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  #1  
Old 04-02-2003, 04:39 AM
aspenextreme aspenextreme is offline
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Default low oil pressure-help!!!

ok guys im in need of some help- i built a 360 10.5 to 1 pistons-2.02 heads and 280 480 cam. it was built in the late 90s and i had all but forgotton it. last summer i put the moter in a dodge aspen and i fired the car up, and no oil pressure, i thought maybe there was air in the gauge line and started it up a couple of times aND no oil pressure. so i pulled the pan and oil pump, and found a plug in the oil hole under the oil pump. took the plug out(kinda looked like a freeze plug, and put the pan back on. i had oil pressure- then on my first drive , the oil pressur went down after the car warmed up. took the pan off and took a main cap off and it looked really worn. so my guess is that i screwed the crank up with the dry starts??????? is that all i did????? if all i need is a crank, and bearings , can i just have this one fixed????
please help.
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  #2  
Old 04-02-2003, 10:16 AM
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amxauto-x amxauto-x is offline
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If the cranks is scored then you would need to polish it or have it ground. The rod bearings will look the same as the mains. The piston skirts may be scored/galled a little also. Look at the skirts that are sticking down low enough out of the hole to see if there is any scratches on the skirts. Look up into the cylinders that have the pistons up high to see if there are any scratches on the cylinder walls. Turn the crank so you can check all pistons and cylinder walls. Then take out the crank if it needs to be polished or reground. If you are real lucky the pistons can stay in. Look up at the cam also. Maybe take the cam out to look at the cam bearings from the underside, looking for wear in the bearing material. What kind of material was in the bottom of the oil pan?
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Old 04-02-2003, 08:39 PM
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It would be cheaper and quicker to just order a crank kit from the local parts store, like Advance Automotive. I bought one a couple summers ago for about $150. Turned .010 Make sure you check the tolerances on those cranks. Plastigage is so cheap, its not funny. Just takes twice as long because you do everything twice. Look for clearances in the .0015 to .002 range. Any looser or tighter may result into things like low oil pressure with a stock pump. If around .0015 take it easy for the first 3000 miles or so. By the time you pull the crank have it turned by the bearings it will probably cost you more and the turn around time will be longer too.
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Old 04-02-2003, 11:57 PM
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66Dart_GT 66Dart_GT is offline
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Default Opps!

There are several small plugs that plug off the passages in the block, I belive there is one under either the front or rear main bearing cap the most people forget. I wish I could remember just exactly wich main but that will dump all the oil pressure.

You are going to pull the engine, so it won't be that tough to find. Please let us know what you find.


Regards

Gt
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Old 04-03-2003, 07:24 AM
SB Racer SB Racer is offline
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The reason is just that loosened plug you said you took out, the same 66GT is talking about. It's hidden in the main galley in the rear main above the oil pump. Not enough pressure without it in the engine, a lot of pressure on the builder...
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Old 04-03-2003, 11:10 AM
aspenextreme aspenextreme is offline
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does that mean i shouldnt have taken it out? your right though it was under the oil pump, and it was just like a freeze plug. i actually had to drill it out. right after i pulled it , the oil pressure was fine till it got real warm. id say 70 pounds down to almost 0 once it warmed and idealing.
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Old 04-03-2003, 12:35 PM
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I have a question???

did you prime the oil pump before you started the engine???

if you didn't prime the pump you could have wiped out the bearings.

If I were you I'd just get another set of bearings some strips of emery cloth polish the crank as good as you can. Put the bearings in and plastiguage them. Like the guys said .002 is ok and you could get away with up to .003 but your getting to the extreme. I've had engines still knock at .004. There is core plug under the rear main bearing cap. If this isn't there you'll starve the rods of oil. There are also core plugs under the oil filter plate (if these aren't there you'd get no oil pressure). and there are core plugs under the cam plate (missing these will cause pressure to drop when it's warmed up).
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Old 04-03-2003, 01:49 PM
Billydelrio Billydelrio is offline
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If the plug above the rear main is missing, then the oil filter will be by-passed. That plug should have been up in the block a wee bit and I thnk it is a 9/16". If you pulled out a 5/8" plug, then the wrong plug was put in during the rebuild and not pressed in far enough.
Billy
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Old 04-04-2003, 02:12 AM
aspenextreme aspenextreme is offline
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sorry guys , the plug im talking about was like a freeze plug-thats not what your talking about , right? i got the motor out and ill be putting it up on the stand tomorrow. ill know more then .
thanks for all the help.
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  #10  
Old 04-04-2003, 09:03 AM
Billydelrio Billydelrio is offline
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Default Oil passage plug

With the motor out and rear main cap off, slide a 12" or longer rod down the oil pressure sending unit hole. If the rod pass all the way out the bottom, then the plug is missing. This plug seperates the inlet from the outlet of the oil filter passage to the main oil supply galley. It installs from the bottom. The bottom of the block is step drilled above the rear main cap. I do believe the plug slides in freely for a couple of inches in a 5/8" bore and then presses into a 9/16" bore against a 1/2" bore. The plug presses into the hole and bottoms against the 1/2" bore step. It will be located between the inlet and outlet intersections of the oil filter passages. If the plug that you removed is not this plug, then someone mistakingly put a plug where it should not have been.

Good luck
Billy
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  #11  
Old 04-04-2003, 09:09 AM
Billydelrio Billydelrio is offline
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Oh yeah, the plug I am referring to is normally a solid plug, but at times I have found the hollow "freeze plug" type pressed in hte hole. I always remove this plug when cleaning a block. Oh, I try to remember to put it back also!

Billy
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Old 04-04-2003, 10:42 PM
rustycowl rustycowl is offline
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Default yup

What Billy said! I don't think leaving it out makes much difference in oil pressure, just filtering the oil. But that's pretty important too, especially on a newly rebuilt engine! I'd pop the pump apart and clean it thoroughly, inspect it and reassemble it carefully. Rotate the inner rotor by hand and suck up some vaseline into the body before you reattach it. Like JV suggested, leave out the quill shaft and prime the engine in the car, first, with a primer -shaft just before starting.
There are several more plugs that need to be installed correctly, and I 'd double chk those, too.
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Old 04-05-2003, 12:32 AM
aspenextreme aspenextreme is offline
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i just tore the engine partially apart and i havent checked the plugs yet, but i looked at all the mains and rods. the mains are screwed-it gets worse as you go to the front of the motor. all the rods are perfect. ill post more when i know more.
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  #14  
Old 04-05-2003, 12:38 AM
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66Dart_GT 66Dart_GT is offline
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sorry to hear that, good luck.

jn
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  #15  
Old 04-09-2003, 02:27 AM
aspenextreme aspenextreme is offline
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you guys were correct, it was the plug under the rear main cap.
it wasnt installed correctly. the plug was blocking off the main oil supply off the pump- not far enough in. then when i drilled it out it was bypassing the filter, or atleast it wasnt seperating the inlet from the outlet.
that combined with the dry starts ruined my crank, but hopfully thats all it needs and ill be back on the road.
thanks guys.
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