well i have got a weird issue gentle men, started happening 2 days ago
'75 freebie 225 super six engine

in the morning or after she has sat till she is stone cold, solid 45psi of op,

driving for a while and gets all warm and toasty, come to a stop drops to 25psi, start driving and around once she reachs 1200rpms back to 45psi.

its weird because before this happened she would hold 45psi at any rpm, I am just worried of a 0psi condition while driving, last thing i need is to *not even gonna say the things that could happen* don't feel like jinxin myself, what could be the issue ??

yes i have double and triple checked the oil level and it is to the full mark on the dipstick,

-Mike

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I am the Guardian, I hate helos, everything leaks.......

Could be a sticking relief valve

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V8?? We don't need no stink'n V8!!

Did you recently change the oil?
What was in it vs now?

Sounds like there is quite a few miles on it......

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

25 psi at idle is plenty. I doubt the oil pump pressure relief valve is stuck, but it's still worth investigating.

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Joshua

didn't have a clue what was in it when i got it, had a 1qt green filter on it, so the first thing i did was change the oil and filter, i am using Valvoline 10W-30, and a mopar MO-080 filter, but why would it constantly maintain 45psi at idle (800rpm's in gear) to ((4500) is my highest shift point i will allow it to go normally i never take it over 3500rpm),

how does the relief valve come out ??

just unscrew the big nut on the oil pump and the spring and relief come out as one ??

how should i clean it ??

I saw the car OD it came out of 85,000+, but who knows if it has rolled over

-Mike

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I am the Guardian, I hate helos, everything leaks.......

Sounds pretty similar to my oil pressure. Starts cold at 45-50psi, after warm it will drop to 20psi and the oil pressure scales with rpm. I've only ever seen it go as high as 50psi, but normally around 40-45psi (I generally don't look at my oil gauge while drive on the freeway so it could go higher but I wouldn't notice).

My oil is 10w-30 Mobile 1.

I always assumed that was normal, is it not?

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'66 Dodge Dart

Sounds normal.

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1973 Plymouth Valiant 225 Torqueflite 904

I really dont think you have a problem. I might think about changing the filter again (and the oil if it looks dirty). This way if something is amiss you can catch it.
Frank

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Scrapple: Because a mind is a terrible thing to waste.
73 Duster - Race Car
66 Dart Wagon - DD
178" FED
82 D150
All Slant powered

change oil/filter again ....I always change oil atleast twice ,like 500 / 1000 mile, just to be sure .... pressure sounds right on....

keep on roddin'

There's nothing wrong. Your engine has tight bearing clearances. The oil pump is exceeding engine demand at 1200 RPM and higher. The relief valve is set to 45 psi. When cold, the oil doesn't flow well, so the engine demand is reduced and the relief valve opens.

Remember that the oil pressure is being measured at the pump, not at the most distant bearing. You can be reading relief pressure at the pump, but be near zero pressure at the most distant bearing due to high viscosity oil.

At your next oil change switch to 5W30 viscosity. Oil viscosity has been discussed numerous times in the past. The general rule is to use the LOWEST viscosity oil that produces adequate oil pressure. Since 95%+ of engine wear occurs at and just after startup, its important to get the oil flowing as quickly as possible. A lower viscosity oil will do that. 10 psi at hot idle and 10 psi/1000 rpm is the general rule minimum pressure.

If you're worried about ZDDP concentration, you can use Mobil-1 0W40 European Formula, which still has ~1200 PPM ZDDP.

Also, you can't tell if the oil requires replacement by looking at it. Only a lab analysis can determine the state of the oil. Spend the money for an analysis at Blackstone (~$35 for basic analysis plus TBN, and postage). Depending on the results, you may be able to extend your oil change interval. (I'm currently running 15,000 mile interval on a 2000 Safari van 4.3 V-6, with filter change at 7,500 miles). The analysis will also give you advance warning of developing problems.

Ken

good info rusty, is that Mobil-1 0W40 European Formula, generally available at any autoparts store ??

I have the mechanical guage at the back of the oil pump, which would be the furthest bearing #1 or #6 ??

-Mike

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I am the Guardian, I hate helos, everything leaks.......

Any well-stocked parts store will have it. Its generally ~$1.00/quart more expensive than the other Mobil-1 grades. Maybe Pep Boys will have another Black Friday sale this year. 2 years ago they had it on sale for a few hours at $3/quart. I cleaned out 3 stores. <g> My 4-ring logo car with the 4.2 V-8 requires 8+ quarts. iirc I bought ~60 quarts.
The most remote bearing will be at one of the connecting rods, either #1 or #6. The most remote oiling point is #1E rocker arm. Turbocharger oil feed plumbing could be even longer, depending on how its routed. Does anyone happen to have a disassembled engine to measure? The flow depends on the cross sectional area of the various passages, the length of each, the bearing clearance, the fluid viscosity and the pressure difference between the supply and demand points. Obviously the only one we can easily change is the viscosity.

Ken