04 2500HD 6.0L low oil pressure.......

Hdwd · January 30, 2016

I'm new here, lurked forever finally signed on....

Seems this topic has a cult following, I now have oil an pressure issue with my 6.0L, with the the lifter filter screen removed and new sensor.... Its legit, lifter tick at an idle and not quite 40 psi when driving......

I am dropping the oil pan next to dig out the oil pump pick up tube to check for a failed o-ring and clean a few things up if needed.

Its got some miles 220,000 but is in very good condition other than this issue now.

Once the pan is off, I have heard of guys doing this and checking the relief valve on the bottom of the pump for being stuck open and even shimming pump relief for a little better pressure. I have done it while rebuilding 350 motors in the past, but has anyone here try this or hear of such a trick in a 6.0L??

I am half tempted, more curious actually, to giving the shim mod a try......

Hdwd · February 21, 2016

O.K no reply's so this is what I did......

Dropped oil pan, found the pick up tube o-ring fine, could not get to the relief valve to disassemble without removing front timing cover. Checked the tube for blockage then replaced o-ring anyway. Got worse oil pressure with additional top end noise.... parked the HD

Ordered a melling 10295 high pressure oil pump, and front timing cover gasket set from summit racing. Upon receiving my order, I shimmed up the pump relief high pressure spring an 1/8 inch to guaranty higher pres. in the engine, tore into the 2500hd's 6.0L engine front and in 12 hours by my self in the garage, I had done the transplant successfully.... Also discovered I had cut the new o-ring when I last had things apart during assembly. I had no qualms of modifying the pump relief cause the warranty is voided on the pump when you take the cover off to properly center it on the crank anyhow.... Melling makes good stuff and I have used there cams and oil pumps in building other chevy engines over the years.

The engine is higher milage 228,000, but now has a idle pressure of around 20 psi according to the dash guage, and at cruise 40 psi, all within GM's specs of oil pressure. That's with the little screen below the oil pressure sender removed also. I suspect a bearing partially mauled somewhere in my case just seems low to me, but they have to warranty these things at this low spec when new so I guess that's acceptable.... I just hope I bought myself some time before needing a new power plant.

Mortgage Paul · February 28, 2016

What was the oil pressure when cold and oil was thicker?

I know some people thought they had problems when switching to 0w30 when Mobil 1 came out with that oil since that would be normal.

I can offer my 8.1 with oil at Normal warm temp say 60* F outside and 10-20 mile drive with 5w30 I have 12-15 on the gauge at idle, and 40-45 at cruising RPM say 23-2500 on the freeway.

When Oil is cold, its never went over 55 Lbs after say 2-3 minutes of warm up idle and is over 40 at startup. when cold.

Hdwd · February 29, 2016

Before the new pump, idle press would be 30-ish tops cold start 20 degrees outside, 40 absolute max, Warmed up cruising 2300-2500 rpms 25-30-ish tops... Idle to long after warmed up, low oil press warning siren started. That would be below 6 psi from what I have gathered...

I guess LS engines were designed to operate with 'minimal oil pressure'. Looks like my 6.0 mirrors your 8.1 in pressure after the new pump, which makes me feel a little better.

I plan on using a little heavier oil next oil change and see if that helps pressure a bit. Pressures after the new pump are with 5w-30 oil.

mjoekingz28 · March 1, 2016

I heard Dodges, I think the Hemis were nearly at 100psi.

cjb321 · March 2, 2016

just had a new oil pump put in my 06 6.0L, before the pump went out it was 20ish at idle and 40ish at startup and higher rpm. Now its 40ish at idle and 55-60 at startup and higher rpm.