1983 f250 6.9 oil pressure problems

[califjeff]

My first visit.
I have a 1983 ford f250 with a 6.9L, 146,000 miles on motor. My problem is Low oil pressure at idle.
While driving pressure is at 40, when i come to a stop (facing uphill goes to 0 and Downhill goes to 20) Level ground stays about 10 or so also noticed when driving pressure changes a little when going up or down a hill but not as bad when stopped. This morning i started it up and the pressure stayed at zero until i gave it a little gas then it came up. truck seems to run good, no smoke and oil changed every 3000 miles. I run delo 400le 15/40. Not sure where to start thinking the pump or pickup tube maybe, the problem just started a week ago no problems before that. Thanks for any help

 

[franklin2]

Does the engine make any noises when the pressure goes to zero? You think it would.

 

[bigoilburner20]

well first the oil pressure switch is just that a switch no more no less just a dumby gauge.also if your really worried put an actual oil pressure gauge on it that reads off pressure not from a current. you see? also welcome to the site always welcome new found owners of idi's here . these trucks will run forever if you give them a chance and if you can turn a wrench you can work on these trucks very simple very easy almost like a gasser 350 easy. also you have the first year idi which is cool to me but i have heard different. but welcome and enjoy the site very knowledgeable people here and do you know of anything like a story with your truck would like to hear that.

 

[icanfixall]

Welcome to the forum. This sounds odd because of the way you point the front of the truck. What are you getting these pressures from. Have you or someone else installed a actual pressure gauge. The factory dash gauge is notoroiusly wrong. Most of them never realy did much more than tell you there was enough pressure to run the engine. Worst case is the oil pressure regulater is failed. Its located in the rear oil cooler header. You need to drain the coolant to get at it after you have removed it from the engine. Big first timer job too. But lests see what else may be causeing this. Might be a bad gauage if you have an after market gauge. Also many times the stock gauge sender wire will make a bad contact and then you see all kinds of funny gauge fluxuations.

 

[califjeff]

Thks, This is my first Diesel so its a learning Experience for me, I installed a after market gauge a while back never have trusted factory gauges. but they both act up. I know the factory one is off, i removed the wire and grounded it and it stopped at the l in normal. Truck sounds like a diesel Haven't heard anything. My friend heard it and said it sounds good also. Not sure what this oil pressure regulater is. I've worked on gas engines, Have no problem with them but diesels are a little different. Got the truck for free. The guy broke a belt and parked it so not a bad deal. Looks like a great site and look forward to great info

 

[wildman7798]

I think I would be going to the nearest parts store and drop $20 for a new mechanical gauge. Take you about a minute to undo the compression fitting and screw it on to the new gauge and test it holding the gauge in your hand. I have kept an old SW Stage 3 oil press. gauge in my shop for decades to check suspect gauges and oil systems. Perhaps you have a mechanic friend that might have an old mechanical gauge or gauge trio laying around you could borrow to do a quick test. I wouldn't be driving her much 'till I knew. Welcome to the forum..great place to hang your hat.

 

[ifrythings]

..... Your not low on oil are you?

 

[OLDBULL8]

Going up and down hill is what's making the pressure fluctuate. To me that is the pick up tube has broken off or it's cracked. You can drain the oil and save it if relatively new, then stick something up the plug hole and see if you can move the pickup screen, if you can't get to the screen, then use something to see if you can move the tube, you should not be able to move it.

 

[califjeff]

Ya its full of oil, the first thing i was thinking was the pick up tube but what about oil pressure regulater? should be one of the two. I dont drive it much just to work and back is all about five miles is all.

 

[franklin2]

Like Oldbull said, it seems your pressure problem is related to the position of the oil in the pan. You would think a regulator problem would be rpm related. So long as you have some pressure, don't worry about it being so low compared to a gas engine. These engines don't seem to run much oil pressure.

 

[icanfixall]

Look at the oil pan. The normal oil level is just below the pan to block joint. Very seldom do we have a pickup tube crack or break. They have a very good mounting setup. The pump is located at the front of the crank and is gear driven. then the suction tube runs all that way back and to about 1/8 inch from the bottom of the oil pan. you can see and feel it when you drain the oil. What oldbull posted about draining the oil and see if the pickup screen on the end of the suction is loose or gone. About half way back the suction tube has a nut holding it to a main bearing cap bolt.

 

[califjeff]

ill give it a check this weekend and it looks like fun if i have to remove the oil pan

 

[wildman7798]

The least expensive and easiest check to make is to verify the gauge. Even though the pressure seems to vary some depending on angle of the truck I would still find another mechanical gauge to test before I even crawled under the truck and drained the oil. If your pressure was truely at zero for any length of time it doesn't take long for "the little man the hammer to go work". Even though this points to a possible suction problem I would need to rule out the meter. There are various levels of quality in mechanical gauges, the bourdon tube can become stretched and fatigued, read low and not be repeatable over time. If it is an electric sender oil pressure gauge there is even more reason to question it as they are less accurate and reliable.

 

[darkbluefoxbody2]

Check gauge but I have had three 6.9 that cracked the pickup tube at mounting bolt then vib'ed for years till broke at pump. Always ran but no psi at idle and NO going up hills!!!! This was a common issue early on So I now plan to pull all 6.9 I get to weld up or replace pickup tube.
Side note: my dad ran with cracked tube for years!!! just never idled and no hills, when I took apart to fix bearings were great still.

Also wont pump when cold in the morning for few minutes.

AT YOUR OWN RISK!!!! I found if you overfill it two-three quarts it works as a test for this, I ran one that way 300 miles across the state. No issues

I've heard or seen 6 of these!

 

[califjeff]

good info to know, thks for all the input think all drop the pan and give it a check. i did install a mechanical gauge when i got the truck it does the same as the factory gauge.