Ford F150 - Just inherited a 92 F150

So, I've inherited a 1992 Ford F150. I am brand new to trucks (and troubleshooting vehicles). I've always driven much smaller vehicles and I have a few questions for anyone willing to take on my list...

1. Would it be ok to get an oil change and change to a synthetic oil?

2. How much oil does this particular truck require for an oil change?

On top of those 2 questions, I have an issue with the truck that I've noticed.

When I start it up and go directly to the freeway, the temperature gauge always seems to peg up to the "A" or higher in "Normal". Sometimes, it goes all the way to the "L".

If I start it and drive around town a little bit, it still goes pretty high but, since i'm not going as fast (I guess), it doesn't go AS high. Once it gets up there, it usually drops down pretty fast to a normal level.

My questions for this part are...

What causes this and is it normal?

I also noticed that my voltage gauge will sometimes rest very high, and other times rest very low. Not sure what that means but..that leads to another question..

If I don't drive for a few days (4+), the truck starts to have trouble starting. If I wait more than that, it plain will not start. I'll just get a loud clicking sound when I try to start it and i'll HAVE to get a jump. After the jump and driving it around for a little while, it'll start on it's own fine.

Thanks in advance

You can save yourself a lot of time & typing by buying a haynes manual (the early blue edition), reading it, then doing everything in Ch.1 . Don't get chilton's. If you want something better than haynes, get a Ford service disk - it's actually cheaper.



Have you checked the coolant level? How old is the coolant? How old is the thermostat? The radiator cap? If you don't know, change them all. Then test the fan clutch.



Remove, clean, & tighten all 7 terminals on both of the heavy battery wires. Many parts stores will test your starting/charging system free in the parking lot. Call around. The battery must be FULLY charged before they can test anything, so if you don't have a charger, be prepared to leave it with them for a few hours.

As far as the switch to synthetic, it's your call, depending on the mileage. Synthetic has heavy detergent properties which can worsen existing leaks, or cause new ones where gunk was holding the oil back before. That said, I switched my Jeep (Mopar 318) to Amsoil full synthetic at 115k with no problems, but I was 99% certain there were zero leaks before I did it. If anything, I recommend running an engine flush through it before putting the synthetic in it. See http://www.amsoil.com/StoreFront/aef.aspx for engine flush.

I'd recommend reading up at www.bobistheoilguy.com - that's pretty much the holy grail of oil sites.

how do you test the fan clutch? my truck seems to run right on the tip of the N on normal and i think it could be my fan is always blowing when its well below 0. could you help me out?

An easy way would be to watch it. Does the fan cycle on and off? If it does come on and off, the clutch is not the problem. Does it stay running constantly? Do you get heat blowing from the vents after the engine has been running for a while? Even if it stays running constantly, it may not be the clutch, you could have a thermostat or temp sensor problem.

Using the stock dash temperature gauge isn't really the best way to troubleshoot the operating temperature of the engine, simply because it isn't showing you an actual operating temperature.

If the fan does keep running try pulling your codes to see if there is a sensor fault. To check the thermostat, pull it out and look at it. Cold, it should be totally closed. To see if it opens properly, put it in a pot of boiling water. Once it gets hot, it should open about a 1/4 to 1/2 inch.

The temp going up at first and then dropping down can just be that bit of time before the thermostate opens up to it's widest. Not abnormal. --If it returns to being rather high and remains there much of the time I would change out the fan clutch. You probably need it with the age of the truck any way.

The difference in the voltage readings is normal and has to do with how much the battery is needing at the time. Just after starting, or sitting a few days, or having lights on, etc it will read high since the battery wants to replace its storage. When the battery is "full" of voltage the regulator will cut back the voltage it feeds out.

You say that leaving the truck sit for four days gets a "click" instead of a start. You probably need a new battery. It could be that your cables need cleaning, but I would rather guess that your battery is going south.

Click that diagram that you quoted, & read the TSB.