Low oil pressure?

[southbaybronco]

Since i bought my bronco a few years back the oil pressure always seemed a little low to me. In the morning when i start it up the mechanical gauge reads 45. As the engine warms up it will slowly drop to 25 on the freeway. At a stop light in gear it reads 10 and if i put it in neutral it reads 15. There has never been any strange noises, knocking, grinding, ticking, etc. The 351w runs strong. I was just curious as to what people thought. Should i open a can of worms and investigate or leave it as is? What would you do? Does it seem too low? I drive it all the time but it's not my daily driver.

Thank you,
Kyle

 

[KRAWLER]

My 302 always idled at about 10-15 psi.

 

[rustbucket]

What oil are you using?

 

[southbaybronco]

Rotella 15-40

 

[SteveL]

Probably getting old and loosing some pressure around rubber in there. If its got alot of miles start putting some cash away for a 351w. I threw some lucas stop leak in my 72 suburban and now it has better oil pressure.

 

[Skiddy]

that oil pressure isn't too bad yet. usually when oil pressure gets way low the main bearings are getting worn

 

[broncnaz]

Sounds fine to me maybe a little wear on the bearings but nothin to get excited about. When the pressure no longer build when going down the road then i'd worrry.

 

[DirtDonk]

Assuming this is your stock dash gauge readings?
Like they said, you're still in the game. It's low, but not dangerous until it gets below 10 psi per 1000 rpm. Though it sounds as if you're pretty close right now.

BUT, do you know for sure that your gauge is reading correctly? You should confirm it with a temporary mechanical gauge of some kind. I have a hand-held gauge my Dad used to use, with a simple rubber tip (like a compression gauge actually) that you simply held tightly into an oil port while someone turned the key.
Not too convenient, but at least it's a "second opinion" on your dash gauge.

Your wiring is 34 years old and so is your IVR. Your dash could be getting a bit rusty and not only would your IVR not be getting a good ground, but the same goes for the rest of the dash and gauges. How do all your others read? How bright are your indicator lights?

Bottom line, when new and on your stock gauge, your engine would have registered 65 to 75 psi when cold, and usually no lower than 40 to 45 when hot. Even at idle.
Mine read in that range it's whole life until about 160k miles, when it stared to dip a few pounds. A little more when it was hot. With a recent rebuild on an 86 5.0 with HV oil pump and reading off the stock gauge still (but with a new wiring harness) he's getting 80 psi when cold.

That's with a stock dampened gauge though. When running an aftermarket mechanical gauge, your pressure will go up and down with rpms practically like a tachometer.
So check your wiring, IVR output, grounds, sending units, and whatnot. Double-check with a separate mechanical gauge to see what's really going on, and go from there.

Like they said too though, no ugly noises coming from the direction of the engine compartment is a good thing. Helps you sleep at night.

Paul

 

[southbaybronco]

Thanks guys for the replies. It's a mechanical auto meter gauge that is new ( 2 years old ). I will check with another type to verify.

 

[Bundy]

Shit, I am in the 40-50 psi range?? :/

 

[DirtDonk]

Thanks guys for the replies. It's a mechanical auto meter gauge that is new ( 2 years old ). I will check with another type to verify.

Well, I was afraid you were going to say that. It'll be interesting to see the comparison, and it's always a good idea to verify questionable numbers, but it'd be a shame to think that a fairly new mechanical gauge would be acting up.
Not only "already" acting up, but frankly, "ever" acting up. Darn thing should be good for 40 years of abuse and then some, you would think.

Good luck.

Paul

 

[DirtDonk]

Sheeooot (edited for content ;D ), I am in the 40-50 psi range?? :/

So what's to be upset about Bundy? Or is that a question?
Seems to me you should be plenty happy to have that pressure. Sure, it's not 70, but it's still more than some engines have and should get you down the road for many years if you treat it right and change oil as specified and keep it running in top form.

In addition, if that's cold psi, you're so good to go you've got nothing to worry about.

Paul

 

[zoob]

Im having the same problem sometimes its at 70 other times 40 then ive seen it go to 0 then back up to 20 what would cause this bad sending unit

 

[Explorer]

Im having the same problem sometimes its at 70 other times 40 then ive seen it go to 0 then back up to 20 what would cause this bad sending unit

Stock gauge I would suspect wiring connections.

 

[DirtDonk]

Yep, first place I'd check would be the 90° push-on connector at the sending unit.
Pull it off, and if it's even the slightest bit loose, gently squeeze it with a pair of small pliers (or your fingers if you have GI Joe Kung Fu Grip) to tighten it up.
You'll find out quick enough if you use too much force. Crunch! But it can usually be opened back up a bit if you go overboard.

Oh, and before you do the squeeze thing, try to scrape out any corrosion or build-up from the contact area. And wire brush the sending units post too.
Basically, you're doing anything to get a better connection. And hope that it's not your wire that's buggered, or you'll be replacing that in the end.

Good luck.

Paul

 

[zoob]

New sending unit all fixed!!!!!

 

[Skiddy]

New sending unit all fixed!!!!!

Good deal, always nice when someone post's back on what the issue was

 

[Bundy]

So what's to be upset about Bundy? Or is that a question?
Seems to me you should be plenty happy to have that pressure. Sure, it's not 70, but it's still more than some engines have and should get you down the road for many years if you treat it right and change oil as specified and keep it running in top form.

In addition, if that's cold psi, you're so good to go you've got nothing to worry about.

Paul

hey Paul, I just was concerned that there was TOO much pressure. I'm a hypochondriac when it comes to anything I've had a hand on with my Bronco LOL. Now I am VERY happy to have 50-60! thanks!


Oh, and stoked for the fixed sending unit for the original thread!

 

[DirtDonk]

Ok, so just a typical "Broncovereaction" then, eh?
No worries though. You can see short-term pressures of 100 psi on a real tight engine and still not really be in any trouble. I don't know what it takes to cause an oil filter can to go all Ballpark Frank on you, but it's more than that.
Before the rebuild, my brother's '65 Corvette's 327 had 5 psi at hot idle and 25 psi when cold. After the rebuild it had 100 upon startup, and down to 60-70 when hot. So you can see the big variations between when things are loose or tight, or from one gauge to another, or one engine design to another.

I think I meant to say "hot" pressure in the previous post, but either way, you're good to go.

Paul

 

[southbaybronco]

UPDATE.. I attached a HF pressure gauge and it read the same pressure as the mechanical auto meter. So i decided to switch from rotella 15-40 to 20-50 weight and add Lucas engine stabilizer. My pressure is now 55 at start up from 45. Freeway driving is now 38 from 25 and hot idle in gear is now 18 from 10. No ticking at startup or any new noises so for now it's going to have to do.