Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Oil Filter Bypass Valve -- How Long Before It Opens?

Oil Filter Bypass Valve -- How Long Before It Opens?

Oil Filter Bypass Valve -- How Long Before It Opens?

Rumor has it that the standard oil filter bypass valve opens due to excessive filter backpressure way before you change your oil.  This doesn't make much sense to me.  Sure, it is possible, but surely it doesn't happen.  Tell me it ain't so!

RE: Oil Filter Bypass Valve -- How Long Before It Opens?

You are right for the wrong reason.  It is unusual for filters to go into bypass because the element is clogged.  Most filters in a normally running engine can easly go more than 20,000 miles.  Here is what you didn't expect.  Filters often go into bypass when the engine is started and the oil is too thick to go through the filter media at the flow rate.  If these things keep you up at night,  buy a filter with the bypass valve at the top of the filter.

RE: Oil Filter Bypass Valve -- How Long Before It Opens?

Well, that makes some sense, as the oil will be thicker at startup.  Any idea which filters are bypassed at the top?  The Motorcraft seems to have a spring valve at the top, but I always thought that was the anti-drainback valve.

RE: Oil Filter Bypass Valve -- How Long Before It Opens?

The anti-drainback valve is the rubber seal just inside the 5 to 8 small holes in the base.  The Relief valve is what you normally see at the end of the long tube.  certain filters combine both at the base (Fram-which is no good for other reasons, and Luberfiner are two I know of with the combo valves.) If you are using oil that is too thick for your climate, you ideally do not want this valve at the lowest position.  The combo valves are excellent for horrizontal, diagonal, or hanging filters. But those mounted vertically with the base down would be better off with the top valve.  Some filters do not have the bypass/relief valves at all, either because they were designed for engines with the valves built into the baseplate by the manufacturer o they are bypass filters that filter down to smaller partical sizes knowing that they are only carrying small percentage of the total oil and when they clog the oil just stays in the normal flow pattern.

RE: Oil Filter Bypass Valve -- How Long Before It Opens?

Thank you.  I'll check for non-combination valve on my Mobil 1 filter and my K&N filter.  My filter is mounted vertically with the cup up, threads at top.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close