Low oil pressure

If a new motor (327) has about 600 miles on it,runs great,good oil pressure on inital start (60lbs) but after it gets warm/idle drops to 10lbs. Rev motor and driving it's ok.......I just changed my oil to 20/50 VR1 Valvoline, is this safe? Thanks in advance!

 

Where are you sensing pressure from? It makes sense for the pressure to drop when the engine and oil warms up but that sounds like alot.

 

your sending unit should come off the intake next to the distrib. 60 is fine at start up.. 10lbs does seem a bit low at idle... what rpm is it idling at?

 

That sounds just like what my Buick does, I never really thought twice about it untill now you got me worried. It has always done that and I have about 2k miles on it so far.

 

A) What are your bearing clearances?

B) What oil pump are you using?

C) What weight of oil were you using before you changed it?

 

Loose cam bearing clearance can cause this, as well as other possibilities. Just that many don't think of the cam bearings. Of course if it was recently rebuilt should have new bearings. Probably worth verifying oil pressure measuring system is good first.

 

Loose cam bearings. haha

IF the bearing clearances are correct you are going to have to pull the pan of and hook a air hose where the oil pump feeds the main cap and look for your internal oil leak. It could be between the pump and main cap if someone ever tapped the cap on with a hammer, if you dont properly install oil galley plugs, the ones behind the timing chain, they will leak oil pressure in the engine and cause exactly what you are describing. There is a big difference between a rebuilt engine with 10 lbs at idle and a wore out engine with 10 pounds, Fix the problem before the crank is toasted.

 

you should be in the 35-45 range hot with a fresh motor

 

Engine is ok with 10 psi at idle so long as it jumps right up to 35-40 at 800 rpm or so.A lot of SBC's have low idle oil pressure...being a new engine and if the bearing clearances are ok,then the oil pump is suspect.Buy a better quality standard volume pump and try it.Running 20/50 oil in an engine with proper street bearing clearance shouldn't be necessasy.

 

I put a Melling pump in it, MV55, started the engine with 10/40 oil,ran it for about 2 hrs and drained it,then put Valvoline VR1 in it with a Wix filter......idles at 900,oil pressure gets better after a few turns on the idle screw.

 

I would verify with a different gauge first to make sure it really is that low.
Mine was similar - 10lbs at hot idle - which worried me. Had my local mechanic check it with his own external gauge and it was really more like 20.

 

My new vette motor was the same way, 10 psi at idle. I ended up installing a high-volume pump & problem solved. My idle oil pressure is now 30.

 

Thanks for the help.

 

Low oil pressure is a loss of oil somewhere! Find and fix it, dont patch it!

 

My 316 ran this way. 60 lbs while driving dropping to below 15 at idle. I was concerned until I looked it up and the manual notes that this is the normal range.

 

Gauge or sending unit probably faulty. I have a 327 sbc in my 39 ford ,stock oil pump ,45lbs cold start up .When hot at idle 20lbs .Going down road 40 to 45 lbs is my normal pressure. See if you have a tight wire contact on the sending unit. Move the wire on sending unit with engine running and watch gauge,if it is loose the pressure will change.My .02

 

Also ,I run straight 30weight all year round .40000 miles no problems

 

If the dude that put your cam bearings in put the oil hole on the top side this will cause a great loss of oil pressure as the cam bearings actually fit fairly loose. The cam is always getting pressure from the top side so the oil hole needs to be under the cushion of oil on the cam journal. I have seen this be a problem before >>>>.

 

Shamedevil,

There is some good advice here, you got to validate the accuracy of your gauge. Keep in mind if you have an internal lose of oil flow ie: gallery plug or bearing clearance exceeding tolerance you will have pre-mature engine failure. It is not going to get better as the engine gets more miles on it. By the way what is you water temp? Tim

 

as long as you have good oil pressure under load/ or above idle speed, you should be fine, you may consult a manual, which will most likely have a spec for oil presssure under different circumstances

 

before you "get too deep" into bearing tolerances, you may want to either use a different gauge, ive had problems with digital and mechanical gauges that were brand new. but also check a manual for a spec before trying to fix something that aint broke

 

I had the same problem with a 360 ci Mopar, two high volume oil pumps didn't help. Turned out the rear cam bearing was shot. I put in a new long block. Drove the car for 3yrs until I heard a banging while idling.

 

Temp is 195 on hot days on the street, 180 or less on highway......motor is still new and tight.

 

I failed to mention I have the stock SS oil gauge and a aftermarket gauge under the dash both hooked up in my 64 Nova SS,would this be giving a false or different reading?

 

Disconnect the stock one you might have a problem there, could be in the sending unit.