While beautiful, from day one (1) this oil filter canister assembly (OFCA) has been nothing but problematic. One of my vendors told me he knew a guy who “knows his stuff and does fantastic work who was in the process of restoring several original OFCA’s with the correct silk-screened instructions on the canister. Knowing that my then current OFCA did not have any instructions on it, I opted for one of these fantastic, original, and restored OFCA’s. I waited a looong time for it. The first OFCA I received got damaged in shipping - a chunk of powder coating was chipped off. After returning the first OFCA, the seller provided me with a second one but I’ve had nothing but problems with the second OFCA:

• The ridiculously excessive mil thickness of the powder coating was so thick (on the outer diameter AND the inner diameter) that it would not properly fit up into the groove in the bottom of the engine block.
• The bolt assembly failed because it was assembled with inadequate and incorrect parts.

Picture 1 -


Picture 2 - restorers PLEASE do not use these retainers to assemble the bolt assembly and if you do PLEASE use the correct size

Picture 3 - the bolt is NOT supposed to nearly fall out of the canister when unthreaded from the engine block


I had a decision to make: throw this one away, bake off all the powder coating and start over, or try to salvage it. If it wasn't for the beautiful silk-screened instructions I would have made another choice but because the silk screening was so good and is the hardest part of restoring an OFCA I decided to try to salvage it and use this as yet another learning experience to learn more about how my car works. I’ll share with you what I learned and how I did it...


But first, let me remind you that this OFCA had been previously disassembled so I didn’t get to learn how to use a cold chisel to remove the deformed metal of the walls of the bolt that retained the bolt, spring, o-ring, washer(s), cup, etc. inside the canister. If you plan to disassemble an OFCA, the first thing you’ll need to do is break the cup free from the bolt. I’ve seen people on the forum talk about using a chisel to cut away the burrs that retain the cup and I’ve seen posts where people pound downward on the threaded end (protected) of the bolt to break the burrs that retain the cup. There may be other ways to do this but, again, I didn’t have to because my OFCA had been disassembled previously. In fact, the seller of this OFCA chose a fastener to retain the bolt’s assembly that was completely inadequate. DO NOT use an internal toothed star washer if you want to be able to service certain aspects of your OFCA again in the future.


Picture 4 - not good



Addressing the excessive mil thickness of the powder coating
Because the mil thickness of the powder coating was ridiculously excessive on the outer diameter surface the opening of the canister would not properly fit up into the groove in the bottom of the engine block. Yah, that’s how thick it was. To remove the excessive mil thickness of the powder coating on the outer diameter of the canister I had to protect the rest of the canister and mask it off leaving approximately 0.9 in of the canister’s lip exposed. Being aware that media blasting can induce heat into a part, and because I didn’t want the canister to get out of round because of the heat build-up, I slowly media blasted the external and exposed surface removing the powder coating and exposing the bare metal of the canister underneath. I was successful at removing the powder coating all the way down to the steel of the canister. After cleaning, degreasing, prepping, applying primer, and repainting the exposed external surface the canister STILL would not properly fit up into the groove in the bottom of the engine block. That’s when it hit me… Maybe there’s excessive mil thickness on the INTERNAL surface of the lip of the canister too! Yep, look at the pix below and you'll see a ridge created where the bypass valve interfered with the ID of the canister. With 180 grit sandpaper I sanded the internal surface of the lip of the canister for what felt like for EVER. Cleaned it up and tried to fit it up into the groove in the bottom of the engine block. No go. Went back to sanding the internal surface of the lip of the canister again. Cleaned it up and tried again to fit it up into the groove in the bottom of the engine block. No go.



Picture 5 - look at the excessively applied powder coating on the exterior surface of this canister

Picture 6 - look at the excessively applied powder coating on the internal surface of this canister


Knowing that I was going to enlist the help of a machinist to cut a groove in the bolt for an external snap ring, I invited him over to help me figure out what to do. Instead of trying and trying and trying to reduce the ID of the internal surface of the lip of the canister with little to no success, he suggested that we remove the oil filter bypass valve from the engine block and take a look at it. Holding the bypass valve in one hand and the canister in the other hand and rotating the bypass valve within the opening of the canister, we could quickly and easily see the interference between the 2 parts. We decided to chuck up the bypass valve on the lathe and take 0.005” off the OD of the bypass valve (maybe it was ten thousandths). Yep, that was all that was necessary to remove because now we could fit (and spin) the bypass valve fit inside the opening of the oil filter canister without binding or without interference. Not something we were able to do just minutes before. Problem solved.


Picture 7 - bypass valve bolted into the engine block

Picture 8 - bypass valve bolted into the engine block

Picture 9 - look at the flashing on the original GM casting (bypass valve) and look at how uneven the flashing is

Picture 10 - look at the flashing on the original GM casting (bypass valve) and look at how uneven the flashing is

Picture 11 - the rough / uneven edge of the bypass valve is gone and what's left is a perfectly smooth and concentric surface



Now to improve the bolt assembly
The seller/restorer of this OFCA used an internal toothed star washer and hope (yes, hope) to keep the assembly together, but both his hope and his internal toothed star washer completely failed to do the job. He just made a series of choices/decisions that turned out to be wrong/bad. Instead of machining a groove into the wall of the bolt, the seller/restorer chose to use an internal toothed star washer WITHOUT also machining a groove into the wall of the bolt. This might have worked (semi-permanently) if he had machined a groove into the wall of the bolt but he didn’t machine a groove into the wall of the bolt and the washer’s ID was too large and did not have a tight enough grip on the bolt to be effective. The internal toothed star washer simply let all the components of the assembly float the length of the bolt. Using a correctly sized internal toothed star washer together with a groove machined into the wall of the bolt would probably have worked very well but this would have made it difficult to service the OFCA in the future if necessary.

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Picture 12 - assembly from seller/restorer. Internal toothed washer without a groove to hold it.


Instead, the ideal configuration is to use an external snap ring and a thoughtful groove machined into the wall of the bolt that matches the installed dimensions of the external snap ring. Easier said than done I know, but that’s it. I know not everybody has a lathe in their shop. I don’t. But most of us have either a friend who does or has access to a local machine shop who can/will gladly do this work for you.

But WHERE do you machine the groove. As my consultant said, “GM already figured that out for you.” Upon a little bit of magnification you’ll likely see some original marks where GM (or their vendor) deformed some wall steel of the bolt to create some burrs that retain the cup. See picture below. The consultant said, “Just below these notches is where you want to locate the groove for the external snap ring.” Once you know this, the rest is common sense.


Picture 13



Picture 14



Picture 15 - cutting the groove

Picture 16 - cutting the groove

Picture 17 - groove cut just below the original deforming marks



Because I had to reverse engineer what I had in front of me, try to find a resolution working with what I had, and knowing the seller/restorer made some wrong choices in the assembly, I had to presume that his poor choice of the internal toothed star washer may not have been the only poor choice he made. For instance, was the o-ring the best o-ring for the job? Was it oil-resistant? Who knows. What about the copper washer? That thing looks pretty thin. Is it the correct thickness? Who knows. What about that really thin washer on top of the spring and below the o-ring. Is it really supposed to be that thin? Who knows. So I reached out to a person who DOES know all these things and who wants to remain anonymous; he helped me make some better decisions regarding the pieces and parts of the bolt assembly. I’ll share with you the decisions that I made and the parts that I used and I invite you to criticize my choices as this will only help me to improve my OFCA and help others do the same.


As you can see, the bolt assembly is comprised of the following parts (from bottom to top) and each one has minimal requirements for the assembly to be successful (retain engine oil):

• Bolt
• Copper washer
• Spring
• Washer
• O-ring
• Cup
• Retainer

Picture 18 - original bolt assembly


After closely examining all the parts of the bolt assembly in front of me I chose to use certain parts and toss (because of the poor choices from the seller/restorer) the rest. I chose to use the bolt because it was an original GM bolt, the spring, and the cup. I chose to toss all the other parts the seller/restorer used: the copper washer, the washer, the o-ring, and the internal toothed star washer/retainer.

Let’s talk about the cup real quick. When the original bolt assembly was broken (when the original burrs created to retain the retainer were broken), the top lip of the cup became irregular with jagged edges. We removed these jagged edges of the top lip of the cup. This helps it to sit level/perpindicular with the bolt against the retainer when the assembly is not under tension but it also enlarges the opening of the top lip of the cup where it interfaces with the retainer. More on this later…

The copper washer between the head of the bolt and the bottom of the canister… When discussing this part with my consultant I told him I could probably get this part at my local NAPA store. He said, “No, they’re too thin. They need to be about 1/16th thick. So, I purchased from McMasterCarr the following items:

• 110 Copper Ring Shim 0.064" Thick, 1/2" ID, part # 94397A643
• Oil-Resistant Buna-N O-Ring 1/8 Fractional Width, part # 9452K185
• 18-8 Stainless Steel Washer for 15/32" Screw Size, 0.500" ID, 1" OD, part # 92141A232
• External Retaining Ring for 1/2" OD, 15-7 PH Stainless Steel, part # 91590A122

Please be aware that the copper washer needs to be a soft copper. That’s one of the reasons I purchased the copper washers from McMasterCarr - because the properties of their parts are on full display. This 110 copper washer is soft and is thick (1/16th) like in the original GM assemblies and is a perfect match for this assembly.

The o-ring listed above is oil-resistant. If you find a better o-ring please share it below.

The stainless steel washer(s)... I used 2 of them and I’ll explain why here… The steel washer in the assembly (on top of the spring and below the o-ring) from the seller/restorer was very thin (too thin for my comfort) and could possibly be deformed under pressure. This washer sits on top of the spring which is not a flat surface where the end of the coil meets the other coil and is the base for the o-ring that sits under the cup. Thinking that the base for the o-ring should probably be a firm, inflexible surface I chose a thicker steel shim or steel washer for the job and replaced the much thinner steel washer in the prior assembly. This is where I used one of the SS washers. The location where I used the other SS washer was between the cup and the external snap ring retainer. Remember (from above) when we removed the jagged edges and irregularities of the top lip of the cup, and remember in doing so this enlarged the opening of the top lip of the cup where it interfaces with the retainer? Well, because the opening of the top of the cup is a little bigger than it was originally I didn’t want the possibility of the cup slipping up/past/around the external snap ring retainer so I installed the second steel washer between the top of the cup and the bottom of the external snap ring retainer.

Picture 19 - external snap ring in place retaining everything nicely

Picture 20 - oil filter canister assembly installed and successfully retaining oil and not even one drip



In review, this OFCA had several tolerances stacked up in the wrong direction - both on the external surface AND the internal surface of the canister. Both resolved with media blasting (external surface) and making sure the OD of the bypass valve was perfectly concentric (internal surface). Additionally, I had to work with a machinist to machine a groove into the wall of the bolt for an external snap ring to hold / retain the cup, washers, o-ring, and spring. More than likely you won’t have the same problems I had with the powder coating thickness and more than likely if you need/want to modify your oil filter canister assembly you’ll just need to work with a machinist to cut a groove for you.

Again, if anyone has constructive suggestions please share them below for ALL of us who are thinking of modifying our car’s oil filter canister assemblies.

Disclosure: I have a VERY limited base of knowledge because I have only one (1) mid year and it's a 1967, and I haven't owned it for very long. Therefore, it's possible that some of the information I've shared above may not apply to other mid year cars. Please don't take my word without verifying for your car.

 

See your original post, your canister was screwed up in the past by someone.

Known original with no milling marks nor increased diameter nor splices. Square surface on the top of the can.

No increased diameter.

 

CADbrian thanks for the extensive and in-depth description of the filter housing mechanism. I’m grappling with my filter leaking past the copper washer and I think you gave me the solution with using a washer made from a softer copper. I had replaced the washer previously and used one that came in a variety pack at the local AP store.
I will order the washers from McM tomorrow.

I do have a question regarding the snap ring approach. Is the snap ring you used readily accessible with snap ring pliers for removal should it become necessary?

bill

 

By another - cheaper in the long run and less headache and work

 

No, the canister is fine but the seller/restorer applied WAY too much powder coating on/in the canister. I resolved the excessive powder coating and now the assembly works perfectly!

 

The copper washer that was used in the assembly BEFORE I took it apart was only 1/32" thick (0.03125) and the ones from McMasterCarr are substantially thicker at 1/16" thick (0.0625). I'm assuming the local auto parts stores probably do not sell the thicker copper washers. My local NAPA store did not have the thickness I wanted. Additionally, I was unable to ascertain the other properties of the copper washers from my local auto parts stores i.e. what kind of copper was it made of? Soft or stiff? With McMasterCarr, all the dimensions and other important properties are on full display.


Yes, that is the main benefit of this modification - to be able to service your oil filter canister assembly if needed. I'll admit that I wish the handles of my snap ring pliers were longer but it wasn't bad.

 

Buying another canister and having it properly silk-screened is DEFINITELY NOT less expensive, and unless you can see and hold the prospective canister in your hand that you want to purchase you won't really know what you've got until it shows up. Remember, I did this to salvage an original canister with a fantastic set of silk-screened instructions. All the lessons I learned along the way were an added bonus!

 

It appears the vendor tried to make a optional heavy duty service, high volume filter canister from a stock canister by adding an inch of wrong size pipe to the top.
The original canisters are 4 inches O.D. tubing with a 1/8" (0.012") wall thickness.
The stock canister is approximately 6-3/4" long measured on the outside.
The heavy duty canister is approximately 7-5/8" long measured on the outside.
If my memory serves me correct, the heavy duty canisters were used on high performance engines, taxi cabs, police vehicles, and agricultural / industrial equipment engines only. I can't remember the source of the information nor the specific oil system changes for those engines other than the canisters. I don't know if the heavy duty canister was used on the high performance automobile engines as well.
[img alt="Heavy Duty canister on the left
Standard Duty canister on the right"]https://cimg7.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/2000x1504/20250127_082622_93befbc9d86a8104761f1853 874586fcff407d2b.jpg[/img]
Heavy Duty canister on the left Standard Duty canister on the right

There were millions of cars using the standard canister between 1958 and 1966, so they are easy to find. The heavy duty canister is not as common.
[img alt="Heavy Duty canister on the left
Standard Duty canister on the right."]https://cimg7.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/1662x1246/20250127_082622_091a658285f8fd35c1c7fb27 a095d202da1dd094.jpg[/img]
Heavy Duty canister on the left Standard Duty canister on the right.

 

Both of my canisters are 6.75" tall and by your description both of my canisters would be the standard canister, typical for my car. I've never seen one of these high performance canisters that you mention. Please tell me how you've come to the conclusion that the canister shown in my OP might not be a standard canister. Thanks.

 

The joint you circled in yellow in your picture in your first post indicates the original canister was either extended or cut off and then repaired with a piece which appears to be about 1" high. The inside of the canister appears to have a bit of an offset at that joint. They made no attempt to hide the modification as they did not weld the joint on the outside. Not knowing what canister you have, I assumed it was a standard canister which they try to extend to appear like a Heavy Duty model for the HP 427.
I have a half dozen or more standard canisters and none have the joint in the sidewalls. I have seen plenty more back in the day and none had a joint. I have only one HD canister, but it does not have a joint in the sidewall. Unfortunately, my attempt to post a picture of it failed. I'll try again.
It just made sense that someone attempted to modify a standard cylinder for some reason.

 

Ok, now I see how / where you got that idea, but if you go back and look at my OP, you'll see that I am talking about and showing the INSANE mil thickness of the powder coating the seller/restorer put on the canister. It's not a modified high performance canister. It's a standard canister with a TON of powder coating on it. So much powder coating that I had to remove some and the ridge you see on the external surface of the canister is the ridge created by removing the PC from near the opening. The ridge you see on the internal surface of the canister is the ridge created (and later removed) by the PC interfering with the OD of the bypass valve.

Everything now fits properly and is retaining oil like a champ!


The powder coating mil thickness interfered with the normal and proper fitment with the OD of the bypass valve

The powder coating mil thickness interfered with the normal and proper fitment with the ID of the engine block

 

I cannot attest to the thickness of the powder coating, only the wall of the original canister is a little less than 1/8" and square on the top thus to fit the square rubber O-ring in the block. Anything greater than 1/8" could indeed prevent a proper fit, but also anything greater than 4 inches O.D. or less than 3-3/4" I.D. could also prevent proper fit. IF an incorrect piece of tubing or pipe is used to add to the top, it could cause a problem.
Your original post shows a ridge around the outside of the canister protruding ~ 1/16" or so as well as the top being machined semi-round, not flat. Photos 2 thru 4 I believe. This will indeed prevent proper fit.
https://www.corvetteforum.com/forums...-canister.html
Like you, I like to fix what I have rather than buy another piece especially aftermarket. The quality just isn't there in aftermarket.
I read up on silk screening and it doesn't appear to be a difficult process to do at home. I am afraid I would be temped to try it just out of curiosity.
Anyway, if it fits now and you are happy, I have no dog in that race.
That reminds me of our move to West Virginia traveling on I-64 just outside of Teays Valley, WV, my wife saw a sign up on the hill at the dog track. The sign read "Grayhound Racing" and she said she didn't know they raced Grayhound buses. You have to love them. Well at least for 57 years or so.

 

Ron:

I lived in Cross Lanes and in St. Albans WVA in the 1970's. Very familiar with Teays Valley and surrounding areas. Purchased my special Z28 Camaro from a Chevy Dealer in Hurricane. The dog track came after I moved to Louisiana, but I remember it from visits I made.

Small world.

Larry

 

I ordered the parts from McMasterCarr at 5:08 pm today. Just got an email that were shipped via UPS and I will have them tomorrow. Amazing. As good as amazon.

I certainly didn't need 25 of these and 100 of those, but the price was OK. I have three canisters to rebuild.

Thanks for the info!

 

Larry,
sent you a PM with more info on WV. Didn't want to steal the thread.
Ron

 

 

R66, I think the taller of the two canisters in your photo is a PF 131 which was used on '56 and '57 GM model cars and trucks with the 265 cu. inch engine including the Corvette. I am no expert on BB's but this is the first i have heard of a heavy duty oil canister on BB's. Was there one?

 

To add to this discussion, I have been playing with the oil canister silkscreen kits thru Etsy. They are pretty good. It looks much better than decals and the NCRS folks prefer them. Here is the link:GasTiresandOil - Etsy
On the canister rebuild, I wonder if the retaining clip is really needed? Seems all it does is hold the bolt in the canister, as the filter should hold everything in place when installed. I am in the process of restoring a few canisters and all this info was perfect timing. If any of you guys want to get rid of the extra McMaster pieces, let me know.

 

I will admit that when I think of true silk-screen printing I am NOT thinking of decals or transfers. With a second canister I too have tried one of these silk-screen transfer decals from Etsy, which, again seems like something other than true silk-screening. The results of the silk-screen transfer decal from Etsy was not great and did not go on evenly. Probably takes several attempts to get good results, but I had only one other canister.

The bolt assembly was loose inside my canister. The bolt was tightly threaded into the engine block but all the other internal parts were loose and floating and it retained oil without leaking any oil, so that might be a partial answer to your question about where or not the snap ring / retainer is necessary.

 

Thanks for the link. I may play with one for R66. Price is right.