Hummer H3 Valve Seat Problems

Here is the playlist for the rest of this series:
My apologies that I did not upload this sooner.
For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available at as an eBook or paper book.
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Steve Guest says:

Great find Paul brilliant work

Don Gamble says:

Good to see this. Thanks Paul.

riverstrat says:

So how does one that’s looking for a used h3  detect whether the ones you’re
looking at have this issue?
What should you expect to pay to have a new and better head installed with
new valves and springs?
Are weak/cheaper/poorly designed valve springs  ever part of the issue?
This is not a correction that could typically  be made by a non mechanic,
owner probably ?

deepsquat600 says:

I wish you could have colored the valve with a black marker ..put it back in the head ..and spun it around and pulled it back out ..would have shown how the seat meshed with the valve

Jesus Ramirez says:

Nice I had the same problem before I Found the problem valve sits there is a TSB I like all you r videos I learned a lot from you thank you scanner danner

isettech says:

Too little cooling in the center of the head. Wall between intake and exhaust overheated and warped resulting in the non contact area. Design has a metal fin between intake and exhaust without a proper thermal path to the coolant.

Peter Zoch says:

fuuu, thumbs up for not giving up!

rhkips says:

Wow… That’s awful! I’ve never seen anything like that! That is not normal wear… I suspect that there’s a valve (non)rotation issue, and the carbon buildup on that valve makes me think it’s involved, too. That’s pretty much not repairable, either. That’ll need new seats. Ah well, time to pass it off to the Engines department! Have ’em knock down that god-awful machinist ridge, too; give yourself some low-lift flow. 😀

Tech Tune Automotive Repairs says:

To add some accuracy to the test i will connect a leak down tester to the cylinder when creating the valve leak and bring it up to the same 70% we seen on the Hummer

freeride202 says:


John Idio says:

Good to see the conclusion thanks for posting. I had a chevy colorado with the same 3.5 motor that had similar issues eg slightly eradic idle, misfire codes that were only intermittent. The truck only had 88k so I sold it fearing it was the dreaded and common valve seat issue.

Richard J Lebens says:

was the conclusion of that GM valve problem that the stem was too weak and some of the valve found a resonance and oscillated?

jajupa78 says:

so I suppose if we follow the rabbit down the hole. Long term it explains why these engines eat up catalytic converters. Because if the intake(air/fuel)valve is constantly bleeding air into the cylinder that’s going to make it run lean, and lean means extremly hot exhaust gas, excessively hot exhaust means melted converter, broken exhaust manifold bolts at the head, ect.. It all makes sense now. Thanks scannerdan, great series, subscribed!:]

Joel Garcia says:

great vid. mine is in the dealer as we speak… mine was leaking oil up through the breather hose in back part of the engine that goes to the airbox. sounds like a minor fix right? lol

Joop Terwijn says:

I was wondering if you pulled from a correct cylinder, to compare the valve seat…

DE Nichols says:

I had to watch the video twice, but everything you worried about showing up, showed up. Thanks for sharing.

wtbm123 says:

Wore plum out

1990lumina says:

All those 3.5/3.7L motors had head problems. I remember when we would get those in on trade they always ended up at GM getting the head replaced under warranty lol

Michael Berg says:

diagnosed a bunch of those valve problems, good to see the tear down

AkshonClips says:

Im wondering if the Valve Springs were the root cause maybe causing valve float and burning the seats. Hence the bulletin says to replace the springs as well.

angelisone says:

what was the total costs of this repairs?

Richard Schmidtendorff says:

The seats are burnt.

A. Shamy says:

thanks Paul, it`s wonderful series.

Lucian Lucian says:

Great videos Paul! Many thanks for all your effort! It seems to me that the valves are also slightly bent, caused by an incorrect heat distribution along them, for using a “not so great quality” material…maybe? Just a thought. Anyways, keep doing what you`re doing man, you really are a very good technician and a great teacher too. Thumbs up!

deano_au says:

From what you’re showing here, it looks like the valve seat was not ground properly in the first place – manufacturing fault?

Super032208 says:

@ScannerDanner for president

DJDevon3 says:

Was this the final conclusion to the RTI Hummer you brought into the classroom last year? Did this video get lost or did it just take that long to find the valve seat problem?

Tech Tune Automotive Repairs says:

Hey Paul.
I just watched all the Hummer series over again and Cook particular interest to the maf sensor waveform. For the exercise i am going to perform the tests using my Pico on a known good vehicle that has adjustable rockers and create inlet leaks and exhaust leaks and compare them with valve sealing properly. I will recharge the battery between each test (although proberbly not neccesary) to eliminate any variable cranking speed. Hopefully the tests will give us good direction by being able to compare the same cylinder in various conditions. I will email the results to you when i have done it.


MrTallnb says:

did you rebuilt the head or did you buy new one  gm has update head with harder valve seatsreason I was asking you  mind at dealer now they want do valve job on it

SidneyCritic ComedyHound says:

I see that all the time on those soft MAZDA heads. They get a hot spot and the alum sags in that area causing a leak. If that area cleans up last when you cut the seat that is pretty much the same thing

Ralf V says:

Very nice, them look like hot spots in the seats that caused the valves to deform the seats. Seen that several times.

George Herrera says:

Two weeks ago, I fixed a 2006 Hummer H3 with this exact same problem. I noticed that there is TSB for this problem. By watching your videos, I felt very confident performing the job. Thank you ScannerDanner.

Mr. Ti says:

When are H3 owners going to file a class action against GM, I and many others are having this problem and it dont look that easy to fix.

Harout Najarian says:

I just purchased your book spent $117 I didn’t have it better be good my friend!!!

Travis R. says:

Gm has a recall about the head issues on the H3 with the V6. They all crack or they have valve issues

Tech Tune Automotive Repairs says:

took not cook 🙂

Johnny Perkins says:

just had the head replaced by a chevy dealer they said #2 &#5 wasn’t seating properly charged my 2600 had my truck over a week got it back still feel a vibration in the truck when sitting at idle any thoughts on what it is? dealer told me it’s an 06 not a 2017 lol

Ozzstar says:

That small amount of wear caused a big headache! Nice work

Troy WT says:

Very good shots of the seat wear.

Allen K says:

I can see it, thanks for the info.

Jesus Malagon says:

thanks Paul


Paul was the valve and seat distortion a cause or a result of the misfire. Your engine professor that was involved in the case did he have any thoughts after viewing the valve and seats ? That was an awesome series .

besssam says:

Was this vehicle using E85?

Johnny Perkins says:

just had the head replaced by a chevy dealer they said #2 &#5 wasn’t seating properly charged my 2600 had my truck over a week got it back still feel a vibration in the truck when sitting at idle any thoughts on what it is? dealer told me it’s an 06 not a 2017 lol

stilkus says:

That would turn me insane trying to discover the reason for this misfire. I have a question though, such valve seat damage didn’t show in compression or leak down Tests?

Billy R says:

Paul, awesome to see physical, tangible evidence to back up the high tech diagnostic evidence ! Even a year later ! LOL !

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