Does my filter have a bypass valve?

[rcy]

I'm just wondering because of two things. One - the recommended filter at the Wix website does not list a bypass valve PSI setting; two - my Factory Service Manual shows an 'oil pressure relief valve' inside the filter mounting thing on the engine itself.

Assuming the car has an internal bypass valve, would there be any benefit, or drawback to using a filter that has a bypass valve in it?

Cheers.

 

[slalom44]

If the bypass setting of the filter bypass valve is lower than the engine's pressure relief valve, then you'll get unfiltered oil (and the resulting larger particulates that the filter media would otherwise trap)passing through to the engine. The benefit: oil pressure to the bearings remains high.

If the bypass setting of the filter is higher than the engine's pressure relief valve, then the filter's bypass valve will never open up, and no unfiltered oil will ever get through to the engine. The downside: Potentially reduced oil pressure to the bearings when the engine needs it most, such as during engine startup in cold weather.

So in my opinion, it's a tradeoff. IMO, it's probably fine to use a filter with a bypass valve. If you go with an oversized filter, you can potentially get the best of both worlds: neither bypass valve ever has a reason to open up.

[ March 20, 2004, 04:40 PM: Message edited by: slalom44 ]

 

[Bill Kapaun]

quote:

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Originally posted by rcy:


Assuming the car has an internal bypass valve, would there be any benefit, or drawback to using a filter that has a bypass valve in it?

Cheers.

---

If the oil filter also has a bypass valve, there could possibly be some advantages/disadvantages-
IF in the unlikely event the engine bypass valve stuck, the filters valve would act as a "safety" valve.
If the filters bypass pressure is lower, it would circumvent the engines bypass valve. One would have to assume that the engineers know what they are doing, so that would be a negative IMO.
If the filters bypass valve is higher, it wouldn't have any effect other than possible seepage past it IF it didn't seal 100%.

 

[TC]

RCY: This link addresses this matter to some extent, although it doesn't directly address the advantages/disadvantages.

http://www.machinerylubrication.com...eid=398&relatedbookgroup=ContaminationControl

Slalom and Bill made some good points. One thing I might add: Your engine is most likely in good shape, and clean. But if it's older, or perhaps you bought it used with some amount of sludge and/or varnish visible inside, a filter with its own bypass valve could be beneficial. If the block's bypass valve is immaculate (because the rest of the engine is clean too), no problem. But if there's gunk in the engine, you can assume the block's bypass valve has some too, increasing the benefit of secondary (in-filter) bypass capability. For such a "gunk" engine, I would attempt to clean it as well as install a filter with its own bypass, just to be safe.

 

[Ken2]

quote:

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Originally posted by slalom44:
If the bypass setting of the filter bypass valve is lower than the engine's pressure relief valve, then you'll get unfiltered oil (and the resulting larger particulates that the filter media would otherwise trap)passing through to the engine. The benefit: oil pressure to the bearings remains high.

If the bypass setting of the filter is higher than the engine's pressure relief valve, then the filter's bypass valve will never open up, and no unfiltered oil will ever get through to the engine. The downside: Potentially reduced oil pressure to the bearings when the engine needs it most, such as during engine startup in cold weather....

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The built-in relief valve and the filter internal bypass valve do the same job...bypass oil around the filter element if the pressure differential is too high. If you have a car with a built-in relief valve, you'd never want a filter with a bypass valve with a lower setting.

It's far better to get the specified filter for an engine than to get caught up in the bigger-is-better filter mania and put the wrong filter on an engine.


Ken

[ March 22, 2004, 01:25 AM: Message edited by: Ken2 ]