High oil pressure concern

[68ford]

What were your numbers?
I think a lot of people have seen higher numbers with thick oil and lower numbers with thinner. Some members have been concerned about low pressure (maybe you posted up about that in the past?) but this is the first I remember where it's gone above and beyond normal from using what is still kind of a normal oil.
Then again, did someone comment that this is a new engine? Maybe the tolerances make a bigger difference here then.

More pressure could be expected from 20w/50 for sure. And maybe even by going from just 10 to 15 like the OP did. Just not double the pressure, from 40-ish to 80, with the same oil many here are using without seeing that extreme.

But he did say in the first post that his 10w oil was Royal Purple too. Maybe his previous readings were falsely low? And maybe his current reading of 80 is what he would have had with another brand of 10w oil.
Guess the only way to know anything for sure is to first verify pressure, then try different oils and filters to see how things change.

Paul

It is physically impossible to go from 40 psi to 80 psi idle while going from 10-30 to 15-40. Going from 0-20 Mobil1 to straight 50wt racing oil would not take you from 40 to 80 at idle. I run 15-40 delo most of the time, but before I raced last time I put in 50wt Swepco, oil pressure maybe 3 to 5 psi more cold start. Aft that no different. It's noticeably thicker coming out of the bottle.

 

[DirtDonk]

Isn’t there an ohm reading you can do on the sending unit to see if it is defective?

Yes, the range for our Fords (all three gauges) is approx. 73ohms is zero and 10ohms is whatever the top reading is. Full and empty on the gas gauge, and a member here even has a tracked resistance-per-degree of angle on the fuel sending units. Not sure how that equates to an oil pressure sender.

If you ohm it with the engine off then, it should read roughly 70-75 ohms, and with the engine running I'm not sure what it would read for specific pressures.
Probably a test range to shoot for, but not sure what that is, or if it's printed anywhere.
Yeah yeah, I know... Google maybe!

I'd rather fiddle around in the garage making threaded fittings and plumb air into it to compare pressures and resistance readings! Could be a fun afternoon project.

Paul

 

[NashBronco]

OK. Update after many miles of driving today. When i start up the pressure gauge slowly goes up to 80 and stays there at idle. However, once i start driving it drops to 40-50. at a red light it slowly starts going up. no other symptoms noticed.

 

[68ford]

OK. Update after many miles of driving today. When i start up the pressure gauge slowly goes up to 80 and stays there at idle. However, once i start driving it drops to 40-50. at a red light it slowly starts going up. no other symptoms noticed.

Gauge, wiring or sender is faulty. No way oil pressure will go up at a light assuming you're just sitting there idling.

 

[broncobilly72]

2 things....I had a pressure problems in the past with my 68 ford truck. The pressure spiked so high that it blew out the side of my oil filter. It seems a spring in my old pump broke and allowed pressure to climb. In the past when i had a sudden drop in oil pressure on my bronco, I took out the sending unit and hooked up a mechanical gauge .... pressure was in the normal range....sending unit went bad.

 

[69_Sport]

I learned a long time ago that when I have been working on something, and then problems show up unexpectedly, that the most likely source of the problem was something I had just done while working on whatever it was.

You said you only changed the oil and filter. Was that all?

Eliminate the easy stuff first. Buy a $10 Motorcraft filter and swap it. If that doesn't work, change the oil back to 10W-30.

Also, thicker oil is not necessarily better. Oil viscosity should be chosen to yield acceptable pressure readings. If your pressure was fine, then what were you thinking by going with a heavier oil? You want to run the lightest oil that gives you adequate pressure under the conditions under which you operate your engine.

 

[68ford]

He has an issue with either his sender, wiring or gauge.

It is impossibly his oil psi raisrd that much from 1 thicker viscosity.

It is also impossible that when you come to a stop and idle the oil pressure goes from 45 psi while cruising then up to 80 at idle.

 

[DirtDonk]

Unless he's sucking air through a defective pump pickup, or a too-low fill level. Higher rpm sucks air, idling lets it collect back in the pan and suck oil only.
But either of those would have to be at the extremes of their range to give these results I think.
A bad pickup or too little oil should read a lot lower than 40psi when cruising I would think. Just being "low" does not lower pressure. It has to be really low and sucking air with the oil. Mine has run on less than 2 qts and had very high pressure.
I could actually tell when my oil was low after that by the gauge reading higher than normal! Can't explain it, just know that it was.

But I do believe that a bad filter can do strange things. Can't say I've ever seen one create this set of circumstances, but I would not rule it out completely at this point.

Paul