Have you measured the pressure? Did you look for walked cam bearings while the oil pan was off? Did he remove a bearing cap and check the bearings? 90% sure now he is going to say it needs a new engine

 

Did you ever replace or clean the sensor?? I just went thru this with my 97 XD. When I bought it I had a leaking oil pressure switch. I ordered a replacement from Rock Auto, I didn't really even look at the brand and installed it. Then when I got the XD on the road I was scared to death when the darn light came on upon stopping at a light with the idle lower than 600RPM. Well a local auto salvage yard had a 50% sale one weekend so I pulled an entire front cover for 10.00. It had the OEM oil pressure switch on it. I figured I had a 50/50 chance on it being the switch or the oil pump. Swapped out the URO oil pressure switch I had installed with an OEM oil pressure switch and I no longer have a flashing light. It's certainly worth checking especially since you have a new oil pump and the old original oil pressure switch.

 

I replaced the oil pressure switch with a rock auto one
everything was fine for couple weeks until I went on vacation for 2 weeks
truck was sitting for 2 weeks when I started last week the oil light was on for a good 40 seconds than went away
just not sure why everything was ok after the pump change for 2 weeks than it sits for 2 weeks and now I’m getting oil light at idle and while driving

when i had the oil pump replaced I asked him to inspect the bearings but mechanic said he could not properly inspected bearings like that
I didn’t feel like arguing with him so he replaced the oil pump and cover and everything was fine
now this damm light again

 

I suppose he tossed your OG sensor too...

 

Would their be any symptoms other than the oil light being on that would indicate bad bearings ?

 

Certainly first confirm the sensor isn't the issue.

If the oil pan is off you can measure movement with a dial indicator but it's not the most accurate method in my experience though it'll ballpark you in some cases.

You won't see any other symptoms, the engine will operate mostly as normal because we're talking about extra play that's only in the .00X range.

If I had to guess the scenario, I'd say you have a worn engine. I'd figure that your new water pump did indeed raise the pressure slightly by functioning perhaps a little more effectively than the worn out one but the problem still remains that your bearings gap is growing and the oil pressure is dropping as a result. You may need to look at a rebuild or a new complete motor if that's the case.

 

I've already purchased my new LM4 motor for the LS swap and paid for the kit, that said......

I'm going to press the sleeve out of my cracked block with 94k miles on it and see if a specialized welder can do a permanent fix on the block. If I had it X-rayd I could confidently check the wall thickness between the jacket and cylinder wall as well as the stud holes and cylinder wall and be sure they're good on all the other cylinders besides the cracked one. If my block was otherwise fine, I'd have the welder fix the one crack and add material so it doesn't reoccur. Then the block would be a fantastic engine candidate as it's an 04 and can't drop sleeves. Having the block Xray'd takes all the WONDER out of another cylinder cracking. It's my intent as of now to press the sleeve out and repair this block and sell this engine as a bombproof block if it proves lucky enough to be such. I inspected all bearings and things look quite nice in this engine otherwise, it'd be worth perhaps just replacing the bearings anyway and slapping this together as a brand new rebuild that'll be reliable.

You might be a candidate for purchasing such an engine or maybe not. Either way I won't know until I have it scanned and see if it's a good block or if there are other cylinder walls that are thin and going to crack in the future, in which case I'll throw the block away and sell the rest of the parts off for someone else to use in their good engine block.

If I do throw the block away, the rest of the parts might well suit you or someone else who's needing a cheap rebuild as all of my components look absolutely fantastic. Just another option, keeping your block and using mine or someone else' components. Just more ideas for you at worst case scenario.

 

It will, he's right. Confirmed "1/2" X 20 UNF"

Fingers crossed that it's just a bad reading and the motor is ok. :fingerscrossed:

 

Thanks for the advise
I don’t think I’ll rebuild this motor just because of the cracked block issues down the road
it’s still running etc but if it dies it will sit until one day I decide to put in a new block from one of the suppliers
just weird series of events as all was fine for 2 weeks after the pump change and after sitting for 12 days it starts acting up again.

 

Yeah the timing is a little strange but, often one small disturbance acts as the straw that broke the camels back.

Just yesterday I helped a friend change some exhaust manifold bolts. Upon firing up the engine, we noticed the leak was gone but a new sound existed....
As I pulled wires one cylinder made no audible difference, I pulled the plug and saw the ceramic had cracked badly and was creating a misfire as the CEL suggested.
Luckily my new LS motor was a perfect plug donor because his vehicle was an 04 Chevy HD2500. LOL I had the plugs and wires to give him as well as the new manifold bolts! What's the chances yet again!

If I'm not mistaken the "new blocks" aren't new are they? Just hopeful units from the past, you might consider your block better in that it's been tried and tested and didn't crack. Just devils advocate on that matter here. Let's hope it's none of this and just a bad sender.