Backfiring

Reply Subscribe

Thread Tools

Search this Thread

May 10, 2011 | 09:40 PM

#16

Phy

Fleet Mechanic

Joined: Jan 2011

Posts: 1,709

Likes: 4

From: 8600 ft in Colo

Quote:

Originally Posted by PLC7.3

If an exhaust valve does not open engine will force combustion into the intake on next stroke... so I'm told.

Yeah it would. I've been trying to think of scenarios that would explain it, but I hadn't thought of that one.

Jun 19, 2011 | 05:51 PM

#17

sams6.9

Thread Starter

Senior User

Joined: Mar 2006

Posts: 175

Likes: 0

From: HALLSVILLE TEXAS

sorry ive been busy and havent had time to play with this truck much, but here is a clip of what it does.

YouTube - ‪6.9‬&rlm;

Jun 19, 2011 | 07:32 PM

#18

bashby

Post Fiend

Joined: Nov 2005

Posts: 7,437

Likes: 4

From: Charles Town, W bygod Va

Hard to hear on my laptop, but is it only doing it on deceleration? I'd take the air cleaner off and listen. Might even see a fireworks show.

Jun 20, 2011 | 05:34 AM

#19

sams6.9

Thread Starter

Senior User

Joined: Mar 2006

Posts: 175

Likes: 0

From: HALLSVILLE TEXAS

it does it worse if your driving it (most notibly taking off) on the other hand if it sits and idles for a min it quits doing it

Jan 11, 2012 | 01:52 PM

#20

glowplugeaters

New User

Joined: Dec 2011

Posts: 10

Likes: 0

my truck is doing the same tghing

Jan 11, 2012 | 04:27 PM

#21

kenpobuck

Cargo Master

Joined: Mar 2006

Posts: 2,789

Likes: 5

From: Sand GAp, KY

Sticky valve maybe?

Jan 11, 2012 | 05:02 PM

#22

eatont9999

Cargo Master

Joined: Dec 2010

Posts: 2,123

Likes: 5

From: Fort Worth, TX

Yeah, that is definitely a valve issue. It may not be sticking open all the time, so the compression test could have come out just fine. Maybe the sticking happens at x RPMs only. I remember hearing somewhere that people have freed up a sticking valve by spraying WD-40 or some similar lubricant down the valve stem. Maybe I am thinking of something else entirely. It's one of those PITA problems because you have no real good way to find out what cylinder has the issue unless it is obvious when you take the valve covers off.

Jan 11, 2012 | 05:16 PM

#23

glowplugeaters

New User

Joined: Dec 2011

Posts: 10

Likes: 0

I hope that it goes away it seems like it only happens the worst after iv driven the truck for a wial . I'm going to put some marvil mystery in the oil and run some transmition fluid through to see if it helps