Ruh roh Raggy! I hear you knocking…

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.

J

JBswth

Full Access Member
Joined
Jan 24, 2022
Posts
225
Reaction score
182
Location
Vallejo, California
First Name
James
Truck Year
1973
Truck Model
C25
Engine Size
292 cubic inches
Disco said:
@JBswth, it was the inspection cover, apparently. They pulled the cover to check inside the bell housing area, found nothing of concern, put the cover back, started the engine to use a stethoscope to track the sound, and the sound was gone.
The only thing we can think is the cover was put on in just the wrong way that something inside the bell housing, something spinning at crank speed, was tapping it. I have had the engine running several times now, and the noise has not returned.
Click to expand...
That's good, maybe something was in there and fell out unnoticed.
 
Matt Lutz

Matt Lutz

Junior Member
Joined
Jul 15, 2021
Posts
9
Reaction score
17
Location
Bastrop
First Name
Matt
Truck Year
Lutz
Truck Model
1500
Engine Size
250 4.1L
So funny this thread is goin on. I have a 81 GMC with a 250 6cylinder. The motor is not the original. I was having an issue with the carb flooding and thru some advice from a mechanic I added a fuel regulator. After a few runs the engine started knocking really bad but it goes away at high speeds. And I am not trying to take over the thread just similar issue.
 
Disco

Disco

Full Access Member
Joined
Feb 13, 2022
Posts
123
Reaction score
168
Location
Texarkana, TX
First Name
Mike
Truck Year
1978
Truck Model
Big 10
Engine Size
350
Matt Lutz said:
So funny this thread is goin on. I have a 81 GMC with a 250 6cylinder. The motor is not the original. I was having an issue with the carb flooding and thru some advice from a mechanic I added a fuel regulator. After a few runs the engine started knocking really bad but it goes away at high speeds. And I am not trying to take over the thread just similar issue.
Click to expand...
He had you add a fuel regulator on a carb? I would suspect a needle and seat or a float if a carb is flooding, unless you added an electronic fuel pump with a higher output that the mechanical pumps. If you are using a mechanical pump, the needle and seat should be enough to stop fuel flow, as long as everything is working properly.
 
75BEASTK20

75BEASTK20

Junior Member
Joined
Nov 5, 2024
Posts
21
Reaction score
39
Location
B.C. CANADA
First Name
Cal
Truck Year
1975
Truck Model
K20
Engine Size
427
USUALLY............if its a ticking sound - it's valve train. Like a bad lifter, broken push rod, that happened to me once. But a loud knocking noise sounds like a rod.
Hard to tell without really hearing it, but sorry you got problems
 
R

Ricko1966

Full Access Member
Joined
Apr 11, 2017
Posts
5,438
Reaction score
8,668
Location
kansas
First Name
Rick
Truck Year
1975
Truck Model
c20
Engine Size
350
I've seen lots of cracked flexplates diagnosed incorrectly as rod knock. Is this thing an automatic?
 
R

Ricko1966

Full Access Member
Joined
Apr 11, 2017
Posts
5,438
Reaction score
8,668
Location
kansas
First Name
Rick
Truck Year
1975
Truck Model
c20
Engine Size
350
Disco said:
Nope. Muncie 4-speed. And it was the inspection cover.
Click to expand...
Sorry,I got sucked back in to a dead thread by post 36. And I think he was referring to post 34 who hijacked your thread LOL.
 
Grit dog

Grit dog

Full Access Member
Joined
May 18, 2020
Posts
6,966
Reaction score
12,216
Location
Auburn, Washington
First Name
Todd
Truck Year
1986, 1977
Truck Model
K20, C10
Engine Size
454, 350
Disco said:
Gotcha
Click to expand...
Know it’s an old thread, but fwiw, I doubt it was the “inspection cover”.
More like took the cover off, saw what they messed up, fixed it, knew their audience and saved themselves the guilt or embarrassment or potential bad reputation of admitting what they messed up.
Either way, great news! (From 6 months ago).
You got it on the road now?
 
Disco

Disco

Full Access Member
Joined
Feb 13, 2022
Posts
123
Reaction score
168
Location
Texarkana, TX
First Name
Mike
Truck Year
1978
Truck Model
Big 10
Engine Size
350
Grit dog said:
Know it’s an old thread, but fwiw, I doubt it was the “inspection cover”.
More like took the cover off, saw what they messed up, fixed it, knew their audience and saved themselves the guilt or embarrassment or potential bad reputation of admitting what they messed up.
Either way, great news! (From 6 months ago).
You got it on the road now?
Click to expand...
I put on a new Holley Q-jet and had her running pretty well. Just needed some fine tuning.

Then the ignition switch disintegrated. All of the plastic in this truck is JUNK. Now that I have some money and it’s not hotter than the fires of damnation, I’ll probably get out there and swap out the turn signal and ignition switches.
 
You must log in or register to reply here.

Similar threads

B
Replacing 454 gaskets opinion
Replies
11
Views
610
Byard-HWJ
B
D
Thank you post to y'all.
Replies
3
Views
1K
Catbox
Catbox
Truck82
Can I use this hole for filling oil?
2 3
Replies
36
Views
2K
78C10BigTen
78C10BigTen
T
Another exhaust options thread - what should I do?
2 3
Replies
32
Views
3K
Reggie1931
Reggie1931
Slooptin
Big block running hot. Can’t figure out the issue
2 3
Replies
31
Views
859
Slooptin
Slooptin

Latest posts

Forum statistics

Threads
44,149
Posts
950,383
Members
36,262
Latest member
Lucky41
Top