L134 Oil Filters and Oil Pressure

I'm rebuilding an L134 in my 47 CJ-2a and have a question about the factory canister style oil filter system.

I currently have an aftermarket screw on type oil filter system that the PO adapted to the Jeep. It's very convenient and the filters are cheap, and it's on the vehicle already.

Here's what I know:
The L134 uses a partial flow/bypass oil filter. The Oil pump draws oil from a floating type pickup, and pumps the oil into the main galley. From here oil runs to the main and cam bearings. The oil filter simply hooks up to one of the ports on the side of the block. From one of these ports (the front most passenger side port on my jeep) it runs up to the filter, and then returns back on a fitting on the timing cover, basically aimed at the cam gear.

Depending on the oil filter's restriction and main bearing clearances you can have anywhere from 0 to XX amount of oil flowing through the filter at any given time. Hence it's a partial flow/bypass filter.

Since my Jeep had somewhat low oil pressure before tearing it apart (it met the minimum book valves, 5psi idle and 10psi/1000rpm) I asked around to see what I should expect after the rebuild. In doing so, one source, a guy who regularly does L134 rebuilds had the following to say:

He said that the worst mistake people do (for oil pressure) is to install an aftermarket screw on type filter. Reason being that the original canister type had some type of relief valve built into it. He said that the stock relief valve opens at about 40psi. Meaning (in ideal conditions) below 40psi, you'd have no filtration, and above it, you would. He said that with a modern (Melling) oil pump to expect it to idle with around 30-40psi, and climb up to 50psi at higher rpms.

Hmm. Sounds a little high to me, but I don't know. One source (Moses Ludel's rebuilder book) states that the relief valve on gear driven L and F heads is 40psi. It's not clear to me what "relief valve" he's talking about: filter, pump, something else? He lists 25psi for the old chain driven L134 (with an operation pressure of 35psi at 2000rpm), so perhaps this is the oil filter valve. I don't know.

I asked this rebuilder if he had any suggestions for what I should do if I want to keep my screw on filter assembly. He said that he's had okay luck brazing a pipe fitting (on the filter assembly) closed, then drilling a small (I think he said .070") hole in it. This would improve oil pressure, no doubt, but I would expect that at higher rpms instead of having more oil going through the filter you'd see the bypass on the oil pump itself open up.

I looked around to try to find a relief valve that I could plumb in. I searched quite a bit at www.mcmaster.com (great place for this sort of stuff) and while they did have a few valves that would work, the cheapest I found was $50 and it wasn't rated for oil or more than 200F. The ones that were rated for this were about 2-3x the price.

Like I was telling my buddy on the phone today, this isn't any big deal, it's just a matter of getting a little valve with the right spring and ball in it.... the hard part is getting the right spring and ball!!

Today I talked to both Carl Walck and another employee at www.walcks4wd.com/ <--great place for parts by the way) and both were fairly certain that the oil filter assembly that they sell has no valves in it, it's a straight through design.

Humm.

So for those of you that are in the know, what's going on? Did just the original canisters have these valves? Or are these valves a figment of some engine builder's imagination? Maybe, are they located somewhere else--on the timing cover maybe? Any suggestions where I might find a relief valve that would work with what I have?

My dad's old CJ-2a had a stock canister filter, and he doesn't recall the details, but does remember mopping the oil out of the canister during oil changes. Suggesting that there was something (like a relief valve) in there to prevent the oil from simply pouring out the bottom and into the timing cover. I don't know, maybe the way the plumbing is situated on the bottom, it just fills up a little bit. I don't know, I've never seen one of these original filter assemblies in person!

Here are some photo's of what I have right now. Obviously the oil lines aren't hooked up, but hopefully it gets the idea across.

 

:iagree:
I recently tore most of my F head apart, and I haven't found any sign of any valves in the external oil system.

 

Just rebuilt my L head and I have around 50+ psi cold and warm its closer to 40. So the numbers you've heard sound about right.

 

I agree with Glenn!
Just switch to the original canister type set up. When I bought my 3A, some genius had taken out the whole canister and plugged the 2 holes! I found a good used one on Ebay, cleaned it up, repainted it and put it in. No problems since. Yeah, the spin-on type are fast, cheap, and easy... but you have a vintage Jeep... they ain't fast, cheap, or easy. If they were, everyone would have one!

 

Mine was "working" too. It was actually only running on the #1 and #4 cylinders. The other 2 were scored so bad there was no compression there. I can't help but think that the lack of oil filtration contributed to the L-head's demise! No matter... oil filtration is a good thing!

 

The old air cooled VWs don't have an oil filter, just a mesh screen that isn't even that fine. I always thought it was a little like not having any kidneys... Even so, those engines seem to last forever. Changing the oil frequently is pretty mandatory though.

 

IMHO. The by-pass system is only going to flow very light, small particulate's to whatever filter is in the path. Put a fine filter in if you are going to change from the canister type. Screen size will not effect oil pressure in this by-pass system. I used an Oberg filter in place of the original canister type on several different rigs I've owned. It has a very fine screen and during maintenance you see what's being filtered. I found myself cleaning it more often than just during oil changes. Screw on filters never come close to matching the Obergs filtering capabilities and you don't know what you are missing. Plus the idiot warning light tells you when the screen is plugged and it's re-useable. After purchase price that's it, cleaning is almost free. I also added a magnetic drain plug. You might as well improve on these weak systems as much as you can. I was never able to afford a new one (@$130+) and always seemed to fine a used setup for under $50.

 

Hmm. Thanks for all the replies guys.

It sounds like:

Stock canister systems possibly will create more oil pressure (have more backpressure) than what I have because:
1. They may have some small orifice on the return to the motor side
2. The filters themselves may create more backpressure than a large spin on filter (like I what I have)

It's still not clear to me why you would have oil remaining in the canister when you go to do an oil change.

Does the stock canister type filter actually have a tube running up a ways from the bottom (creating a trap more or less) or is there some other reason that residual oil will stay in the canister? Something like this (sorry for the very crude sketch

On the left would be a filter canister assembly.

On the right would be the filter canister with the lid off and the element removed.



Again, I've never seen one of these filters in person, so sorry if this question seems just silly.


I'm just trying to understand if the oil is trapped in the bottom of the canister during oil changes due to a valve (which it sounds like is not the case), or junk/gunk in the bottom of the canister (which sounds like it may be the case)or because of the geometry of the canister (as drawn above).

Here's something else I'm trying to understand (that also lends possibly some credence to the idea that there is some kind of valve in the factory oil system, besides the one in the oil pump itself). This is from Moses Ludel's Jeep CJ rebuilders manual, 46-71. I don't have my other manual handy right now to verify these numbers (it's uh, about 5000 miles northeast of me at the moment). What in the world could these "relief valve" values refer to? I can't see the oil pump bypass being lower than the operating pressure. Maybe it's just a typo? But note, he left that spot blank for the V6, which is a full filtration type engine.




neptco19: When you say you have 40psi warmed up, is that at idle? What viscosity oil do you use?

Sorry if I'm beating this thing to death. :smash:

 

Floating Oil Pickup o-ring ??

Well I still haven't really made up my mind on the filters yet. I'm leaning towards either putting a needle valve inline with my existing filter or... just coughing up the cash for a stock housing. By the time you get both oil lines, straps, and housing it's around $100 or so. We'll see. If anyone has one they'd like to get rid of, PM me! Thanks.

Next question, also oil related. I was assembling my floating oil pickup today and it looks like there should maybe be an o-ring between the floating pickup and the fixed tube. I didn't see it mentioned in either of my manuals, and there wasn't one in there before. Anyone know if there should be one?? Seems like it would be good insurance, as long as it didn't cause the thing to bind up.



Side note: I almost didn't bother to disassemble my pickup and clean it out. Holy heck, I'm glad I did. I think it's a mix of paint and dirt... not much metal anyway.



Side note 2: It's starting to look like a motor again!

 

Try calling Border Truck Equipment in Irasburg, Vermont. He has 250+ Willys Jeeps in his salvage yard. He will find what you need and ship it for a fair price. He helped me with some hard to find parts for my 3A restoration!

 

So, I've read lots of threads on oil filters, but my "new" '42 MB has nothing. No oil filter canister, no mounts, nothing at all and can't tell if ports are plugged off. My s/n is MB193352, Ford engine s/n GPW 8050 s/n 239018, was made in late 42. I've heard that early ones didn't have them as the vehicle was disposable?
So, I found one on ebay and will plumb it in as the manual shows. I considered a spin on, but most of the threads point towards keeping the canister. Plus I'd like to keep it original. Anybody have any info to share regarding this?

 

I have re-built NUMEROUS L and F head engine..Oil pressure after break-in stayed at 58 to 60 lbs at start-up...

After about 15-20 minutes of idle the oil usually lowers itself to 46-53 lbs..and yes going up the road it gets a little better than 55 and stays there..

Honest opinion if you re-build your engine watch ebay or buy a canister type filter..wally-mart has fram C3P or C4P filters on there shelf thats what I use..either one will work as one is just smaller than the other..

On your new engine try to find some 30w NON-Detergent oil and break it in with that..
I have been running 20w50 in all mine ..I have one now that does need rebuilt and I am running ROTELLA 15w40 for diesel engines..keeps the knocking down on it a bunch..besides it free...

This is my opinion and you know what everyone says about opinions....