1972 Ford F-100, 360FE, 3 Speed Column Shift, ODO says 99,000 (may be 199,000, not sure)

I picked this thing up a few weeks ago. I test drove it and it ran great. I drove it home two hours with no issues other than an occasional hesitation when cruising in 3rd at around 2300rpm. Happened every 15 mins or so, but just a slight hesitation for a second. My plan was just to drive this thing around town and slowly do cosmetic work. First thing I did was put an oil pressure gauge on. 50psi cold at idle, 35-30 hot at idle. Not great, not terrible. Didn't go up much when cruising.

I ended up having to drive it back to where I bought it to fix a typo on the title. 4 hour round trip, mostly at ~2300rpm in 3rd on the highway. Truck ran fine all the way out. On the way back, about 20 mins in to my drive, oil pressure suddenly dropped from 35 to around 20 and hovered between 15-20 for an hour occasionally dipping to around 10. Noticed what sounded to me like a lifter tick, not deeper like rod knock. About 10 mins from home back on slower roads, the noise went away completely, and oil pressure rose a bit. In my driveway with the engine still hot, I revved it up and it sounded totally normal with oil pressure up about 10psi.

I fired it up just now, stone cold, and as soon as it started, oil pressure went up to around 50, held for a few seconds, then fell to around 10. It'll rise with rpm. but not much. Mild ticking noise.

My first thought was that the oil pump might be going out. I wouldn't expect a tired engine to behave erratically, and I wouldn't expect the drop to be so sudden. I also don't think the gauge is faulty because the lifter tick (I think that's what I heard) was very noticeable.

What do you all think?

 

This sounds like the oil pump pick up is getting clogged. The pan has to come off.

 

Make sure the drains in the heads are free. You could be pumping oil up into the valve covers and running low in the pan.

 

I agree with removing the valve covers first. Then the next move will be removing the pan. It could be the oil pump screen is getting blocked or pieces of the plastic timing gear. If so then also pull the timing cover and replace the timing gear set. After unbolting the engine mounts raise the engine and put a 2X4 block under each mount which will give enough clearance to drop the pan. Get a new oil pump and the screen.

 

What was the oil level on the dip stick when you bought it and now?

 

Thanks for the replies everyone.

Oil level hasn't dropped much on the dipstick. leaks a bit of oil, but not more than a couple drops if I get it up to temp then leave it over night. I like the ideas about checking under the valve covers and a potential clogged screen. I have a borescope, so as a first check I think I'll drain the oil, see how it looks, then snake the scope up through the drain plug hole and see if I can get a look at the screen. I don't have access to an engine crane at the moment. Can the engine be safely lifted from the bottom with a jack?

Thanks.

 

Lifting the engine with a jack and some wood works good. If you have a pressure washer that makes the job a little easier by cleaning under the engine and frame.

 

Dumb question, but where specifically on the engine are you using as a jack point?

 

The harmonic balancer and pulleys is what I have used when there was not enough room to get under the pan.

 

Change the oil pressure sensor and the oil
Use a Motorcraft filter FL-1A
Plan on replacing the oil pump someday (better yet, now and replace the valve cover gaskets too)
Then you can inspect the motor for being carboned up
The oil pan comes right off those old ones easy
Add 1 quart of trans fluid for the first couple of oil changes and change it quick
That may clean out those old varnished up lifters and clean the rocker shafts
That will plug the oil filter quick if there is a bunch of carbon in the motor
Buy a few filters at Walmart if they still have them

 

I dont think you will be able to use the bore scope in thru the drain hole to check the pick up as the pickup sits maybe 1/4" off the floor of the oil pan.
I would pull the valve covers to give a look see at the drains and if it has sludge.
With all the driving you did and if the motor has sludge it could be now in the filter plugging it and why the oil psi has changed.
10 psi at hot idle is not bad in my book and should go up with rpm but thinking not over 50 psi. Remember oil filters can only take so much psi before the split open pumping out all the oil. Note you have a filter bypass and a pump bypass and if anything held open the bypass the PSI will change.
Also rule of thumb 10 PSI for every 1000 of RPM.

I also run a qt of ATF just before an oil change to help clean the inside of my motor (300 six) of sludge.
I dump it in start the motor and let it get up to temp at idle. I may bring the RPM up a little but mostly idle.
Then I do the oil & filter change.
Dave ----

 

If it has a Fram filter on it, try changing to a better brand and bringing the oil level back up to full and see what happens.

 

We don't know if the P.O. drove it as a daily driver or driveway queen. If a driveway queen why? I think you ought to drain the oil and change the filter. Check the old oil for nasty's. Like bearing metal particles or something temporary the P.O. might have put in there to fix a low oil pressure problem for the sale. While the oil is draining, pull the valve covers and inspect. Look for sludge, plugged drain back holes, foreign material, etc. There has to be a reason everything was fine in the beginning and then turned south. Report back to us with what you find. With pictures would be ideal. I agree with Dave on the Fram. Buy a Motorcraft (Ford), Wix, or K&N. Also, a name brand 15W40 Diesel oil. There is an ongoing debate on whether these old flat tappet engines really need the zinc that is still in the diesel oil. I won't take the chance. If you are in a cold climate now in the winter, there is a thinner diesel oil out there.

 

Isn't oil supposed to go into the valve covers Oh I see u were thinking clogged drains...........Yeah u may have broken valve seals in the drains

 

Hey everyone, sorry for taking so long to give an update. I've been out of town and haven't had much time to mess with it, but I think I have it figured out... I'm dumb. I think the oil was just low. I realized that I had never checked the oil level when the engine is cold. When it's been running, I think the bottom of the dipstick gets covered in oil, and looks like the level is way higher than it actually is. When it's cold, the dipstick was reading way below the fill line. I filled the oil back to the fill line, oil pressure came back, truck runs great. I've never worked on a car that wont give me an accurate reading on the dipstick while it's running, or just after it has been run. Maybe oil flings up on the dipstick on this engine? I'm not sure. Even after wiping the dipstick and reinserting I couldn't get a good reading unless then engine had been sitting for a bit. I'm also not sure how the level got so low to begin with. Maybe previous owner never filled it enough? But it really doesn't leak very much. Like I said earlier, no more than a few drops if I park it hot and leave it overnight.

Anyway, thank you all for your help. The fluctuating oil pressure issue seems to have been solved.