Another Oil Pressure Question...sorry

-
N

Not-A-Duster

Member
Joined
Aug 13, 2012
Messages
14
Reaction score
0
Location
SF Bay Area
First off.. sorry for the novel :sad7:

I am having issues with little to no oil pressure at idle when hot in my 360. I have only had the car about a month or so. I drove it home the 250+ miles, and put maybe 250 other miles on it since. Everything was good until the oil pressure light started to flicker or come on at idle when hot (180-190).

I did the usual things. I went and got a mechanical gauge, and a new filter and 30w oil and got to work. On a cold start it is around 60-70psi then gradually lowers down with heat until it eventually reaches 0 or just above. It does always go up with with RPMs. I don't have a tach so I can't give readings per RPM. I don't hear any knocking or see any smoking and the temp is good. I did however start to hear some random noise but I don't think it is a knock. I thought it could have been a torque converter bolt backing out or something but those are all fine. Could it be something in the bottom of the pan like a bolt or something with the oil pump?

Here is a video that shows the pressure and you can hear the noise a little. [ame="http://youtu.be/WSUqnY1BZUQ"]http://youtu.be/WSUqnY1BZUQ[/ame] It is noticable around the 25psi mark in the video. The sound is bad. It does not always happen and not around the same PSI or RPM range. It seems totally random. I am not even sure these 2 things are related.

From all of the research I've done on here it seems that other than the gauge people say the the following.

Try 20w-50 and Lucas stabilizer. - Will this make that much of a difference from the 30w?

Cam/main bearings are worn or incorrect. - It seems like it just suddenly happened, although I guess it could be. The old oil and cut open filter looked fine.

Pressure relief valve stuck open. - Is this on a 70's 360? Looking here I only found the info about this regarding slant sixes.

Dented pan or clogged pickup. - I do see that there is a slight dent in the bottom of the pan. Could this be it?

Is it feasible to pull the pan with the motor in the car or should I just pull the motor? It is in a 73 Dart sport.


Other than that occasional tinking noise and what the oil pressure gauge says everything sounds/feels good in the car. I was hoping to drive this car around for a while so I could take time getting some things together for a rebuild down the line. I really hope I'm not forced into parking the car until then. Any suggestions would be greatly appreciated. Thanks for the time guys.

Edit - Here is another video of the noise. It is hard to tell where it is coming from. [ame="http://www.youtube.com/watch?v=vxZ1RDuZiGk"]http://www.youtube.com/watch?v=vxZ1RDuZiGk[/ame]
 
The Rattle sounds like an exhaust rattle to me or something under the car not the engine.

As far as the low oil pressure. Try using some thicker oil 20/50 or straight 40wt and top it off with some Lucas Oil Stabilizer. Seems that your bearing clearances are going away.

The 60-70psi when cold is normal and the lower oil pressure at Idle is normal also. My Fresh 410 Stroker use to have 80-90psi Cold and around 12-18psi when warmed up at Idle. Cruzing at 65 MPH it would keep 50psi warm. This is normal.
 
The rattle could be an exhaust rattle. It could also be coming from the dust cover on the trans (i.e. converter bolts hitting it, or just a bad harmonic at that RPM that causes the cover to vibrate).

I would try thicker oil first (20-50), but if that didn't help I would say pull the pan and inspect/replace the oil pump.
 
Could the oil pump be going/worn? Cold oil, the pump will have better pressure at idle, once it warms up, it won't work as well until the RPMs come up. I would think a dented pan would restrict the oil no matter what the RPM.
 
DJC said:
Could the oil pump be going/worn? Cold oil, the pump will have better pressure at idle, once it warms up, it won't work as well until the RPMs come up. I would think a dented pan would restrict the oil no matter what the RPM.
Click to expand...

The only way that a dented pan will restrict the oil is if the pan is smashed up against the pickup. Usually if the pan is hit that hard there would be a hole also. Or the pickup would twist up on the treads that are in the oil pump. I doubt that is the issue here.
 
I had a similiar problem on the first small block that I built. 20 psi cold start and under 10 at idle.


Turn up the idle until you get enough oil pressure... LOL!!! (just kiddin)


My problem turned out to be the machine shop that hot tanked it did not put the oil galley plugs in the holes behind the camshaft thrust plate. You have to remove the camshaft thrust plate to see them.

They are an odd size plug, not every parts store will carry them. However the Mancini Racing freeze plug/galley plug kit has these. They also carry them seperately.
 
If thicker oil helps, it just confirms your main/rod bearing clearances are excessive, or you pressure relief valve is not seating. I wouldn't however consider thicker oil a "cure" for you problem. Remember that the term "viscosity" describes a liquid's resistance to flowing. So yes, you may have 60-70 PSI cold, but that really means nothing especially considering your pressure relief spring is set at 45 PSI or so. What you're seeing there is oil that is so thick that it can't even flow through the bypass. Do you think it's getting to the rocker arms?

At some point you will need to remove the oil pan to inspect the pump and bearing inserts on this engine. It could be something as simple as a bit of crud holding the bypass open, which may free itself in due time. But an engine moving enough crud to cause the valve to stick has probably moved enough to trash the bearings.

The owners manual even says it's "normal" for the oil pressure light to flicker at idle. The engine really does not need much pressure at idle with no load on it. If the lifters aren't banging, whatever oil pressure you have is "adequate". I would be more concerned about what it is cruising at a steady 30 MPH (1500 RPM or so in high gear).
 
if you have at least 10 lbs at idle with engine at operating temp , and it increases with rpms , and it isnt making a racket , drive it. if it is making internal noise and you have less than 5 lbs at idle, personally, i would be yanking it out
 
Thank you everyone for the input. Yeah it does have less than 10. It's pretty much at 0. I will try 20w-50 and lucas stabilizer. If that doesn't help the car may go up for sale as is :(
 
this may sound stupid but is the fan flexing at that rpm and hitting sumtin like a shroud or the rad as far as oil pressure goes one can only guess until its been apart but the oil pump would be a good start
 
I had the same issue on my 360 magnum. You can try a new oil pump, maybe a high volume one would help a bit (I gained around 5 psi when hot) and thicker oil, but I bet your bearings are worn out. It took 200 miles before I spun a rod bearing... I was lucky it didn't get more damage
 
Motors are so cheap. It'll probably do 10,000 miles before it lets go, and even if it puts a leg out of bed, what's a running 360 worth from a wrecker? Don't sell the car - drive it and enjoy it!
 
ValiantHardtop said:
Motors are so cheap. It'll probably do 10,000 miles before it lets go, and even if it puts a leg out of bed, what's a running 360 worth from a wrecker? Don't sell the car - drive it and enjoy it!
Click to expand...

Yeah you are right. I will try the 20w-50 and lucas stabilizer and drive it till it starts knocking or something. Hopefully the new oil and lucas product will get me 10psi at idle. At the least I hope it gets it off of the peg.

Thanks for the feedback guys. I swear I have been members of many racing and car sites for years and you guys are by far the most helpful and friendly out of all of them. I really appreciate it. Honestly it makes me like mopars even more.
 
If you decide it is the bearings, I think you can change them in the car by pulling the oil pan, at least I did so in my C-body w/ 383. You might have to jack the engine up a bit. The trick is to push the top cap around to pull it out. I cleaned all the oil with a rag soaked in gasoline so no risk of the new bearings spinning in the block. Also change the rear seal similarly using the newer design of two piece rubber.
 
You must log in or register to reply here.
-

Back
Top