blue thunder

The spring that you show as "leaf" or "spring" is the bypass portion of the filter. The entire filter elment will work against this spring and when over pressurized bypass oil on the top. At least that is alway how I've understood it to work. The coil spring is best because it can be over pressurized without being destroyed. The leaf can become rendered useless after repeated over pressurization. Correct me if I am wrong, but that is my understanding of hydraulic filter operation.

Dave

Grease

Normally that is the case, however in the PF1218 family of filters, there is no by-pass at all. That is the spec. Oil filter companies call this a full-flow filter. Here is a good example:

(remove the Z)

Zhttp://www.osuweb.net/~mccarter/gw/Image6.jpg

You can see that the end away from the filter opening is completely closed. That is the case on every one of these filters -- except for the Fram. The Fram's only have an opening because the endcap is paper and not metal. The leaf spring on the Fram would distort the paper endcap, so they put a hole in it to seat the leaf spring instead of the indent as the rest of the filters.

Not sure of the filter you are using, but if it is this family / application, by-pass is handled by the engine.

If you application is different you can look up that filter and see if there is a by-pass listed on that mfg's web site. If they don't say either way, look up cross references on other's sites. Someone will indicate whether full-flow or by-pass valve.

Hope this helps.

Grease

blue thunder

I'm still not understanding Grease. If the media becomes clogged, the pressure builds onto of the closed end, as shown in the link you posted. This pressure forces the element assembly against the spring, leaf or coil which ever is applicable. When the spring deflects, the element moves away from the inlet side of the filter (stamped piece) and allows oil to bypass the element. If this was not the case a spring would be unnecessary.

Dave

Grease

The spring on these filters is used to seat the anti-drain back valve against the open filter end and the baseplate -- and to center the media within the can.

Take the Baldwin B1428 for example (which is a cross to the AC Delco PF1218. Here is the listing from their web site:

Descriptions : Microlite Lube Spin-on

Contains : Anti-Drainback Valve

Fits : Chevrolet, GMC Automotive

Replaces : GMC 25160561

Thread : 13/16-16

O.D. : 3 11/16 (93.7)

Length : 5 11/32 (135.7)

I.Gskt : G383-B

Related to : B6 (without Anti-Drainback Valve)
B1438 (Short Version)
B1441 (with 14 PSI By-Pass Valve)

At the end, they describe other filters that have other attributes. In this case, they have the B1441 that has a by-pass valve.

What filter are you using?

blue thunder

I have been using the delco 1218 for the last couple of years. I also have had functioning engine mount bypass valves. In an effort to control excessive oil temps, among other things I have blocked the engine bypass valve. Now all the oil will be forced through the cooler (and filter). Because I have blocked the engine bypass, it becomes imperative that I have a filter with a bypass. I always thought the leaf or coil spring made up the bypass of the filter, the element being the poppit. I guess what you are saying is a filter with a bypass will have a seperate poppit and spring to act as a bypass.

This being said, is it safe to assume the baldwin part number B1441 (with 14 PSI By-Pass Valve) would be the filter for me? I'll have to get on their site and check it out. Thanks for the info.

Dave

Maritime_Eng

Grease-

I would be interested to know what you think of the Donaldson filters. I am a Mechanical Engineer at Donaldson Company in the Diesel Exhaust Group and would like a outside opinion of our filters compared to the others.

Thanks
Don

blue thunder

I called and talked to Baldwin today. They confirmed that the bypass valve is a seperate spring/poppet and that the B1441 would be a good choice for me with the blocked engine bypass. I order (4) at $6.47 each. Thanks for the heads up on that Grease.

Dave

formula31

Good Job BT and Grease. Heck, you should have waited, we could have gotten case quantities. I have always assumed the 1218 had a bypass valve too. So what happens if the engine bypass is plugged and the filter has no bypass and gets plugged? Oil pressure drops? Is the oil pressure sender downstream of the remote stuff or before it? if the pressure drops, maybe its better to have filter without a bypass, at least you know. Im still out on the whole block bypass thing anyway.

Grease

Excellent. I think you will be happy with the B1441. The Baldwin filters are very well built. They are a good compromise between filtration and flow.

Grease

I have a Donaldson P550964 in my hands that I will be adding to the comparison -- it is the map to the PF1218. It will take a few weeks to get the tests run, compiled, and updated. I will also be ordering a P166564 to test the synthetic media as well. I will hold off on my comments until then.