383 lost oil pressure

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gdbuick

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Hello,
I previously had a thread going "383 intake gasket and valve cover choice" but new issue so starting this thread. Just finished putting new intake gasket, oil/filter, new valve covers and a different carb. Two rides later lost oil pressure, was able to stop engine - just backed out of driveway hopefully before any other major damage as it just seem to start sounding a little off. Reading forum I pulled one valve cover so far and found #6 cylinder having one bent pushrod and one pushrod that just starting to go thru the rocker arm. Not sure why this happened unless old engine or spirted drive by my son. The motor came with the car but I don't no much about it. He did install a cam but it's basically a stock grind - I do have the paper work. I would like to get this back up and running if possible for a few more months of driving weather. Planning to build another motor this winter. My motor is a 68 383 not sure if I can use any parts from the 73 or 74 400 motor (the one in pics on a tire) assuming I just need a couple of pushrods and rocker arms as I just picked up this motor a few days ago ?

Currently planning on buying an oil prime rod for testing later and a new intake gasket as I assume I will likely need to go in there again. I also have a fiber optic light that can look inside spark plug hole to inspect for any damage.

Looking for advice what others have done to recover. Especially what parts I need to order and from where.

Thanks
Greg

383 bent push rod.jpg


383 rocker.jpg


400 used 73 or 74.jpg
 
If you decide to just replace push rods and rockers you don't need to remove intake.
 
If you lost oil pressure, you probably had a lifter pop out when the pushrod bent. You should be able to see that with a flashlight, when you remove the rocker arm assembly. And, you can use the rocker assembly, and pushrods from the 400. Just make sure the pushrods are the same length, and assemble the rockers on the shaft the way they came off after you clean them, and the shaft, including the inside.
 
If you decide to just replace push rods and rockers you don't need to remove intake.

Understood. Any thought which one went first? Trying to understand what went wrong in what sequence.
 
The stock rockers are known to punch through, but the bent one, and your mention of your son driving it, makes me think he might have over revved it. JMO
 
The stock rockers are known to punch through, but the bent one, and your mention of your son driving it, makes me think he might have over revved it. JMO

I looked down the bent push rod hole and it looks like the lifter is still in place.
If it’s still in place would I have zero pressure ? Or does the lifter have to be totally out to have no oil pressure ?
Cool on my recent 400 for possible parts.
Thks
 
Let's pull the other v/cover to inspect. Maybe someone else can help about the Why? The original rockers are known to do this. When you build the new motor I recommend replacing all the rockers- the Mopar replacements are stronger. Even better- my '68 383 resto motor has hydraulic roller cam and roller rockers more compatible with todays oils. Even though I don't understand the Why?, I would fix the obvious stuff and put it back together. When the new motor is built, pay attention to the proper push rod length.
 
Let's pull the other v/cover to inspect. Maybe someone else can help about the Why? The original rockers are known to do this. When you build the new motor I recommend replacing all the rockers- the Mopar replacements are stronger. Even better- my '68 383 resto motor has hydraulic roller cam and roller rockers more compatible with todays oils. Even though I don't understand the Why?, I would fix the obvious stuff and put it back together. When the new motor is built, pay attention to the proper push rod length.

Just took another look and the lifter with the bent push rod is up high out of its bore but not laying on its side. Almost like I could just push it back down. The one with the push rod thru the rocker arm is not in the lifter cup at all but the lifter is still in its bore.
I will pull the other cover for be safe.

Ordering the oil primer tool now and intake gasket in case I dive in deeper.

I fully understand better hardware for next rebuild. Planning aluminum headed 383 or 400.
Thanks
Greg
 
If this isn't your oil pressure issue, it's possible you sheared the oil pump drive.
Pull the distributor, after marking it's location, and the rotor location. Note the position of the slot in the top of the oil pump drive gear. You will want to put it back the same, to keep everything where it was.
Get a pair of long needle nose pliers, and grab the gear you see down there, and pull up with a twisting motion to remove the oil pump drive shaft/gear. See if the bottom tip is sheared off. But repair the valve train issues first. Then see if you have oil pressure. The lifter being part way up, could be uncovering the oil hole to the lifter, killing the oil pressure.
 
If this isn't your oil pressure issue, it's possible you sheared the oil pump drive.
Pull the distributor, after marking it's location, and the rotor location. Note the position of the slot in the top of the oil pump drive gear. You will want to put it back the same, to keep everything where it was.
Get a pair of long needle nose pliers, and grab the gear you see down there, and pull up with a twisting motion to remove the oil pump drive shaft/gear. See if the bottom tip is sheared off. But repair the valve train issues first. Then see if you have oil pressure. The lifter being part way up, could be uncovering the oil hole to the lifter, killing the oil pressure.

Okay, I will do that as I should have the tool to prime oil pump tomorrow or Wednesday. Lucky I just picked up the 400 engine to scavenge parts. Is it likely I will be able to push the lifter down and in its bore with a magnet and a screwdriver to release the magnet or something similar? Or I will have to take the intake off I guess again but no big deal.
Thks
Greg
 
The 'up' lifter is probably stuck a bit because of oilresidue build-up on the lower part.
With the lifter way up, oil pressure is lost through the almost 1" hole on the bottom.
 
I was able to pull the lifter out with a magnet examine it. It looked like it survived was able to put it back down in the hole. I removed some old rockers and pushrods off the spare 400 which I know nothing about. I have them side-by-side now the one with the tire wrap is in my 383 now with the bent pushrod. Although they look very similar on closer inspection the pushrod has a different dimple on outside (383 much larger dimple). Also the bottom of the rocker arm is also different in the center can I still use these? I can’t really tell where the pushrod sets in to the rocker if the recess is the same. I do see they don’t seem to have the same part number stamped on them. The one from the 400 engine is stamped I47 + The one from my 383 that I’m trying to fix it it’s kind of hard it’s some kind a triangle with the number in it so it appears. The pushrods from my spare 400 or the same length as my 383.

BC287B32-E8EC-4E08-8328-56E2B1CB011F.jpeg


E50D8015-B139-46EC-807E-AE1F06E7B9E5.jpeg


8085EB81-DFEE-4FA8-B43A-A3FFA4B6D200.jpeg
 
Update well I’m not sure if they’re the same exactly but I installed the 400 rockers and push rods in my 383. Spun the engine by hand a few times and the pushrods from 400 rotate just like any other pushrod to the touch so it looks like I might be OK. I have a mini starter. I don’t have the pump priming tool yet so I tried a few cranks and I instantly started seeing oil pressure . Should’ve changed my oil and filter first but but I will now. If this had been a performance engine obviously I would’ve changed oil and filter first. I’m sure I have a few metal particles in there from the push rod thru the rocker arm But I might just survive my sons likely first over reved engine.
 
Thanks For everyone’s help I couldn’t of got her up this fast without this forum!

For got to mention I did pull the other valve cover on drivers side and all was good.
Hopefully the rockers although different will work hopefully somebody will comment on that. Changed oil and filter and it started right up with good oil pressure (There was a few seconds where you could hear she was missing or filling a void with oil )but it went away in seconds. No ticking or other strange noises now fingers crossed.

35E6CBFA-25A6-4027-BF01-04217C6981EC.jpeg
 
Good to hear.
These rockers are def. not precision machined items, but the 400-rockers are most likely updated overtime and therefore have a different number in them.
I'm fairly sure they should be better than the 383 rockers.
 
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