'99 F-150 5.4L 4x4 120K miles, auto

After the engine warms up real good (10 mins or so), the oil pressure drops to nothing and there is a tapping/clanking noise coming from the engine. Is trash being picked up by the oil pump screen? And are the automatic adjusters making the noise? Nothing strange came out of the pan when the oil was changed, even after adding a 'cleaner' to the oil and running it a while.
Let me add that, although this routinely occurs after warm-up, sometimes it'll run fine for days and then act up.
Thanks in advance.
Pete

 

Change the oil again, SOON. If the problem persists, drop the pan to inspect. You're destroying the engine by running it like that.

 

I've changed the oil about 3 times so far. So now, I should drop the pan for inspection...... If the inspection yields no obstruction to the screen, then what should I look for?
Thx for the reply!

 

You need to check the actual oil pressure the system's delivering - most ford gauges don't really display anything other than 'normal' or low, and you also need to have your compression tested.

Chances are your engine's already quite damaged, but don't make it worse by continuing to drive it.

 

While you have the pan down, pull the #1 or #5 rod cap & HOPE you don't see this:

 

From what you discribe your engine has interminent oil supply. Inspection of the oilpump and lube system is needed. If the clanking has been happening for a while you might have distroyed the crankshaft and/or camshafts.

 

I had the same problem with a 98 f-150 4.6 romeo.I replaced the oil pump immediately and cleaned the pickup screen.This took care of the problem.I hope this helps.

 

are company work truck does the same thing so when you are coming to a stop light or whenever going to a crawl put it in nuetral it will keep the oil pressure up and less damage we have been running this truck like this for over a year and a half

 

I thought the check valve in the remote oil filter adapter might be the villain, so I was going to replace the adapter first and then change the oil pump screen/pick-up tube. Sound like a good plan-of-attack or not?
I agree about checking the connecting rod journals, i'm glad that was brought up. I'm trying not to change the oil pump as I've heard that they dont produce the symptoms that I have right now... aka oil pressure then no oil pressure. I've heard that it either works or it doesn't. (plus it's a PITA to get too!)
BTW, thx for all the replies and input. It is GREATLY appreciated!!

 

Any updates would be appreciated!

Thanx

-=Fred=-

 

If all checks good then I would look closely at the oil pumps regulater valve. If its sticking it would cause your problem, possibly loosened up some crud with flush you put in and cause the problem. I have seen them stick closed and cause no psi to stuck open and blow filters........

 

I doubt you have any damage yet. I have the same problem with mine and Im pretty sure its the screen for the pick-up tube. The noise is probably coming from the timing chain tensioners they are oil feed to make tighter and low or no pressure will make chains sloppy. Pull the pan very soon and check the screen. I would not drive it anymore or you may screw up your bearings or jump timing from the slack in the chains.

 

Problem: intermittent drop in oil pressure, had slight ticking noise in the timing chain cover on passenger side that eventually worsened to the point that I parked the truck.

First changed the pressure switch to make certain the drop showing was real. Which it was.

Dropped the transaxle in order to drop the oil pan to look at the pick up tube. I found pieces of black plastic sitting in the pan. Both small and large. These were clogging up the pump screen. Bearing still look good.

Diagnosis: broken chain guide in the timing chain system.

Will fix this week...

-=Fred=-