Oil Pressure Light

[jackspade21]

Hey all!

I'm new here, so please bear with me if I make dumb n00b mistakes. I've got myself a 1985 720 king cab, 98,000 miles, with an automatic. I've started doing some work on it, and so far it's going well. I'm expecting more rebuild in the future, but for now, I just want to get it running nicely and back up to the mpg I remember from my first one of these trucks.

To that end I did a tune-up over the last couple days - new plugs, wires, air filter, oil change, fuel filter, etc. I also replaced the oil pressure switch, as it was leaking engine oil all over the side of the engine block. Yuck. Everything was fine, but yesterday I started getting an oil pressure light when I'd come to a stop at stop lights. Once I'd put the engine under load and pull away from a stop, it would go out, but the minute it dropped to idle the pressure light would come on. Now it seems to stay on the whole time I'm driving, it only goes out briefly for a few seconds when I first start it up.

Any thoughts? I don't want to destroy this engine! I've been checking the oil obsessively, and it's topped off nicely. Would it be the oil pump?

Thanks for all your great threads on here. I'm looking forward to doing some suspension work, inspired by the threads I've seen here already.

Here's a pic of the truck, just for fun:

[PEZi]

Welcome man! I'm about to head out, but I'll give this some thought and see what I come up with. Will report back later!

[jackspade21]

Great, thanks! I appreciate any input anyone can offer.

If it helps, here's an update. I checked the oil again this afternoon, no leaks, still topped off. Taking a cue from my repair manual, I also checked the oil pump pressure regulator, which seems to just be a spring and a little metal cylinder. The spring is springy, and it seems to be working, as far as I can tell. When I started it up after all this, I still get the light.

Thanks for the reply, I look forward to hearing any tips or advice!

[Rev_D21]

Time the ditch the light and get a real oil pressure gauge, that's the correct thing to do.

[jackspade21]

Ah, not a bad idea. I hadn't thought of that.

Honestly, I've driven it a bit, despite the light, and it seems to be running fine. I'm starting to think the cheap-a** pressure switch from advance has just crapped out a week after I put it in. I'd love to put in an oil pressure gauge and a tach too. Are there threads on doing such a thing here? I'd love some guidance.

Any recommendations on where to get a good oil pressure gauge?

[86 720]

Take it back and get a replacement. If that one is bad, look into getting a good aftermarket one.

[jackspade21]

So here's the latest. I pulled the pressure switch, and put in a pressure gauge. I'm getting around 25 or so at idle, and up to 45ish when I rev. I don't have a tach, so I can't be more specific with RPMs, but I'd say I'm idling a little below 1000, and revving in the 2k range.

What are the PSI specs for oil pressure? I can't seem to find a range listed in my Haynes manual.

Thanks all!

[flinterman2000]

25 is good at idle. Get a 1/8 tee and nipple and install a new pressure switch along with the gauge. The light should be off after you start.