I have a 2006 H3 with the 3.5L 5 cyl. Just recently rolled over 100K. My check engine light came on upopn re-starting the vehicle one day after running in for a cup of morning coffee. OnStar said it indicated a misfire. Called & made appointment with GM dealer, in the meantime, added Injector cleaner to fuel. Light went out, seemed to be running ok, but went in for appointment, assuming at worst case might need a tune-up. Dealer said valve not closing, need new cylinder head, 5K to replace, suggested I go trade vehicle off as soon as possible if I didn't want to fix. I felt like I had been cold-cocked in the head with a 2x4 and walked away stunned!
Then slowly, I began to recall someone warning me about a characteristic fault of this 3.5L 5 engine that I should expcet to encounter & now I'm wondering if it was this.
Also, wondring how drastic it actually is, seems to run fine, no change in gas mileage 17.5-18 mpg. Run her till she drops?? Or is it possible that there is a mis-diagnosis & simply cleaning up my injectors etc. will solve the problem?
Thanks in advance for your help!

 

Have you done a spark plug change on it?

 

I can only suggest you use the SEARCH function above in the RED box and Read, Read, Read!

It will make you a better informed consumer if you do need a head and can save you $1000s if you follow the posts and contact the proper department/people at GM!

 

A cylinder head replacement is not any where near a $5K job. That dealer is FOS. They want you to trade for something, then they will fix your truck and sell it at a profit as well.

I have seen many of the I5s that merely had a weak or broken valve spring, so if you can find a real mechanic that could be fixed without a complete tear down.

Gas additives do not do squat. Always use top tier gas, forget the snake oils.

2006 3s had a know issue: The S/Ns affected is any 2006 H3 lower than 287591 .... the first one started with 100,001, your truck build date will be Nov. 06 or earlier. Not all have the problem, but some could. The head issue affected not only the I5, 4s and 6s were subject to the same issues. Call GM with your vin# and build date (from the sticker in the driver's door jam) and ask questions (like was this fixed on this truck, will you cover it under good will).

 

Thanks to all for the advice! No, I have never changed the plugs, so was assuming that a tune up would be in order, maybe should have done it anyway, but they just said "That's not the problem"..and yes, the service managers demeanor did NOT impress me at all.

 

and....my VIN ends with 274783 with build date of 03/06, so looks like it would fall into that category. Thanks again!