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Oil Pressure Chrysler LM318

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uniflite_27

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"Hey guy's, I noticed that

"Hey guy's, I noticed that my oil seems a little high, I'm using 10w30 oil, the idle is set at 700 rpm , the pressure reads around 40 psi at a idle , if I give it more throttle ( 2000 rpm ) it sometimes as high as 80 psi,now when I do this it is just at the dock, haven't tried it while under load yet, not sure if that would have any bearing on it. The manual says it should be at 20 psi at a idle. Your thoughts on this would be outstanding.

Thanks very much,
Gerald."
 
"wish mine went that high, not

"wish mine went that high, nothing to worry about, higher the better, although I would use a heavier oil, I use 15w 40 in mine, 10 w 30 might break down faster under load."
 
"..."the higher the better

"..."the higher the better"

Not so! You're beating the hell out of the distributor/ cam gears.

1. Are you sure the gage is accurate? Suggest using a mechanical gage as a test.

2. If pressure is that high, I suggest you go to a thinner oil, possible Mobil One or a 5W20.

Jeff

PS: Ran 90 pounds in my autocross car and had to replace the distributor cam gears on a regular basis."
 
"OK ! , I used a mechanical gu

"OK ! , I used a mechanical guage for the oil pressure, both engines read 45 psi@ 900 rpm , now once again this is just in neutral. What could cause the higher oil pressure? , or is this in the ball park, the manuel says it should read 20 psi and I think the rpm they use is 550rpm. For oil filters I am using Fram PH43, That type was on the boat when I bought it, could the type of filter have any bearing on the oil pressure.

Thanks yet once again,
Gerald."
 
"On initial start up the press

"On initial start up the pressure was @ 75 psi, then dropped to around 45 after a few mins. The engine temp was at about 160.

Thanks,
Gerald."
 
"Gerald,
Has something cha

"Gerald,
Has something changed? Did this condition just start? Same for both engines? Do you have new or rebuilt oil pumps installed? If so are they stock, high pressure, or high volume oil pumps?

I never had a Phram PH43 increase my engine oil pressure.

Fastjeff says thin up the oil. I'm with him on that as I've had an oil pump drive hex shear off on a 440. A stuck oil pump relief valve was the culprit. Can't see that with your situation though."
 
"Dave,

It seems to of chang

"Dave,

It seems to of changed since I did an oil change, when I bought the boat in the fall, at 2000 rpm the oil pressure was at 60 psi +/-, and that was under load. It seems when I warm it up to 160 and take it to 2000rpm and bring back to 900rpm, the pressure drops to about 45psi and stays it starts at 75 psi cold. Both engines do pretty much the same thing, the previous owner used 10w40 on the oil change I put in 10w40 with new oil filter, noticed the pressure high( for both engines ) so changed to 10w30, however didn't change oil filter again thinking it would still be ok. Would the idle be set high ( 800 - 900 ) reflect that high of pressure?.

Thanks again.
Gerald."
 
Possibly....What kind of drive

Possibly....What kind of drive do you have? My 300
stern drive doesn't like any idle over 650.
 
"I have velvet drive the boat

"I have velvet drive the boat is a 1972 Uniflite Sportfisher, however the boat is still tied up when it has been running. It has all happend since I did the oil change, that's I wondering if the right oil filter is on, I read that the pressure relief is set to the type of filter that is on the engine, perhaps I read this wrong. If anyone can tell me what they have on their 318's that would be great, they are 1970's vintage.

Thanks,
Gerald."
 
"Hi Jeff & Dave,

I know

"Hi Jeff & Dave,

I know when I changed my oil, it was pretty black !, is it possible the oil pressure was lower because the filter was part clogged, and now it has new filter and oil it shows higher oil pressure. Both engines are exactly the same for pressure, one person told me it may have high volume oil pump. I may sound paranoid, just don't want to blow any engines up, or damage them at all.

Thanks again guy's,

Gerald."
 
"Gerald,
Mopar Performance

"Gerald,
Mopar Performance books tells me 35-45 psi minimum @ 1000 rpm for new / rebuilt engine at startup. Does not indicate a maximum. Your oil pump relief spring tension should be in control of the maximum oil pressure seen. To me it is unlikely that both reliefs are stuck at the same point providing the same pressure. Rather they are set to that maximum via the spring pressure. A clogged filter should go into bypass and not restrict flow so I can't see a rise in oil pressure.
I think I would drop the oil to 5w20 as Fastjeff recommends.
You could try a different filter on one to see if that makes a difference and go from there. I'd be surprised to see much difference at all.
DS"
 
I have twin 1985 318. They bo

I have twin 1985 318. They both have always been at 80#
 
"i don't know if you want

"i don't know if you want any more info, but i agree with the more the, the better theory. In a car, there is no such thing as high oil pressure. Also, your idle seems a little high. Personally, my 69' 318 idles at 500-600 rpms. My oil pressure never goes below 60psi, and when i am running anything over 1500 rpms, the pres gauge is pegged at over 80psi. hope this helps."
 
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