***Please give me some input. I own a '81 Ford F-250. When I start it in the morning the engine oil pressure gauge reads normal. After about 5 - 10 minutes driving the gauge is reading low (real low). From there on the oil pressure fluctuates from really low to just below normal.
***The first thing I checked of course was the oil level. It is fine.
***Can anyone shed any light on this situation???????

 

Could be sludge in the engine plugging up oil passageways, could indicate a failing oil pump, or could be a failing oil sending unit.

Steve

 

I had the same thing on my 93 Van (5.0) and it turned out to be the sending unit. They are easy to change.

 

Ford oil pressure gauges are little more than symbolic; if they were real they would have meaningful numbers on them. Get a mechanical gauge from your local parts store or K Mart and put it on. You can tee it in and have the light, factory gauge and your mechanical unit. You should have about 15 psi at idle and about 45 psi at 2000 rpm. Oil pressure is much too important to trust to that mickey mouse gauge your truck came with. If your pressure is good the problem is most likely the sender. Most newer trucks no longer use a constant voltage regulator for the instruments.
Fl Panhandle

 

May not be related at all. However, my '89 Ranger with 2.3 engine had a completely clogged pickup screen. The silicone gasket kept disintegrating and being drawn up to the pickup. I would check to see what is up there. One enterprising poster described how he fashioned a clotheshanger to scrape off the residue and flush it down the oil drain. I pulled my oil pan which was and is a miserable dirty job.

 

I've been kicking around putting in a mechanical oil guage like you suggest. Can you give any more details on the installation? The guages I've looked at have a tube for the oil to go up to the guage. Where does this tube get inserted for the oil feed? How much work are we talking for this operation if I do it myself?

Guy

 

Typically the gauge set up is pretty simple. You can connect the engine end of the gauge simply by removing your sending unit and replacing it with the parts in your package that comes with your gauge. The instructions are usually pretty clear. You can even put a 'tee' fitting in at the block and run both gauges. I prefer Autometer's sending unit that picks up the signal similar to your standard Ford sending unit. You then only need to run an electrical wire between your sending unit and gauge and wire the rest up per instructions. Once again, you can use a 'tee' to run both gauges off the same oil port.

'82 F150 w/351W (orig 300 I6)
Steve

 

>I've been kicking around putting in a
>mechanical oil guage like you suggest.
> Can you give any more
>details on the installation? The
>guages I've looked at have a
>tube for the oil to go
>up to the guage. Where
>does this tube get inserted for
>the oil feed? How much
>work are we talking for this
>operation if I do it myself?
>
>Guy

Putting in a mechanical gauge is a "no brainer". Recommend you get a short 1/8 inch pipe nipple and matching tee fitting (availible at hardware stores) so you can retain your factory gauge by putting the factory sender in one side of the tee and placing the tubing with provided fittings in the other side. Be sure and route the tubing away from sharp edges and exhaust manifolds. Reading your actual pressure is "revelation". You will notice that the pressure is higher at idle when cold and drops significantly when hot. If your pressure is consistantly low there may be an obstruction in your pickup, however, on an older engine it usually means the bearings are worn and unable to hold oil due to excessive clearance. In this instance the short term fix is to use heavy weight oil. Good luck. Would like to follow your story.

 

Being someone that has watched their oil pressure gauge go from good to bad, I know how you feel. In any event, in my problem, the truck was idling low. This prevented the oil pump from getting enough power from the engine to pick up the oil and give it any pressure. The gauge would always drop to nothing when i was stopped, but then was fine when my foot was on the gas. After much reading and hard thought, I finally figured it out. OK. So, on the top of the engine where the two big hoses come from the air box...into the efi, take off those hoses and with a can of carb cleaner in hand, make sure that the plates inside are clean and moving freely, next go to your right and down, at least if its a 302, and find the ICV (Idle control valve) Take this off, just two bolts, make sure the gasket is good, otherwise there will be a vaccum leak. Then take the can of carb cleaner and really bathe this, or go get another one, around $60. Then re-install, the truck should idle 100% better, and the oil pump problems are gone, and there is no big worries of blown heads, and a worn block.

hope that I have helped,

Marino

 

Well, I've read over the BB on this. I came in with the same question. I have an 86 F150, 351W, and Slick 50 did me in. I had to change the oil pump. It lasted only 18 months. Good pressure at cold temps, but when it heats up, pressure drops at idle. Heard that the connecting rod bearings go around 150K mi. Mines 170K. Sending units will either work or won't. If it looks good then drops..... then you've got a real problem. Good luck. I'm looking at pulling off the oil pan, changing out the rod bearings, or just biting the bullet and go through it. It deserves a good rebuild. I'm sure yours does, too.

 

i will almost guarantee that your oil pickup screen is caked up with grime. you'll have to drop the oil pan and clean it. this, in my opinion is the first thing you should do. i had this same problem with my mustang. I replaced the oil pump, changed the oil,and did everything else posibible to get some oil pressure, but nothing worked. As soon as i cleaned the screen, which was unbelievably caked with grime, the oil pressure shot up and stayed up.

 

Do you remember what type of oil (valvoline, penzoil, quaker, etc) you used in that vehicle? Were you consistent with the same type at all changes or did you switch oil types a lot? Just wondering if there's a connection between oil type and the screen getting clogged.

Guy

 

The problem with the oil pressure existed already when i bought the car.I hadn't even driven the car or changed the oil, so i didn't know what could possibly be wrong or what to expect. The previous owner of the car had it sitting in his yard for a few years, which probably helped cake up and contaminate the oil. Then when the car was running it just sucked up all the grime into the screen, which eventually cut off the oil pressure completely. The car would always have pressure when i first started it up, but as soon as the oil thinned out it dropped like a stone.