Oil pressure gauge and low oil high temp light on

[Moco de gorila]

I have an '03 Expy with 136k. Was driving yesterday morning and everything was fine. Did a random check on all my fluids, everything good. Yesterday afternoon I start it up and its making a terrible knocking sound, kinda sounds like a diesel, and my oil pressure gauge was all the way down with the light coming on as well. I checked oil level and it was still good. It would do this sporadically and when it wasn't doing it, it would go back to normal still making knocking sound. As I drove to work today it started out fine still making noise but gauge was normal, 1/3 of my thru a 20 mile commute it went back down again for another 1/3 of the drive and then back to normal the rest of the way. What could be causing this? I am only a month in since my last oil change.

Second question: Why am I going through a gallon of antifreeze a month? I never see any puddles or anything?

 

[GAINMOB]

u have a leak somewhere...could be going into ur manifold but I think u would see smoke from the back if that was happening...check all ur hoses...could be one came loose or has a hole in it and is dripping on road only when truck is on...idk

 

[Bedrck47]

Just some suggestions You may want to drain the oil and check if its all oil or a mix of antifreeze and oil. You could have a bad oil pressure switch. The switch does not measure pressure but is strictly a off on switch either you have pressure or you don't. Same for the oil pressure gauge It does not read pressure just gives an indication that you have or have not any pressure. You also could have a failing oil pump.
You could have a actual oil pressure gauge installed.

Also agree with 10K-Watts

 

[stamp11127]

You should establish if you have the correct amount of oil pressure with a mechanical oil pressure gauge before driving it anywhere. These engines are known to have timing chain / guide issues that can block the oil pickup tube when the guides grenade. When that happens you end up running the engine without any lubrication. That means big bucks to fix.

If your oil and coolant mix in the crankcase, you will notice the "oil" level increasing when you haven't added any and a change in color to a milky brown. If that has happened the bearings are toast, from a longevity standpoint the engine will be toast also.