Well, on my last trip I was really starting to notice that the oil pressure gauge for my '87 van's 302 is sitting pretty much around the "N" only, and I remember it being higher. Sender is the one that gives a real reading, not the idiot light switch.

So I put in an actual mechanical gauge this time. I'm running 10W30 oil. I get 50 PSI when the engine is cold (high idle), revved or not. 40 PSI when hot and driving around. 17 PSI when it's hot and just idling at low RPM. But anyways I don't know what the idle pressure USED to be.

Wow, the stock gauge was not showing that kind of difference, I half thought you guys might be full of it saying you gotta get the mech gauge. It was a pain to run an oil line through the firewall and frankly having a plastic line that could vent oil out under the engine on on my legs scares me but that gauge was accurate, fast/animated, and has a lot to say.

So... is 17 PSI at idle too low? I read on the "oil and lube" page (not visited very often) where someone said "20PSI at 2000RPM" was a min, but I don't have a tach to figure out 2000RPM. It was pretty much 40 PSI whenever I looked down while driving, just low at the stoplights. Maybe I should try to figure out where 2000RPM is from the gear ratio and spedometer?

The 10W30 in higher temps (like 80F outside today) wouldn't explain the reading would it? I'm not hearing any lifter chatter at idle. And me being a ******* who forgot to check oil for an extended period, I once heard what lifter chatter sounded like.

I've heard people say low oil pressure at idle is due to shot crankshaft bearings letting the oil pressure leak out, essentially requiring a rebuild (which sounds like a titanic job even getting the engine out of the van!). However this guy suggests that there's an oil pressure control valve on the oil pump that may stick leading to low pressure at idle or very high pressure at speed. Anybody wanna back this logic for an '87 302?

 

your fine...if you don't like having the oil line in the cab...try replacing the sender unit you removed to install the fitting for the gauge.

your oil pressure looks just like mine in my truck. been that way for a few years now.

 

My 88 5.0 Mustang with 161,000 mile has 60cold, 40 driving hot and about 20 idling hot, so you should be fine with those numbers that you are getting.

 

Sweet- I tell you, I was hours away from home this weekend when I started to notice that the pressure had been sitting below the "N" of NORMAL but still to the right of the outside-of-normal bar on the left. Wuz getting really nervous.

That really is a hilariously bad gauge. I mean, if the PSI varied from 17 to 50 and that was basically the width of the "N", it'd be at like 300 or 400 PSI by the time it reached the right side limit of the "normal" range. And it didn't seem to be responding to the changes in any accurate way, it doesn't go down visibly when I come to a stop. Actually, if that low reading was 40-50, then there's no way the "O" or "R" I remember seeing awhile back could be reached with a real pressure. So probably that low reading is from the sending unit going out of calibration.

And man that gauge has almost the entire range of needle deflection covered as "/ NORMAL \". If it was ever out of range, I would have no idea just how far it was out of range.

BTW, I'm still listening if anybody thinks my pressure may be bad, so please post if you have another opinion.

 

10 PSI per 1000 RPM is generally accepted as OK. Sounds like you're in that range.

 

My old beater LTD has a 351W and still pulls off about 13 at hot idle and it still runs great. I run mechanical gauges too - but many people, like myself, don't use the plastic line that is included with the gauge kit for the oil pressure line. I use a copper line instead. Less chance for leaks. The plastic line is unreliable.

 

65 289 with rebuilt eng and crank turned .010 about 45,000 miles ago and oil pressure is 20-25 idle and 60-65 at speed. I think I replaced the oil pump then too. Several years ago.

 

35 to 60lbs is the recommended pressure @ 2000rpm. so your engine is healthy Danny.

 

The stock gauge is really nothing more than an idiot light with a needle. It will generally read in the normal range till the pressure drops below something like 7 PSI and then the needle will drop to zero. This was Ford's bright idea to stop complaints about oil pressure fluctuations and still let people think they have an actual gauge.