Oil pressure in 340 need help

[BigTown3]

Hi,
I have a 340 Cuda. The engine was rebuilt by an engine shop in Texas and now I have having oil pressure issues. I was driving the cuda for the first time since the rebuild (about 3 years ago installed this spring) and the oil pressure slowly dropped as I ran the motor. I was not running the motor hard. I drove 5 miles and the oil pressure slowly dropped and then it was gone. I could hear the motor was running louder (More lifter noise). This lends me to believe the pressure did actually drop. I was reading the pressure on the rally tac gauge which was replaced new when the motor was rebuilt. I let the car cool down for 2 hours(90 degree day… I know it was hot not the best day for the first long drive) and started it again the gauge did not read any oil pressure. So…. I shut it down. I then took the oil out and removed the oil pan and can’t find anything obvious. I know there is an issue but not sure how to trouble shoot the problem. The oil pump replaced during the rebuild. I have run the car around the block many times( about 5) and the oil pressure has held steady. The first long drive (5 miles) I lost it. I do need help!! what do I do???
Thank you in advance from Denver. 70-B5-340-4 speed-Number matching

 

[Adam]

Maybe the oil pump shaft snapped. Pull the Distributor and use a large screwdriver to rotate the oil pump gear backwards and remove it for inspection...

 

[moparleo]

Also check the check valve spring in the oil pump, if you still have the pan off. There is a cotter pin holding the pressure valve on the oil pump body with a spring behind it. Some times they get stuck. Also you could have a defective oil filter.

 

[72*birdman]

Make sure they put the allen wrench plug at the end of the oil galley. you will have to pull the distributor to be able to see it. Had this happen to me.

 

[BigTown3]

Well. It looks like I had a piece of metal got into my oil pump. This broke the oil pump driveshaft. Now I shall be replacing the old pump and the driveshaft. I have one question. When I put the oilpan back on do I need to use a lot of oil pan gasket sealer or any at all ? I did buy the Fel-Pro oil pan gasket. So I guess do I need to use Gasket sealer with the Fel-Pro oil pan gasket?

 

[js29]

If it was me, i would clean all matting surfaces. apply a light coat of RTV siiicone to the oil pan after i know the flange is straight.put the gasket on the pan let it set with a few bolts through the holes so the gasket stays in place for 15 to 20 minuets. and then install the pan. fill the filter with oil, add oil in to the engine, and prime the pump.,

 

[Adam]

You may have other debris floating around; get a magnetic drain plug... I wonder how that metal got past the pick-up screen

 

[moper]

You should pull and inspect the bearings too. They are designed to catch debris and if there was a chunk that big in there - there's bound to be more. Not sure how the relationship with the shop is, but if they assembled it this seems like it's thier problem.

 

[VeteranCosmicRocker]

Check your oil pick- up, as well, make sure no metal is inside. I use Indian-head gasket cement for 45 years.. no leaks.