72 318 Scamp. Low oil pressure 1 minute after startup.

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Imo since you haven to pull it anyway. Go ahead drop the oil pan and change the oil pump clean it as much as possible. My vote is also something stuck in the tube screen I'd say sludge has it stopped up
 
oldkimmer said:
If it’s scraping it probably has a bad bearing. Kim
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Oldkimmer makes a great point the scraping you heard may have been a bearing and not the flexplate!! In that case pull the mains and inspect the bearings and crank.
 
Scampi said:
Hi everyone. I recently bought a 1972 Plymouth Scamp with a 318 and 904 automatic. The engine/Transmission has to come out because of a broken flex plate.

I have a question. The engine starts up fine with no noises besides the flex plate scraping... ok I didn't run it for long. When the engine first started it has 50 to 60 psi oil pressure. Then about a minute later the oil pressure drops to about 5 psi! Any suggestions on what to look for when I take the engine apart? I did put new oil and filter in it after towing it home and the oil pressure was still the same. Going to try and pull it out this weekend for inspection. Any help would be appreciated.

P.S. Sorry for the dumb question. I have worked on a lot of Chevys but not a lot of Mopars so I am learning.

Thanks

Eric
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Check to make sure all the oil galley plugs are in... Especially the two behind the camshaft thrust plate and then the one at the back of the lifter galley under the distributor hole....

One method to trace the leak is to get an oil pump priming shaft and spin it with a drill... Gradually tear the engine down until you see oil gushing when you spin the pump with a drill --> that is where you are losing pressure...
 
Thanks everyone for all of the ideas kn the problem. The scraping sound is the flex plate. It has a chunk out of and it's hitting the edge of the bellhousing. I will post a picture here. I changed the oil and filter and put in dino 10-30. Oil pressure starts off at about 50 psi and the stays there for about a minute. Maybe it was 40 seconds. Then it drops to 5 ... maybe so I shut it down.

I am going to do a compression test today and a maybe cylinder leakage test too.
Do the oil priming test sounds like a ingenious idea! I have never heard of this before. When would I get the oil priming tool? Or just get a old distributor from the junkyard and hook my drill on to that?

Also when I pull the pan I will look for sludge, loose pickup, clogged pickup, bad oil pump/shaft and bearing clearances.

Is there anything else that I should check?

Also what weight/type oil do you normally run in a old 318. I live in Montana and it gets cold here but unless it's an emergency I won't be driving it in the winter. Here is a picture of my thermometer on March 9th. It was -29 F. It bottomed out at -31 about and hour later!

Thanks again everyone.

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10w-30 is fine. In the cold time of the year 5w-30. You can buy a oil primer shaft off of ebay, or summit, etc.
 
The quickest, easiest priming rod I have made is to get a 2' or 3' of 5/16" mild steel rod from the hardware store. Then with a machinist's hammer on a vise or other heavy metal block, just hammer one end into a hex shape and cut to desired length for the drill. Works fine. Pull the distributor and intermediate shaft and use the hex shape on that shaft as a pattern.

Does not have to be a perfect hex with the slow speeds of a drill. A typical drill's slow speed will be 500-600 RPM and that will be like 1000-1200 engine RPM.

You have to pull the intermediate shaft out first because it holds the gear that is meshed with the cam to drive the pump and distributor. So just an old distributor will not do. Pulling the intermediate shaft can be a bit tricky and may be eased by putting a loop of string around the gear on the top.
 
nm9stheham said:
The quickest, easiest priming rod I have made is to get a 2' or 3' of 5/16" mild steel rod from the hardware store. Then with a machinist's hammer on a vise or other heavy metal block, just hammer one end into a hex shape and cut to desired length for the drill. Works fine. Pull the distributor and intermediate shaft and use the hex shape on that shaft as a pattern.

Does not have to be a perfect hex with the slow speeds of a drill. A typical drill's slow speed will be 500-600 RPM and that will be like 1000-1200 engine RPM.

You have to pull the intermediate shaft out first because it holds the gear that is meshed with the cam to drive the pump and distributor. So just an old distributor will not do. Pulling the intermediate shaft can be a bit tricky and may be eased by putting a loop of string around the gear on the top.
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Very good cheap idea!! I love it!! What I was gonna do is use an old extra intermediate shaft and cut the gear off and then weld a longer piece of tubing on the end with and extension welded to the other end
But i like your idea better for one saves an extension for two saves my extra intermediate shaft. And some guys my not have an extra intermediate shaft to use!! And they are not cheap!! Great idea thanks for sharing.
 
You're welcome... I just had a scrap piece or 5/16" rod, and voila, it worked LOL. Took like 2 minutes with a hammer....
 
jimjimjimmy said:
just get a piece of 5/16 '' hex rod it can be had just about everywhere .
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I dont know if I have ever seen hexrod at the local hardware store but that is a good idea also!
What do you do with the other end just chuck the drill straight on the hex??
 
I think that I will order the oil priming rod today. Hopefully the engine and transmission will get pulled today so that hopefully will figure out what is wrong.
The inspection cover is missing. Probably had a hole in it when the flex plate broke. Does anyone sell these. Or is a junkyard my best bet?
 
Scampi said:
I think that I will order the oil priming rod today. Hopefully the engine and transmission will get pulled today so that hopefully will figure out what is wrong.
The inspection cover is missing. Probably had a hole in it when the flex plate broke. Does anyone sell these. Or is a junkyard my best bet?
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you can get one at the same place your buying that oil prime rod .
 
Grab the harmonic balance and push it back and forth to check thrush bearing, Excessive movement will cause converter bolts to scrape. If it moves alot do
a compression test before you remove engine to determine overall engine condition
and then ... formulate a plan.
 
dartfreak75 said:
Very good cheap idea!! I love it!! What I was gonna do is use an old extra intermediate shaft and cut the gear off and then weld a longer piece of tubing on the end with and extension welded to the other end
But i like your idea better for one saves an extension for two saves my extra intermediate shaft. And some guys my not have an extra intermediate shaft to use!! And they are not cheap!! Great idea thanks for sharing.
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I used an intermediate shaft and an old LA pushrod welded to it, I made it over 30 years ago.
The reason I like the intermediate shaft is it is round, and will not tear your shaft bushing up in the block.
Hex's can flex and you take the chance of destroying the soft bushing.

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Back to your oil pressure problem, if I read right, it dropped right after changing the oil and filter?
If so maybe the filter is defective.
 
He said he changed the oil and filter and the pressure was the same.... sounds like it made no difference.
 
Well if he going to pull the engine and trans, replace the bearing shells and new oil pump at least...New HV pump would be nice, if you find valve stem seals parts floating around the pan, pretty much know everything needs some attention...
 
Engine and tranny is out! I will inspect the engine tomorrow. The previous owner didn't know what a torque wrench was. Mufflers ready to fall off. Transmission is loosely attached to the engine. Grill is zip tied to the radiator support, etc.
My wife helped me with the hoist to get it out. She's a keeper.

Here are some pics.

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