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-   -   Bad rod bearings? (https://www.thirdgen.org/forums/tech-general-engine/505459-bad-rod-bearings.html)

t_raven 12-28-2008 06:35 AM
Bad rod bearings?
 
Just curious about this really.....my 89 GTA with a 350 started making some bearing noise, it's got about 110k miles on it. I owned a different 89 GTA with a 350 a few years back and it spun some rod bearings at about 120k miles. They were both about that mileage when I bought them so I have no idea what the service history was like. Is it possible that GM used weak bearings that year? I didn't think much of it with the first one but when the second one started making what sounds like some rod bearing noise it made me a little curious. I've had 3 trucks with 350s (84,90,92) that had over 200k miles and oil changes on those were always pushed further than they should've been, and they made it that many miles w/o spinning bearings. Have rod bearings been a common issue with these cars? I'm working as a civilian in Iraq right now, so when I go home I'll pull the engine and see how the crank and rods look. I might just throw the ls1/t56 in it that I have laying around lol.

Viprklr 12-28-2008 08:47 AM
Re: Bad rod bearings?
 
Nope. Not a common problem.

Dakine858 12-28-2008 03:42 PM
Re: Bad rod bearings?
 
Originally Posted by t_raven (Post 3988772)
Just curious about this really.....my 89 GTA with a 350 started making some bearing noise, it's got about 110k miles on it. I owned a different 89 GTA with a 350 a few years back and it spun some rod bearings at about 120k miles. They were both about that mileage when I bought them so I have no idea what the service history was like. Is it possible that GM used weak bearings that year? I didn't think much of it with the first one but when the second one started making what sounds like some rod bearing noise it made me a little curious. I've had 3 trucks with 350s (84,90,92) that had over 200k miles and oil changes on those were always pushed further than they should've been, and they made it that many miles w/o spinning bearings. Have rod bearings been a common issue with these cars? I'm working as a civilian in Iraq right now, so when I go home I'll pull the engine and see how the crank and rods look. I might just throw the ls1/t56 in it that I have laying around lol.
Spinning out rod bearings isn't common on any GM motors. There are 2 main causes of bearing failure; 1. driver neglect (not paying attention to the oil level, changing it at proper intervals, failing to properly prepare the car for storage/long periods of non-op etc.) 2. a foreign object found it's way through the oiling system and into the crank journal.

t_raven 12-28-2008 10:58 PM
Re: Bad rod bearings?
 
Just an interesting coincidense then I guess. I just thought it was weird that I've owned 5 vehicles with 350s and the two almost identical trans ams spun bearings at similar mileage, yet the trucks were still going strong at twice the mileage. I've seen 2 buick v6s spin bearings but they are known for oiling problems and they were seriously neglected, like 20k miles on an oil change.

Well when I get a chance I'll pull the engine and check the crank out. The bearing noise on this one isn't really bad yet so hopefully the crank is ok. If not then I'll either stroke it or maybe put my LS1 in it.


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