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1933/34 oil system questions??


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Let me first set the stage.  After using ply33's site to decode the engine serial number, it appears that I have a '34 PF standard in my '33 PD.


When I brought the car home in September, I drained the oil and refilled as a precaution.  I am preparing to change the oil again after driving the car several trips and putting almost 30 miles on it while making adjustments.  I plan to drain the oil, drop and clean the pan and pump screen.  I thought of possibly flushing the oil system, has anyone done this on these engines and is it safe?


When ordering the pan gasket, is there a manufacture or gasket type that is better than others?  Want to make sure that I order the best gasket, as I do not plan to drop the pan again in the near future.  When doing this, is there anything I should know ahead of time or look for once it's dropped? 


Also, since I have no idea when the sealed oil filter was changed last, I would like to replace it.  I can locate the sealed replacements for around $45 but was thinking of switching to the replaceable element oil filter kit.  This canister seems to be harder to locate but the elements are available.  Does anyone know where I could find a direct replacement kit and what are the associated costs?


As always thanks for any feedback!!

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When you drop the pan to clean things you probably want to pull the valve covers, lots of gunk settles out there too.


On the pan, the two end pieces need to be left long, don’t cut them down to be flush. Keeping the side pieces in place while you get the pan up can be tricky. Some use gasket cement on one side. I have used thread tied through a couple of holes. On the plus side, the pan gasket and procedure to change it are identical from 1933 through the end of production (1959 for cars, later for industrial) so there are plenty of tutorials and guides. And any Plymouth factory service manual from 1934 up through the end of L6 production will give the details.


I don’t know if there is a better or worse brand for these gaskets but I do know that fresh manufacture is better than old stock. I have always just called up my local auto supply and ordered it. Often available in the afternoon if I call in the morning, if not then almost certainly there the next day. If you can’t get the valve cover gaskets separately, they are the worlds easiest gasket to make out of some cork sheet stock.


There is a clearance problem with oil pan and the drag link, so I just remove the pitman arm from the steering box and push it out of the way. You will need a puller for that.


With the pan off it is a good time to look at the bottom end for any glaringly obvious issues. Like missing cotter pins on the bearing cap bolts (or maybe the engine was rebuilt using so bolts that don’t use cotter pins).


There is a screen, held on with a cotter pin and some washers, to keep the biggest pieces of crud from being sucked into the oil pump. That should be cleaned. In fact, cleaning it periodically is one of the items in the instruction book for the '33 Plymouths though with modern detergent oils and fairly frequent oil changes this should not be the problem it was in the 1930s.


Oh, by the way, over tightening the pan and/or valve covers will generally make things leak so be gentle. And when you have your pan off look along the edges to see if if the sheet metal has been deformed by someone over tightening in the past. If so then you will want to level out the mating surface as best you can.


With respect to the sealed canister oil filter, the $45 you mention seems about right for current price. You really only need to replace it ever 8,000 to 10,000 miles. So if you are driving the car 2,000 miles/yr you are looking at once every 4 or 5 years. Or about $10/year, not a big cost. . .


Looking at eBay I see a bunch of housings that take drop in elements varying in price from $10 to $150 depending on condition and greed. Almost any of them would work, being lazy I’d probably go for one that doesn’t need refinishing to look good. Bear in mind that the replacement cartridges used in many of the later canisters are surface media versus depth media (i.e. the don’t filter as well). There are some Chrysler made that take a ‘sock’ style insert that is actually a depth media, in the parts book those were listed for heavy duty applications. There were a host of aftermarket ones in addition to at least two from Chrysler, try to figure out what inserts they need (surface vs depth filtering) and the availability before buying the unit.

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  • 2 weeks later...

After receiving the ordered parts for the car I began with the oil pan removal.  Last weekend I was able to drop the pan with no issues and then inspected the pan and pump screen.  Very minimal sledge but had some fine dirt/sand clumped in the bottom in the pump screen area.  The screen was partially clogged with hard residue.  Was able to clean both with no issues and reinstalled.  As mentioned by others, installing the pan can be tricky but I believe I have it on correctly.  I have not refilled with oil yet as I wanted to clean the filtering system first.  I inspected the bottom end and all looks well and appears to have been rebuilt at some point.




Sorry for the upside down pic but I can't seem to correct it......


Last night I decided to change the oil filter and clean the oil relief valve and tubing.  After loosing the top fitting on the oil filter...




I was greeted with a surprise.




I had no idea that this was a replaceable filter assembly and I now have an extra disposable filter to place on the shelf!?!  Fortunately there was not a lot of crude in the bottom and cleaned up nicely.  The tubing that attaches to the top (oil return tubing?) was partially restricted when blowing through it.  After cleaning air blows through unrestricted now.  The bottom hose and tubing was not restricted. 


So I moved to the relief valve spring and plunger and was greeted with another surprise.  I loosened the nut and removed the nut and spring together and went to pull out the plunger and found nothing, nada, ziltch!  Ummm....




I do not fully understand the oil relief valve filtering concept on these engines but does not having a plunger create any issues?  When driving the car the pressure seemed to be in the 30 - 40 range and dropping a couple of times to 20 at a operating temp idle.  So before moving on with the reassembly, I wanted to get some feedback on the missing plunger.




Also, would it be necessary to clean the tubing and hose going to the oil pressure gauge?  The connection to the rubber hose in the middle of the metal tubing has a small seepage / drip.  Wanted to correct that drip.  If I decide to clean the tubing, is there a proper procedure so I do not damage the gauge?





Edited by Crazyred (see edit history)
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You have an engine built toward the end of 1933 or later when they moved the oil pressure relief to the drive side of the block. Mine is an earlier block that came with the pressure relief inside the crankcase.


You absolutely need the plunger and spring!


The setup has several functions:

  • First, the tip of the plunger blocks a return passage from the pressurized oil galley to the pan. Without the plunger the easiest path for oil is directly into the pan without going through the engine at all.
  • Second, with the correct spring, the plunger should open to avoid an over pressure situation.
  • Third, and this one is tricky to figure out from the diagrams, if the pressure is very low the plunger is set to block off the return from the oil filter to the pan. This is to keep the pressure up in the case of hot idle, especially when there is some wear in the engine that could result in lower than needed oil pressure (cam bearings, oil pump, etc.)

I am not sure where one can buy that plunger and spring separately but I think I’d try Vintage Power Wagons first. Oh, by the way, there are different springs with a color coding system. If the pressure is too high or too low then you are supposed to change the color spring that is installed. I would hope that a place that sells the plunger would carry the various color coded springs. Not knowing the condition of the engine, I’d suggest starting with the middle spring but don’t know what color that would be.

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ok, I have been looking up plungers and noticed that the ones I see on the online have a hole in the back end where the spring would touch.  




one with a tap in it




Could I be mistaking what I thought was a internal port to be the back end of the plunger? 



I have never seen one before so I do not know what to look for.  I placed a magnet in the hole but nothing came out.  Is there a better way to confirm if it's still in there?  Maybe the tap idea?



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31 minutes ago, Crazyred said:

Could I be mistaking what I thought was a internal port to be the back end of the plunger? 


I have never seen one before so I do not know what to look for.  I placed a magnet in the hole but nothing came out.  Is there a better way to confirm if it's still in there?  Maybe the tap idea?

Maybe. As mentioned above, the engine in my car was built before they went to this style pressure relief so I have never seen one outside of pictures similar to the ones you have posted.


I hope someone with a 1934 or later Chrysler product vehicle with this style pressure relief steps into this discussion and lets us know what they think.

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So the plunger was still in there.  Since the magnet trick did not work, I tried using a 1/4" tap.  Slowly inserted it and angled it for a grip and slowly removed with the plunger attached. 





The plunger was not stuck as it removed easily, figured the magnet should have grabbed it.  The plunger does have a hole in the end that allows oil to travel through it to the two holes in the recessed area on the other end. 


With plunger inside



Without plunger inside




Total parts for the oil relief valve





All items inspected and cleaned and reassembled.


On to the next tinker!

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