Knock knock?

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Mark1

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Hey guys 07 Tahoe all stock, oil leak that went unrepaired and driving down the road heard a knock as if something had broken, oil pressure /dash lights came on and it seemed to loose power. It still ran till safe stopping point but very rough. Mechanic said engine needs to be replaced but never got specific diagnosis. It does have a knock but I'm thinking it's a spun bearing maybe he didn't want to deal with. Any ideas on if it could be a spun bearing or where to start? Also I know about the proper way things should be done but if there's a will there's a way. Any help appreciated.
 

iamdub

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Hey guys 07 Tahoe all stock, oil leak that went unrepaired and driving down the road heard a knock as if something had broken, oil pressure /dash lights came on and it seemed to loose power. It still ran till safe stopping point but very rough. Mechanic said engine needs to be replaced but never got specific diagnosis. It does have a knock but I'm thinking it's a spun bearing maybe he didn't want to deal with. Any ideas on if it could be a spun bearing or where to start? Also I know about the proper way things should be done but if there's a will there's a way. Any help appreciated.

Chances are, if it's an '07 and had an oil leak, it has some high miles. Pretty much regardless of what exactly is causing the knock whether it be a spun bearing, rod or wristpin bearing, etc., the repair will far exceed the value of saving the motor short of a complete rebuild.

What have you checked so far? Have you topped off the oil to see if it'll make any difference?
 

OR VietVet

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So, you said an unrepaired oil leak. How bad of an oil leak was it? How often did you have to add oil? Did you get used to a quart every 200 miles and then it got worse but you had not checked oil level because was not close to 200 miles? Sounds like you lost oil pressure for sure and when you do that the damage has already started and depending on how far you drove after that means more and more damage. You did not say but I hope/assume you had it towed. If you like the vehicle and it meets your needs then it does sound like engine time but should still get a diagnosis unless of course the tech is a guy you trust and he knows when it sounds and is as bad as it probably is. Now may be a time for an upgrade of power in a new engine.
 

BG1988

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Hey guys 07 Tahoe all stock, oil leak that went unrepaired and driving down the road heard a knock as if something had broken, oil pressure /dash lights came on and it seemed to loose power. It still ran till safe stopping point but very rough. Mechanic said engine needs to be replaced but never got specific diagnosis. It does have a knock but I'm thinking it's a spun bearing maybe he didn't want to deal with. Any ideas on if it could be a spun bearing or where to start? Also I know about the proper way things should be done but if there's a will there's a way. Any help appreciated.
same thing happened to me but due to a loose oil filter and oil nut Bank 1 (AFM) is toast you can hear rod knock on cylinder #3 or #5. and a ton of chatter on the valves on bank#1 (it's a bit different then yours this is VVT equipped Gen4 engine)


i would just run it tell its dead
 
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So my 2009 with 130k miles has started knocking as well. Regular oil changes and tune up within the last year or so. Knock is coming from below, sounds like its in the oil pan. I'm pretty sure it's a rod knocking the cam, BUT, my oil pressure is great and other than the knocking and vibration, it seems to run fine. That is until I accelerate too much, then the engine light and Stabilitrak flashes.
 

donjetman

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Send in an oil sample for analysis to: Oil Analyzers Inc, or Blackstone Lab, or JG Lubricant Services.

If its a rod knock lead and copper will be high
 

R3cord303

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Send in an oil sample for analysis to: Oil Analyzers Inc, or Blackstone Lab, or JG Lubricant Services.

If its a rod knock lead and copper will be high
+1 for Blackstone. Very very pleased with them.

OP: Fill it up with one step thicker oil and see if the knock goes away. My old S10 blew the oil cooler line off, and ran itself out of oil, and was knocking bad before I could get it stopped. Replaced oil cooler line, filled it up with 5w-40, good to go. If you're not so lucky, time for a rebuild/replacement.
 
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Send in an oil sample for analysis to: Oil Analyzers Inc, or Blackstone Lab, or JG Lubricant Services.

If its a rod knock lead and copper will be high
+1 for Blackstone. Very very pleased with them.

OP: Fill it up with one step thicker oil and see if the knock goes away. My old S10 blew the oil cooler line off, and ran itself out of oil, and was knocking bad before I could get it stopped. Replaced oil cooler line, filled it up with 5w-40, good to go. If you're not so lucky, time for a rebuild/replacement.


Thanks fellas,

changed the oil yesterday and included Marvel Mystery. The volume has decreased but the knock is still consistent. I'll look into the sample testing. I read something about possible torque converter or flywheel bolts being loose???
 

swathdiver

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Thanks fellas,

changed the oil yesterday and included Marvel Mystery. The volume has decreased but the knock is still consistent. I'll look into the sample testing. I read something about possible torque converter or flywheel bolts being loose???

Kendrick, with the engine idling, get yourself a long extension, screwdriver or mechanics stethoscope and touch various parts of the engine, block, heads, accessories like alternator until you pinpoint the noise. A loose torque converter bolt will sound like the engine is about to blow.
 

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