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I've read that the external oil pump will moan for the first few minutes of operation. However mine moans all the time and is most noticeable from 900 RPM through 1500 RPM. Thus, around town cruising, you hear the moan. It's even noticeable as speeds up to 70 MPH when cruising in 7th. Oil temperatures seem to be stabilizing at about 180 degrees F and it's still there.
I don't see anyone complaining about it, so either it's really common or it's really rare. Is this really normal for the Z51 LT1 engine package? Is there a way to sound insulate or quiet the pump?
I've read that the external oil pump will moan for the first few minutes of operation. However mine moans all the time and is most noticeable from 900 RPM through 1500 RPM. Thus, around town cruising, you hear the moan. It's even noticeable as speeds up to 70 MPH when cruising in 7th. Oil temperatures seem to be stabilizing at about 180 degrees F and it's still there.
I don't see anyone complaining about it, so either it's really common or it's really rare. Is this really normal for the Z51 LT1 engine package? Is there a way to sound insulate or quiet the pump?
Maybe I should have typed 'external sump' oil pump?
Also, I double-checked oil temperature and it's not much about 110-120 degrees, since it's only 43 degrees outside. So perhaps I just need to wait for a warmer day. The oil is fresh, so it's not full of water (yet).
Maybe I should have typed 'external sump' oil pump?
Also, I double-checked oil temperature and it's not much about 110-120 degrees, since it's only 43 degrees outside. So perhaps I just need to wait for a warmer day. The oil is fresh, so it's not full of water (yet).
Dry sump? Open the hood and listen closer. Oil temp should heat up to 195 and stay there.
Last edited by BrunoTheMellow; 03-25-2019 at 05:50 PM.
Dry sump! Sorry, I am still living in Gen1 small block land; it's going to take a few weeks for me to acclimate. But yes, I'll pop the hood and listen, and double-check that oil temperature just to make sure. It didn't seem to get very warm after the five-mile drive home: Water temps were normal, but the oil temperature gage looked kind of low. Oil pressure looks to be in the high 20's / low 30's at idle.
My question is, how do you know it is the oil pump. I believe I would be heading down to the dealer & have them take a look & listen.
Yup, once I have a better idea of if it's something to worry about, I will do that. Unfortunately most dealerships are quite happy to take your stuff apart at $100 / hour to diagnose the problem. The more zealous ones will even throw parts at the problem at retail cost until they find the one that fixes the problem. First I want to find out what "normal" is.
Last edited by tychoaussie; 03-25-2019 at 06:13 PM.
Dry sump! Sorry, I am still living in Gen1 small block land; it's going to take a few weeks for me to acclimate. But yes, I'll pop the hood and listen, and double-check that oil temperature just to make sure. It didn't seem to get very warm after the five-mile drive home: Water temps were normal, but the oil temperature gage looked kind of low. Oil pressure looks to be in the high 20's / low 30's at idle.
Mine cruises at 35 psi. Take a good 10 minute to get up to temp.
Hmm, never heard of an "oil pump" making noise! I got my 2014 Z51 early, October 2013 and have had a dry sump every since!
There are some who hear oil going from the oil pan to the dry sump tank on start-up IF the car has been sitting overnight. Oil will drain back to the pan when the engine is shut off. Frankly I never heard it! But then can't say I ever tried to listen. That would occur over a very short time having nothing to do with oil temp. That would be an oil flowing sound.
Don't know what I was supposed to hear on the video?? But whatever you hear it's likely NOT either off the oil pumps. The one is called a Scavenge pump that pulls all oil out from the pan to the dry sump tank. It also pulls in air as if you're going to get all oil out you have to take air as well.
The other puts pressurized oil into the engine bearings etc.
Okay then, it will have to remain a mystery. I warmed the oil to 200 degrees, and recorded 'sounds' both inside and out. The low pitched whine is inside the car, varies a little with RPM, and is no longer heard once revs go above 2000 RPM. I think I can fix it by simply staying in second gear whenever I drive anywhere. Sort of like the international students at MSU in their stickered-up BMW's.
Okay then, it will have to remain a mystery. I warmed the oil to 200 degrees, and recorded 'sounds' both inside and out. The low pitched whine is inside the car, varies a little with RPM, and is no longer heard once revs go above 2000 RPM. I think I can fix it by simply staying in second gear whenever I drive anywhere. Sort of like the international students at MSU in their stickered-up BMW's.
Hard to tell from the video what you're referring to. Looks like you can hear it with the car stopped. If so get a 3 or 4 foot length of water hose etc and use it as a stethoscope and put the open end around the engine and the other near your ear. Whatever your hearing is not likely from inside the engine. Might be the belt tensioner (have been know to be an issue and if so will get worse.)
Must admit the C7 has so much road and tire noise I have my sound system playing >1000 songs in shuffle mode as soon as the car starts. Comes on automatically! Guarantee, Janis Joplin signing "Cry Baby" will drown out whatever your worried about! When on an Interstate I am usually below ~1700 rpm. Would be a waste to drive over 2000 rpm to eliminate whatever you're hearing!
It sounds like an electric motor, and it's related to engine speed; I'll quit assuming its oil pump related for now and chase it down, if I can, using the low-buck stethoscope method. I've had louder ticks and whines in my Trans Am but this one seems particularly annoying. Maybe I could drown it out with an aftermarket exhaust system and a slightly bigger cam. Maybe that'll be the approach I take in a few seasons?
I've read that the external oil pump will moan for the first few minutes of operation. However mine moans all the time and is most noticeable from 900 RPM through 1500 RPM. Thus, around town cruising, you hear the moan. It's even noticeable as speeds up to 70 MPH when cruising in 7th. Oil temperatures seem to be stabilizing at about 180 degrees F and it's still there.
I don't see anyone complaining about it, so either it's really common or it's really rare. Is this really normal for the Z51 LT1 engine package? Is there a way to sound insulate or quiet the pump?
Is the noise happening right as the RPM cross about 1k and up to about 1,300 RPM? It's hard to tell in the video if that's the noise you're referring to? If so, that sounds more like a torque tube issue than anything oil related. Does it make the same noise with the clutch pedal depressed or only with the clutch released?
Yes, the same noise is present, regardless of whether it is in gear, in neutral, with or without the clutch being depressed. It almost seems like an electric motor kind of sound, or a hydraulic pump with a bit of cavitation. It reminds me of the sound I would get when testing power steering pumps as a co-op student for General Motors. ...and yes, I know that this is an electric power steering car without a hydraulic pump. I may be ignorant of C7 technology and terms, but I am trying to learn as fast as I can. I'm hoping to actually find and purchase a service manual for this car sometime later this spring. Since its a 15,000 mile 2014 without warranty, it would probably be a good investment, assuming such things still exist.
Yes, the same noise is present, regardless of whether it is in gear, in neutral, with or without the clutch being depressed. It almost seems like an electric motor kind of sound, or a hydraulic pump with a bit of cavitation. It reminds me of the sound I would get when testing power steering pumps as a co-op student for General Motors. ...and yes, I know that this is an electric power steering car without a hydraulic pump. I may be ignorant of C7 technology and terms, but I am trying to learn as fast as I can. I'm hoping to actually find and purchase a service manual for this car sometime later this spring. Since its a 15,000 mile 2014 without warranty, it would probably be a good investment, assuming such things still exist.
Sorry, video no help BUT a comment you made might.
That silver round cap in front of the brake fluid reservoir is an electric motor that maintains a vacuum level. Folks have said they have heard it after the car was shut off and found a leaking vacuum hose. Check it out!
I'm having the same exact issue with my 2017 Z06. Did you ever diagnose the issue?
No, I never figured out the root cause. I learned to live with it, and it hasn't changed in 5000 miles. I heard the same noise, but at reduced volume in someone's 2017 Grand Sport so I figured it was probably just a an annoying trait of the model.
^^^
Hmm, looking at the posts in this old Thread: First: There is no external oil pump. See my post #10 for sketch of the two LT1 oil pumps from the 4 volume Service Manual. This is not a NASCAR etc external dry sump scavenging pump! Second: If in fact the noise is coming from the front of the engine, might be the belt tensioner as this has been reported. BUT it would get worse not better. The very high pressure fuel injector pump is underneath the intake manifold and some found the noise insulation was not properly in place. BUT that makes a ticking sound. Third: Hard to isolate noises as far as location. Not easy for dealer either. A ~3 foot length of garden hose, held to your ear and the end placed in various areas might help. Be careful NOT to get the end into the moving belt! Fourth: My 2014 Z51 and now my Grand Sport have so much tire and road noise my sound system start playing the ~1000 songs in shuffle mode I have on a thumb drive as soon as I start the ca! It's seldom off! Janis Joplin singing :"Cry Baby" etc drowns out most external noise!
03-25-2019, 09:14 AM
Z51 external oil pump moans all the time
Good question!
