No oil pressure?

[rkyroadrcr]

I have an 01 4.0 SOHC automatic with 155,000 miles. A couple of weeks ago I noticed when I started it up in the morning no oil pressure. I figured it was just the switch, since I didn't hear any knocks or funny noises. It is intermitent at start-up. After a minute it goes up. This morning it knocked a little until pressure came up on gauge. What could cause oil pressure loss only sometimes? It is not always in the morning either.

 

[Original_Ranger84]

It could be the sensors just going bad, or it could be the dummy gauge. I guess as long as the sensor reads 6psi in the oil system its good and it jumps up to the half way mark no matter what. I have a bad sensor in mine that takes a minute to pop up if its cold. but after 1.5 months i think its just the sensor or my engine would be dead by now from lack of oil at start up all those times.

 

[rkyroadrcr]

no oil pressure

I originally thought it could be the sensor. Except today, I noticed it knocked a little if I gave it any gas until the gauge came up (approx. 1 minute). I have seen it idle for a few minutes before it would come up.

 

[Original_Ranger84]

hmm.. well I would replace the sensor as they aren't too expensive.. and it should either fix your problem or not. If it does then good, if not well then atleast you know you need to stop driving ASAP till its fixed.

 

[AgPete139]

Check your oil dipstick. Low pressure may be a result of air getting into the oil pump. Too little oil means that the pump is sucking up air & some oil. Too much oil in the pan means that the crank+rods can be spinning/churning in the oil and making small bubbles, also causing air in the oil pump.

Debris and other shit (like old varnish, perhaps RTV sealant, sand grit, or bits of metal) can clog the oil pickup tube also causing low pressure and reduced oil flow. This is also why you always change filters at each oil change. One solution to clear out varnish is to run Seafoam Solution brand or Marvel Mystery Oil for a few days before doing an oil change. When was your last change?

Sand grit and contaminants can also wear your journals and bearings. Too much space and decreased tolerances will show low pressure. Hopefully this isn't your case and we can rule out the others before going here.

The pressure relief valve can also stick open from old gummy oil, varnish buildup, or from even using a heavier oil weight than recommended.

I would check the dipstick level first. If it's low, you could be burning oil at the rings, or have bad leaking seals. If it's normal, I would run those cleaner products. If overfilled, drain it a bit or just change the oil & filter altogether (I would do the complete change to rule out bad oil and clogged filter). SOHC can have a hard time starting in colder weather (my '93 Civic D16Z6-1.6L SOHC does), so you gotta use the right oil. If you are further north, I don't know what they normally use, but a 5W-30 should be okay. Even here in Texas @ 30*F, a 10W-30 can take a couple spins before catching.

Hopefully this works for now, and gives a lil bit of insight to your dilemma.

Pete

 

[AgPete139]

Also, the reason pressure may suck at first is that it takes a couple minutes before the oil to get up to normal temperature. Thicker oil MAY mean slightly improved oil pressure, BUT really thicker oil will just make the oil pump suck oil in through a secondary relief valve/tube causing low pressure.

Again, I would run the cleaner for 2 days and do a full oil change. That's a good place to start diagnosing the problem.

Pete

 

[dock83]

I seen a colasped oil filter on my buddies 2.9 liter and it was doing the same thing you described ticking by times. New fliter no problem oil pressure returned too normal.