Need help low oil presser

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mwls73duster360

mwls73duster360

Bad as Buddy Holly
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ok so i have a 360 changed my oil pump put high volume in it changed filter and put 10w 30 in it it reads correct on start at 40lb then drops down to right around 20 at idol like normal but after i drive for awhile and the oil heats up its reading like 8lb and can hear a lifter tick was told to just run like 10w 50 and it should fix it idk need suggestions of what it could be i also changed the oil pick up unit in the pan when i changed the pump :banghead:
 
while the pan was off...should have checked a few main and rod bearing....
 
sorry didnt add that i did check a main and it was fine no groves and still silver idk what oil was in it before but it had good pressure before i changed it i didnt check the rod bearings though
 
this motor was suppose to have been rebuilt a few years ago and not ran much from what ive looked at it seems realy clean and parts do look pretty new i changed the pump just for the heck of it when i did the oil change
 
It sounds like the cam and lifters are a little wore.
How many miles on the motor, etc
Why did you replace the oil pump? If it had no oil pressure before the motor may be just wore out and needing a rebuild.
And yes heavier oil can bandaid a problem, but will not fix it.

The small block in my duster will have a lifter tick when you first start it after sitting for a couple of months, but will clear up when it gets some oil, hot it only has 10 psi on the gauge, I consider this a wore out motor, but the FSM says 10 psi for every 1000 rpm and it has not came apart yet.
 
Did you dissemble the oil pump and clean it before install?
 
it was "suppose" to have a cam and lifter kit put in it and heads redone i took off a valve cover gasket and made sure they were torqued right and it all looks new in the heads too it had pressure before i changed it about 12 to 13 when hot the oil pickup was a little clogged with the rtv they used to seal the pan i replaced it and got rid of all the rtv cleaned it very well ran oil through it then checked again to make sure it was still clean put it all back together no leaks or anything oil still clean there was no rtv in the pick up line only in its filter
 
also dont know milage on motor but was told very little on since rebuild bought this as a project daily driver and its mostly driving me nuts lol spent easy over 800 making it a daily driver mostly on exhaust
 
Raise the idle rpm till it sits on 10psi hot and don't worry about it. If cold the oil pressure is only 40lbs you have something off,very loose clearance somewhere. 10psi at idle is fine as long as the pressure goes up quickly off idle to 50lbs or more I wouldn't get too shook up,if there are no other issues.
 
A switch to a high volume pump alone will not always raise the pressure. Maybe the engine was built to the high side of the tolerances and the pressure is what it is. I'd try a oil in the 15/40 - 20/50 range and see if it makes a significant difference. If it does, then it's just a little on the loose side and a long as you can keep 10lbs hot at idle and it still goes to 40ish with some rpm's, your probably ok for a while.
 
ok im confused was told it should start cold at around 40 then drop to 15-20 at warm idle which is what it is doing my problem is after i drive it and it heats up more not over heating though temp reads fine then it drops low like around 8 and it only goes to about 20 with rpms i was told 10lb/1000 rpms but it only does that when cold or just after warm idle after i drive say 5miles then the pressure drops
 
also just for info i dont drive the car right now because of this issue and even when fixed probley not very much i will be doing a rebuild my self on it in jan just so i know its all done right
 
I dont know of any gauge that is accurate enough to distinguish between 8-10 psi that is sold in the automotive world. Industry yes, but not automotive gauges.
You need aroud 10 psi at idle to presureve the bearings on the bottom end.
Ticking is the sign of low oil pressure.
If you rev it slightly does the tick go away?
 
lol im guessing at 8 cause its slightly below 10 the ticking actually doesn't start intel i rev it but when cold or just warm idle i can rev it and hold the rpms all day and oil pressure is great its just after it gets hot from driving
 
my road is out of the city and is 50mph store is about 4 miles away if i go to the store my oil pressure is fine all the way there and half way back then it drops and i can hear the lifter tick
 
run some valvoline 50 in it till you rebuild. if it still has low pressure with that in it rebuild time needs to be sooner
 
From what you've said, i would just drain and refill with some 20/50 and if it helps, drive it until Jan. and go thru it and make sure what you have at that point like you planned.......BTW, nice looking car you have :thumbup:.
 
thanks everyone i know its hard to know what to suggest with so little knowledge about the motor really appreciate the info this has turned out to be a bigger project than planned also found out after i bought the car its a 72 that they put a 73 bumper hood and grill on you can tell from fenders qtrs and rear bumper and vin and title of course tail lights however were replaced with these ugly leds when they replaced the sheet metal so in jan or maybe sooner ill be selling all those parts to get this back to a 72 lol
 
How many times has this engine seen 5500 rpm or higher? Ever?

The reason I ask is: I have seen many SBM with two separate but serious oiling problems.

I think you have killed your mains, and your rod bearings are next. The main oiling feeds that intersect the lifter galley probably were not drilled the right diameter the entire depth from the factory. I cannot believe how many times I have seen this. I use a VERY long 9/32" drill bit and drill EVERY block I come across now. The most recent 2 blocks took over 4 inches of drilling before I reached the main feed galley!
The hole IS there from the factory but it is too small and cannot supply the VOLUME (pressure yes) when that big main is spinning much over 5000 rpm.

The second problem is with the lifter bores themselves. The funky lifter angle causes the pushrod to constantly drive the lifter downwards into the valley wall side of the lifter bore. This wears out the bore into a an eccentric shape (egg) and causes a major oil leak (pressure loss). The only good news about this is that it doesn't really cause a problem for the bearings as the volume is usually still sufficient. It does however make you nervous when observing the oil pressure guage at hot idle. As long as the guage "acts" normal when revving it up, you are fine. If the guage reacts slowly and doesn't really get up to the pressure it should, you have problems elsewhere (mains).

Hope this helps J.Rob
 
Is it safe to assume you have a temp gauge and know its not running too hot ?
 
do you have at least a 7 qt. pan with that h.v. pump? could be sucking the pan dry especially if your pick up to pan distance is too much....
 
forced 340 said:
do you have at least a 7 qt. pan with that h.v. pump? could be sucking the pan dry especially if your pick up to pan distance is too much....
Click to expand...
I could not wait to read all the posts so I could jump in here and say the same thing... I put a H.V. oil pump in a 360 and did this just because my cousin wanted it, this was about 11 years ago.. this engine ran great before we changed the cam and new water pump.....
It had good oil pressure, the gage would jump to 50 lbs and ran great till he drove it to school 8 miles away and it started ticking and oil pressure dropped and some times bottomed out :-( we was thinking something got clogged up and he parked it at school.. as he was dropping his niece off to school.
he walked across the street and had breakfast and walked back to the charger and started it up and bingo! oil pressure was back to 25 lbs because the engine was still warm, drove it about 3 miles and the oil gage started jumping again :-( Well being smart enough to realize that the H.V oil pump was emptying the stock pan we put a new stock oil pump back in and to this day it runs great :cheers: Yes!! High Volume oil pumps will suck the pan dry and has to wait for the oil to return to the 5 quart pan.
 
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