pifo1964

1993, manual, 100% standard.

Sorry for the following long story, but I tried to be as clear as possible detailing what I have done and checked.

There is ticking noise coming from somewhere around the engine. From above you barely can hear it but from underneath, mostly from drivers side, is more audible.
When I just start the engine and until it begins to warm up, maybe 3 minutes, there is no noise or at least I canīt hear it, then it begins to be more audible until engine reaches normal operating temperature when the noise is very noticeable.
Over 2000 rpm I canīt hear it anymore, either standing or moving, also canīt hear it with revs going up or down. If I walk away a few meters from the car I only can hear the engine and the exhaust but not the tic. Also canīt hear from inside, only with windows down and when standing at a light, tic bounces another car.
Itīs being there since I bought the car, 2 years and 5000 miles ago, never increased. Maybe now Iīm getting old but the noise is starting to bother me.
Tried to isolate it with a stethoscope, from above and from underneath, but was impossible, itīs a very vague noise. Also asked a mechanic and he tried with an electronic stethoscope with the same conclusion: nothing concrete from where is coming.
The car has no cats. I pulled them out, and my first thought was to blame this, but the tic is not from there, either from the transmission, or upper or lower part of the block, or the oil pan, and so on….The flywheel makes “its noise” and is independent from the tic, also injectors noise is very clear.
When I put the stethoscope on the valve cover, the sound is smooth like a quiet sewing machine, nothing abnormal. I only hear the same sewing machine but a little bit louder when I put the stethoscope just above the valve cover bolts.
The car has only 11k miles and never being abused, the only thing that I can say and according to the carfax, is that from ī04 to ī13 was driven only 400 miles, but when I changed the oil for the first time just the day I recived the car, it was really clean and still a little bit clear, so maybe the oil was old, but it wasnīt dirty at all.
Although it canīt be heard from above the engine, can a bad lifter make this kind of noise?
And if you think itīs one o more lifters, should I change them or leave the engine (and the tick) original as it is?
Checked spark plugs and wires (new Delco), all fine and nothing loose down there.
Also couldnīt find an exhaust leak…
Correct oil, correct oil filter, normal pressure: 25psi at idle warm and 55 cruising at 2000 rpm, increases normally with acceleration and reaching more than 65 at 4000 rpm. Pressure is maintained when I decelerate.
Last change, oil was clean and still quite clear, I also cut and opened the filter and found no traces of metal. 3000 miles on oil and filter. The engine is really clean inside.
Good compression on all cylinders. No smoke. Not a simple leak. Car accelerates, pushes and runs perfect. Time to time and only at idle you can hear a very slight and eventual popping coming from the exhaust, but idle is smooth.
I read a lot in this forum to learn how to identify and deal with all kind of noises, but Iīm still lost, is like the tick is coming from nowhere, but you can clearly listen to it.
Though I doubt, perhaps itīs a normal noise on a LT1 whit the ZF, but canīt compare with another since there is no other LT1 in my country, only a couple of 1990 ZR1 and the rest of the C4 are L98 (all automatic), also the videos from internet arenīt clear enough.
Thanks in advance for any advice.

PS: first video is half away from normal operating temperature; second one is totally warm up and the noise is clear.

antfarmer2

loose or cracked exaust manifold or other connection?

FASTAZU

pifo1964

With my limited experience I looked for cracks or leaks and found none, but surely the search wasnīt 100% efective.
Bolts seem tight.
How can a find a leak eficently? any advice?
Use a stethoscope but can not hear nothing abnormal, maybe was looking and hearing on the wrong place of the manifold.
What do you mean with other conection?
Thanks.

bow tie guy

LT1's are noisy

sounds normal to me. you're hearing an exhaust leak or the roller lifters
plastic rocker covers were used on 93-96 for this reason

whalepirot

The frequency of that tick sounds like a lifter, but I'd expect to hear that more clearly above versus under the car.

pifo1964

and thatīs one of the reasons iīm so confused

csthews

I hear the same tick on my engine (95 LT1). I assumed it wasn't a big issue. I have replaced the exhaust manifold (for other reasons) and the tick remained. One way to check for an exhaust leak is to hold a piece of cardboard (about the size of a playing card) in your hand. Run the cardboard around the exhaust. If there is a leak, you will feel it pulsing the cardboard.

antfarmer2

the exaust manifolds like to crack under the heat shields

DGXR

I always thought the cats were necessary for the oxygen sensors to get a good read on how the engine is running. The ECM adjusts the fuel injector pulses based on information from many sources, including the oxygen sensors. This might cause more injector noise and/or cause a mild popping exhaust. You said the plugs were "all fine"?

Just an idea.

pifo1964

On my car (i think all Lt1s) the O2 sensors are before where the cats were, so i think the ECM "doesnīt know" there are no more cats. Please correct me if iīm wrong.
Yes, the plugs and also the wires are new and just in case i rechecked them.
Anyway, thanks for the advice!!

94c4seminole

I'm an amateur so take this for what it's worth:

I have a 1994 LT1 and had a ticking noise that was hard to pinpoint. Mine varied with the engine speed when I blipped the throttle by hand. I replaced the fuel injectors because I was having fuel pressure trickle down slowly with the car hot. The fuel pump was new and the fuel pressure regulator was fine. New injectors resolved my issue and the ticking sound.

I wouldn't replace them just for the noise (if that's what it is), but maybe if you were having performance or starting issues. My car is still noisy regardless