C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Balancer issue and detonation, aftermarket junk

 
Old 10-12-2010, 04:49 PM
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bjankuski
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Default Balancer issue and detonation, aftermarket junk

I have been fighting a detonation issue for the last month with my 406. Ever since I put on the USM stealth ram the car pings at WOT. I checked all the basics and could not solve the problem, timing, fuel pressure, fuel injector health, tune, basic engine health, heat and whatever else I could come up with. I eventually switched to E85 fuel and the detonation problem was gone and the car made excellent power. Then the detonation problem started slowly coming back even on E85 fuel. I exhausted every possible issue I could come up with and finally concluded that I must have an internal engine problem and was going to yank the engine and find the issue. One issue kept nagging at me, and that was, what if the actual SFI approved balancer on my engine had somehow slipped and was giving me an incorrect timing reading. I thought this was an unlikely scenario since it was a SFI approved internally balanced damper and it would have to advance the ring (which only happens on engine deceleration) to cause an advanced timing condition. I spent a few hours determining exact TDC and to my surprise the balancer was advanced by 16 degrees. I reset the timing to the correct 6 degree base and the engine no longer pings.

Another case of aftermarket junk, I need a new SFI balancer and I wish I would have checked this first. I just assumed my expensive aftermarket balancer would not be the issue. I checked it when I installed it and have not checked it since. It makes me wonder how long it has been moving and how it was affecting my dyno runs.
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Old 10-12-2010, 05:07 PM
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Originally Posted by bjankuski View Post
I have been fighting a detonation issue for the last month with my 406. Ever since I put on the USM stealth ram the car pings at WOT. I checked all the basics and could not solve the problem, timing, fuel pressure, fuel injector health, tune, basic engine health, heat and whatever else I could come up with. I eventually switched to E85 fuel and the detonation problem was gone and the car made excellent power. Then the detonation problem started slowly coming back even on E85 fuel. I exhausted every possible issue I could come up with and finally concluded that I must have an internal engine problem and was going to yank the engine and find the issue. One issue kept nagging at me, and that was, what if the actual SFI approved balancer on my engine had somehow slipped and was giving me an incorrect timing reading. I thought this was an unlikely scenario since it was a SFI approved internally balanced damper and it would have to advance the ring (which only happens on engine deceleration) to cause an advanced timing condition. I spent a few hours determining exact TDC and to my surprise the balancer was advanced by 16 degrees. I reset the timing to the correct 6 degree base and the engine no longer pings.

Another case of aftermarket junk, I need a new SFI balancer and I wish I would have checked this first. I just assumed my expensive aftermarket balancer would not be the issue. I checked it when I installed it and have not checked it since. It makes me wonder how long it has been moving and how it was affecting my dyno runs.
Great catch. Engine's OK?

It seems everthing is coming from China these days so the manufacturers can save a few bucks to pad their margins.

I think I'd get the balancer manufacturer &/or retailer on the phone and/or send them a lovely certified letter detailing what they are going to do for you.

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Old 10-12-2010, 05:08 PM
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Aardwolf
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What brand is it? I've been happy with the Fluidamper brand, I don't believe it has anything that can slip. My stock dampener was losing chunks of the elastometer.

Glad you got it solved.
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Old 10-13-2010, 06:26 AM
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I'm wondering if it was required for you to change the timing tab when you installed the new balancer/damper.

Even GM use to change the TDC mark on their dampers/balancers by moving the TDC indicator (the hash line). There's a photo floating around on the web showing the different locations GM put on theirs.

So I'm wondering if your new balancer also required a specific timing tab or an adjustable one in order for your timing to be set accurately.

Diameters matter too. Were the diameters of both dampers the same?

Just some thoughts.

Jake
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Old 10-13-2010, 07:50 AM
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Good to hear you found the cause of the problem. I would be interested to know which brand, and if you were able to determine what was actually failing in the dampner. tia
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Old 10-13-2010, 07:53 AM
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Originally Posted by JAKE View Post
I'm wondering if it was required for you to change the timing tab when you installed the new balancer/damper.

Even GM use to change the TDC mark on their dampers/balancers by moving the TDC indicator (the hash line). There's a photo floating around on the web showing the different locations GM put on theirs.

So I'm wondering if your new balancer also required a specific timing tab or an adjustable one in order for your timing to be set accurately.

Diameters matter too. Were the diameters of both dampers the same?

Just some thoughts.

Jake
I degreed the balancer when I installed it to make sure the zero mark was actually TDC. Six years ago it was correct, since then it has walked 16 degrees.
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Old 10-13-2010, 08:42 AM
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Originally Posted by bjankuski View Post
I degreed the balancer when I installed it to make sure the zero mark was actually TDC. Six years ago it was correct, since then it has walked 16 degrees.
I thought Chevy balancers were keyed to the crankshaft?
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Old 10-13-2010, 10:42 AM
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Originally Posted by bjankuski View Post
I degreed the balancer when I installed it to make sure the zero mark was actually TDC. Six years ago it was correct, since then it has walked 16 degrees.
Man - if it is 6 years old I'd say it made a pretty good run of it.

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Old 10-13-2010, 11:27 AM
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Bummer, two questions:

1) Brand?

2) How did you tell it was 16 deg off? It is cloudy, but for some reason I thought the key may line up with 0deg, but I'm not sure on that.
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Old 10-13-2010, 11:43 AM
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The balancers are keyed but the outer ring isnt sometimes it can slip on that rubber piece it sits on and read different, can also give out some vibration thats unexplainable or even worse yet come apart. Like a small grenade, btdt.
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Old 10-13-2010, 12:52 PM
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Originally Posted by bjankuski View Post
One issue kept nagging at me, and that was, what if the actual SFI approved balancer on my engine had somehow slipped and was giving me an incorrect timing reading. I thought this was an unlikely scenario since it was a SFI approved internally balanced damper and it would have to advance the ring (which only happens on engine deceleration) to cause an advanced timing condition. I spent a few hours determining exact TDC and to my surprise the balancer was advanced by 16 degrees. I reset the timing to the correct 6 degree base and the engine no longer pings.
My search for a balancer was an interesting one, I had a hard time finding one (a brand) that did not have some negative feedback where it had failed. I found it surprising that a damper would have such a high failure rate. I'd be interested in knowing the brand of your damper as well.

I'm also curious,,,you must have limited the amount of retard in your tune? I thought there was at least 20-deg retard built-in. Since you were inside that window, you'd almost think the ESC would have covered you.

It's gotta feel great discovering you DON'T have an internal engine problem though!!!!

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Old 10-13-2010, 01:51 PM
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I always degree may balancers and then adjust the timing tab because the machining of the crank, balancer and timing tab rarely come out perfect. I almost always find some error in the actual TDC indiactor when compared to actual TDC.

I have the WOT knock retard limited to 10 degrees based on previous scans and if it exceeds 5 degrees I now something is not correct.

I have never had a stock balancer move on me, (maybe good luck) and they are 20 years old. I did not expect my SFI balancer to move one me.

Last edited by bjankuski; 10-13-2010 at 01:54 PM.
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Old 10-13-2010, 05:37 PM
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steven mack
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Default balancer

So what brand was it?Inquiring minds would like to know.
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Old 10-13-2010, 06:18 PM
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I always mark my balancers accross the elastomer so I can see if the ring moves in relation to the hub. Usually with "dimples" from a punch straight accross from each other since paint can get covered or removed
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Old 10-13-2010, 07:30 PM
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Glad to see that you verified TDC when you installed the balancer, too few do that. Any chance the manufacturer will warrant it if you ship it to them to examine?

What brand is it? I'm lke the others and would really like to know what brande it is. I'll be in the market for a new one in a month or two which makes this particularly important to me.

I've read several posts about the outer rings moving but all those were stock dampers with a lot of miles and age on them.

When I visited Reher and Morrison's shop a week or so ago to drop of my new block I noticed that every one of the 1,000 HP engines they had sitting on the shelves, ready to install and run, had ATI Superdampers on this. I can't help but believe they chose ATIs after careful consideration of other brands.

Thanks for posting about it.

Jake
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Old 10-13-2010, 07:41 PM
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My money is on "professional products", a friend/member on here had an SFI approved PP damper and it slipped in no time flat.
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Old 10-14-2010, 07:39 AM
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Originally Posted by Shark Racer View Post
My money is on "professional products", a friend/member on here had an SFI approved PP damper and it slipped in no time flat.
"Ding Ding you are the winner" It is a professional products damper, I have not had time to pull it off yet or look up what I purchased but I will post the model number as soon as I have it.
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Old 10-14-2010, 06:10 PM
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There stuff must have a history.

Hey, but they chose are really nice name didn't they. "Professional Products", makes you feel all warm and fuzzy all over.

Jake
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Old 10-14-2010, 06:54 PM
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Originally Posted by Black89Z51 View Post
I thought Chevy balancers were keyed to the crankshaft?
They are keyed to the crank snout but the outer balancer ring is press fitted onto the center hub with a rubber ring sandwiched between the two. The keyed centered hub won't budge but the outer ring with the timing mark can. They walk backwards and begin to grind on the front timing cover after time. Sometimes the grinding sound is muffled and drowned out by the engine running so they go undetected.

Originally Posted by bjankuski View Post
One issue kept nagging at me, and that was, what if the actual SFI approved balancer on my engine had somehow slipped and was giving me an incorrect timing reading.
Good catch.
Exactly what was driving me crazy. I could not figure out WTF was wrong. I failed smog and car ran poorly no matter what I did. Then someone here suggested I check the balancer for slippage. Sure enough I was unknowingly setting timing to a false timing mark that has shifted. Since then I've been able to spot slipped balancers on other cars in no time. Lesson well learned.

Here's my old vs new:



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Old 10-14-2010, 10:12 PM
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Originally Posted by bjankuski View Post
"Ding Ding you are the winner" It is a professional products damper, I have not had time to pull it off yet or look up what I purchased but I will post the model number as soon as I have it.
That was the brand I found TONS of negative feedback on because of the high volume of failures. Every builder I talked to said they've had more than one fail. The parts company where I bought my balancer SAID the problem was with the adhesive used to bond the two halves together and was "fixed" a couple of years ago. But, complaints continue.

After learning this, I sent my balancer back and had to pay a restocking fee to get a different one. Based on the high degree of complaints, I didn't think PP balancers were worth trying. (I was pissed about the restocking fee because the online retailer said [after explaining why they were fixed] that PP was the ONLY choice that would work in a 6 1/2" model for L98's). Butt-head! If it weren't for RecklessDriver, I wouldn't have found a more promising option. His recommendation is what I ended up using. So far, so good.

BTW: Scat still sells complete rotating assemblies with PP balancers. I also noticed one on a 572 being installed on an Overhaulin' episode. So, maybe some of them are "O.K".

Last edited by GREGGPENN; 10-14-2010 at 10:16 PM.
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