Knocking Noise

Reply Subscribe

Thread Tools

Search this Thread

May 29, 2008 | 06:58 PM

dwkremer

Thread Starter

Junior User

Joined: Jun 2005

Posts: 50

Likes: 0

Knocking Noise

91F250 7.3 250,000miles

I just started getting a knocking noise that sound like it is coming from the top of the motor on the passenger side. There is a small puff of white smoke when I shift. I put NEW injectors in about 1,000 miles ago.

I have read that this might be a bad injector? Any suggestions to diagnose and repair would be appreciated.

Tks David

May 29, 2008 | 07:42 PM

bigredtruckmi

Lead Driver

Joined: Jan 2005

Posts: 7,782

Likes: 221

From: Huntington Indiana

I would wonder if a valve is going bad. No/low compression = no burn = puff of white smoke

May 29, 2008 | 08:32 PM

PLC7.3

Post Fiend

Joined: Nov 2004

Posts: 5,638

Likes: 1

From: Manitoba

Did you replace the return lines and caps......... do you get the noise at idle.

May 30, 2008 | 07:44 AM

dwkremer

Thread Starter

Junior User

Joined: Jun 2005

Posts: 50

Likes: 0

Yes, caps, lines and o-rings replaced with injectors. I do not here the noise at idle. When I crack the fuel line to 2nd cyl back on the pass side the noise goes away.

May 30, 2008 | 08:01 AM

dwkremer

Thread Starter

Junior User

Joined: Jun 2005

Posts: 50

Likes: 0

I took out the new injector and replaced it with one of my old ones, but this made no differance.

Does anyone know if a bad injector pump would effect one cylinder?

May 30, 2008 | 05:47 PM

catfish101

Posting Guru

Joined: Mar 2005

Posts: 1,701

Likes: 0

From: KY

That depends on the pump. An inline pump is very possible and not uncommon. On these pumps it is possible but not as common to pick on one cylinder.

May 31, 2008 | 07:12 AM

mistakenID

Posting Guru

Joined: Jul 2004

Posts: 1,627

Likes: 0

From: West Valley Utah

If the plastic coupler is starting to come apart in the IP, it's possible for the pieces to lodge in a line or injector. If it holds the injector open slightly, I can see where it might get a puff of white and why the knocking went away when the fuel line was cracked.