Lt1 tapping sound - LS1LT1 Forum : LT1, LS1, Camaro, Firebird, Trans Am, Engine Tech Forums
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post #1 of 21 (permalink) Old 09-28-2016, 07:49 PM Thread Starter
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Lt1 tapping sound

Okay so I got this engine used, it had issues but when installing it my mechanic said it had good compression etc.

It has 1.6rr and long tube headers.

I've attached a link to a video where you can hear the sound. It only seems to do it when warm.

https://youtu.be/VIdaLUV9dgg
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post #2 of 21 (permalink) Old 09-28-2016, 08:55 PM
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Sounds like Mine did when it spun a rod bearing.
I hope it isn't that friend. Hold good oil pressure ? Even after warmed up ?
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post #3 of 21 (permalink) Old 09-28-2016, 09:22 PM Thread Starter
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Sounds like Mine did when it spun a rod bearing.
I hope it isn't that friend. Hold good oil pressure ? Even after warmed up ?

Yes it holds about 50psi at idle and about 60psi while driving.
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post #4 of 21 (permalink) Old 09-29-2016, 09:44 AM
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Some video/audio with a few revs in it might be more helpful. Sounds more like in the valve train. Might want to pull the valve covers off and observe.
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post #5 of 21 (permalink) Old 09-29-2016, 11:31 AM
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50 PSI at idle - hot? Holy crap. My engine is new with about 1000 miles on it, built by Karl Ellwein, and once its hot I get about 35 psi at idle while in gear (800 RPM). Cold, is another matter.

Get a mechanic's stethoscope and get to work. See if its coming from the top-end, bottom-end, or somewhere in-between. Don't be afraid to pull off a valve cover and put the stethoscope to each rocker stud. Mine started making a tick about 100 miles after a heads/cam change. Turned out to be a rod. Never heard a rod "tick" like that before - but that's what it was.

1995 LT1 Wagon. ERE 383

Last edited by AtlantaDan; 09-29-2016 at 11:34 AM.
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post #6 of 21 (permalink) Old 09-29-2016, 10:40 PM Thread Starter
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Some video/audio with a few revs in it might be more helpful. Sounds more like in the valve train. Might want to pull the valve covers off and observe.

I'll record another video tomorrow. I'm honestly just afraid to harm the car any more.
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post #7 of 21 (permalink) Old 09-29-2016, 10:43 PM Thread Starter
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50 PSI at idle - hot? Holy crap. My engine is new with about 1000 miles on it, built by Karl Ellwein, and once its hot I get about 35 psi at idle while in gear (800 RPM). Cold, is another matter.

Get a mechanic's stethoscope and get to work. See if its coming from the top-end, bottom-end, or somewhere in-between. Don't be afraid to pull off a valve cover and put the stethoscope to each rocker stud. Mine started making a tick about 100 miles after a heads/cam change. Turned out to be a rod. Never heard a rod "tick" like that before - but that's what it was.

My gauge may be a little off, considering the engine sits in a 1979 corvette using that cars oem gauges. I just looked again and it's closer to 40psi hot idling around 600-650 rpm.

It does and has fluctuated a bit since I've got it running.

I'll use my scanner and see if I can get a more accurate reading on the oil pressure.

I just ordered new lifters for the cam I got, so I may just wait to fix it when the rest of the parts arrive.

I want to be sure it isn't something more catastrophic than that, the engine has about 125K on it.
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post #8 of 21 (permalink) Old 09-30-2016, 05:30 AM
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I wouldn't lose too much sleep just yet. It could very well be a noisy lifter or some other valvetrain issue (which would be my first guess), so wait and see. 125k is nothing for a well-kept LT1.

1995 LT1 Wagon. ERE 383
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post #9 of 21 (permalink) Old 09-30-2016, 05:35 AM Thread Starter
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I wouldn't lose too much sleep just yet. It could very well be a noisy lifter or some other valvetrain issue (which would be my first guess), so wait and see. 125k is nothing for a well-kept LT1.

Well I've ordered new lifters, springs, push rods, and a cam (CC503) as well as a new timing chain, I may just leave it parked until that gets done to avoid damage.

I do worry about my oil pressure. 50-60 psi while driving is ok? I've just put a lot into this swap work and the guy who sold me the engine was shady and knew it had problems when he sold it to me, just "forgot" conviently.

I'm a very paranoid person when it comes to mechanics, the smallest change in sound and I think it's about to explode.
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post #10 of 21 (permalink) Old 09-30-2016, 08:24 AM
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That sort of PSI while driving is fine for a fresh engine. Its that sort of pressure while idling - hot - that can be problematic, because it means your pressure goes up to 70 and beyond while driving. It can cause excessive wear on the oil-pump drive gear, cost horsepower, and even cause oil filters to explode.

The common metric that's cited for Gen 1 & 2 SBC's is 10 PSI per 1k RPM - hot - for a well-used, but still healthy engine.

Verify the pressure with a mechanical gauge. Then if it still reads high at hot idle, the relief valve on your oil pump may be stuck closed.

1995 LT1 Wagon. ERE 383

Last edited by AtlantaDan; 09-30-2016 at 08:27 AM.
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post #11 of 21 (permalink) Old 09-30-2016, 08:51 AM Thread Starter
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That sort of PSI while driving is fine for a fresh engine. Its that sort of pressure while idling - hot - that can be problematic, because it means your pressure goes up to 70 and beyond while driving. It can cause excessive wear on the oil-pump drive gear, cost horsepower, and even cause oil filters to explode.

The common metric that's cited for Gen 1 & 2 SBC's is 10 PSI per 1k RPM - hot - for a well-used, but still healthy engine.

Verify the pressure with a mechanical gauge. Then if it still reads high at hot idle, the relief valve on your oil pump may be stuck closed.

It never exceeds 60psi.

I just uploaded a new video as well and attached a screenshot from my scanner.

https://youtu.be/WrDL_aipCt8
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post #12 of 21 (permalink) Old 09-30-2016, 09:01 AM
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Quote:
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It never exceeds 60psi.

I just uploaded a new video as well and attached a screenshot from my scanner.

https://youtu.be/WrDL_aipCt8
What is the reading at say, 3k hot? (Also, I can't see anything in that picture - its too small.) If it stays at 60 psi at hot idle as well as hot 3k, then something is going on. Confirm pressures with a different mechanical gauge.

Back to the ticking - bad exhaust manifold gaskets can tick exactly like that as well.

A mechanic's stethoscope would be of great use to you in the search.

1995 LT1 Wagon. ERE 383

Last edited by AtlantaDan; 09-30-2016 at 09:05 AM.
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post #13 of 21 (permalink) Old 09-30-2016, 09:03 AM Thread Starter
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Quote:
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It never exceeds 60psi.

I just uploaded a new video as well and attached a screenshot from my scanner.

https://youtu.be/WrDL_aipCt8
What is the reading at say, 3k hot? Also, I can't see anything in that picture - its too small.

About 50 psi. That's close to what I run on the interstate (2750 rpm)

How do I make the picture larger for this forum?
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post #14 of 21 (permalink) Old 09-30-2016, 09:07 AM
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About 50 psi. That's close to what I run on the interstate (2750 rpm)

How do I make the picture larger for this forum?

So wait... Its 60 PSI hot idle, and 50 PSI hot 3k? Meaning it drops 10 PSI at higher RPM's?

1995 LT1 Wagon. ERE 383
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post #15 of 21 (permalink) Old 09-30-2016, 09:09 AM Thread Starter
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Quote:
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Quote:
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About 50 psi. That's close to what I run on the interstate (2750 rpm)

How do I make the picture larger for this forum?

So wait... Its 60 PSI hot idle, and 50 PSI hot 3k? Meaning it drops 10 PSI at higher RPM's?

No no I corrected myself it hovers closer to 40psi. It actually doesn't seem to change whether it is hot or cold.
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