Weird knock under load

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

chevyfs

Full Access Member
Joined
Jan 21, 2022
Posts
55
Reaction score
17
Location
michigan
First Name
ray
Truck Year
1986
Truck Model
Chevy C10 Rwd P/U
Engine Size
4.3liter V6
it also ticks at idle(which is very low once warm) but once i first start it in the morning it idles nice and doesnt tick. But in the video (don’t mind whats going on in the video just what i have at the moment) it knocks under load and full thottle. Im wondering if its a lower end noise or a top end https://share.icloud.com/photos/0966x14XxtrDo-c23R8Qx0M0Q#Jefferson_Township
Anyone know a better way to post videos?
 

AuroraGirl

Full Access Member
Joined
Sep 8, 2019
Posts
9,693
Reaction score
6,875
Location
Northern Wisconsin
First Name
Taylor
Truck Year
1978, 1980
Truck Model
K10, K25
Engine Size
400(?), 350
it also ticks at idle(which is very low once warm) but once i first start it in the morning it idles nice and doesnt tick. But in the video (don’t mind whats going on in the video just what i have at the moment) it knocks under load and full thottle. Im wondering if its a lower end noise or a top end https://share.icloud.com/photos/0966x14XxtrDo-c23R8Qx0M0Q#Jefferson_Township
Anyone know a better way to post videos?
if it changes then it sounds like a clearance or multi wear issue. Knocks under load id say your oil is buffering it when cold but the valvetrain maybe isnt getting oil pressure or something idk when warm. Oil pressure? When did it start doing it...?
Youtube.
 

chevyfs

Full Access Member
Joined
Jan 21, 2022
Posts
55
Reaction score
17
Location
michigan
First Name
ray
Truck Year
1986
Truck Model
Chevy C10 Rwd P/U
Engine Size
4.3liter V6
xc_hide_links_from_guests_guests_error_hide_media
heres a video of what it does under load
 

chevyfs

Full Access Member
Joined
Jan 21, 2022
Posts
55
Reaction score
17
Location
michigan
First Name
ray
Truck Year
1986
Truck Model
Chevy C10 Rwd P/U
Engine Size
4.3liter V6
if it changes then it sounds like a clearance or multi wear issue. Knocks under load id say your oil is buffering it when cold but the valvetrain maybe isnt getting oil pressure or something idk when warm. Oil pressure? When did it start doing it...?
Youtube.
The gauge says it has 30-35 psi of oil pressure at idle when cold and it will be idiling fine until i rev the engine after its just warmed up then it drops to a very shaky damn near stalling idle
 

OldBlueDually

Full Access Member
Joined
Jun 8, 2020
Posts
2,428
Reaction score
8,518
Location
Minnesota
First Name
Justin
Truck Year
1976 GMC
Truck Model
C30
Engine Size
455 Olds
What kind of engine? What kind of truck? (86 S10 with 4.3 V6?)

A tick is "usually" just lifter/pushrod noise, you may have a weak lifter possibly.

Under load and knocking could be a sign of a loosed rod/worn rod bearing. If you are driving it and have it under load it knocks....what does it do when you let off, does the knock go away?

I had an 02 Impala (3.4 V6) that developed a knock like you describe, only under load. Pulled the dipstick at night after running it and used a very bright LED light, could see tiny little particles in the oil. Ended up replacing the engine.
 

Bextreme04

Full Access Member
Joined
May 13, 2019
Posts
4,464
Reaction score
5,630
Location
Oregon
First Name
Eric
Truck Year
1980
Truck Model
K25
Engine Size
350-4bbl
I cant really tell anything from those videos or descriptions. What have you already done to it? How long have you had the truck? Video of the engine while running? Pics of the engine bay? It sounds like the engine is bogging under load... but hard to tell.
 

chevyfs

Full Access Member
Joined
Jan 21, 2022
Posts
55
Reaction score
17
Location
michigan
First Name
ray
Truck Year
1986
Truck Model
Chevy C10 Rwd P/U
Engine Size
4.3liter V6
What kind of engine? What kind of truck? (86 S10 with 4.3 V6?)

A tick is "usually" just lifter/pushrod noise, you may have a weak lifter possibly.

Under load and knocking could be a sign of a loosed rod/worn rod bearing. If you are driving it and have it under load it knocks....what does it do when you let off, does the knock go away?

I had an 02 Impala (3.4 V6) that developed a knock like you describe, only under load. Pulled the dipstick at night after running it and used a very bright LED light, could see tiny little particles in the oil. Ended up replacing the engine.
as soon as i let of the pedal it stops it make little no noise under normal driving conditions
 

AuroraGirl

Full Access Member
Joined
Sep 8, 2019
Posts
9,693
Reaction score
6,875
Location
Northern Wisconsin
First Name
Taylor
Truck Year
1978, 1980
Truck Model
K10, K25
Engine Size
400(?), 350
What kind of engine? What kind of truck? (86 S10 with 4.3 V6?)

A tick is "usually" just lifter/pushrod noise, you may have a weak lifter possibly.

Under load and knocking could be a sign of a loosed rod/worn rod bearing. If you are driving it and have it under load it knocks....what does it do when you let off, does the knock go away?

I had an 02 Impala (3.4 V6) that developed a knock like you describe, only under load. Pulled the dipstick at night after running it and used a very bright LED light, could see tiny little particles in the oil. Ended up replacing the engine.
id be curious to know what spark plugs he has and what the inside of cylidner looks like. i bet he may find a lot of carbon.
 

OldBlueDually

Full Access Member
Joined
Jun 8, 2020
Posts
2,428
Reaction score
8,518
Location
Minnesota
First Name
Justin
Truck Year
1976 GMC
Truck Model
C30
Engine Size
455 Olds
id be curious to know what spark plugs he has and what the inside of cylidner looks like. i bet he may find a lot of carbon.

Yes, it could very well be some carbon too that let loose, but I would think you would hear that all the time.....??
 

bucket

Super Moderator
Staff member
Super Moderator
Joined
Aug 3, 2010
Posts
30,620
Reaction score
28,869
Location
Usually not in Ohio
First Name
Andy
Truck Year
'77, '78, '79, '84, '88
Truck Model
K5 thru K30
Engine Size
350-454
I can't tell what's going on in the video, but a knocking or rattling under load is often just detonation, AKA spark knock or ignition knock.

If it's actually rod knock or something else major, it will usually make the noise while reving just in park or neutral too.
 

AuroraGirl

Full Access Member
Joined
Sep 8, 2019
Posts
9,693
Reaction score
6,875
Location
Northern Wisconsin
First Name
Taylor
Truck Year
1978, 1980
Truck Model
K10, K25
Engine Size
400(?), 350
Yes, it could very well be some carbon too that let loose, but I would think you would hear that all the time.....??
Carbon deposits would change the sound of the combustioin chamber but the worst possible thing is that it would insulate it very well. And cause detonation either in it being hot enough to cause combustion(could diesel) or the heat just poorly transfering out compared to another etc etc
 

chevyfs

Full Access Member
Joined
Jan 21, 2022
Posts
55
Reaction score
17
Location
michigan
First Name
ray
Truck Year
1986
Truck Model
Chevy C10 Rwd P/U
Engine Size
4.3liter V6
Carbon deposits would change the sound of the combustioin chamber but the worst possible thing is that it would insulate it very well. And cause detonation either in it being hot enough to cause combustion(could diesel) or the heat just poorly transfering out compared to another etc etc
Im going to upload a better video of the knock it does really sound like a deisel tho
 

chevyfs

Full Access Member
Joined
Jan 21, 2022
Posts
55
Reaction score
17
Location
michigan
First Name
ray
Truck Year
1986
Truck Model
Chevy C10 Rwd P/U
Engine Size
4.3liter V6
xc_hide_links_from_guests_guests_error_hide_media
In the video you can hear the engine in idle, then in gear under load spinning tires, then me starting the truck after it stalled, then it also goes into an extremely low idle after warmed up. Now that its low on gas it sounds worse or the knock is just getting worse
 

chevyfs

Full Access Member
Joined
Jan 21, 2022
Posts
55
Reaction score
17
Location
michigan
First Name
ray
Truck Year
1986
Truck Model
Chevy C10 Rwd P/U
Engine Size
4.3liter V6
xc_hide_links_from_guests_guests_error_hide_media
In the video you can hear the engine in idle, then in gear under load spinning tires, then me starting the truck after it stalled, then it also goes into an extremely low idle after warmed up it also sounds worse now that its low on gas or the knock is just worse
 

Blackbeard44

Full Access Member
Joined
Jun 14, 2020
Posts
280
Reaction score
258
Location
Washington State
First Name
andy
Truck Year
1985
Truck Model
K20
Engine Size
6.0 LS
not sure exactly what that is, maybe wristpin? whatever it is though it would motivate me to remove the motor and take a closer look before somthing catastrophic happens and its not rebuildable anymore, please keep us updated if you do teardown that motor
 

Latest posts

Forum statistics

Threads
44,416
Posts
957,115
Members
36,752
Latest member
78 squarebody
Top