fresh engine blowing oil filter o ring on start up
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big block
Well-Known Member
I did test it with a drill before startup. It ran over 50 lbs of pressure and blew the oil filter o ring out just priming the motor. I reused a melling high voluem oil pump. It was running on a motor that broke a piston and split a cylinder wall. The pump only had about a thousand miles on it if that much.
I drilled 2 holes in the mounting plate and put on a wix filter. same result. It blew the o ring again. this is the 4th filter.
Next question is can you pull a 360 la oil pan without pulling the motor? It is in a 1994 plymouth duster front sump pan.
Anyone got an original front sump pan and pickup for sale?
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Grumpy Old Man
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What the heck is a 1994 duster with a front sump pan?????
You still never told us how much oil pressure it has on start up when the gasket blows out. 50# shouldn't make that happen. If it pegs a 100# gauge I'd bet you have a stuck pressure relief valve in the oil pump. Especially if the engine grenaded. Any metal big enough to go through the pick-up screen will get in the pump and relief valve.
big block
Well-Known Member
Didn,t mean to hurt you thought pattern, but a front sump oil pan is one with the sump for the oil pickup is in front of the motor. Trucks use a rear sump pan for the oil pickup. Older cars use a front sump.
big block
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Guys I,ve run out of ideas so I guess I,ll pull the pan tomorrow and install a new oil pump. I think I,ll go with a stock pump and see how it works. I appreciate the input.
big block
I agree 100% with this.
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Well, not to hurt your thought pattern either, but mopars use a mid sump pan..... trucks use a rear sump, and real early trucks used a front sump. I have NEVER seen A a body mopar with a front sump pan.
big block
Well-Known Member
It never gets to max oil pressure because it blows the o ring out of the filter then looses all pressure.
big block
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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Hang on
There is a cup-plug just upstream from the pump. It's purpose is to separate the oil coming from the pump, that is going to the filter , from that going to the mains, after leaving the filter. So it's a re-direct.
There is a shoulder in the end of the passage, against which the cup is supposed to stop, during the install.
What if;
What if that plug in not in the right place, but has been driven up too far? Then it could be a restriction or a complete blockage, depending on where it sits.
That plug is only accessible by removing the pump.
However, you can prove that the plug is probably in the right spot, by checking for oil-flow out the oil pressure sender passage. However, I think it would be prudent to put a large diameter hose on there and direct the flow back into the crankcase, or,if you want to measure it, into a container in a way that the hose cannot come loose.
Pulse the trigger,
you're no longer looking for pressure, but rather flow. You may have to test with a thinner fluid.
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Got to be a reason why the pump is building so much pressure. You could put the pump in a bucket and if the relief valve is stuck it will build pressure until something blows.
AJ/FormS
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I agree, but if that passage is plugged/restricted, and even if the relief valve was correctly functioning, It would not take much pressure to blow the filter off, oil is not compressible, and I bet the pump has enough reserve to blow it, and not enough bypass capacity to prevent it. But of course I have never tested it so it's just a thought,lol.
and the test is easy and quick.
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That is a possibility. There are a lot of "leaks" in the oiling system to reduce pressure once it builds up. . We will see when the OP replaces the pump. I still can't believe if the pressure relief was working properly the pump wouldn't build enough pressure to blow the filter. Time will tell. It's another one of those issues that is hard to diagnose over the internet.
yellow rose
Overnight Sensation
That plug doesn't affect pressure. If you leave it out, the pressure doesn't change. I'd have to get the drawing out and look, but I don't think it would ever make a pressure difference.
Ah, inquiring minds want to know! Let us know what you find.
AJ/FormS
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if someone drove that plug in too deep .........The oil flow would stop right there, and the pressure would instantly rise, and POP goes the filter.
I've only ever replaced that plug once, and I carefully measured the distance to the stop. But the plug stopped when it hit that ledge, anyway. I can't imagine the force it would take to drive that plug any further.
And I'm not saying this is OPs problem. I'm just suggesting this is an easy, quick test. Just pop the pressure sender and watch the geyser flood the hood, and everything else too. The sender only measures pressure, and not flow, so it could read the pressure accurately, yet with the flow nearly stopped up, My opinion is the pressure relief inside the pump can only bypass so much,and if it's not enough then the filter is the weak link.
I mean the drill is what rpm 750, maybe 1000,so that's equivalent to double that in engine rpm, and at 10 psi per 1000, there should only be way less than bypass pressure there. There has got to be a stoppage somewhere upstream of the filter,and/or not far down the oil-gallery, else the bearings would be leaking it out. That cup-plug was just my first thought.
Yeah you can leave it out, and then you can take the filter off too and just put a plate there, for all the good the filter would then do.
I've only ever replaced that plug once, and I carefully measured the distance to the stop. But the plug stopped when it hit that ledge, anyway. I can't imagine the force it would take to drive that plug any further.
And I'm not saying this is OPs problem. I'm just suggesting this is an easy, quick test. Just pop the pressure sender and watch the geyser flood the hood, and everything else too. The sender only measures pressure, and not flow, so it could read the pressure accurately, yet with the flow nearly stopped up, My opinion is the pressure relief inside the pump can only bypass so much,and if it's not enough then the filter is the weak link.
I mean the drill is what rpm 750, maybe 1000,so that's equivalent to double that in engine rpm, and at 10 psi per 1000, there should only be way less than bypass pressure there. There has got to be a stoppage somewhere upstream of the filter,and/or not far down the oil-gallery, else the bearings would be leaking it out. That cup-plug was just my first thought.
Yeah you can leave it out, and then you can take the filter off too and just put a plate there, for all the good the filter would then do.
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I wish I was accused of that! Just once in my life!
big block
Well-Known Member
does anyone have a diagram of where this plug is located. can you see it with a light when the oil pump is removed? is this something the machine shop would look at or work on because this block is one I just bought and sent to the machine shop to be cleaned, cam bearings installed and just honed. so I don,t know the history of the block before this. This plug you speak of is it the one that holds the pressure relief spring in the pump or it it mounted in the block? if so will I have to remove the main bearing cap to see it because the pump mounts to the main bearing cap?
Thanks for the intrest guys.
big block running a small block for now.
The plug everybody is talking about is straight down below the oil pressure sending unit. You can take a long rod and stick in there and it should be approximately 8 in below the China wall.
When you had the adapter plate for the oil filter off of the side of the block was the screw-in plug in the passage underneath it. Or has it been left out.
When you had the adapter plate for the oil filter off of the side of the block was the screw-in plug in the passage underneath it. Or has it been left out.
big block
Well-Known Member
The screw in plug behind the plate is installed. This plug everyone is talking about. How can it be replaced and why would anyone fool with it to begin with? Is it something the machine shop would do while they had the block? I sure haven touched it. The block was a complete engine when I got it so no one had messed with the plug before. only time it could have been changed or adjusted was while it was at the machine shop.
if a block is tanked or baked a lot of times machine shops will drive that plug out and replace it. But the only way to replace it is to drive it down from up above out through where the main cap is.
What year is this car?
What year is this car?
big block
Well-Known Member
The car is a 1974 duster. Original slant 6 then 318 and this is the second 360 engine which is a 1978 bored .060 over. Where would I get one of these caps and can I drive it out with the crank still in place? How far down in the passage is the plug driven? I,m really trying not to have to pull this motor out of the car.
on a 72 Duster I had I dropped the center link for the steering and unbolted the pan 2 pull it right off to change my oil pump.
If you take the oil sending unit out and just took A-Rod and stuck yet down there and measured it should measures around 7 and 1/2 to 8 inches when it hits that cap.
When you have the oil pan off and the oil pump off you would remove the rear cap and from up above drive that plug out downward.
When you go to install the new one it drives in until it hits a seat and it will stop.
If you take the oil sending unit out and just took A-Rod and stuck yet down there and measured it should measures around 7 and 1/2 to 8 inches when it hits that cap.
When you have the oil pan off and the oil pump off you would remove the rear cap and from up above drive that plug out downward.
When you go to install the new one it drives in until it hits a seat and it will stop.
RAMM
Well-Known Member
Oh boy is this getting convoluted and fast. It ain't the plate not having enough holes, it isn't a plug that is out or driven in too far. That plug that is being discussed seats on a shoulder or ledge where the hole necks down to a smaller size. Very hard to drive past it's intended position. It's your relief valve in the oil pump. When you can blow the oil filter o'ring when priming it is always the pump/relief valve. Don't waste anymore time chasing anything else. Seen this more than a few times. The last time it was on a 440 and that was a 10 minute job to remove the relief, polish it, re-install and get running. J.Rob
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