low oil pressure at idle

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glhx

glhx

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my 76 318 has no oil pressure at idle. it is a mechanical gauge. upon rev the oil pressure goes up 10 psi for every 1000 rpm. im getting 40 psi at 4000. then t goes down to zero at idle. so far i dont hear any noise and the dip stick looks clean of metal shavings.

worn bearings
worn oil pump
stuck pressure relief valve
bad gauge

any thoughts on this
 
glhx said:
my 76 318 has no oil pressure at idle. it is a mechanical gauge. upon rev the oil pressure goes up 10 psi for every 1000 rpm. im getting 40 psi at 4000. then t goes down to zero at idle. so far i dont hear any noise and the dip stick looks clean of metal shavings.

worn bearings
worn oil pump
stuck pressure relief valve
bad gauge

any thoughts on this
Click to expand...

You're not going to find shavings on the dipstick.
Change the oil, and cut open the oil filter.

If you're getting oil pressure as you rev it, you may have a clearance issue somehow. But do the cheaper thing first and check the gauge.
 
were is the perrsure releave valve cause my friend said cheys are by the oil filter ,but didnot remember if dodge had one behide the adapter for oil fliter. i have the allen head block in there but to other hole is open?
 
no oil pressure when cold. it was 50 when cold and when the engine warmed up stayed steady at 20 psi. i checked the copper line to the gauge for kinks and there are none. upon changing out the intake manifold i did find sludge in there.... i scraped it out under a shop vacuum hose to get it out but some may have fallen in to the pan. not saying this is the cause but it might help with the diagnosis. it was doing fine...i drove it and didnt notice the low pressure until later.
 
sounds like you may have a cloged pick up, if the gauge checks out, drop the pan and take a look see, when you rev it up, it's sucking the oil thru the blockage, don't ask me how I know.
 
After you check the guage Do the following.

Going OLD SCHOOL here!!

Since the motor is old and you say it has sludge in it I would put 2 Quarts of Transmission Fluid in the motor on top of the oil in it now and run it for a few hours. Automatic Transmission fluid is a VERY good cleaner and will help to get the SLUDGE out for sure! I do this on ALL of my older motors and at each oil change I run it for 15 minutes with the old oil. Drain the mixture and do the oil change like normal. You will be surprised at how clean it will make the inside of the engine! I would also run Straight 30 or 40 weight in it or possibly 20/50.
 
glhx said:
no oil pressure when cold. it was 50 when cold and when the engine warmed up stayed steady at 20 psi. i checked the copper line to the gauge for kinks and there are none. upon changing out the intake manifold i did find sludge in there.... i scraped it out under a shop vacuum hose to get it out but some may have fallen in to the pan. not saying this is the cause but it might help with the diagnosis. it was doing fine...i drove it and didnt notice the low pressure until later.
Click to expand...
I once bought a used Bronco, full of sludge, put some cleaner in it. The sludge went down and clogged the pick up, and spun a rod. You might pull the pan..And while in there, check some bearing clearances.
 
green1 said:
I once bought a used Bronco, full of sludge, put some cleaner in it. The sludge went down and clogged the pick up, and spun a rod. You might pull the pan..And while in there, check some bearing clearances.
Click to expand...

I have used transmission fluid on some REALLY SLUDGED out motors and it has worked EVERY time. I myself have never spun a bearing or anything like that. I am not saying that it can't happen but it has never happened to me. I have pulled the engines apart after doing this and you can not believe how clean it makes them, looks almost like new inside.
 
it stopped doing it. my oil pressure is now 45 at idle and when it warms up it is 20. i may have had blockage to the gauge.
 
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