engine temp up and down?

[AllBlackBimmer]

(I posted this on another ranger website too, but am trying to get as much info about this as possible)

Was driving to work this morning - about a 15 min. drive, and noticed my engine temp. gauge was going up and down...

About a week ago, my oil pressure gauge was reading really high - I am told these guages are "fake" but it has to be doing something?? at the same time this was happening, my truck was running a little hot - temp gauge reading about 3/4 of the way to the right but wasn't getting any hotter. then the next day or two, sometimes it would do this, and other times would run a little hot - How I drove the truck, how fast, how long, etc, didn't really seem to impact this in any way.

Back to this morning, the temp. guage was going from 3/4 of the way to the right (running hot) to back to the middle and being "normal", my oil pressure gauge was reading high - there seems to be a direct relationship to my "oil pressure" and my truck running a little hot.

I NEED to change my coolant, I know this, it it old old old. I also will be getting my oil changed - these 2 things are going to get done within the next week or so...

any thoughts as to what is causing the temp to go up and down?
what is casuing my "fake" oil pressure gauge to read high?
...these things are related how?

will I damage my engine at all if the engine temp gauge is about 3/4 of the way to the right (hot side) for like a 10-15 min drive?

what else?

 

[PilotJO]

Just a guess here but given the temp and oil pressure "gauges" are just idiot lights without the lights then to have both these gauges go flaky at the same time... and both of them reading "high"---- I'd look to the charging system--- a bad battery that is not accepting a charge with an alternator working overtime in an effort to force a charge into it. or a bad regulator that could also be internal to the alternator!

 

[AllBlackBimmer]

Just a guess here but given the temp and oil pressure "gauges" are just idiot lights without the lights then to have both these gauges go flaky at the same time... and both of them reading "high"---- I'd look to the charging system--- a bad battery that is not accepting a charge with an alternator working overtime in an effort to force a charge into it. or a bad regulator that could also be internal to the alternator!

What actually controls the oil gauge and engine temps then if they are both "idiot" lights? ... something has to make that little needle move one way or the other...

but..

electrical issues seem to be the answer. I guess this makes somewhat sense, as my driver side window quit working about 2 weeks ago - didnt work for the next 2 days and I thought the motor was broken, a day later and a hard door slam, and my drivers window goes up and down just fine.

I posted this on another ranger site and heres what others had to say: http://www.fordrangerforum.com/4-0-sohc-4-0-ohv-tech/57362-engine-temp-goes-up-down.html


seems to be a grounding cable? anyone know what I can find this on my 93 4.0 ohc to see if this is my problem - and hopefully can just tighten this back up.

 

[pcollins]

I can tell you with the Oil gauge, the moment the engine hits 8 psi pressure, it shoots up to the middle and sits there.

 

[AllBlackBimmer]

... well I thought "normal" operating conditions for the oil gauge was in the middle?

just like the engine temp, the "middle" or pointing "straight up" is what I always thought was "normal operating conditions"...

guess not? or can others please chime in?

 

[pcollins]

No, on a vehicle (such as the farm tractors I work on) with a real oil gauge, the oil pressure fluctuates with the throttle, moves up and down as your driving and change your RPM. Ford did this to avoid people calling in a complaining that the oil gauge is reading low, or moving constantly. Cause at least on the IHs that i drive, at operating temp at an idle, the oil pressure literally reads low on the gauge (its not low enough to damage things, but you can see how this plays over to the auto world and people complaining).

As for the coolant gauge i'm not sure the exact numbers, but I'm pretty sure it works the same way. Its on a variable resistor tho. But when i lost my idler pulley on my old ranger and the water pump stopped, the temp gauge didn't climb slowly as the temps increased. It shot up to hot after about 10 seconds.