New Cast Iron Oil Pump pressure low

[Mandy0917]

(12-06-2020 )Rawze Wrote:  

(12-05-2020 )Mandy0917 Wrote:  Hi there , I just did the bottom end of my 485 isx on a 2010 t660, I replaced the oil pump and when I tested the truck found the same issue with the oil pressure dropping at times to the low 30s bobtail every time I was shifting gears and the rpms got to 1400 or southern, so I got scare and went to Kenworth and they told me that was perfectly fine, so the new pumps are designed like that, I obviously didn’t like it so I decided to shim the pump and did it today, I did put 10 USA dimes making a half of an inch, when I took out the oil pan I found out that they’re slight differences on the top part of the pump that you have to work on, now instead the pin to hold all the parts including spring in place, there’s a threaded cap with that you get unscrewed with a 14 mm hexagonal tool, when i putted it back together and start the truck it was giving me 80 psi at 800 rpms, then started to go down as the engine heated up to eventually drop to 39 at 185 degrees coolant temp , but when I hit the throttle up to 1500 it would go up again to 80 psi and as soon as I let it go it would go down to 39. It seems to much change for me , maybe if I put just 5 dimes would it be better? What do you guys think?

The dimes trick was for the old style pump only. You obviously made it too strong trying to do the same trick to the new style pump. - 80 psi is too much for that engine, you would be doing good at about 50 psi. Your going to loose a front cover gasket and have other issues trying to drive it with that much oil pressure. Not only that, the oil filter pressure relief valve will open and completely bypass the filter causing it to not function at that high oil pressure as well.

Anything above abut 48~ish is not going to be safe to run long term.

So what do you think would be a starting point? If I put 10 dimes and getting 80 ish, how many would you take out to make it work at those 48ish? I was thinking taking 5 out, it could be even more, let’s see, thanks for your advice Sir