so my h3 started idling rougher than normal and since i have one of the first 06's i am always concerned about the dreaded cylinder head issue. The rough idling wasn't that drastic so i figured if i changed the spark plugs out(just hit 75k) and cleaned the throttle body that should smooth things out, and if not maybe it is time to worry. Also, since i was changing out the plugs i figured i should do an engine compression test considering my buddy had a compression tester laying around. I posted the process below from my repair manual. Anyway, as i changed each plug out i would thread the tester in the spark plug hole and turn the engine over a couple of times. I started with cylinder 1 (closest to the radiator) at this point i still have 4 old plugs in the rest of the cylinders. I got a reading of about 150 psi. next was cylinder 2 which read a fraction more and so on till i got to cylinder 5 which was the highest reading of about 165-170. at that point of the test i did have 4 brand new plugs installed in front of cyl. 5. the pressure of all 5 cylinders ranged from 150-170psi. consistent enough, but yet low for the normal spec.callout of 215 psi on this vehicle.
Now for the real test: Test Drive!
I couldn't be happier with the results so far... It sounds and feels like a brand new engine. so crisp and responsive. Well worth the $35 for ac delco iridium plugs and a couple hours of hanging out in the garage.

I'm still wondering about the low pressure readings and was hoping some of you might have input or some recordings of your own 06 compression test results. The compression tester we used is pretty old and might not be 100% accurate.but are those readings drastically low? i read elsewhere that typical readings of an engine compression test in your average vehicle is between 125-160psi and the cylinders should all read within 5% of each other. The H3 seems to have significantly different specs. Any comments are welcome and i hope this long winded thread maybe helps somebody else to.



Engine compression test

Tools Required
J 38722 Compression Tester

Important: The battery much be at or near full charge. Do not block the throttle open.

1. Remove the air duct from the throttle control module.
2. Remove the ignition control module.
3. Disable the fuel system.
4. Remove the spark plugs.
5. Measure the engine compression, using the following procedure.
5.1 Firmly install J 38722 to the spark plug hole.
5.2 Have an assistant crank the engine through at least four compression strokes in the testing cylinder.
5.3 Check and record the readings on J 38722 at each stroke.
5.4 Disconnect J 38722
5.5 Repeat the compression test for each cylinder.
6. Record the compression readings from all of the cylinders. A normal reading should be approximately 1482 kPa (215 PSI).
The lowest reading should not be less than 70 percent of the highest reading.

 

with 75k on it, I think the compression you have would be normal. I plan to do my plugs when I hit 70k and I will do the test as well and post back to this thread my findings for comparison. Thanks for the info.

 

Can you list steps to clean throttle,have an 08 base,77,000miles,thanks

 

Gotafish > If you look at the throttle body you will see an electrical connection and a line connection. Unplug both of those. (this is after you have removed air box, intake etc) 4 bolts at the corners of the TB hold it in place, remove those and the throttle body comes off. Look inside and you will see it is probably covered with bronz to black crap. Spray the heck out of it with TB cleaner and wipe the crud out. There is a green gasket on the inside of the throttle body. You can pull it and wipe it down carefully, making sure not to stretch it. Once clean, reattach bolts, snugging opposite bolts like you would a tire. If I remember correctly, the bolts are somewhere around 15-18 psi for tightening but you should double check that number. Only takes about 30 minutes.

 

Great breakdown

 

Hello everyone, i'am a new member of this side and i have a hummer h3 .
I have a problem with the compression of the engine shall ,and read about some problems on the cylinder head on some holders hummer h3, probably some faulty?
How can I see if the hummer is my own to this list? is the problem from the factory?
Please tell me, i do not know what to do because the delegation did not have succeeded.
Thanks a lot (sorry but my english is not very good).

 

explain the above. differently. not understood.

try searching for head problems or other head issues.
this has been discussed here many times.

greetings,hope things go well for you

 

The problem with the cylinder head i understand very well, i read all of the topic.
Just looking for my VIN NUMBER but from the official site hummer (bulletin 1845907) and i did not find it

 

If you have an 06 h3 and the last six digits of your VIN is LESS than 287575 you have a chance of bad cylinder heads.