On two other threads, I posted about finding my oil switch sensor and then how to remove it. After both of those tasks were accomplished, I bought a new oil switch ($8) and I need your advice.
1. Oil "dumb" gage on dash is 2 position and runs off the oil switch that just grounds out when oil pressure is high enough and causes oil gage to jump to mid-position. It does not really "read" oil pressure on a analog basis.
2. My gage was going to mid range on start-up but then, after warm up, the gage started to wiggle, and then after engine was warm the gage would go to zero and red "check gage" light would come on. When driving with normal RPM, the gage would go to mid-range OK, but on coasting down a hill, the gage would chatter.
3. With my old oil switch and my new oil switch on the kitchen table, I pumped them up with a pressure bulb and put a VOM on them and found that each of them made "contact" at above 7 psi. So, the Ford truck engine designer wanted the driver to know when the oil pressure was above 7 psi. Huh? The manual says 40 to 60 psi is the norm, so why 7psi as the warning level. I can imagine that if you got below 7 psi, the designer wanted you to stop the truck and get help...? Is that the reason?
4. Anyway, I decided not to install the new switch, but install a fitting, a copper tube to above the engine, then a plastic tube to inside the vehicle and then put an analog gage on the end. Here is what I found out. On cold start the oil pressure was 20 psi and would top out at 25 psi on engine revving. It steadily went down over 10 minutes until it went below 7psi and that is just the right amount of time my idiot gage would start to wobble before. After 12 minutes the oil pressure went to 3.5 psi and I decided to stop the test. On revving, it would go to 12 psi.
5. The oil gage has been doing this for two years during which my daughter drove the truck to California and back.
6. Here are my questions:
a- Is the location of the oil switch port, 1/2 way up engine, in a place where oil pressure should normally be lower than specified? (I probed the open oil switch port with a piece of 1/4" plastic tubing and I was able to slide the tubing inside the port about 6 inches. So this was not just a slender gallery, but some sort of open area in the engine.)
b- Since Ford designed the oil switch at 7psi, does that mean you could drive the truck forever with 8 psi and not cause damage? You would never know it was at 8psi, would you? Why wouldn't Ford have designed it at 20 or 30 or 40 PSI if the spec is 40 to 60 psi?
c- Since replacing the oil pump requires removing the engine and since budgets are tight for me, could I drive the truck for several more years and just cut off the engine instead of idling the engine at long lights, etc? My analog gage inside the truck could tell me when the PSI went too low.....

Thanks, again.

 

IMO, driving it with such low oil pressure is only going to cause more internal damage, if it hasn't all ready. I'm not so sure you have to pull the motor. You might be able to just un-bolt the motor mounts and life the engine up. I'm sure there will be a few more things you will have to take off to get it lifted up. Fan shroud, etc.... You may even have a main bearing gone bad and that why your pressure drops after the oil get warmed up.

 

all your assumptions are pretty good fordopie. THE on- off pressure gauge on most trucks is set at 7-8 psi. Basically it is there to tell you if you have "off" at idle, but "on" when you rev it up and drive, that you are on the border line.. I remember years ago a design engineer told me their "design" for all motors was to maintain 10 psi for every 1000 RPM. Driving down the road you only need 25 psi for most situations. If you have 40 thats good. Just some room for future wearing out. Your at that point now. It may not be critical, and as you said you MIGHT be able to drive another year... MAYBE.. but your pushing the limit at this time........ FYI, i have seen many motors (small tractors) that only had 3-5 psi at idle and 15-20 psi when you rev them up and they ran fine. YOu need volumn to the bearings, not necessarily psi. Just enough lube to keep it from sticking is enough. NOrmally the designers will give you 2-3 times that much and look forward to future wear. ... what are you using for oil ?? What is the ambient temp ? How about trying some 10w 40 to drag your life out a year or two ?????

 

V8R: did you are anyone else out there lift the engine to get to the oil pump. How high? I looked at it today and found that the oil sump is molded right over the transaxle and the exhaust pipe so there is not anyway to get it out in place, can't even get to several of the bolts.

Steve: I will try the higher viscosity oil and let you know. What if I go up to 30 wgt or 40 wgt oil? Any advice on STP or other snake oils?

 

No, I have never tried to take the pan off one of them yet. Most vehicles you can just lift the motor up and take the pan off. As far as oil additives, I like the Lucas oil. I swear by it. I use it in all my vehicles.

 

The easiest method is to drop the front axles/pumpkin, change to a high mileage oil, this is normally an indicator of general bearing wear and a new oil pump may make no difference..

If you have the X engine they are noted for being bullet proof... Good luck..

 

Wow... that is extremely low oil pressure. I would replace the oil pump asap... when I built the new 383 that I dropped in my 59 Dodge I was having oil pressure problems, but now at idle she has 40 pounds and when cruising down the highway she sits at 80-90 pounds... I had a friend saying his engine only made 5 pounds. I told him replace the pump, as I went through 2 on my engine, blew them both....

 

you dont need 40 psi at idle or 90 psi at speed. You need 10 psi per every 1000 RMP of motor speed. 8-10 psi at ilde will work. I would LKE to have 20 psi, but that is not a necessity. RUnning down the road 40 psi would be great... 25-30 would be adequate.

 

Thanks for that info..... so I could lower my pressure then... this is on my 59 dodge with a melling oil pump, 383 engine. you change the springs to change pressure.... thanks.

 

after replacing my oil sensor the oil pressure still runs on the low side on my 86 ford f150 when i drive it what to do now? its quite stressful!