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.....

[BigJohn]

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

[32valvZ]

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]

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.

[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

[lfalzarano]

BTW - Marc H’s chip includes all the GM updates that cures the idle and stumble.
“If the octane is too low, and the engine detonates, the knock control system will reduce the spark advance for about one second. The driver would notice a one second sag in acceleration as power is reduced by about 20 hp for the one second period.” From Marc on a stumble I had with OLD gas!


Lou

[Tommio RS]

Hmmmm interesting info about the Marc H chip there.
Can I just remove the DRM chip and still run the car as a "stock" tune?
I ask because on JDM cars like subaru's and nissan's you have a socket JUST for a tune. You cut or add a jumper in most ECU's and the car will run on your tune at that point. This is of coarse on older JDM cars.


The ZR-1 from what i can tell you pull the chip out then you need a "stock" chip in place of the tuned chip? I think i right in saying that?


And for this possible clutch issue.
How do you check if the dual mass flywheel is failing?
Is there an inspection port maybe?
From what i can hear at idle in my garage the bearings "sound" ok like pilot and throw out. The rest is unknown to me.


Any input is great!
Tom

[lfalzarano]

Tom,

I recommend you contact Marc about the chip installation and impact.


Lou

[Tommio RS]

Cool beans.


Ill contact Marc about the chips and such.


Still trying to wrap my head around a possible flywheel issue.
Going to have to so more research i guess about that.

[QB93Z]

I will try to describe the "fly wheel" sound you asked about. The Dual Mass Flywheel has two separate rotating masses that have a dampening mechanism relative to each other.


For a healthy engine, the rotational pulsations are small enough that the flywheel makes no noise. At idle, with the transmission in neutral, when one injector is not passing fuel, it causes a rotational pulsation that can cause the flywheel dampening to over travel and make a ticking sound.


Jim

[Tommio RS]

Hmm very interesting QB93Z.
That makes sense now!

Also! This possible high idle seems to be driving me kind of nuts! Lol

I have used a boro scope/ tiny snake camera to look under the intake manifold and such, and i dont see any vac. lines off that i can tell.

So my next step is im going to smoke leak check the intake manifold and such. If i see smoke coming out from under the intake manifold.....Im going to pull it.

Now if i don't see smoke from under the manifold. Im now leaning towards a leaking fuel injector or a none firing injector. Are the ZR-1 known for injector balancing issues or injector issues in general? My car did sit for 3 years before i got it.

I would think a leaking injector could very well make the car idle higher than normal or a vacuum leak would do the same also.

Thoughts?

Tom

[QB93Z]

When you are driving, is the secondary system operating properly? That is, do you have strong acceleration at full throttle all the way to ~6000 rpm?


The high idle issue is most likely NOT related to an injector issue.


Jim

[Tommio RS]

OK.

I have done a little more testing since last time.

I had the car hot and checked with the HVAC how accurate the tacho is.
Im reading a 32/33 about so 32X25 is 800. So i think my tacho is reading 150 to 200 RPMS to high. But the gauge does not look all the accurate form the get go! Sorry to say that. Will likely replace the PCV valves and MAP rubbers over the winter months now.

For the ticking noise after being hot/warm and such.
I swapped the plugs as with the AC 41602's and set there gap to .38
The plugs i removed were from what i could tell were the ORIGINAL PLUGS!!!!!
No joke! The gap i was seeing on some of the plugs was .80 plus!
So now doing the same drive.....Car does not tick! Im happy!

The only side effect from all this "diag" work is now i know i need some new tires! I can very easily spin the tires in 1st gear and chirp them fairly hard into 2nd gear. Again. I don't how how much power the car really has in it due to the tires. Also i have NO idea if this motor has been opened up before. The hardware all over the motor looks untouched to me so i would think not but you never know.

Thanks again.

Tom

[conesare2seconds]

It’s nice when the solution is simple. Glad you found the problem.

[WARP TEN]

OK.....The only side effect from all this "diag" work is now i know i need some new tires! I can very easily spin the tires in 1st gear and chirp them fairly hard into 2nd gear. Again. I don't how how much power the car really has in it due to the tires.....Tom


You haven't even BEGUN to have fun until you can chirp the tires in fourth gear!--Bob

[Paul Workman]

You haven't even BEGUN to have fun until you can chirp the tires in fourth gear!--Bob

510 HP and 410s cause that....

[Tommio RS]

Hmmm i could only imagine 510hp and 4.10 rear gear.
That would feel incredible!!!!

[WARP TEN]

Hmmm i could only imagine 510hp and 4.10 rear gear.
That would feel incredible!!!!

Intoxicating. You should try it sometime....Bob