Funny thing happened on the way home from work. Started the truck (86) and the oil pressure came up pretty high, almost 3/4 of the way up the guage. (probably about between the M and A in "Normal". I went off on my way home, oil pressure stayed up. I only live about 10 min. from work, so temp is still coming up, but finally rests a little bit past the middle of the guage, a little higher than it normally goes. (it's about 50* outside) Alt guage is fine, slight charge. Got gas a few days ago, so it's still pretty full, but it's reading above F.

I get home, use the truck to take out the trash, and the oil pressure went back down to the middle of the gauge. Also, the temp dropped down to about midguage, or even a little below. I think the gas guage also dropped a little, down to the F, not past it.

SO I'm thinking there are two possibilties:

1- There is some internal problem that caused all of the guages to read a little high, and then went back to normal. Do these trucks have a voltage regulator for the guages on back? would this cause this?

2- It's a fluke, the oil pressure was high because it was cold, the temp went up because the t-stat was closed. By the time I got home, the truck warmed up, the oil thinned out, oil pressure drops to midguage (normal) T-stat opens, temp drops a little bit because of cool air flow through rad. And gas guage is a fluke, chalk it up to slosh in the tank? Sounds logical. If this is what it is, I'm not worried, just as long as I know what's going on.

I'll keep an eye on it tommorow and we'll see how it goes.

 

my f-150 did that almost _all_ the time. I'd have a little over 3/4 of a tank, and then it'd jump to over full. same with the temperature & oil pressure. get aftermarket guages man.

 

The thing you need to know about the ford oil pressure gauge is that it's not a gauge. It's an idiot light that looks like a gauge.

It doesn't measure the real pressure. As long as the pressure is within acceptable tolerances (decided by the sending unit) then the gauge floats about halfway up. As far as the fluctuation goes, you may have a lose or corroded connection on the gauge.

As far as the temp goes, you might want to do a coolant flush if it hasn't been done in a while. Also change the t-stat while you're in there. You do NOT want your stat to stick closed while you're out and about.

 

The answers to your questions are...

1) Yes,Yes
2) Trying to reason that out, are you?

There is a reg and it will cause this. The biggest is that they will all fluctuate at the same time.I think I would just watch it for a while and if it gets to be a problem, change it.

 

My 86 with 302 EFI does almost the same thing, except the alt shows a charge always-just above the C mark, the Oil pressure gage when first started up will always be pepping the L mark, but will go down close to the M or A marks after warmed up, but then the weird part is the Temp gage...sometimes it'll show just a tad over the C mark then stay there the whole day, or it'll go to the first (/) mark and stay. I already changed the temp gage with a new one...so it doesn't matter unless its wrong...(which it is)...haven't changed out the other temp sender unit...yet.

 

1986's use a real guage, not the fake one, that came a few years later ( 87-88 airc)

I changed the thermostat a month ago with the heater hoses and new coolant.

I never had a problem until now

 

Well, I don't know but I don't think there is anything wrong. Today the temp seemed fine. Oil pressure stayed high until it warmed up then went down to the middle of the guage. I think it's because it was in the 40's outside (for the first time this year), and the last oil change I used 10w-40 and a half quart of Lucas, which is pretty thick. Maybe I'll change the oil and see what happens.

The gas guage still read above full, then went to F, then went back above full on my way home from work. I did get gas last week, and when the pump clicked off at $14.12, I topped it off all the way to $15. I'm thinking after I use some more gas I'll get a decent reading again. We'll see. I'll keep posted

 

I love Fords, but their gauges are goofy. I have rolling blackouts on both my Cobra and my F150. Turn the lights on and half the dash will light up sometimes, then other times it's fine. Sometimes they'll pop on, and other times they'll pop off... I cleaned every connection on the dash of the Cobra (replaced heater core... had to have the whole dash out of the car.) so I know it's not a bad connection (unless it's got to do with poor tension or it's corroded somewhere else).

Also, I've noticed them jump arround, like when you turn the lights on the temp moves up an 1/8 of an inch. Turn the lights off and it comes back down...

On the F150 the gas guage reads 3/4 when it's full untill you drive for like 10 minutes then it goes up to full slowly. Stop and come back a little later and it's anyone's guess; 3/4's full, 7/8's... I know it's full 'cause once I kept clicking the pump till gas came out of the filler neck. Not the best way to test I'm sure, but I had to know and I was a little PO'd at the time.

to answer your question, I think it's may be a little of both...