Truck : 1994 F-150 swb straight 6 / 4.9L 2wd 155,xxx MILES

I've done some research, and my noise seems to differ from everyone elses.

I have loud lifter tap after driving the truck for a good few minutes on the interstate. No difference in performance whatsoever. Doesn't tap at idle unless you cut it off after initial interstate drive and start er back up.

A few times the oil pressure gauge has gone all the way to 0 side and if I throw it in Neutral it returns to Normal. Put it back into Drive, it remains Normal until I get about half way down on the throttle then shows No oil pressure once again. Repeat. This happened to me for about 30 minutes solid I just kept driving it and it did just fine.

Yesterday I had to drive for about 30 minutes on the interstate, the noise came about again during interstate driving, but this time my oil pressure showed normal during the entire drive. Weird?

Hasn't tapped at all in city driving Yet.

I've had this truck about 2 months. When I bought it the oil that was in it looked very bad. Truck ran great though. Spent about 200 on a good tune-up including of course oil change, I went to 15-40 Delo. Ran it for about a week or so and after I heard the noise I figured I'd go a little thicker, now running 20-50 Castrol.

Considering Marvel myster oil / ATF run through it then change oil again.

Anyone else similar experience / advice / solution?

Thanks for your time. - Jackson

 

I suggest you are going backwards on the oil weight. Try 10w30...it is the factory recommended weight.

 

Sounds to me that the screen on the oil pump pick-up is beginning to clog. On short trips the particals in the pan don't get as organized to block the screen. On the highway they are traveling faster in the pan and block the screen therefore less oil to the lifters.
Had this happen to me just before the fibre timing gear went south. Now have steel gears and new oil pump pick-up tube.
Mine was in a van. The only pita was lowering the pan for the new pick-up tube............. Goodluck

 

This is a very good possiblity, in conjuction with the previous said possibility...


5w30 is the thinnest oil recommended by the owners' manual...10w30 in warmer climates/5w30 in colder climates...

I vote he uses 5w30, and sees where that goes....Then continue trouble shooting if the problem persists after going back to OEM specs...

 

I agreee with the thinner oil. This will allow oil through the partially blocked screen if that is the problem. Be sure to watch the gage religouslly.

 

Thanks for the replies.


Was yours acting as I described? Only after highway driving?

I might include the first time this happened, I pulled off the interstate and let it idle for probably 20 minutes and it slowly got quieter and quieter and eventually disappeared (oil cooling off) I assume is why. Drove it home (city) and it didn't tap a lick.

I watch all my gauges religiously.

 

Yes highway or long drives without a break resulted in low pressure. Since I changed the pick-up tube it never drops at all... even if idol drops. I am so happy.

 

Tried to add pic but I must not know how ....... sorry. I have a pic of pick-up tube in my album. Try to see it maybe.

 

Your "Gauges" are simply switches really...Mainly the Oil Pressure gauge...Anything above 5-7psi, it'll read "NORMAL"...

 

Now running 4 quarts of 10w-30 with 1 quart MMO. Problem seemed to worsen from dropping from a thicker oil to a thinner oil. The thinner oil drains out of lifters faster compared to a thicker oil, but I figured I would give it a try because a few people on here recommended it.

The first video is after driving about 45 minutes <NOBR>round trip</NOBR> mostly interstate. With about a 2 hour break in between. Oil pressure never showed any erratic readings, but it started tap about half way there and continued the entire way back.

The 2nd video is a cold start after letting it sit for roughly 24 hours.

Oil pressure seems confused. I'm ready to begin work and was thinking dropping the oil pan and checking that pickup screen would be a good place to start. I want to be effecient as possible. Any opinions/advice appreciated. Thanks.


CAM00022 - YouTube
CAM00023 - YouTube

 

I read a lot of different methods of removing oil pan for the 4.9 engine. Some say you gotta do things and some don't. If I do this I'll be doing it in my driveway on the ground outside. If it's going to be a complete pain in the *** I'll just have a shop do it. Of course I'd rather save money and do it myself.

My truck is a 94 model, does anyone have first hand knowledge of what it takes to drop the oil pan?

 

Could be a valve sticking once it gets good and hot.
Be careful using regular motor oil unless you are adding a zinc additive or you will risk camshaft damage.

 

Would a valve sticking cause erratic oil pressures? Note that it acted up on me bad at cold start. (2nd video)

 

I think the pan is a great place to start. It will tell you many things looking at contents also. It may tell you if your timing gears are doing ok by the lack of fiber in the screen.
Mine is in a van. I did not have too much trouble doing mine in the driveway. I did have a good size dent in the pan from some as---le jacking it up on the pan. The dent was hitting the counter weights on the crank which made it harder to get the pan up high enough in front to pull pan out back. Be sure to get the engine an inch high required to get it out. Then reach in to take the pick-up tube off ..... then the pan.
The gasket was easy with the little blue plastic holders. They came with the Felpro gasket. No sealer used on the silicone gasket.
If I were close I would help. I like to do it myself to get it right and save $. Hope that may help.......

 

Oh and please let us know what you find out ......thanks