lost oil pressure

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strad

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I've been running my 340 for about 200 miles and she's been doing real good. I had had a privious oil pressure issue and had solved it by replacing the oil pump, Now, all of a sudden (after a jack rabbit start) the oil pressue went way low 5-10psi, and the valvetrain is not oiling properly , rattling. We dropped the pan and the oil pump seems good, but in looking up into the cam journals it looks as though one of the cam bearings is out of the journal about 1/16". WE plan to replace the oil pump again just for peace of mind but also have these questions:
1. Does this sound like an oil pump problem, i.e pressure relief valve?
2. Is it possible to spin a cam bearing to lose oil pressure and what in the world would cause this? and if so how do you fix it?
3.any other thoughts?
 
Sounds like the pressure spring stuck open in the oil pump. Had it happen to me in a very simular condition. Remove the pump. disasemble it and clean it real well. Make sure there is nothing in the bottom of the pan that could get sucked up and couse a repete and use rtv very sparingly so a chunk dosent break off and cause this to happen again.
 
I don't know why the cam bearing would work itself out of it's bore but if it did that could cause your problem. The cam is the last to oil in the block before the oil is sent to the heads. The oil pressure sender is on top also. The cam bearing is probably blocking off the oil to the heads and the top of the block that's why the upper end clatters and your oil pressure gauge reads low. I would pull the engine and take it apart to check for damage. Pay close attention to how the cam bearings fit and make sure the plug down in the distributor hole is installed properly and tight. If that plug wasn't replaced after the block was cooked (boiled before machining) you could have low oil pressure problems also. Good luck and keep us posted. Toolmanmike
 
take it apart... you need to knoe why the cam bearing came loose. Was this 200 miles after a rebuild?
 
if it is sticking out almost 1/16'' then it is getting fairly close to the lobe that is all most ceartinly your problem blocking that oil galley
 
toolmanmike said:
I don't know why the cam bearing would work itself out of it's bore but if it did that could cause your problem. The cam is the last to oil in the block before the oil is sent to the heads. The oil pressure sender is on top also. The cam bearing is probably blocking off the oil to the heads and the top of the block that's why the upper end clatters and your oil pressure gauge reads low. I would pull the engine and take it apart to check for damage. Pay close attention to how the cam bearings fit and make sure the plug down in the distributor hole is installed properly and tight. If that plug wasn't replaced after the block was cooked (boiled before machining) you could have low oil pressure problems also. Good luck and keep us posted. Toolmanmike
Click to expand...
Happened to me, too, the cam bearing loosened on a 440 a long time ago.
 
I found crack in a cam tunnel assembling that way.. the ebaring went in too loose. The crack was missed by magging. Cost me a std bore block and some cash to replace the block for the customer.
 
strad said:
I've been running my 340 for about 200 miles and she's been doing real good. I had had a privious oil pressure issue and had solved it by replacing the oil pump, Now, all of a sudden (after a jack rabbit start) the oil pressue went way low 5-10psi, and the valvetrain is not oiling properly , rattling. We dropped the pan and the oil pump seems good, but in looking up into the cam journals it looks as though one of the cam bearings is out of the journal about 1/16". WE plan to replace the oil pump again just for peace of mind but also have these questions:
1. Does this sound like an oil pump problem, i.e pressure relief valve?
2. Is it possible to spin a cam bearing to lose oil pressure and what in the world would cause this? and if so how do you fix it?
3.any other thoughts?
Click to expand...

I had a similar problem this week, it turned out to be a bad oil filter... only had the thing a week... it was a pure one filter, which I heard are supposed to be good... put a wix on today and the problem went away.

probably a long shot, but worth trying anyway?

-j
 
Found the problem of lost oil pressure. A rocker arm was busted in two.Never had this hapen before, but on close inspection you could see where the rocker arm was defective and had a hairline crack before it separated. FYI I could hear the valves clattering on one bank and that is how I noticed the problem , no lfiter no oil pressure, this is very unique happening for a MOPAR, but luckily there was no major engine damage.
 
If you havent looked, you dont know if there was damage. I've had roller lifter pop out of bores due to valvetrain failure. The pressure loss caused the engine to eat a few bearings. It didnt require machining, but there was damage. the only indicator was about 5 less psi at idle. Then it started to knock.
 
Buddy of mine popped out 1 lifter after rocker adjuster broke, lost oil pressure, he put her back together after replacing the push rod and rocker and proceeded to tear up the crank. He to thought everything was good to go also and he was wrong. If he had inspected the bearings he would have saved the crank. Morale of the story, Murphy is alive and well, don't give him the opportunity to bite ya in the ***. Tear that engine down.

Terry
 
That was also the reason I wont build a roller cam engine without lifter bore bushings.
 
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