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1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 09-15-2005, 12:33 AM   #21
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smoking it would be a good test. hit it with some seafoam, kill 2 birds with one stone. just dont let the smoke get in your eyes, thats not pretty
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Old 09-15-2005, 12:41 AM   #22
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Jolly, that'* not the type of smoke we're referring to. Heating and Air Conditioning techs use smoke to determine where leaks or currents may be. It can be tough on a car with a belt and pulleys spinning, but it can be done if you know what you're looking for.

Ultimately, Seafoam too often will clog your cat.
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Old 09-15-2005, 12:42 AM   #23
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Quote:
Originally Posted by willwren
The cracked manifolds or exhaust leak will be REAL KR. But with the frequency you're getting a lifter could be the cause for false. Your thoughts on a piston pin (the pin holding the rod to the piston itself) could have merit, as on the L27 and L36, they're floating pins, where on the L67 they have bearings. There'* so many things, you're not likely to narrow it down unless you get the stethescope out. And I'd use a real mech'* scope, not a screwdriver for this one.

Do me a favor to rest my mind. On a COLD engine, before you fire up, spray some soapy water on your manifolds and heads. ALOT. While it'* wet, fire it up and look for bubbles. use a 50/50 mix of dish soap and water. You have to be quick before it starts to heat up and evaporate. Try to rule out an exhaust leak first.

But in the long run, if you HEAR something, odds are the knock sensor can too. I have to trust your ear on this one. If you hear something, odds are it'* false. If you don't, it'* got to be real. This will determine where you look for the problem.

If you think it'* a lifter, try a bit of diesel or marvel mystery oil in your engine oil to thin it out some. Any lifter clatter should go away temporarily.
Here'* the strange part. I HAVE a mechanic'* stethoscope, not expensive, but not a piece of hose, either. I could not isolate which lifter was ticking, except that it seemed to be coming from the rear bank. So, I replaced those six lifters. I reused both the lower and upper gaskets as they are only about 9 months old and like new. You could have knocked me over with a feather when I fired it up and still had the tick tick tick. So today, I replaced the front six lifters again reusing the upper and lower gaskets. (BTW, no apparent leaks from these.) I am getting pretty quick at this job by now. So when it was still ticking after 12 new lifters, that'* when I started looking for something else. I figured the sound of a pin might resonate up and become vague rather than point-source, but ???

Great idea about the soap. Will do this first thing in the AM. If nothing there, I will pull the knock sensors and re-torque to 14 ft-lb as Foghorm suggested.

I sure appreciate the help, guys.
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Old 09-15-2005, 12:49 AM   #24
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Quote:
Originally Posted by willwren
Bill,

The RTV will not reduce the sensors sensitivity unless you entirely coat it with the stuff. On the threads is fine, and preferred. You need SOMETHING there to make sure any movement of the sensor to the block will not be interpreted as knock. The knock sensors listen for knock through the coolant. As long as the END or face of the sensor is clean, use whatever you prefer on the threads.

It might be interesting to disconnect them one at a time for back to back scans.

Might help isolate the problem to the front or rear sensor or to the front or rear bank for false KR.
Thatis another good idea, Bill. I will do it. An ASE friend had advised me to umplug both sensors to see if the car ran better. Default KR with no sensors is supposed to be limited to 10 degrees. I did this and the car did run better - not great, but better. But I had not thought to use the little buggers to help me find the knock.
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Old 09-15-2005, 12:51 AM   #25
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Bill, coolant and water are like sound distributors. A grinding bearing in a water pump can be heard as easily at the thermostat housing as it can at the water pump itself, so don't kick yourself over not nailing it the first time with the stethescope. It'* tough. I've been through this type of thing time and time again. In the end, it'* the stethescope that CONFIRMS other troubleshooting, rather than nailing it down by itself.
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Old 09-15-2005, 01:06 AM   #26
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Quote:
Originally Posted by willwren
The cracked manifolds or exhaust leak will be REAL KR.
Quote:
Originally Posted by willwren
If you hear something, odds are it'* false. If you don't, it'* got to be real..
Hmmm, not sure what you're saying here Bill. Anyway, it'* unlikely the knock sensors will pick up exhaust leaks as detonation and then introduce KR.

Bill B, I still think the most likely culprit of that noise is exhaust. It'* the single leading candidate that can be confused for valvetrain noise.

Seperately, use anything you like to seal the knock sensors, I prefer GM pipe sealant because it cures faster. Whatever you use, give it time to cure before you refill the coolant and then fire it up. Over torquing them has caused many a grey hair

As a side note, I'm not up on the parameters for your PCM, but you might want to give the MAF sensor a clean with alcohol and a q-tip to ensure it'* clean...just in case it'* not reading all the air correctly.

Cheers,
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Old 09-15-2005, 01:11 AM   #27
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I agree with the crazy on the exhaust. That'* why I pointed out the cracks, leaks, or restrictions right off. Even the clogged cat is a very likely candidate at this point.
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Old 09-15-2005, 08:59 AM   #28
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Quote:
Originally Posted by Foghorn

Bill B, I still think the most likely culprit of that noise is exhaust. It'* the single leading candidate that can be confused for valvetrain noise.
Seems I remember a Chevy pickup that fooled me that way once too. I will check this first and carefully. For the cat, I am thinking about making a fitting for the O2 sensor to measure back pressure directly.

Quote:
Originally Posted by Foghorn
Seperately, use anything you like to seal the knock sensors, I prefer GM pipe sealant because it cures faster. Whatever you use, give it time to cure before you refill the coolant and then fire it up. Over torquing them has caused many a grey hair
I wonder if the sensors were damaged if I did overtorque them :(

Quote:
Originally Posted by Foghorn
As a side note, I'm not up on the parameters for your PCM, but you might want to give the MAF sensor a clean with alcohol and a q-tip to ensure it'* clean...just in case it'* not reading all the air correctly.

Cheers,
This was done not too long ago, but it is easy enough to do again
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Old 09-15-2005, 04:14 PM   #29
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Went up to Wally World first thing this AM and bought dish soap, sprayer, and batteries for my flashlight to do the exhaust leak check. After several minutes with my mirror and light, I decided the only way to properly examine the manifolds was to remove them. So I did.

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Look at what I found on the back side (could not see this on the engine) of the front manifold. Hee hee, Bill and Foghorn were right on the money with this. Kudos, guys!

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Even Ben was on the right track with exhaust, though we will have to see if the EGR values change with the new part. Seems everyone had a clue but me!

The plan now is install a junkyard manifold, fire it up and scan for KS counts and KR. If still there, out come the sensors for a gentle re-torque.

More as the story unfolds. Are these guys good or what?
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Old 09-15-2005, 04:41 PM   #30
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Bill it looks like the exahust gaskets for cylinder 3 and 5 were also leaking.... I can see the carbon tracking on the front manifold face...

Let us know how it goes when you get the new( used ) manifold installed...

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