Piston damaged? - Pontiac G8 Forum: G8 Forums - G8Board.com
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post #1 of 33 (permalink) Old 05-28-2018, 01:34 AM Thread Starter
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Piston damaged?

So I pulled the driver's side head this weekend as the lifters had started to tick again recently. I had broken 2 inner BTR springs about 6 weeks ago and there was a damaged valve stem seal. Figured the cam and lifters were damaged from metal shavings. The plan was to change the lifters, cam, oil pump and timing chain, clean the pan and reassemble.

However piston #1 looks to have some damage or burning at the locating dimple with a lack of carbon buildup around it, like it was a hot spot causing denotation. The car had also been pinging on highway acceleration the past few weeks.

Question- should I change the piston? Should I have the injectors tested? The scratching in the carbon on cyl #1 was from me.
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NEW- 2009 PSM GT- 0.020" over/ Vararam/ RCR 223/232 cam/ Kooks 1 7/8" LT/ 3" exhaust/ 3200 Yank/ 3.45 gears/ HPT self-tune

SOLD- 2008 LR G8 GT /
Intake / HPT self-tune / E85 / 160* stat / Kooks mids / Dynomax ST axlebacks / Xpipe / 219/233 Comp Cam

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post #2 of 33 (permalink) Old 05-28-2018, 05:20 AM
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Originally Posted by blkscooby View Post
However piston #1 looks to have some damage or burning at the locating dimple with a lack of carbon buildup around it, like it was a hot spot causing denotation. The car had also been pinging on highway acceleration the past few weeks.
It sure looks like it. A leak down test found that I had a bad piston in my engine and the rings were leaking oil. The result was oil covered the spark plug and caused preignition. It looks like you have oil in that piston too, especially in the second pic.


2008 Pontiac G8 GT | PBM | Premium Package
BMR suspension | GForce Engineering 750hp axles | GM Camaro 3.27 rear diff., Camaro trans pan + G8 GXP trans cooler | Livernois L92 Stage 1 Cam | Manton LS trunnion kit | Pedders bushings | PRC LS3 260cc heads | RCR intake + throttle body | Rotofab 102mm CAI | Stainless Works 1 7/8" headers | SuperPro front control arms + motor mounts | Texas Speed LS3 short block | Tuned by Patrick G. | Wrenched by ESP
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post #3 of 33 (permalink) Old 05-28-2018, 07:41 AM Thread Starter
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No, that's only coolant from removing the head. There isn't oil in any of the driver's side cylinders. I'm going to finish removing the pass side head this morning.

NEW- 2009 PSM GT- 0.020" over/ Vararam/ RCR 223/232 cam/ Kooks 1 7/8" LT/ 3" exhaust/ 3200 Yank/ 3.45 gears/ HPT self-tune

SOLD- 2008 LR G8 GT /
Intake / HPT self-tune / E85 / 160* stat / Kooks mids / Dynomax ST axlebacks / Xpipe / 219/233 Comp Cam

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post #4 of 33 (permalink) Old 05-28-2018, 09:01 AM
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Have you had the head off the engine before (how many miles ago?) Looks like a bunch of carbon buildup to me.

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post #5 of 33 (permalink) Old 05-28-2018, 11:17 AM Thread Starter
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Yes, heads have been off before at least twice. Last time was about 50k ago when I replaced the last bad cam.

Someone on LS1tech suggested to pull the piston to check the rings

NEW- 2009 PSM GT- 0.020" over/ Vararam/ RCR 223/232 cam/ Kooks 1 7/8" LT/ 3" exhaust/ 3200 Yank/ 3.45 gears/ HPT self-tune

SOLD- 2008 LR G8 GT /
Intake / HPT self-tune / E85 / 160* stat / Kooks mids / Dynomax ST axlebacks / Xpipe / 219/233 Comp Cam

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post #6 of 33 (permalink) Old 05-28-2018, 11:19 AM Thread Starter
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Finished removing the pass side head and that side is totally normal, just typical carbon buildup on the Pistons. Valves are good, plugs were good, although cyl 2 could use a deg or so less timing based on the mark on the spark plugs and ground.

NEW- 2009 PSM GT- 0.020" over/ Vararam/ RCR 223/232 cam/ Kooks 1 7/8" LT/ 3" exhaust/ 3200 Yank/ 3.45 gears/ HPT self-tune

SOLD- 2008 LR G8 GT /
Intake / HPT self-tune / E85 / 160* stat / Kooks mids / Dynomax ST axlebacks / Xpipe / 219/233 Comp Cam

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post #7 of 33 (permalink) Old 06-04-2018, 11:55 PM Thread Starter
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So the motor is going to a machine shop tomorrow. The crank journals need to be polished or maybe ground. Cylinders need to be honed or maybe bored. We'll see. I'll post pics later.

NEW- 2009 PSM GT- 0.020" over/ Vararam/ RCR 223/232 cam/ Kooks 1 7/8" LT/ 3" exhaust/ 3200 Yank/ 3.45 gears/ HPT self-tune

SOLD- 2008 LR G8 GT /
Intake / HPT self-tune / E85 / 160* stat / Kooks mids / Dynomax ST axlebacks / Xpipe / 219/233 Comp Cam

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post #8 of 33 (permalink) Old 06-04-2018, 11:57 PM Thread Starter
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Pistons don't have any broken ringlands but it may not matter if I have to bore the block.

NEW- 2009 PSM GT- 0.020" over/ Vararam/ RCR 223/232 cam/ Kooks 1 7/8" LT/ 3" exhaust/ 3200 Yank/ 3.45 gears/ HPT self-tune

SOLD- 2008 LR G8 GT /
Intake / HPT self-tune / E85 / 160* stat / Kooks mids / Dynomax ST axlebacks / Xpipe / 219/233 Comp Cam

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post #9 of 33 (permalink) Old 06-05-2018, 12:32 AM Thread Starter
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Pics...
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File Type: jpg IMG_20180602_213551006_1528176738223.jpg (126.4 KB, 45 views)

NEW- 2009 PSM GT- 0.020" over/ Vararam/ RCR 223/232 cam/ Kooks 1 7/8" LT/ 3" exhaust/ 3200 Yank/ 3.45 gears/ HPT self-tune

SOLD- 2008 LR G8 GT /
Intake / HPT self-tune / E85 / 160* stat / Kooks mids / Dynomax ST axlebacks / Xpipe / 219/233 Comp Cam

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post #10 of 33 (permalink) Old 06-05-2018, 12:33 AM Thread Starter
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NEW- 2009 PSM GT- 0.020" over/ Vararam/ RCR 223/232 cam/ Kooks 1 7/8" LT/ 3" exhaust/ 3200 Yank/ 3.45 gears/ HPT self-tune

SOLD- 2008 LR G8 GT /
Intake / HPT self-tune / E85 / 160* stat / Kooks mids / Dynomax ST axlebacks / Xpipe / 219/233 Comp Cam

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post #11 of 33 (permalink) Old 06-05-2018, 11:08 AM
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That's a lot of carbon buildup that I am sure was causing some pre-ignition. Do you have a catch can? What did you install the valve stem seals with? You either had excessive blow by, or valve seals were leaking from the looks of the piston.

PBM G8 GXP M6-Self flex fuel tune,OBX LTs, Kooks A/B, Monster clutch, 3.45 gear,LSA S/C, cam, fuel system, stock block and stock heads, 12 PSI.
Best e.t 10.41/ best mph 138.7 Half Mile: 168.3 mph
2007 TBSS-Self tune, bolt ons [email protected], 1,560 D.A
1991 GMC Syclone- Self tune/catback [email protected], 4,200ft D.A
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post #12 of 33 (permalink) Old 06-05-2018, 07:11 PM Thread Starter
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I have a budget oil separator but yes the valve seals had been leaking. One was missing completely when I changed the springs 6 weeks ago, lol.

Motor is at Duffee Motorsports now. Brian is a great guy. He's going to measure everything and see where we are.

NEW- 2009 PSM GT- 0.020" over/ Vararam/ RCR 223/232 cam/ Kooks 1 7/8" LT/ 3" exhaust/ 3200 Yank/ 3.45 gears/ HPT self-tune

SOLD- 2008 LR G8 GT /
Intake / HPT self-tune / E85 / 160* stat / Kooks mids / Dynomax ST axlebacks / Xpipe / 219/233 Comp Cam

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post #13 of 33 (permalink) Old 06-06-2018, 03:49 AM
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You did the right thing taking it to a machine shop. That piston was a hand grenade with the pin removed: it was only a matter of time before it got real ugly and expensive. While it won't be cheap, it will be right, and without the drama of a more expensive detour. Give yourself a pat on the back.
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2009 MGM GT: VCM CAI, ARH LT headers (no cats), Vector Tune, MT drag radials
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PB: 12.533 @ 111.45 w/ 1.951 60' CLAIMING THE INTAKE/LT/TUNE/DR RECORD


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post #14 of 33 (permalink) Old 06-06-2018, 09:06 AM
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Its amazing what too much carbon buildup on a piston can do. Especially when the carbon buildup is in the first set of rings. If you need help with anything, let me know!

PBM G8 GXP M6-Self flex fuel tune,OBX LTs, Kooks A/B, Monster clutch, 3.45 gear,LSA S/C, cam, fuel system, stock block and stock heads, 12 PSI.
Best e.t 10.41/ best mph 138.7 Half Mile: 168.3 mph
2007 TBSS-Self tune, bolt ons [email protected], 1,560 D.A
1991 GMC Syclone- Self tune/catback [email protected], 4,200ft D.A
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post #15 of 33 (permalink) Old 06-06-2018, 09:55 PM Thread Starter
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Thanks Rhett!

Looks like about $1400 in machining and new parts. Cylinders bored, new pistons, new cam bearings, crank ground and new bearings.

NEW- 2009 PSM GT- 0.020" over/ Vararam/ RCR 223/232 cam/ Kooks 1 7/8" LT/ 3" exhaust/ 3200 Yank/ 3.45 gears/ HPT self-tune

SOLD- 2008 LR G8 GT /
Intake / HPT self-tune / E85 / 160* stat / Kooks mids / Dynomax ST axlebacks / Xpipe / 219/233 Comp Cam

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post #16 of 33 (permalink) Old 06-07-2018, 06:36 PM
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Ditto on the carbon build-up. After having to buy a new outboard powerhead back in the 90's I started using a product from Yamaha called Ring-Free. I prefer it to SeaFoam.

2009 MGM GT: VCM CAI, ARH LT headers (no cats), Vector Tune, MT drag radials
Procharger D1SC still powering the box it came in January 2010, hiding somewhere in the back of my man cave.
PB: 12.533 @ 111.45 w/ 1.951 60' CLAIMING THE INTAKE/LT/TUNE/DR RECORD


"There are but three true sports...mountain climbing, bull fighting, and motor racing. The rest are merely games." Ernest Hemmingway
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post #17 of 33 (permalink) Old 07-16-2018, 11:13 PM Thread Starter
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It was a process but the car is running again finally. I wanted to write a brief summary since this "build" was out of necessity and somewhat budget constrained. I also did my research and chose the best route for my needs as a reliable daily driver that is unlikely to have any other power adders.

I cant say enough good things about Duffee Motorsports in Glendale. Brian is a great guy and knows how to build engines.

After examining my block, crank and rods, he found that the crank journals were 0.001" under min spec, the cylinders were 0.0015" tapered, but the rods were fine. There isnt a shop in AZ to machine cranks and I didnt have 3-4 weeks to wait for the shop in Denver so I decided to purchase a new factory crank, use factory bearings, polish and balance. the mains were fine.

I only needed to bore 0.005" in order to correct the cylinders but I wanted to stay with a hypereutectic piston as opposed to forged for noise and cost. The smallest cast flattop piston I could find was 0.020" over so thats what we did. Then the block deck needed to be decked 0.002" to get it flat.

I cleaned the heads, re-lapped the stock valves, and re-installed the BTR dual springs that I had only installed 3 months ago.

New factory crank
New factory main and rod bearings
Reuse stock rods and mains
New factory main and rod bolts
Block bored 0.020" over
Speedtech flattop pistons and pins
Speedtech rings
New oil pump and pickup oring
New timing chain
New dampener
New seals and gaskets
New LS lifters
New cam bearings
New RCR 223/232 .612/.599 111+0 Lunati cam
New 7.350 BTR pushrods
New factory head gaskets
Reuse stock heads, previously milled 0.040"
BTR dual platinum springs, new seals
New Summit solid bronze trunnion kit
Reuse ARP head bolts
New ARP intake manifold bolts

While installing the rockers, I found that several of the BTR trunnion kit bearings installed 50k miles ago were damaged or broken. Decided to use solid bronze replacements.

I used Amsoil assembly lube on the lower engine and Permatex lube on the cam and upper engine. I primed the engine using my Motive brake bleeder through the oil pressure sensor location. I used Amsoil break in oil for the initial startup and first 60 mile break in. Drained, and filled with 1 qt break in oil, rest std Valvoline 5W-30. Will run for another couple hundred miles, change again with Valvoline and then at 1,500 miles, switch back to Amsoil synthetic.

I painted the valve covers, TB, water pump and various brackets wrinkle black just to dress it up a bit.

I tucked the top wire harness a bit by running it under the TB, not over. The SS ARP intake bolts are a nice touch and I plan to use SS bolts on the coils also.

Of course, tweaking the tune for the cube gain and new cam using HPTuners but it is running great.

Here are some photos-
Attached Images
File Type: jpg IMG_20180623_091239085.jpg (129.3 KB, 15 views)
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File Type: jpg IMG_20180623_092720348.jpg (143.3 KB, 17 views)
File Type: jpg IMG_20180623_093616694.jpg (134.1 KB, 18 views)

NEW- 2009 PSM GT- 0.020" over/ Vararam/ RCR 223/232 cam/ Kooks 1 7/8" LT/ 3" exhaust/ 3200 Yank/ 3.45 gears/ HPT self-tune

SOLD- 2008 LR G8 GT /
Intake / HPT self-tune / E85 / 160* stat / Kooks mids / Dynomax ST axlebacks / Xpipe / 219/233 Comp Cam

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post #18 of 33 (permalink) Old 07-16-2018, 11:14 PM Thread Starter
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File Type: jpg IMG_20180623_123401003.jpg (145.4 KB, 16 views)
File Type: jpg IMG_20180623_100249665.jpg (146.1 KB, 14 views)
File Type: jpg IMG_20180623_112950947.jpg (137.6 KB, 14 views)

NEW- 2009 PSM GT- 0.020" over/ Vararam/ RCR 223/232 cam/ Kooks 1 7/8" LT/ 3" exhaust/ 3200 Yank/ 3.45 gears/ HPT self-tune

SOLD- 2008 LR G8 GT /
Intake / HPT self-tune / E85 / 160* stat / Kooks mids / Dynomax ST axlebacks / Xpipe / 219/233 Comp Cam

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post #19 of 33 (permalink) Old 07-16-2018, 11:16 PM Thread Starter
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Install pics
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File Type: jpg IMG_20180625_235525571.jpg (133.8 KB, 12 views)
File Type: jpg IMG_20180707_090105978.jpg (134.7 KB, 13 views)
File Type: jpg IMG_20180630_170746159.jpg (145.8 KB, 11 views)
File Type: jpg IMG_20180705_171536597.jpg (142.7 KB, 16 views)
File Type: jpg IMG_20180626_001436967.jpg (141.2 KB, 17 views)

NEW- 2009 PSM GT- 0.020" over/ Vararam/ RCR 223/232 cam/ Kooks 1 7/8" LT/ 3" exhaust/ 3200 Yank/ 3.45 gears/ HPT self-tune

SOLD- 2008 LR G8 GT /
Intake / HPT self-tune / E85 / 160* stat / Kooks mids / Dynomax ST axlebacks / Xpipe / 219/233 Comp Cam

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post #20 of 33 (permalink) Old 07-16-2018, 11:18 PM Thread Starter
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I had some help too! My 5 yr old son installing the gaskets...

Completed pics.
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File Type: jpg IMG_20180707_093415149.jpg (131.0 KB, 20 views)
File Type: jpg IMG_20180707_124734177.jpg (140.2 KB, 19 views)
File Type: jpg IMG_20180707_102953462.jpg (142.1 KB, 16 views)
File Type: jpg IMG_20180707_100122768.jpg (149.0 KB, 20 views)

NEW- 2009 PSM GT- 0.020" over/ Vararam/ RCR 223/232 cam/ Kooks 1 7/8" LT/ 3" exhaust/ 3200 Yank/ 3.45 gears/ HPT self-tune

SOLD- 2008 LR G8 GT /
Intake / HPT self-tune / E85 / 160* stat / Kooks mids / Dynomax ST axlebacks / Xpipe / 219/233 Comp Cam

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