Exploding Oil Filter

Engines, Transmissions, running gear, etc.

Moderator: Larry Jowdy

Re: Exploding Oil Filter

Postby RBP » Sun May 07, 2017 4:34 am

There is a bypass valve built into the filter that operates at 8-11 PSI, the bypass will open if the DP across the filter media exceeds this amount.

The other bypass is the one in your engine and has nothing to do with the filter. What some of the posters are saying is that if you use the thick oil (20-50), a 30 mm high volume pump on an engine not tapped for full flow with the remote cooler and filter it will not work right as the engine bypass will stay open due to the excessive pressure. If you have a gauge I would check it to see what oil pressure you have at say 2500 RPM cruising on the hwy. I think I remember Larry saying the ideal would be around 35 - 45 PSI to work properly with the engine bypass. If the pressure is too high you can go to a thinner oil.

If the pressure is too high it means that the bypass will just stay open diverting oil back to the sump.
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Re: Exploding Oil Filter

Postby RVosari » Sun May 07, 2017 4:59 am

On a cold start, the oil is thick(er) and does not easily pass through the filtration medium, thus building up to a high pressure drop. The bypass valve opens to prevent oil starvation to the motor. When the pressure drop across the filtration medium drops below… the bypass valve setting… the valve closes and filtration resumes.

In (very rough) terms the filter bypass pressure is 8-10X less than the motor oil pressure…so an 8 psi bypass pressure suggests that the filter is fully operational when the motor is showing 60 psi of oil pressure.

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Re: Exploding Oil Filter

Postby DannyP » Wed Jun 28, 2017 2:57 pm

I run 10w40 now. I used to run 20-50(Jake recommended) but it's really not necessary unless you're desert running. My oil temps dropped 10 degrees Fahrenheit with no other changes. Hmmm, imagine that. I have been using Valvoline 4-stroke Motorcycle oil for about 5 years now. It is specifically designed for flat tappet engines(Harleys?). It can be cheap if you buy a case when it's on sale, but otherwise is $6 at every Advance and Autozone in America. Sometimes, ease of purchase trumps all else.

Also, I have been using the Wix 51515 or NAPA Gold 1515 which is always in stock at every NAPA. It has almost if not the same pressure rating, but filter down to smaller microns than the R version, plus it's about $5. Better filtration for half the money, yes, I'll take it. We had a discussion about filters over at Speedsterowners and someboby posted the specs. You can look them up on the Wix site, I did years ago. Good enough for me.

Biker, isn't it possible that one filter is defective? If you never had a problem before, you're probably OK.
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