Random tick/tap noise?

[Tommio RS]

Hello everyone.

I come today with a odd noise question.
I have a tick or tap noise from the engine area after driving for while of driving.

Situation:

Cars hot, coolant is over 85C oil is over 70C
I have been driving the car for over 20mins.
Oil level on the dip stick when cold is high.

Car does NOT tick tap or rattle on start up at all.
Car is 1995 ZR-1 no engine mods from what i can tell.
When the noise is heard. This is what i have done to hear it.

At a stop sign or in slow area like 1st gear a ticking/tapping noise will happen for a quick second or two
If i shift gears the noise is gone.
If i free rev to motor half the time it will go away some times return until i shift a gear.


From my knowledge, the speed at which this happens sounds like valve train noises.

My best guess is that the engine oil is the wrong grade like too thin.
When i got the car, the oil was fresh changed buy the seller.
So from my searching, people like to use Amsoil 10W40?

If anyone else has an idea im game.

Tom

[BigJohn]

What grade of gasoline?

[lfalzarano]

If it is the valves warm it up again to those temps. Park it with the engine running and use a automobile stethoscope to go over the heads. If you find nothing, it could be the flywheel. You would need a lift to check it and also double check the crankshaft bearings for noise.

Yes, use Amsoil 10w-40 when you can.


Lou

[Tommio RS]

Ok.
The grade of gas i have is Shell 91 V power.
I use it because it does not contain ethanol.

I like the idea of using a scope on the motor once this noise happens but, its very hard to catch.
It will happen for maybe tops 5 seconds and its only when the RPM is over i would guess 1500.
If the RPM drops to idle and i start moving again, the noise is gone.....And seems to not return.
Also upon further inspection of the oil level, its about half way between low and full, so its down on some oil. How much i have NO idea yet because i personally have not changed my own oil yet.....Sad to say that.....

[32valvZ]

Originally Posted by Tommio RS

Ok.
The grade of gas i have is Shell 91 V power.
I use it because it does not contain ethanol.

I like the idea of using a scope on the motor once this noise happens but, its very hard to catch.
It will happen for maybe tops 5 seconds and its only when the RPM is over i would guess 1500.
If the RPM drops to idle and i start moving again, the noise is gone.....And seems to not return.
Also upon further inspection of the oil level, its about half way between low and full, so its down on some oil. How much i have NO idea yet because i personally have not changed my own oil yet.....Sad to say that.....

Kind of sounds more like its clutch related..... and top off the oil.

[A26B]

Originally Posted by Tommio RS

Ok.
The grade of gas i have is Shell 91 V power.
I use it because it does not contain ethanol.

I like the idea of using a scope on the motor once this noise happens but, its very hard to catch.
It will happen for maybe tops 5 seconds and its only when the RPM is over i would guess 1500.
If the RPM drops to idle and i start moving again, the noise is gone.....And seems to not return.
Also upon further inspection of the oil level, its about half way between low and full, so its down on some oil. How much i have NO idea yet because i personally have not changed my own oil yet.....Sad to say that.....

About checking oil level:
Check when cold, before start. The LT5 retains a lot of oil top side & drains back slowly. Checking after shut down will always read less than true.

[Tommio RS]

Thanks for the input guys!

Ill check my oil next morning after i drive it.

BigJohn you might a point about possible knock/ping.

I do have a chip in the car. Its a DRM chip that im yet to figure to out what it does.....

Also this knock/ping idea could be more true than i think maybe?
The car seems to idle when hot at 1000-1100 RPMS and does have a stubble thing around 1000-2000RPMS some times on warm up.

My first thought is that i have a vacuum leak....Having a air leak on a cylinder or bank of cylinders could for sure make bad stuff.

The clutch being loud seems odd to me? If the flywheel is poor or a bearing is going out the temp should not matter what so ever. Thats just my opinion BUT what do i know about these ZR-1 yet! Lol.

[32valvZ]

Its not necessarily the clutch, but the dual mass flywheel that can make strange noises under different conditions.....if you still have that.

[BigJohn]

I had a knock sound at about 1500-1600 they adjusted the program to add more fuel at this rpm.

[lfalzarano]

A blown dual mass flywheel will sound like a noisy valve, and will disappear at higher higher rpms due to normal engine noise and exhaust. Been there and was costly to replace.


Lou