Bosch 3323 Cut Open

[mohammadali]

I am not sure what the rules are around self promotion, but I made a YouTube video cutting open and explaining the basic function of the Bosch 3323 oil filter. I would love to hear feedback from the BITOG community so I can better assess the next oil filter I buy.

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[fantastic]

Add in where it was made & dry the filter out, then stretch it out on a table. Other than that great video.

 

[ZeeOSix]

Seems the Bosch filters still look good these days because Bosch spit off from Purolator and went on their own, and are not involve with Mann+Hummel like Purolator is now. This Bosch filter looks to have a Purolator format date code on the dome, but maybe they still use the same format as Purolator even though there is no affiliation.

 

[Cressida]

I doubt that the filter in this video came from the Mexico plant? Looking at this same filter Bosch 3323 from Mexico I note:

1. One cannot look down the center opening to see that rivet on top of the bypass valve. It might be there; but there is about a 1/2" wide metal strip that goes over the top of the bypass valve and is connected with what looks to be small crimps at the base on both bottom sides of this metal strip. This strip covers the top of the bypass valve.

2. There is adhesive or glue that was used around the bottom of the metal center core. As has been shown and noted by others, examples are showing glue blobs to have dripped onto other areas inside of the filter - including spots of glue that I can see up on the top side of the pleated core (near the threads) indicating the glue gun is dripping as it is lifted up and out. I saw no evidence of this same glue having been used at all in the filter shown in this video.

3. As noted in the video, the opening area in the metal center core is smaller than what might have been expected. How or when / if there might be any flow restrictions is unknown but assuming the design allowed enough openings in total. Nevertheless, what I do know is the louvered openings are not consistent, with some filters having smaller openings in the louvers than others. It's like the machine did not complete or do the full punch on the metal, and with those examples, I do not have confidence that there is enough opened space for the oil to flow as it was designed.

Hopefully we will start to see more consistent examples being produced from Mexico, but I'm going to pass on them for now.

 

[Sayjac]

In my fairly extensive experience with multiple BP 3323 c&p here, you are fortunate to have received the US M&H Purolator made Bosch Premium 3323, as opposed to current M&H made in Mexico version. The latter as shown here in anecdotes are of poor quality.

How tight the sealing gasket fits on the baseplate (not "endcap") while somewhat important, not critical. As long as the sealing gasket ("oring") on when removed, all that matters. And, even if it comes off, which it didn't, supposed to clean the engine block filter mating surface after removal anyway which would/should indicate a gasket left behind. IOW, double gasket is a rookie mistake, not a sealing gasket issue per se.

That you were surprised that the blended cellulose media not "directly glued to endcap" shows you're new to filter dissection. The blended cellulose media is set into "potting/(glue)" material in the endcap with heat to form the media/endcap seal in that area.

Showing the louvers with media removed and with flashlight a good confirmation point for their true state. I'm confident they functioned properly. Otoh, pushing the flat spring bypass with finger, subjective info/result. A member here posted a practical test of it to show they open at stated psi. Showing the bypass staying sealed no matter position closed position a good one though. And the orange/reddish adbv is silicone. What I see shows the filter did its job as designed. If you want some further examples of video filter dissection, WhipCityWrencher on yt does a decent job, imo.

Lastly linked are a couple 3323 I c&p here for comparison.
https://bobistheoilguy.com/forums/threads/two-bosch-premium-us-3323-cut-open.391863/

 

[ZeeOSix]

In my fairly extensive experience with multiple BP 3323 c&p here, you are fortunate to have received the US M&H Purolator made Bosch Premium 3323, as opposed to current M&H made in Mexico version

Does M+H have any connection to Bosch these days? Searching around says they split ways years ago.

 

[Sayjac]

Does M+H have any connection to Bosch these days? Searching around says they split ways years ago.

That's a good question, can't say for sure. Being former partners in Purolator ownership and also a German company, I would think at least some association. Bosch Prem looks like it could be made by M&H, but now the Wix filter factory in Mexico. WCW has a 3421 dissection that has the appearance of similarities to the now Puro like Wix. So, can't say 100%, but possible, at least the Bosch Premium OF an M&H made filter.

 

[ZeeOSix]

That's a good question, can't say for sure. Being former partners in Purolator ownership and also a German company, I would think at least some association. Bosch Prem looks like it could be made by M&H, but now the Wix filter factory in Mexico. WCW has a 3421 dissection that has the appearance of similarities to the now Puro like Wix. So, can't say 100%, but possible, at least the Bosch Premium OF an M&H made filter.

My searching shows that in 2006, M+H and Bosch formed a 50/50 joint venture to buy Purolator filter division. M+H then bought Bosch's 50% share of Purolator in 2013 to fully own Purolator and Bosch went on as an independent company. Searching also says that today there is no connection between M+H and Bosch. Do any Bosch oil filters say "Mann+Hummel" on the can or box? The oil filter business is worse than a Soap Opera.

 

[Sayjac]

^^^^^ Being a previous and sometime more recent user of P1/PL14610 and and more recently its virtual clone topic 3323 (from Rock Auto) all that info well known me. And while Bosch sold their Purolator ownership share in 2013 the topic Bosch Premium Filter continued to be made by M&H Purolator US at least until 2020. The previous link I posted shows the F series date format with M year code to prove that point. Plus I have one left in my stash also with "M" year date code. So, at very minimum there was a contractual relationship between Bosch and M&H to make the topic filters for at least 7 years after the M&H sole acquisition of Purolator. Be interesting to see date code of topic filter.

As for who's currently making them in Mexico, it remains unclear. But seeing as M&H Wix has a plant in that country, without more info, I can't 100% rule it out. One thing is clear though, who ever making them now, c&p anecdotes posted here and on youtube prove their quality has taken a turn for the worse.

 

[ZeeOSix]

^^^^^ Being a previous and sometime more recent user of P1/PL14610 and and more recently its virtual clone topic 3323 (from Rock Auto) all that info well known me. And while Bosch sold their Purolator ownership share in 2013 the topic Bosch Premium Filter continued to be made by M&H Purolator US at least until 2020. The previous link I posted shows the F series date format with M year code to prove that point. Plus I have one left in my stash also with "M" year date code. So, at very minimum there was a contractual relationship between Bosch and M&H to make the topic filters for at least 7 years after the M&H sole acquisition of Purolator. Be interesting to see date code of topic filter.

As for who's currently making them in Mexico, it remains unclear. But seeing as M&H Wix has a plant in that country, without more info, I can't 100% rule it out. One thing is clear though, who ever making them now, c&p anecdotes posted here and on youtube prove their quality has taken a turn for the worse.

But do these newer Bosch filters say anything about Mann+Hummel on the can or box? If not, then I wouldn't think M+H is involved with Bosch in any way. If M+H was making them for Bosch, I'd think there was be some kind of M+H info on the filter and/or box.

The date code on the Bosch in the video is shown below ... snapshot from the video. It's pretty old - 12L05 is Dec 5, 2019.

 

[Sayjac]

But do these newer Bosch filters say anything about Mann+Hummel on the can or box? If not, then I wouldn't think M+H is involved with Bosch in any way......

'To my knowledge' the current made in Mexico Bosch Premium (not topic US made) do not have any indication of a manufacturer. If they did I wouldn't have said current manufacturer "unclear". As noted, possible it's not M&H Wix Mexico, but without more info 'I' can't 100% rule it out either. For reference, the previous made in the US Bosch Premium made by M&H Purolator also had/have no indication of M&H anywhere on the box or filter label. I still have one US made 3323 in the box, so I can confirm that as fact.

As for the Bosch Premium Purolator date code, my reading of the previous post was the implication that Bosch had completely severed ties with M&H in 2013 when the latter bought out Bosch' share in Purolator. As shown, for at least 7 years after that, Bosch maintained at minimum a contractual relationship with M&H to make Bosch Premium oil filters. That could be over now, or possible M&H Wix Mexico could be making them.

 

[ZeeOSix]

'To my knowledge' the current made in Mexico Bosch Premium (not topic US made) do not have any indication of a manufacturer. If they did I wouldn't have said current manufacturer "unclear". As noted, possible it's not M&H Wix Mexico, but without more info 'I' can't 100% rule it out either. For reference, the previous made in the US Bosch Premium made by M&H Purolator also had/have no indication of M&H anywhere on the box or filter label. I still have one US made 3323 in the box, so I can confirm that as fact.

If the US made Bosch Premium had no indication of M+H on the filter can or box, then how would someone actually know M+H was involved? Seems like M+H likes to put their stamp on every filter they make, regardless of the brand made by them.

As for the Bosch Premium Purolator date code, my reading of the previous post was the implication that Bosch had completely severed ties with M&H in 2013 when the latter bought out Bosch' share in Purolator. As shown, for at least 7 years after that, Bosch maintained at minimum a contractual relationship with M&H to make Bosch Premium oil filters. That could be over now, or possible M&H Wix Mexico could be making them.

I don't think the date code format would prove it was made by M+H/Purolator. We don't now the details of the agreements when M+H and Bosch spit their joint venture in Purolator back in 2013. It could be that Bosch was able to retain the "Purolator" design (like the flat spiral looking bypass valve spring) and even the date code format, but make their own Bosch branded filters without any M+H or Purolator involvement.

I'm not trying to argue this subject, I'm just interested in finding the truth to the mystery. I sent and email to M+H corporate in Germany to see if I can get a straight answer. All my searching says that M+H/Purolator doesn't have any connection to Bosch anymore, so now digging deeper to find the truth of the puzzle. Some search info below, for what's it worth. I'll post what M+H says if they respond to my email. I also called Bosch USA tech line, and they didn't have info if any other company beside Bosch was involved in manufacturing their oil filters. The guy told me I'd have to contact Bosch corporate, probably their office in Germany. Maybe I'll dig into that some.

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• Purolator: An American brand, now owned by German company MANN+HUMMEL, with manufacturing in Fayetteville, NC, producing their own branded filters (including BOSS).
• Bosch: A separate German automotive supplier, also making quality filters, with production in various global plants, including the USA.
• The Confusion: Historically, Bosch licensed the Purolator name for some products, leading to people thinking they were the same or connected, but today, they are distinct brands with separate filter lines.

So, if you're buying a Bosch filter, you're getting a Bosch product, and if you're buying a Purolator, you're getting a Purolator product, both with potential US-made options, but not one making the other's primary line.

 

[Sayjac]

.....I don't think the date code format would prove it was made by M+H/Purolator.....

.I'm going to agree to disagree then. I'm 100% confident the topic 3323 and all the multiple 3323 I've c&p on this subforum are made by M&H Purolator, i.e. made by Purolator oil filter division solely owned by M&H since 2013. That's the case until at least 2020 as proven by both the posted Puro format date codes and the filter construction the 3323 filters. Seen and used enough of both the Bosch Prem now and Puro P1 to know that as fact. All the rest is extraneous info, at least to me. That includes what's happening now, a completely separate topic. Pointless for me now to continue the circular discussion.

 

[ZeeOSix]

.I'm going to agree to disagree then. I'm 100% confident the topic 3323 and all the multiple 3323 I've c&p on this subforum are made by M&H Purolator, i.e. made by Purolator oil filter division solely owned by M&H since 2013. That's the case until at least 2020 as proven by both the posted Puro format date codes and the filter construction the 3323 filters. Seen and used enough of both the Bosch Prem now and Puro P1 to know that as fact. All the rest is extraneous info, at least to me. That includes what's happening now, a completely separate topic. Pointless for me now to continue the circular discussion.

I'm missing your point in the bold statement above - is Bosch not using a Purolator style date code anymore. I'll post in this thread what I hear back from M+H in Germany about their connection or not with Bosch. I also sent an email to Purolator to see if they have any info in their involvement manufacturing Bosch oil filters. I don't see how they could still be connected by all the search results I keep getting. Info keeps coming back that they split ways and have no connection with each other anymore unless there is some secret agreement going on that nobody in the public knows.

 

[ZeeOSix]

I'll post in this thread what I hear back from M+H in Germany about their connection or not with Bosch.

Response from Mann+Hummel when I asked if Purolator and/or Mann-Hummel makes Bosch oil filters now. Couldn't get any details of exactly when this started being the case. Also have an email into someone at Bosch corporate in the filter department to see what they say.

 

[TooManyWheels]

I'm missing your point in the bold statement above - is Bosch not using a Purolator style date code anymore. I'll post in this thread what I hear back from M+H in Germany about their connection or not with Bosch. I also sent an email to Purolator to see if they have any info in their involvement manufacturing Bosch oil filters. I don't see how they could still be connected by all the search results I keep getting. Info keeps coming back that they split ways and have no connection with each other anymore unless there is some secret agreement going on that nobody in the public knows.

I don't know if this will clarify anything -

I recently (March 20, 2026) bought a closeout Bosch 3323 from Amazon. The can sticker lists Mexico as country of origin, the bottom-of -can code is 57430. I'm having trouble visualizing that as a date code at all.