H3 Head Question!

[Wrcklsmestiso619]

Hi guys I have a 2006 Hummer H3 adventure package I just purchased for 7,900 with 167,000 miles. I noticed the check engine lightcomes on(p301) randomly and typically happens at idle. The code is p301(cylinder 1 misfire) I replaced the spark plug(oem) and tried a new coil pack and another from the next cylinder and still comes on. Also cleaned the throttle body and maf(idled alot better now) What is weird is I can sometimes drive 100-200 miles with no issues even at idle and then magically the lovely cel comes back on..There are times where the light will come off on it's own other times I reset it with a obd scanner. **My question is should I be concerned? Next question is if I do nothing and continue driving it as is will I have anything to worry about other than a check engine light?** Additionally I tried calling gm about if the head is the original and they weren't able to give me any information. I tried looking for a stamped number on the head but couldn't read the one under the air intake tube(seems to be dot etched) is there another location for head serial number? Thanks!

​

 

[alrock]

Sorry to hear about the issues. You've done good troubleshooting so far. It could be a head issue, regardless of whether or not it fell under the original series of bad heads. I know one H3 that had his 06 head replaced and 50,000 miles later the second head is having issues. My 07 had the head replaced at 98,000 miles. If you're worried about it, I think the next step would be a compression test. But I'm not enough of a tech to say if you'll have any issues while continuing to run it with that code.

 

[Wrcklsmestiso619]

Appreciate the reply. That's also another thing I don't want to run into if I end up replacing the head! I'll hoping I can just use as is. It's runs perfectly fine other than the times it misfires. I've already put almost 3,000miles in it like this..

 

[Kick'n Dust]

Bad valve seats can be diagnosed by either a running compression test or a leak down test. I take the time to do both on all cylinders to get a full health report on the engine. A good machine shop can replace your valve seats, valves and seals for a quarter of the price of a new head. I recommend replacing the hydraulic valve lash adjusters and camshaft timing components at your mileage also. Also, if you hear a rattle for the first 1 to 5 seconds on startup replace the exhaust camshaft actuator (the hydraulic controlled camshaft sprocket). I know this sounds all bad and super expensive but if you love your H3 stay positive and have fun working on it and take pride in a job well done. Good luck

Sent from my Coolpad 3622A using Tapatalk

 

[Wrcklsmestiso619]

Bad valve seats can be diagnosed by either a running compression test or a leak down test. I take the time to do both on all cylinders to get a full health report on the engine. A good machine shop can replace your valve seats, valves and seals for a quarter of the price of a new head. I recommend replacing the hydraulic valve lash adjusters and camshaft timing components at your mileage also. Also, if you hear a rattle for the first 1 to 5 seconds on startup replace the exhaust camshaft actuator (the hydraulic controlled camshaft sprocket). I know this sounds all bad and super expensive but if you love your H3 stay positive and have fun working on it and take pride in a job well done. Good luck

Sent from my Coolpad 3622A using Tapatalk

So it does have the rattle noise for about a second on cold startup. I pulled the camshaft actuator out and all screens appeared to be in place. Should I still replace it?

 

[Kick'n Dust]

The part you are describing is the camshaft actuator solenoid. The part I'm talking about, camshaft actuator, goes on the end of the exhaust camshaft and acts as a hydraulic adjustable cam sprocket. The seals fail and it leaks down over night causing the internal vanes to rattle on each other until it fills with oil. Ford calls the camshaft phasers, GM calls them camshaft actuators. Now the camshaft actuator solenoid that you inspected the screens on has a known problem, but usually for camshaft to crankshaft correlation codes. With my experience as a GM tech I have heard the camshaft actuators rattle on later model cars which GM actually releasing technical service bulletins for regarding this problem.

I work a lot of hours and only check my phone in the am over a cup of coffee

Sent from my Coolpad 3622A using Tapatalk