L83 Engine Buzzing with Tick

300 Blackout · March 3, 2019

Front of the engine is buzzing with a tick near cylinder 7. I don’t have access to my stethoscope right now to pinpoint the source. It increases and decreases with engine RPM. It’s the same regardless of what gear the transmission is in. No codes. AFM is deactivated. Factory dash gauges all within normal spec.

The noise started after being rear-ended last month. I noticed it the day of the crash. The next day when I dropped the truck off at the shop, it was quiet. I mentioned it to the shop, but they didn’t hear it and the repairs weren’t focused on the engine. I got the truck back yesterday and the noise is there with the tick.

I am going to torque the exhaust header bolts and see if that eliminates the tick. I’ll also remove the serpentine belt to examine the pulley’s and check the cooling system for air. My biggest concern is if the oil pump is going bad. I would much rather pull the engine now and replace the pump (and cam and lifters *wink*wink*) than wait till it catastrophically fails.

I’m not able to find a method to diagnose an oil pump failure (or impending failure) prior to it actually decreasing it’s output. Do you guys have any input on this?

silveradosid · March 3, 2019

could be the bearing for the a/c compressor

300 Blackout · March 3, 2019

could be the bearing for the a/c compressor

I replaced the A/C pulley bearing, clutch and stator just a couple months ago because I thought they were making a different noise. I guess it’s possible the bearings inside the compressor are failing. I’ll see if there is a correlation to the noise and AC clutch engagement. Thanks for the suggestion.

300 Blackout · March 4, 2019

The ticking noise was a loose spark plug. The headers were tight. Used a stethoscope to listen around for the buzzing. The water pump is silent. A/C compressor is quiet. I took it to a local shop without telling them what I suspected and the mechanic said it sounded like the oil pump. So, it looks like the engine will be coming out soon. Oil pump is $130.

Sierra Dan · March 5, 2019

There is one particular spark plug boot/wire that is notorious for falling off or coming loose.

Happened to me.

Another ticking culprit could be the vacuum pump.

To my knowledge, You do not have to pull the engine to change the Oil pump on an L83

300 Blackout · March 5, 2019

There is one particular spark plug boot/wire that is notorious for falling off or coming loose.
Happened to me.
Another ticking culprit could be the vacuum pump.
To my knowledge, You do not have to pull the engine to change the Oil pump on an L83

I don’t have a mechanical vacuum pump. My plugs and wires were all new as of 2 months ago. I just didn’t tighten the plugs enough and cylinder 1 and 5 backed out. The wire boot was tight on both.

Some guys can pull the pump from the front of the engine. I’m sure some can even manage to get the pick-up tube out with some finesse and cutting tools. The manuals say to drop the pan to replace the pump which requires removing the steering rack and other steering components, alignment when done, etc...

Melling recommends installing the pump with the block stood up on end to allow the crank to center itself in the bearings.

I think pulling the engine and getting a good look at everything, room to work, etc.. has a lot of benefits without too much more labor.

300 Blackout · March 16, 2019

So, I’m changing course on this. I’m just going to keep running it as is. I’m not seeing any decrease in oil pressure nor any metal in the oil. After reading more about this, there is a possibility the pump is just noisy and isn’t actually failing.

The labor involved in replacing just the pump is at least 12 hours. The labor in pulling the engine is obviously more. If I’m going to do all that labor, it doesn’t make sense not to put a cam in it and overhaul the entire block and heads. Maybe if it was a LT4 but on an L83, not worth it at this point.

So, I’m gonna run it hard. If it kills the engine, then I’ll drop something bigger in it and make some crazy power. If it survives and is just noisy, then I save a few thousand.

HondaHawkGT · March 18, 2019

On 3/4/2019 at 12:08 PM, 300 Blackout said:

The ticking noise was a loose spark plug. The headers were tight. Used a stethoscope to listen around for the buzzing. The water pump is silent. A/C compressor is quiet. I took it to a local shop without telling them what I suspected and the mechanic said it sounded like the oil pump. So, it looks like the engine will be coming out soon. Oil pump is $130.

The oil pump on these engines is naturally more noisy than a gerotor oil pump. Our engines use a vane-style oil pump and the earlier version of the pump made noise no matter what. Probably due to the spacing between vanes, which can create pulsation noises (harmonics) that are heard but doesn't mean there's anything wrong it. It's similar to the noise you'll typically hear from a big hydraulic pump. It's up to you though. I don't blame you for wanting to do something about it. It's hard to judge what's normal and what's not. My pump is noisy but the noise is similar to what it was like when it was new.

Edited March 18, 2019 by HondaHawkGT

300 Blackout · March 18, 2019

Thanks for the info and pics. My truck was built late 2013 so it’s possible I have one of those early, noisy pumps. I don’t ever recall it being this loud though. And what confuses me is it isn’t always the same volume. Sometimes it’s loud and sometimes it’s barely noticeable. I haven’t been able to pinpoint under what conditions it’s loud and what triggers it to stay quiet.

I just did an oil change after only 2,500 miles and cut apart the oil filter to examine it for any metal. I learned a couple things. Changing the oil didn’t do a thing for the noise. There wasn’t even the slightest trace of visible metal anywhere in the filter or filter media. Mobil M1-212a filters are of excellent construction and quality.

I installed a Fram Ultra XG10575 after changing my oil just in case there was an off chance the Mobil filter was somehow vibrating and causing the noise. It wasn’t and the new filter made no difference in sound. Both the Fram Ultra and M1 filters are great and I’d have no problem running either of them.

I’m gonna mess around with the viscosity a little and see if that has any impact. Nothing crazy, just thicken it up a little and see what happens. I’m not well researched on the validity of using a heavier weight as the engine gets more miles on it but it stands to reason that tolerances likely have opened up a little after 75k and perhaps a 30 weight would be a better match.

300 Blackout · March 18, 2019

Now that I think about it, when I first bought the truck, it had a non-dexos 0W-20 in it. It burned a couple quarts in 1,000 miles so I changed it to dexos Gulftec 0W-20 and added a quart of Lucas oil stabilizer. It didn’t burn a drop of that over 9 months and 5,000 miles.

Come last October and I switched to Valvoline Advanced MaxLife 0W-20. Great wear properties but it’s a volatile oil and I had to add a quart and a half over the last 2,500 miles.

I found an old video from October when I heard a buzzing noise that I assumed was my transmission at the time. Perhaps it’s no coincidence the noise was first observed around the time of that oil change.

This engine had a tough life in its first 65k. It spend its days in northern Canada and I’m sure all of the sub-zero cold starts took their toll on the tight tolerances of the engine. I’m gonna thicken it up tomorrow and see what happens.

BALJIT SINGH · November 9, 2022

On 3/17/2019 at 9:57 PM, HondaHawkGT said:

The oil pump on these engines is naturally more noisy than a gerotor oil pump. Our engines use a vane-style oil pump and the earlier version of the pump made noise no matter what. Probably due to the spacing between vanes, which can create pulsation noises (harmonics) that are heard but doesn't mean there's anything wrong it. It's similar to the noise you'll typically hear from a big hydraulic pump. It's up to you though. I don't blame you for wanting to do something about it. It's hard to judge what's normal and what's not. My pump is noisy but the noise is similar to what it was like when it was new.

Mine l83 oil pump failed. I was making pretty bad whining noise. Code P06DD. Replaced it with new pump. Gm Part #12686433. Open up my old oil pump oil flow solenoid seemed working fine. But it was broken from inside. I assume whining noise was coming from those fan style pivots, I assume those were hitting constantly to the broken part.