Oil Pressure Light & Rough Idle

[ahighfivetolife]

Hey guys!

First post on the site. I bought a M1008 a few months ago and had to leave it with family while I was training with the military. I finally got home and spent the weekend going through everything and replacing fluids an gaskets like crazy. The truck ran fine before I started working on, just leaked everything.

After some maintenance I get the Oil Pressure Dummy Light and a rough idle until it finally wants to die. Here's a list of the engine stuff I did:

For the oil change I used 7 quarts Rotella T 15-40w and a Fram PH5 Filter. Pretty normal oil change. After I put the 7 quarts in I checked the dipstick and it read 1.5 quarts high. Made me wonder if I have an aftermarket pan or the wrong dipstick. I drained 1.5 quarts and tried it again. Light was still on. Anyone else have this issue?

Changed the water pump.

Changed the fuel filter by pulling off the old one, pouring some diesel in the inlet hole of the new one, put the new filter on, unscrewed the plastic knob on the top, pulled the pink wire, cranked it until it started spitting fuel through the clear hose, and tightened up the plastic knob. I reattached the pink wire, and started up just fine.

After starting I have the above listed issues. Messed with different oil quantities, changed the oil pressure sending unit, and checked all connections in the engine bay. I let it run for about 5 mins the first time and the light never went out. Unfortunately the truck is 2.5 hours away from me right now, but I have a friend troubleshooting it. I've searched this forum and there isn't a whole lot on oil pressure. Any ideas what the solution would be?

 

[Skinny]

Welcome to the site! Nice looking rig.

7 quarts of oil sounds on the high side. I think your oil light is on because it is idling too low. I would double check the idle speed and also confirm good oil pressure with a mechanical gauge. Rough idle could be a bad IP or injectors, could also be incorrectly set with the adjusting screw.

 

[doghead]

7 qts is what the LO calls for with a filter change.

 

[Skinny]

It's been a few months but I think mine is somewhere around 6.5 qts for an oil change but I also pre fill the filter so maybe 7 qts is close. Not sure it would read 1.5 qts over, something is not right there.

 

[Drock]

Agree with Skinny about the idle, but to add. Is your high idle solenoid coming on? Have you tried throttling up to see if the light goes out? Did you prefill the oil filter before installing it? For that matter did you check to see if the oil filter is filling up?

 

[Skinny]

I would kill the Fram filter and install a Wix, equivalent, or higher quality filter just for peace of mind. I typically run a Napa Gold or Wix (probably the same filter just reboxed). I've never been happy with Frams quality. Just opinion...

 

[cpf240]

I was wondering if perhaps the lift pump is dumping fuel into the oil...

 

[CUCVLOVER]

Hello and welcome!!!!!!!

7 qt is ok. I changed mine and with a new filter ( filled before install) it held about 7 QT. Also I was forced to use a stock filter because of the trans cooler lines. If I used the biggest filter napa had for the 6.2 it rubs the lines.
The oil light on my m1008 used to never come on then a while after the oil change it comes on every time I turn the key and stays on some times for minute or two after it starts. But I don't worry about it since I check the oil once a week and I have a mechanical gauge that works great. I tapped mine into the oil test port next to the radiator since it was easy to get to and also if the gauge or the hose feeding the gauge fails I can shut the valve off and be on my way until I get the gauge going again.

chase

 

[Keith_J]

Filters without the internal check valve will let oil drain back to the crankcase, causing low oil pressure on startup until the system reprimes. That being said, I don't know which filters for the 6.2 have a check valve.

 

[ahighfivetolife]

We haven't messed with the idle. We did give it a little more RPMs and the light stayed on. One time after I gave it some gas it died when I let off the pedal.

 

[ahighfivetolife]

Thanks for all of the replies and ideas guys.