Spun bearing or?

[77GMC396]

Hi guys,
Ive got a 77 gmc k25. over my holiday break i swapped out the stock 350 for a built 396. i got it up and running but on the last day of tunning and running it, as i was pulling into my driveway, it started to have a very slight squeak. i drove down my driveway towards my house. which then it became louder. i parked it and checked the oil. it was about 3 quarts low (out of 7) when i started the pickup again it squeaked but not as often and much more slight now. so my question is, could it be a spun bearing or could it be the flywheel rubbing against the block? (which my father seems to think so) because i did put a new flywheel and clutch kit in with the motor. help?
thanks

 

[chengny]

You will hear from people who know a lot more about engines than I on this but;

In my experience spun crank bearings don't make a noise that would ever be described as a squeak. Squeaks are usually caused by something minor and repairable - and should be cause for relief, rather than alarm.

And while it is never good to run an engine with nearly half of it's oil missing, I also don't believe you spun, wiped or scored a bearing (or did any kind of damage to any part of the rotating assembly).

For that short ride down the driveway - as long as there was oil pressure - the bearings had sufficient lubrication.

You could drop your flywheel/flexplate cover and inspect the fly/flex for shiny spots (which would indicate interference) - or just turn your radio up really loud for awhile.

But really, don't stress out. There was a kid a couple of weeks ago that was running his 454 without any oil pressure - he most certainly wrecked his motor.

But you should check for a simple problem with your belt driven auxiliaries first. Maybe misalignment, loose bracketing, a failing water pump, etc.

Keep in mind that these are reciprocating engines. While the journals do rotate within the bearings, most of the force and stress on the rotating assembly is in the up/down plane. Same goes for the valve train. In the engine, the only components that really spin are the cam/timing gears/chain and the fly/flex assemblies. Look at the the distributor shaft and oil pump group too.

Pull your plugs and roll the engine over with a breaker bar- if it rolls smoothly through a couple of revolutions, you probably gonna be alright.

 

[Skweegle89]

Did you have to break this new motor in or were the rings already seated? Just wondering where all your oil went. I'm with Chengny on the belt/pulley/water pump/alternator.


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