360 Oil Pressure Issues

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MonkeyTrev

MonkeyTrev

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I have a 360 installed in my 65 Barracuda and it has been in the car for about 2 years now. I do not get to drive the car as much as I wish I could, but ever since I started taking the car out on the town I have noticed that my oil pressure gets quite low. When I first fire up the car oil pressure jumps to 30psi and holds steady for 15-20 minutes. After the 15-20 minutes the oil pressure begins to slowly drop off at a steady rate until it pretty much is at 0. The pressure will jump up if I throw some extra RPMs into the motor, but even then it only jumps 5 psi up and instantly goes back down. I am lost on what the issue could be. I bought the engine pre-built, but I tore it down to just a short block. It has a new stock oil pump, pickup, and pan. I think I might try a new gauge to see if possibly my current one is faulty. But other than that I am completely lost.
 
Put a dial indicator on the damper and see if you have a bunch of thrust bearing clearance.

If that’s good, change the oil and filter.
 
So it may have been an issue from the start
I would get a second gauge on there and see what it says, if it reads the same we may have an issue, and i would expect excess clearances in the bearings (but that would just be a wild guess)
 
diymirage said:
So it may have been an issue from the start
I would get a second gauge on there and see what it says, if it reads the same we may have an issue, and i would expect excess clearances in the bearings (but that would just be a wild guess)
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One of my fathers friends had mentioned to me before that it might have been an oil plug under the intake missing. I do not remember plugging any thing in the lifter valley before installing the intake. I did not know what he was talking about.
 
1..Try another gauge

2...Are you aware of the pitfalls of the oil gallery plugs, IE the one inside the rear of the block, and the one in the vertical passage coming up to the oil sender? You can check both without much work. Remove the dist, look down the hole, and verify the plug is INSIDE the block at the end of the gallery. The vertical one, you use a rod and measure down to it. I'll have to find the dimension.

3...Are you using the proper part number filter? There may be several that fit, but if they are not recommended for Ford/ Mopar you need to try "a correct one" 51068 Wix or equivalent "short" filter, 51515 Wix or equiv "1 quart" filter
 
No "aftermarket" gauges. Remove sender and install a mechanical gauge made for this purpose. Take readings cold and hot. If you confirm what you are seeing, then likely your engines bearings are worn out and it is time to re-build.
 
MonkeyTrev said:
One of my fathers friends had mentioned to me before that it might have been an oil plug under the intake missing. I do not remember plugging any thing in the lifter valley before installing the intake. I did not know what he was talking about.
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Screenshot_20210728-170122_Gallery.jpg

Plug goes into the back of the driver's side lifter oil galley run. If not in there it just dumps oil back into the pan.

Get another oil pressure gauge on it and see what you got.

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Easy thing to do is cut your oil filter open with a tin snips and see what's in there. Excess foreign material in there is not a good thing.

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When all else checks out good, it's the rods, mains, and cam bearings that hold the good oil pressure.

Low oil pressure, bearings are letting too much oil by to keep the pressure up.

That dial indicator on the from damper is a good way to check for excess end play ware on the main thrust bearing.
 
I too had a 360 over 35 years ago that was hot tanked and I was not aware of the plugs the shop removed during that process. It had good oil pressure on startup but would drop to next to nothing warmed up. It took awhile but I finally found all of the missing plugs in the oil galleys that were missing. Much effort and a set of bearings ,some welch plugs and all was better.
 
There is also the plug between the oil pressure feed by the distributor and the #5 main cap.
 

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340_duster said:
I too had a 360 over 35 years ago that was hot tanked and I was not aware of the plugs the shop removed during that process. It had good oil pressure on startup but would drop to next to nothing warmed up. It took awhile but I finally found all of the missing plugs in the oil galleys that were missing. Much effort and a set of bearings ,some welch plugs and all was better.
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Well I'm going to check with another gauge and I guess I will start looking for the missing plugs.
 
MonkeyTrev said:
So I can check for that oil plug by just pulling the distributor and looking for it?
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No, that plug you referenced, you check by inserting a rod down through the sender hole. There is a measurable dimension that you check

Plug BELOW, posted earlier by George Jets is checked via the dist. hole. You pull dist, shine light down, and you can see the plug sort of "sticking out" towards the rear plug

screenshot_20210728-170122_gallery-jpg.jpg


MEASURING FOR THE SENDER GALLERY PLUG:

From here:

Oiling problem. HELP!!!
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From post 28:

I have an engine going together in the garage. The plug above the rear main cap can be measured from the top of the block. Use a long (at least 10') small rod and place it in the hole on the rear of the block next to the disty hole. This hole is for your oil pressure gauge or sender. Mine dropped in 7.7" until it hit the plug. Someone on here said 7.5". Its an easy way to check without pulling the pan.
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The answers I found were sparce, the one above seems best. Seems that if the rod goes down further and certainly if it goes beyond 8", the plug is missing.
 
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I've also seen those symptoms when standard bearings were installed on a .010 under crank. No noises, just crappy oil pressure.
 
cudamark said:
I've also seen those symptoms when standard bearings were installed on a .010 under crank. No noises, just crappy oil pressure.
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Didnt someone do a youtube video on that recently ?
 
What oil are you using? If it's thin, i'd try a 40ish straight weight and see how it reacts. If it's much better, i think you may have a bearing clearance issue.
 
Regardless of the reason at this point, looks like you'll be pulling the engine back out to repair whatever's necessary. If all the plugs are there, you're looking at pulling the pan and checking the bearings. If any plugs are missing, you need to pull the engine to install them. :(
 
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