5.3 LS w/4L80 Mystery Noise

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.

Jrgunn5150

Questionable methods
Joined
Jan 11, 2016
Posts
2,739
Reaction score
1,412
Location
Ionia Mi
First Name
J.R.
Truck Year
1979
Truck Model
C10
Engine Size
6.slow
I've never heard a pump sound like that.

Do you have a stethoscope to isolate it to the engine or trans?
 

Rustybucket73

Junior Member
Joined
Dec 5, 2017
Posts
22
Reaction score
27
Location
SF Bay Area
First Name
John
Truck Year
'73
Truck Model
C10 Stepside
Engine Size
5.3 LS
So I found a problem with my trans cooler plumbing.

It was like this:
You must be registered for see images attach


Re-plumbed it with the fluid return coming out the top like this:
You must be registered for see images attach


Don't know if that was the reason for the noise, but the noise is gone now.

Crossing my fingers.
 

Jrgunn5150

Questionable methods
Joined
Jan 11, 2016
Posts
2,739
Reaction score
1,412
Location
Ionia Mi
First Name
J.R.
Truck Year
1979
Truck Model
C10
Engine Size
6.slow
So I found a problem with my trans cooler plumbing.

It was like this:
You must be registered for see images attach


Re-plumbed it with the fluid return coming out the top like this:
You must be registered for see images attach


Don't know if that was the reason for the noise, but the noise is gone now.

Crossing my fingers.

Well that would be wild...
 

idahovette

Full Access Member
Joined
Aug 7, 2016
Posts
6,558
Reaction score
14,084
Location
Weiser Idaho
First Name
Perry
Truck Year
1975-1979
Truck Model
K20-K10
Engine Size
350
Did moving the lines just a little bit take the vibration out of something ?
 

tahitiansoul

Member
Joined
May 29, 2017
Posts
43
Reaction score
60
Location
TAHITI
First Name
Marc
Truck Year
1981
Truck Model
JIMMY SIERRA CLASSIC
Engine Size
5.3 LM7
Unbolt the torque converter from the flexplate and start the engine, if no noise, then it is not the flexplate neither engine but somewhere in the tranny.
 

Rusty Nail

Full Access Member
Joined
Jan 29, 2015
Posts
9,786
Reaction score
9,681
Location
the other side of the internet
First Name
Rusty
Truck Year
1977
Truck Model
C20
Engine Size
350sbc
Maybe it's simply your '73 protesting the molesting of that crap engine you put in it? Junkyards are full of those things for a reason...
 

Rustybucket73

Junior Member
Joined
Dec 5, 2017
Posts
22
Reaction score
27
Location
SF Bay Area
First Name
John
Truck Year
'73
Truck Model
C10 Stepside
Engine Size
5.3 LS
Did moving the lines just a little bit take the vibration out of something ?

I think the problem was that air was trapped in the cooler since it was being filled from the top.

Once I flipped the lines around and filled the cooler from the bottom, all the air was able to be purged and properly lubricate whatever is on the cooler return side of the transmission.
 

Jrgunn5150

Questionable methods
Joined
Jan 11, 2016
Posts
2,739
Reaction score
1,412
Location
Ionia Mi
First Name
J.R.
Truck Year
1979
Truck Model
C10
Engine Size
6.slow
I think the problem was that air was trapped in the cooler since it was being filled from the top.

Once I flipped the lines around and filled the cooler from the bottom, all the air was able to be purged and properly lubricate whatever is on the cooler return side of the transmission.

It's as good a theory as any lol. Glad you have it sorted out!
 

Latest posts

Forum statistics

Threads
42,128
Posts
909,755
Members
33,622
Latest member
timk
Top