The Hastings/Amsoil Bypass story

[Pablo]

Wrote the following:

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Dear Hastings,
I am an Amsoil dealer on a quest to gain more knowledge (not steal "secrets").

1) I have a question about the pressure bypass valve in the Amsoil SDF-42 (also SDF-15). I took this filter apart and found it to be constructed differently than typically depicted in Amsoil cutaway artwork. In the case of the artwork the bypass "valve" is at the far end of the filter away from the oil inlet/exit endplate. I have not cut one like the artwork apart to see exactly how it works but I can visualize it. - Now when I cut open the SDF-42 the bypass valve is a very neatly engineered little valve with a captive spring, etc right at the outlet. The spring way at the far end just serves to hold the filter element in place. I like this design because if the a bypass valve opens you don't get all the filtered debris flushed into the system. Are my observations correct? Is this a new feature? Will it appear on other SDF filters? I already have worked with Amsoil Tech, service and the fellow I spoke with was largely ignorant of the two types of bypass valves.

2) Amsoil told me the LF-490 is obsolete. I don't think it is. The application is Volvo - car gasoline motors from 196X to 1999. SDF-42 is the Amsoil choice for the Volvo OEM Mann W917. Is the LF-490 equivalent and does it have the great bypass valve mentioned in #1).

Thank you very much,

Paul A. Seminara

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And got this answer:

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Paul,
You are very astute in your observations and for your reference, we call the sub-assembly a "front-end by-pass" when it is located next to the filter thread. When located opposite the thread-end of the filter, it is naturally referred to as a rear-end by-pass. You already recognized the advantage of the former in that it minimizes the amount of debris that could be flushed back into the system when in a by-pass condition.

Besides SDF-15 & SDF-42, there is a third filter in the Amsoil line w/ this by-pass assembly & that is SDF-96. You'll notice the common "thread" (no pun intended) for all these is 3/4-16 and unfortunately, the front-end by-pass can only be used with that thread. The other restrictions for it's use are in the 3.69/3.75" diameter filters and the 8 psi operating pressure.

The front-end by-pass has multiple parts and by the nature of the design & function, the fit with the thread backside is very tight. In other words, each thread size would require a separate sub-assembly and we simply chose "not to go there" because tooling costs would have been prohibitive. For the most part, the filter industry as a whole follows a similar pattern. To my knowledge, no one has the front-end by-pass in all their products!

The rear-end by-pass, though lacking the advantage described, is very flexible in where we can use it and there are only a few variations for the various diameters and operating pressures.

Question #2 related to the Hastings LF-490 and you're right, it is not obsolete so this may be a misunderstanding. This filter, though 3/4-16 thread & 3.69" diameter, requires a 20 psi by-pass so we use the rear-end valve for it.

I hope that answers your questions but if not, I have copied Dave Anderson at Amsoil for follow-up. We normally refer all questions through Dave but in this case, I felt he would probably need some input from me and a direct response would save all some time. Thank you for your continued use of Amsoil & Hastings products.

Regards,
r c

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[Spector]

Nice follow up work and a great response. The explanation on when they use the different location makes sense

 

[Pablo]

Thanks - I thanked the guy profusely and followed up with a burst strength question, because Amsoil tech rep would only say "2X-4X OEM"....

 

[BOBISTHEOILGUY]

You may want to invite him to visit the site sometime as his expertise would be highly welcomed on here.

 

[Ken2]

Pablo,

I read on some SHO page that the front end bypass was a Ford requirement. Ford uses a lot of 3/4-16 threaded filters, so this is maybe one reason why only these filters have the front end bypass valve.

You might find that if you contact Baldwin tech line or Hastings tech line, you get answers from the same helpful person.

Ken

 

[dragboat]

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Originally posted by BOBISTHEOILGUY:
You may want to invite him to visit the site sometime as his expertise would be highly welcomed on here.

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Yep it seems a little old oil drain back valve and how they work cannot be agreed on in another thread,,hoping someone will step in and educate there

 

[G-MAN]

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Originally posted by dragboat:

Yep it seems a little old oil drain back valve and how they work cannot be agreed on in another thread,,hoping someone will step in and educate there

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If I'm wrong, I'd love to be educated on this topic.

But in reading several oil filter mfg tech papers and catalogs over the past 20 years, the function of the anti-drainback valve has always been described as I stated it in the thread you're referring to.

[ December 05, 2002, 05:14 PM: Message edited by: XHVI ]

 

[metroplex]

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Originally posted by Ken2:
Pablo,

I read on some SHO page that the front end bypass was a Ford requirement. Ford uses a lot of 3/4-16 threaded filters, so this is maybe one reason why only these filters have the front end bypass valve.

You might find that if you contact Baldwin tech line or Hastings tech line, you get answers from the same helpful person.

Ken

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Ford has stepped to M22x1.5 threaded filters for ALL of their modular engines. The Motorcraft FL-1A for 3/4 threaded blocks do have the front-end bypass, as do some of the Wix counterparts. But there are quite a few replacements out there for the 3/4 threaded filters that DO NOT have the front-end bypass.

In fact some of my modular oil filters do not have them either. I've been using them for 3 years w/o noticing anything really different.

 

[shoz123]

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Ford has stepped to M22x1.5 threaded filters for ALL of their modular engines

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Does this include the newer Duratec motors?

[ January 01, 2003, 09:39 AM: Message edited by: shoz123 ]