Top end clatter / lifter tick?

[cmb]

Thanks everyone for your input. It sounds like my best course of action now is a combination of warmer weather, lower-viscosity oil, perhaps more Marvel, and longer runtime to really allow the oil to come up to temperature.

Sure enough, the oil temp gauge had just barely moved off its lower stop after 15+ minutes of idle in 30-35 degree ambient.

[KILLSHOTS]

Originally Posted by cmb

Thanks everyone for your input. It sounds like my best course of action now is a combination of warmer weather, lower-viscosity oil, perhaps more Marvel, and longer runtime to really allow the oil to come up to temperature.

Sure enough, the oil temp gauge had just barely moved off its lower stop after 15+ minutes of idle in 30-35 degree ambient.

Best of luck with this issue. Hopefully it will resolve itself without requiring a teardown.

[Karl]

I always start my car in the winter if I am not driving it. Last start up was last weekend. Temp was at most 10°.

I always run mobile 1 full synthetic 5w 30.

After water temps reach 180° I usually hold the engine at 2000 RPMs until oil temp reaches 160+.

Hopefully a oil change and warmer weather will help solve your problem.

[1991ZR1]

My engine makes this noise too. I assumed that it was the tensioner. Or at least hoped that was the cause. I really hope it's not the timing chain. Maybe we have different causes of the noise.

I have a very rough running engine and that may or may not be related. I was thinking the rough running and the Goodyear belt being long contribute to the tensioner making a clacking sound.

When I increase the rpm a little, the noise goes away.

The noise also goes away if I turn off the air conditioner. I don't think the noise is the air conditioner though. I think taking the load off the engine helps it run a little smoother.

I can't hear the noise while driving. I can only hear the rough running engine.

[Dynomite]

Originally Posted by 1991ZR1

My engine makes this noise too. I assumed that it was the tensioner. Or at least hoped that was the cause. I really hope it's not the timing chain. Maybe we have different causes of the noise.

I have a very rough running engine and that may or may not be related. I was thinking the rough running and the Goodyear belt being long contribute to the tensioner making a clacking sound.

When I increase the rpm a little, the noise goes away.

The noise also goes away if I turn off the air conditioner. I don't think the noise is the air conditioner though. I think taking the load off the engine helps it run a little smoother.

I can't hear the noise while driving. I can only hear the rough running engine.

A rough running....and rough idling engine noise would probably be dual mass flywheel noise. But you can definitely here where that is coming from. The rough running would probably be caused by poor injectors assuming you have good plugs, coils and not running on a dead cylinder.

Does your engine make more noise on one side or other?

Originally Posted by cmb

Thanks everyone for your input. It sounds like my best course of action now is a combination of warmer weather, lower-viscosity oil, perhaps more Marvel, and longer runtime to really allow the oil to come up to temperature.

Sure enough, the oil temp gauge had just barely moved off its lower stop after 15+ minutes of idle in 30-35 degree ambient.

It is hard to believe that a lifter would not pump up after 15 minutes.....or even 15 seconds no matter what oil you used. I assume the oil pressure comes right up within 3 or 4 seconds after start and is probably near 75 lbs? An ambient temperatures of 30 deg is not all that cold. I have started engines (not LT5s) at zero with 10W-30 Penzoil. After 15 minutes of idle the engine should be near 180 deg F even in 30 deg ambient temperatures. The thermostat will just not open as far in cold ambient temperatures.

A collapsed lifter is one that has excessive (very excessive) leak down as all lifters will collapse (leak down) after sitting for hours or days.
In other words....excessive internal plunger wear would have caused the excessive leak down of the lifter and unusual for a low mileage engine. A lifter that has clogged oil ports would not pump up and essentially be a collapsed lifter.

The oil will remain cooler given the oil pan and bottom of the engine is not cooled by coolant but by air flow and outside air temperates (assuming the oil cooler flow is zero at those temperatures). Oil flow is about 1.5 gpm at idle so would take about 2 minutes for oil to completely circulate giving a 2 minute cooling off period once back in the cool oil pan.

On Wed Mar 4th the high will be 3 deg F and low will be -12 deg F. In those temperatures would have to turn on Good Ole Val6 diesel Infrared 112,000 BTU Heater

I would do a compression test because it is such an easy test and only takes a few minutes just in case there is something going on with the valves, pistons.

Keep us posted on what is determined to be the cause of this clatter on the LT5 engines. Good information for everybody

[LGAFF]

Here is a bigger question: Is it always the same lifters that tend to tick...is there something in the head design that oil starves one or two lifters more?

I was thinking about this as I was looking at Jeal cam failures...is it always the same lobe?

Additionally the motor in #966 had a lifter tick and when I swapped in #702...same result...lifter tick.

[batchman]

Originally Posted by efnfast

Welcome aboard. I'm not far from you and can offer help for what it's worth. I've owned mine four 4 years, and am no stellar mechanic. But willing to lend a hand, or an ear.

I resemble that remark! Me too on all counts, except our Z has been ours (really my wife's) for a bit longer. I do have a cheapie contact stethescope (ok, how do you spell that) if that'd be helpful.

Jerry's done some good sleuthing to match it to idle speed, rules out the cam timing stuff. I can't really listen to it but another possibility could be an exhaust valve seat problem. If you do compression test don't stop there - do a leakdown too.

Best of luck and happy to help however I can,
- Jeff

[RyanChappel]

injectors sounds very scary...I loaded up mine a few years back and took it ot Marc for new Accels...I was actually relieved that it wasn't what it sounded like...a spun main or rod bearing...first ocurred on a slow drive about town..

[1991ZR1]

I have had a bad flywheel before and the sound is different. My noise sounds similar to what cmb is experiencing. It comes from the front passenger side.

I did have 2 wires with high resistance so I reinstalled the original wires and coils which were working fine when I removed them. I also replaced the plugs and injectors since the injectors were the originals anyway. There was no change in how the car runs.

I checked the function of the throttle position sensor with a Tech 1A and it appears to be functioning normally.

I guess I have to go look for my compression tester. It may be tricky trying to get it attached in the deep spark plug holes.

I just tried pushing down hard on the tensioner with a stick and the sound goes away. I'm thinking the long Goodyear belt allowing the tensioner to unwind too much together with the rough running causes the tensioner to make noises.

I have a new tensioner to try out but removing the old one seems impossible with the air-conditioning pipe in the way.

[5ABI VT]

I had this EXACT same noise on startup just a few weeks ago, My car was down for 5-6 months since end of july and I did work plus had my top end sent out. I had this EXACT clatter. I have some vids but Im at work and I can upload them and post when im at home on wifi.

Long story short.. idled for a few mins.. gave a tiny bit of rpm to increase oil pressure.. clacking tapered down and then disappeared. A little bit of run time later it was breaking new acceleration numbers on the g-tech