'll pull the heads. Really regret not inspecting the lifters on the first go-round. Good lesson for others considering a DIY head swap.

Will update as I learn more.