Cylinder 5 misfire
Member
Joined: Jul 2010
Posts: 46
From: Toledo
my 2006 H3 @89k now the head valve misfires codes
Yes my VIN is in the soft valve seat range, question is although I know many of you had heads replaced by GM under warranty, how many others off warranty were able to have the head rebuilt or was the valve seat area too porous to be machined or re-milled?
Super Moderator
Joined: Jul 2007
Posts: 13,056
From: Boat Town USA MI
If, please note IF.... your problem is actually the valve seat itself, the only way to fix it permanently is replace the head with a new one post 03/31/2006.
Lots of other and simple stuff can cause the misfire code, most of which can be fixed.
OLD THREAD ALERT!
Lots of other and simple stuff can cause the misfire code, most of which can be fixed.
OLD THREAD ALERT!
Last edited by Doc Olds; Mar 10, 2015 at 02:58 PM.
Member
Joined: Jul 2010
Posts: 46
From: Toledo
Thanks Doc I'm aware having read all your old posts on the subject, just preparing for the decision when my shop starts tearing into it. I've even gone as far as a Jasper Engine quote $4,520. AutoZone has Surefire engines for $3300 to 3700 for a Tri Star. A new head is $950 as it is. With the new engine you get a 3 year warranty so maybe a couple grand more is worth it. It's a different call you have to make when your not your own mechanic, welcome any comments.
Member
Joined: Jul 2010
Posts: 46
From: Toledo
A certified Hummer tech at the GMC dealership that took over servicing the Hummer line said my '06 H3 needed a new head after 88,000 miles, had the cylinder #5 misfire and same symptoms previously mentioned in this and similar threads on this forum. Having him replace the radiator also. Talusfan's comments as a master mechanic seem to carry a lot of weight pointing to design flaws experienced by many H3 owners. Even so I wouldn't be putting the $3k into the vehicle at this point unless I've enjoyed driving it.
Posting comments on this older thread because I determined it the most appropriate thread in presenting information regarding engine misfire codes, etc to those owners seeking explanations for similar symptoms.
Posting comments on this older thread because I determined it the most appropriate thread in presenting information regarding engine misfire codes, etc to those owners seeking explanations for similar symptoms.
Junior Member
Joined: Nov 2017
Posts: 3
Prone to what problem???
"The head issue", the one and only one that caused warranty extension, involved only L52 motors built before March 31. 2006. Those heads did not have properly hardened valve seats. EVERYTHING since does.
Can an Atlas motor (I4 through I6) have a valve-train or head/head gasket failure issues? Hell yes, but to assume they are all related is like ...... grassy knoll and Pearl Harbor conspiracy theories.
A cracked or broken valve spring, broken spring retainer, improper valve assembly or lash adjustment, blown head gasket, bad coil on ignition pack, bad connection to a coil pack, bad spark plug, cam position sensor failure, and VVT PCM mapping errors can all cause misfires.
"The head issue", the one and only one that caused warranty extension, involved only L52 motors built before March 31. 2006. Those heads did not have properly hardened valve seats. EVERYTHING since does.
Can an Atlas motor (I4 through I6) have a valve-train or head/head gasket failure issues? Hell yes, but to assume they are all related is like ...... grassy knoll and Pearl Harbor conspiracy theories.
A cracked or broken valve spring, broken spring retainer, improper valve assembly or lash adjustment, blown head gasket, bad coil on ignition pack, bad connection to a coil pack, bad spark plug, cam position sensor failure, and VVT PCM mapping errors can all cause misfires.
Junior Member
Joined: Jun 2019
Posts: 1
same plus i have coolant thermostat ( coolant below thermostat regulaiting temperatur
it seams to be running normal the coolant being to cold realy has me thinking. then it disappeared and came back with the cylinder 5 misfire . the chrck engine light is on but not flashing
Super Moderator
Joined: Jul 2007
Posts: 13,056
From: Boat Town USA MI
READ: Old Threads/'Necro-Bumping'
Senior Member
Joined: Sep 2008
Posts: 6,126
From: SE Michigan
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