Oil pressure is crazy high!

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Budgetmoparman

Budgetmoparman

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Earlier this winter I dynoed my 340 and the oil pressure on the dyno was hitting 140psi. We made 10 pulls and it kept hitting the 140 mark. At that time it had a melling HV pump and 15/40 oil with zddp additive for break-in. When I got home I swapped the hv pump for a melling standard volume pump and dumped in 10/30 with zddp additive. I finally got the motor in the car and fired it up today. Oil pressure at idle is 80psi. I haven't ran it up in rpms yet because I don't have the radiator hooked up so I don't want to run it too long. Any ideas why the oil pressure would be so damn high? Motor is bored .030, comp XE268H cam, adjustable rockers from a 273, 340 X heads. I didn't do any oiling mods to the motor. It ran great on the dyno except the oil pressure. Any help is greatly appreciated.
 
my engine has 80 psi cold, 30 psi in gear at 185. I got a feeling your oil pressure will be ok, it will drop when you have the motor running in gear and the thermostat temperature 180 and up
 
d1970 said:
my engine has 80 psi cold, 30 psi in gear at 185. I got a feeling your oil pressure will be ok, it will drop when you have the motor running in gear and the thermostat temperature 180 and up
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It just has me a little nervous since it was hitting 140 psi on the dyno. I am waiting for my electric fan to show up before I put coolant in it and run it up to temp.
 
Old pump was an issue.

As long as the new has not bursted the filter and sent oil everywhere you should be just fine. 80 PSI cold is fine. My 383 holds that or more cold and 50-60 at temp and idle.
 
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Why in the world would you be putting that heavy oil in a fresh motor?
 
I had a similar issue with my dyno run. Hit 90 psi at 6000rpm. I was told it should not be a issue but shouldn't the relief valve open? Why would psi keep going up? What did your dyno guy say about the psi? Are you going to share your dyno results with us? :)
 
Check the Melling pump, you might have an HP pump, not an HV pump or it might be an HV/HP pump & it was boxed wrong. I've had this problem in the past with Melling, exploded an oil filter in the process. It WAS not pretty....LOL...
 
Have you tried a different gauge, bad gauge?
what kind of oil filter? you can't run a high micron filter, it wont flow enough of the thick oil and the relief will open in the filter.
The relief should open in the pump at about 75psi.
 
sireland67 said:
Why in the world would you be putting that heavy oil in a fresh motor?
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I agree. Why would you run 15/40 in general? Wouldn't that take away some power due to the weight of the oil? It would make sense if it was to solve oil leakage in a worn out motor, but in a brand new one, it just doesn't make sense. Especially in a winter area? Unless it's not driven regularly in the winter. I'm not knocking your choice of oil, it's just that if it were me, I wouldn't run that thick of an oil at all, especially in a new motor. Again, there may be some advantage to it that I am unaware of (if so, please tell me), but 15-40 just doesn't make sense to me.
 
15/40 is not thick oil, I use to run straight 40 Kendall in my 340 and spun it 7600 rpm
never had a problem and that was thicker than 15/40, had 100 psi cold if you revved it a little but at 180 60-65 psi. straight 30 is thicker than 15/40. I'm curious what oil do you run?
 
Chained_360 said:
I agree. Why would you run 15/40 in general? Wouldn't that take away some power due to the weight of the oil? It would make sense if it was to solve oil leakage in a worn out motor, but in a brand new one, it just doesn't make sense. Especially in a winter area? Unless it's not driven regularly in the winter. I'm not knocking your choice of oil, it's just that if it were me, I wouldn't run that thick of an oil at all, especially in a new motor. Again, there may be some advantage to it that I am unaware of (if so, please tell me), but 15-40 just doesn't make sense to me.
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If you don't live in Alaska you don't need a 0 winter grade oil. If his clearances are set up for a 40 grade oil he won't see **** for HP going to a 30.

Do any of you know why oil has gotten thinner over the years? Even David Reher wrote about it because the monkey see, monkey do with engine oil was causing him fits.
 
Oil gets better all the time so it gets thinner, thinner takes less HP to drive the pump, less friction to rotate the engine, more fuel efficient, new engines have very low tension rings, tighter tolerances more pressure with thin oil, Cadillac northstar runs 100 psi oil pressure.
 
brian6pac said:
Oil gets better all the time so it gets thinner, thinner takes less HP to drive the pump, less friction to rotate the engine, more fuel efficient, new engines have very low tension rings, tighter tolerances more pressure with thin oil, Cadillac northstar runs 100 psi oil pressure.
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One word.

C.A.F.E.

That's why.
 
With the big drop between the HV and STD pumps, then the problem is likely in the pump being wrong (HP as suggested) or the relief valve was stuck in the HV, or the wrong spring was installed or the piston was installed backwards. The 2 types should make the same pressure when revved on the same oil; they only are different at lower RPM's.
 
nm9stheham said:
With the big drop between the HV and STD pumps, then the problem is likely in the pump being wrong (HP as suggested) or the relief valve was stuck in the HV, or the wrong spring was installed or the piston was installed backwards. The 2 types should make the same pressure when revved on the same oil; they only are different at lower RPM's.
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I have tested and there isn't 5 HP between a HV and a standard pump.

Again, who says what is standard and what is high volume? I've lost power with a standard volume pump. Lower engine speeds it didn't have enough volume to feed the rockers and they grabbed the shaft.

There is way more power to be had in controlling windage than there ever will be in oil pressure or volume.
 
fez440 said:
I had a similar issue with my dyno run. Hit 90 psi at 6000rpm. I was told it should not be a issue but shouldn't the relief valve open? Why would psi keep going up? What did your dyno guy say about the psi? Are you going to share your dyno results with us? :)
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Dyno guy said it was the highest psi he has had on his dyno. It didn't have any oil leaks so we let it ride. At least I know it is sealed up good.
 
brian6pac said:
Have you tried a different gauge, bad gauge?
what kind of oil filter? you can't run a high micron filter, it wont flow enough of the thick oil and the relief will open in the filter.
The relief should open in the pump at about 75psi.
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2 different gauges and same thing. Using napa gold filter.
 
Budgetmoparman said:
Dyno guy said it was the highest psi he has had on his dyno. It didn't have any oil leaks so we let it ride. At least I know it is sealed up good.
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Had an issue like that with my 69 Bee and put 7 quarts all over my fathers driveway! He was laughing his *** off the whole time I was cussing and cleaning it up! The one time he had a sense of humor and I did not!!!
 
Chained_360 said:
I agree. Why would you run 15/40 in general? Wouldn't that take away some power due to the weight of the oil? It would make sense if it was to solve oil leakage in a worn out motor, but in a brand new one, it just doesn't make sense. Especially in a winter area? Unless it's not driven regularly in the winter. I'm not knocking your choice of oil, it's just that if it were me, I wouldn't run that thick of an oil at all, especially in a new motor. Again, there may be some advantage to it that I am unaware of (if so, please tell me), but 15-40 just doesn't make sense to me.
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I was told by a friend that has way more experience than me building motors to run 15/40. I am in a colder climate but the car is only driven in the summer.
 
Get rid of the filter and run a fram HP-1, don't believe me call fram tech on monday
 
Budgetmoparman said:
I was told by a friend that has way more experience than me building motors to run 15/40. I am in a colder climate but the car is only driven in the summer.
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Huh. That's interesting. I didn't mean to challenge your oil choice, it just didn't make sense to me. If it works, and especially if an experienced engine builder advised it, then I wouldn't listen to some stranger on the internet :)

(Hell, I wouldn't listen to me period)
 
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