Oil pressure in a 360

[PhattyX]

Well, I've been having some trouble keeping Oil pressure in my AMC 360. It starts up around 55psi and drops down to ~25psi when it's warmed up. That doesn't sound right to me. However, I just read an old post from Redrooster that seemed to suggest that starting at 60 and dropping to 25 was OK / a good thing.

That being said, am I running alright at 25?

-X

 

[88Wrangles]

RE: A need for all us computer users

yes, that is quite good.

It starts off high because the oil is cold and thick...then the pressure drops because the oil warms up and gets thinner, which means it flows easier and creates less pressure.

 

[Sparky-Watts]

Yeah, what 88 said.....

 

[LVRockCrawler]

if it drops below 10psi or so then you'd want to start checking the mains or the pump out - 25 hot is real good for an older mill... had an old ford 390 that went to about 7psi when hot... yea... it was a REALLY tired motor!

 

[88Wrangles]

RE: NOT STARTING CORRECTLY (ignition switch) question HELP!

And just to add something else, my 2000 Yukon Denali idles at 20 psi when it's warmed up. At full throttle, it is at about 65 psi or so if I remember correctly. My '74 Chevy with a new 468 idles at about 25 when warm and 60 when cold...and that's with brand new everything, including oil pump, guage, etc.

So yes, don't worry at all.

 

[PhattyX]

Sweet! Thanks for the input guys. That's one more thing I can mark off my list.

-X

 

[jps4jeep]

RE: Hood Vents?

Thats very good if it is a older engine. The 305 in my 92 chevy with well over 150K mile on the original block runs at 35, and drops to about 10 at warmed up idle, been doing it for a long time.

 

[redrooster]

RE: Hood Vents?

For a 304/360/390/401, I would look to replace the oil pump housing and gears when the oil pressure gets below 15psi at idle. You probably already know this, but the oil pump housing/timing chain cover/water pump plate/distributor mount are all the same piece of aluminum. The housing for the oil pump is machined into the aluminum and has two steel oil pump gears rotating in there. Whenever small particles pass through the pump it scars the aluminum walls of the pump. The more scarred the pump walls are, the less oil pressure it will make.
When you get ready to replace the housing, I would highly suggest a new unit rather than used one unless you are an expert at building pumps and know the proper clearance of the gears to the housing and are able to lap (surface) the gear cover plate. You may likely get a used one and be in the same boat you were in before.
I think 4 Wheel Drive Hardware has the best prices on new ones at around $259 or so. You can also buy new Melling pump gears from them. The actual swap is not that hard, you just have to pull the water pump, fan and all off to get the thing out.

 

[cymbash]

Re: A need for all us computer users

yes, that is quite good.

It starts off high because the oil is cold and thick...then the pressure drops because the oil warms up and gets thinner, which means it flows easier and creates less pressure.

what grade oil are you using,

 

[carnuck]

Make sure it doesn't have an orange filter on it!