8.1 engine knock or something else? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

kljfamily · 07-09-2020, 02:54 PM

2003 2500 suburban lt 8.1

The ongoing saga..

The oil line to the radiator blew and I loss all pressure(and oil all of it). Oil was everywhere!!!

The ecu shut down the car.

After fixing the line and replacing the oil it started up hesitantly at first but then came back to life..everything was fine..for about 2 miles then a small knock started happening. I turned around and headed home.

The engine starts and idles perfectly and is not overheating.

When you give it gas however at idle or in drive I can here the knock.

thoughts on where to start?

1. I've heard bad exhaust gasket or exhaust bolt could make similar noise.
2. heard bad cat could make similar sound?
3. pull valve covers and look at guides? What am I looking for?
4. Drop pan and look for shavings? Hopefully not a lower bearing?

Thanks for any advice.

I went and listed it for sale as a parts car. I was so done with it at the time but now rethinking it. I love that burb..well love hate...

I can post a video up if that would help

**hatzie** · 07-09-2020, 04:41 PM

A video would help.
Rod knocks are a very distinctive noise.
Loose Torque converter bolts can mimic a rod knock. Not much else I can think of.
Exhaust leaks don't quite sound the same.
Broken rocker arms on a smallblock kinda sound similar til you get the stethoscope out and discover it's coming from up top.

If it's wiped a rod bearing or two you'll usually see the teltale glitter in the oil when you drain it into a catch pan. Kindof a sinking feeling in the pit of your stomach when you see that glitter in the oil.

kljfamily · 07-10-2020, 10:48 AM

I'll load 2 video links one at idle where there is no noise and one after about 10 or so seconds. For the first few moments it makes no sound even when I rev the engine..sounds great and gets my hopes up and then the noise on the second video starts.

https://www.youtube.com/watch?v=Y9VTDFQsMqo
https://www.youtube.com/watch?v=z9rqfFalC78

thanks

**hatzie** · 07-10-2020, 08:06 PM

Your videos are marked private.
You must've missed a setting somewhere.

kljfamily · 07-10-2020, 08:31 PM

I fixed it should be public now

kljfamily · 07-10-2020, 08:51 PM

ok now its searchable and viewable on youtbe..man that was a tutorial on youtube for 30 mins

**hatzie** · 07-11-2020, 03:06 PM

A rod knock should be more pronounced and rhythmic. Not saying it's not but I'd start looking for loose stuff.
If it is the beginnings of a rod knock it will get progressively worse.

If you wiped out some rod bearings the oil pressure will probably be lower than it was before.

You can drain your oil and look for the teltale glitter of wiped bearings.
You can also cut an oil filter open with a big pipe cutter. Opening them up with other tools can leave shavings behind. Pipe cutters or oil filter cutters cut through with sharp wheels unlike a die grinder or hacksaw.
I have an old 4 wheel Ridgid 44S I picked up at a yard sale for cutting open spin on oil filters.

**truckdude239** · 07-20-2020, 07:58 AM

its eaither a rod or a cracked flex plate if it only startted after loosing an oil line id say rod

07-09-2020, 02:54 PM	#1
kljfamily Registered User Join Date: Sep 2014 Location: Albuquerque NM Posts: 98	8.1 engine knock or something else? 2003 2500 suburban lt 8.1 The ongoing saga.. The oil line to the radiator blew and I loss all pressure(and oil all of it). Oil was everywhere!!! The ecu shut down the car. After fixing the line and replacing the oil it started up hesitantly at first but then came back to life..everything was fine..for about 2 miles then a small knock started happening. I turned around and headed home. The engine starts and idles perfectly and is not overheating. When you give it gas however at idle or in drive I can here the knock. thoughts on where to start? 1. I've heard bad exhaust gasket or exhaust bolt could make similar noise. 2. heard bad cat could make similar sound? 3. pull valve covers and look at guides? What am I looking for? 4. Drop pan and look for shavings? Hopefully not a lower bearing? Thanks for any advice. I went and listed it for sale as a parts car. I was so done with it at the time but now rethinking it. I love that burb..well love hate... I can post a video up if that would help

07-09-2020, 04:41 PM	#2
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,912	Re: 8.1 engine knock or something else? A video would help. Rod knocks are a very distinctive noise. Loose Torque converter bolts can mimic a rod knock. Not much else I can think of. Exhaust leaks don't quite sound the same. Broken rocker arms on a smallblock kinda sound similar til you get the stethoscope out and discover it's coming from up top. If it's wiped a rod bearing or two you'll usually see the teltale glitter in the oil when you drain it into a catch pan. Kindof a sinking feeling in the pit of your stomach when you see that glitter in the oil. __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

07-10-2020, 10:48 AM	#3
kljfamily Registered User Join Date: Sep 2014 Location: Albuquerque NM Posts: 98	Re: 8.1 engine knock or something else? I'll load 2 video links one at idle where there is no noise and one after about 10 or so seconds. For the first few moments it makes no sound even when I rev the engine..sounds great and gets my hopes up and then the noise on the second video starts. https://www.youtube.com/watch?v=Y9VTDFQsMqo https://www.youtube.com/watch?v=z9rqfFalC78 thanks

07-10-2020, 08:06 PM	#4
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,912	Re: 8.1 engine knock or something else? Your videos are marked private. You must've missed a setting somewhere. __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

07-10-2020, 08:31 PM	#5
kljfamily Registered User Join Date: Sep 2014 Location: Albuquerque NM Posts: 98	Re: 8.1 engine knock or something else? I fixed it should be public now

07-10-2020, 08:51 PM	#6
kljfamily Registered User Join Date: Sep 2014 Location: Albuquerque NM Posts: 98	Re: 8.1 engine knock or something else? ok now its searchable and viewable on youtbe..man that was a tutorial on youtube for 30 mins

07-11-2020, 03:06 PM	#7
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,912	Re: 8.1 engine knock or something else? A rod knock should be more pronounced and rhythmic. Not saying it's not but I'd start looking for loose stuff. If it is the beginnings of a rod knock it will get progressively worse. If you wiped out some rod bearings the oil pressure will probably be lower than it was before. You can drain your oil and look for the teltale glitter of wiped bearings. You can also cut an oil filter open with a big pipe cutter. Opening them up with other tools can leave shavings behind. Pipe cutters or oil filter cutters cut through with sharp wheels unlike a die grinder or hacksaw. I have an old 4 wheel Ridgid 44S I picked up at a yard sale for cutting open spin on oil filters. __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

07-20-2020, 07:58 AM	#8
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,217	Re: 8.1 engine knock or something else? its eaither a rod or a cracked flex plate if it only startted after loosing an oil line id say rod __________________ David fuller Ase Certified Mechanic Click here to help support our board!! 1971 Chevy c-10 under going a 4.8l LSx swap Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305 2007 Honda Accord my daily 145kmiles 2002 Honda Accord 4 door With 330k(sisters car) 2005 toyota Avalon 228k( brothers car) 2002 Sububran 5.3 245k 2000 Tahoe 5.3l 378 General manager for Marco's Carwash & lube



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