Loss in oil pressure

[phlyntstone]

I have read many posts on this topic and I have installed a real guage and it verifies that I am losing oil pressure. At start up I have pressure but shortly there after It falls to nothing. I have taken the oil pan off in preparation for changing the oil pump, then I read on here that one fellow had done that only to find that it was not the culprit. Just wondering if anyone has had this problem and if they had actually figured out where the problem lies. The pump seems to function alright when pumped outside the truck in a bucket of oil, and the driveshaft for the pump seems to be o.k. So I am scratching my head on this one and searching the forums so any help would be appreciated.

[mustangmike351c]

losing oil pressure means you have in internal leak somewhere. could be the pump or a bearing giving up. does it make any noises?

[phlyntstone]

When the truck is running it clatters on the top side but there also sounds like something knocking down lower. I have removed the oil pump and by turning it by hand it seems mechanically sound. I am going to replace it anyway since I have it out but it just didn't seem to be as questionable as I thought before I removed it. I removed a couple rod bearings and they showed just a little copper, and removed the front main which needs replaced. I guess what I am wondering is if I would be losing all my pressure due to my mains being worn. And I plan on replacing the rod bearings and main bearings. Was planning on going back with standard size (.000) but then saw a .001 size. Was wondering if that would be a better option than standard, if it takes up for any wear that has taken place. the truck has 250,000 miles on it.

[Austin8214]

Originally Posted by phlyntstone

. Was planning on going back with standard size (.000) but then saw a .001 size. Was wondering if that would be a better option than standard, if it takes up for any wear that has taken place. the truck has 250,000 miles on it.

I don't think it would hurt to go to .001 over. Just rember when you put it back together that it spins smoothly and does not bind up.

[mustangmike351c]

if you can mic the crank and compare your numbers with the stock numbers, they set them a little tight from the factory. you will be ok with up to .0025" on your oil clearance (should be .0008 to .0025 on rods and the same on mains)

[pies]

some of these are also known for camshaft bearing wearing out early which can also lead to a loss of oil pressure