Engine Knocking Noise

Robochop

Robochop
Joined
May 16, 2017
Messages
29
Reaction score
10
Location
Virginia
Hi, I got a weird one for y'all. 2005 3.7 rebuilt engine about 2 years ago. Drove fine the day before but went out to start it the other day and here is what I heard. It seems like it's skipping a cylinder, but after a few seconds it starts making a knocking noise that I can't figure out where it's coming from. I checked compression and got an even 165 on all cylinders so I don't think it dropped a valve. I replaced all plugs and coils but still get the noise. I'm asking for any recommendations before I start pulling the valve or timing covers. Here's a youtube video for any advice anyone can offer. Thanks in advance.
 

tommudd

Moderator
Staff member
Moderator
Joined
Jul 14, 2005
Messages
21,801
Reaction score
2,932
Location
Southeastern Ohio
I would pop the serp belt off first thing to eliminate any of the water pump, alternator etc out of the loop
Then if still there, narrows it down some
 

Robochop

Robochop
Joined
May 16, 2017
Messages
29
Reaction score
10
Location
Virginia
I would pop the serp belt off first thing to eliminate any of the water pump, alternator etc out of the loop
Then if still there, narrows it down some
LOL, that's the first thing I did! Noise is still there.
 

tommudd

Moderator
Staff member
Moderator
Joined
Jul 14, 2005
Messages
21,801
Reaction score
2,932
Location
Southeastern Ohio
Have you tried a stethoscope to try and determine what area of the motor the noise is coming from
At this point its kind of a throw a dart and hope it hits something trying to determine a sound by a simple video
If you could determine that it is in the front area around water pump, or very rear of the motor would help narrow it down
 

Robochop

Robochop
Joined
May 16, 2017
Messages
29
Reaction score
10
Location
Virginia
Well I narrowed it down to a misfire or a timing guide issue so I started to take it apart. Got the driver side valve cover off and here's what I found! I'm hoping it's just a broken valve spring as I still have compression. The lifter is till good too. Any ideas on how to get the spring off without removing the cam? I would hate to have to remove the head! More info to come.
 

Attachments

  • Motor Noise.jpeg
    Motor Noise.jpeg
    510.9 KB · Views: 20
  • Motor Noise1.jpeg
    Motor Noise1.jpeg
    545 KB · Views: 19

lfhoward

Well-Known Member
KJ Supporting Member
Joined
Dec 9, 2012
Messages
1,398
Reaction score
1,194
Location
Philadelphia, PA
Here is a fun series from Eric O. on South Main Auto. On this Liberty, a gummed up lash adjuster caused a rocker to fall off, which let a valve stick open, killing the compression in one cylinder. He cleaned the lash adjuster, stuck the rocker back on, and it worked! You may find out what you need to know here.

Part 1:
xc_hide_links_from_guests_guests_error_hide_media

Part 2:
xc_hide_links_from_guests_guests_error_hide_media
 

Robochop

Robochop
Joined
May 16, 2017
Messages
29
Reaction score
10
Location
Virginia
Problem solved! Thanks to everyone for your input. Had to order a valve spring remover tool to get the spring out, but couldn't see anything wrong with it or the lifter. Took them and a couple extra springs to my local machine shop and measured the tension. It seems the bad one only measured 100lbs. The 2 I brought with me were 105 and 110. I purchased a new spring and lifter from local O'reilly's auto parts and replaced them. Put back together and it runs great! I have attached a pic of the springs and tool. Total cost about $70!
 

Attachments

  • Spring Tool.jpeg
    Spring Tool.jpeg
    361.7 KB · Views: 3
  • Springs.jpeg
    Springs.jpeg
    528.9 KB · Views: 3
Top