Newbie post on this forum. It was recommended I post here. Maybe you fellas can help..

Removed the oil pan (Off LS1 motor) and the pickup tube was loose where the flange bolts into the block at the front of the motor.

Automatically thought this was the culprit of the low oil pressure and Rod bearing failure. Bought new bearings for the rear most rods (they were both damaged) but the crank was ok. Buttoned it up and it ran fine.

Then again today after about 4 hours the knock is back. I can hear it better at the rear which would tell me the same bearings are bad again.

Oil pressure at idle is 25pds. mid-throttle is 35-45ish I can get the oil pressure up to 50+ but that is moving at a good pace. Pressure was lower but not much before fixing the pickup.

What is a safe/good pressure for these motors. I did a google search and no luck.

I will wait to tear it apart again until I get home.

WTF is going on here.

I will buy a Oil pump from Summit and put that in as well but is there more than that wrong?

Rod caps were also fine.

anything else??

Thanks.

 

well seeing how your rod bearings went south maybe you damaged your rods. or possibly the crank . normal oil pressure is around 40 at idle and 60 at wot if i remember readin my gauges correct. im sure someone else with mor eknowledge than i will shime in.

 

i second that, you need to get the rods measured for size, depending on how long you ran the engine with it knocking they may be out of round and if the bearing spun in the rod bore well then they are flatout worn and not providing enough bearing crush. same with the crank, have someone measure it. not what you wanted to hear but....

 

Did you clean the crank journal oil holes good? Trash from the other bearings could still be in the motor if it wasn't cleaned good, resulting in the same failure.

 

I think I forgot to mention that I am using a LS1 oil pan and pickup.

 

I finally got a chance to look at the damaged bearing for the 2nd time. It is the rear most Rod Bearing in the block and I purchased a service manual today and tested the existing damaged bearings with Plastigauge and either the crank or rod is out of round.

I want to know if it is cheaper/better to have the exisiting crank machined or just buy a new one. And where to get the quality parts from.

Also, since I am going to tear into this and it will not be cheap. Anything I should do besides Bearings?

Thanks

 

How about shopping for a running 6.0l and install that? It has to cost less than taking your 5.3l apart and paying to have it remachined plus replacing some new rods, bearings and who knows what else. And then you still have a 5.3l when your done. I ocassionally see complete 6.0l engines for $750 or less. In fact I know someone selling a complete 6.0l engine with all the accessories, intake, coils and flexplate for $1400.00. Let me know if I can help.

Good luck.

Richard

 

I agree with Richard.. If your goin to have to pull your motor and have work done to it, just get you a 6.0L. Probably alot easier and it will drop right in. Or check out the GM classifieds for a crank?

 

I have some good rods and pistons and crank from my 2002 tahoe5.3. The motor ran fine and everything looks good. Had 70k on it. I,m turning that block into a iron ls6 for a mazda conversion. PM if interested

 

I can get another 5.3 for $500.00 from the same place I got the first one. But some of you raise a good point. Why not put a 6.0 in it. However, the ecm and harness I purchased are for the 5.3. Is everything interchangeble??

Thanks for the help.