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RB20 oil filter housing - Oil Filter Bypass or plug?

TurboTapin
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TurboTapin Rising Star

TurboTapin

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As I'll be doing an external oil cooler, I'm replacing my stock RB25 oil cooler with an RB20 oil filter housing. My RB25 left passage is currently plugged.  Is it best to keep it plugged or too remove and replace with bypass valve? I have a bypass valve on hand ready to install but I've never seen any concrete info on which is best. Most discussions seem to have a split vote.

My concern is that without bypass valve, will oil pressure be higher on occassions it should not or does it only bypass due to a clogged filter? 

 

Thanks

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joshuaho96 Veteran

joshuaho96

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With an external oil cooler I would imagine that you want a bypass both for filter pressure and the oil cooler. In the RB26 the factory housing has a relief valve on it for either scenario. I'm pretty sure that the block itself does not have the relief valve.

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TurboTapin Rising Star

TurboTapin

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On 4/14/2022 at 7:45 PM, joshuaho96 said:

With an external oil cooler I would imagine that you want a bypass both for filter pressure and the oil cooler. In the RB26 the factory housing has a relief valve on it for either scenario. I'm pretty sure that the block itself does not have the relief valve.

Yea I think bypass is the way to go as well but I want to get other peoples thoughts before I drill out the plug. 

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TurboTapin Rising Star

TurboTapin

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After taking the night to think about it, I could see a lot more positives then negatives to removing the plug and fitting in a bypass valve.

I center punched, drilled and taped the plug M8x1.25. Used a plate and a bolt as a puller and it came right out. After lots of cleaning with a magnet, shopvac with a small vacuum hose and brake cleaner; I gently hammered in the new bypass plug using an appropriately sized socket. 

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discopotato03 Grand Master

discopotato03

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Your calls but I think the filter bypass valve is there for two reasons .

Firstly some careless or clueless never change oil and filters . 

Secondly really cold climates may make it hard for oil to flow through the filter .

When I was playing with L20B fours back in the late 80s I had that bypass removed and plugged , I was using a remote filter as well . Note that L20Bs use a larger Z115 style filter std .

I don't think oil filters magically clog up , if you are prepared to change your oil and filter at reasonably regular intervals you should never have a problem that a filter bypass could solve .   

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TurboTapin Rising Star

TurboTapin

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On 4/15/2022 at 6:44 PM, discopotato03 said:

Your calls but I think the filter bypass valve is there for two reasons .

Firstly some careless or clueless never change oil and filters . 

Secondly really cold climates may make it hard for oil to flow through the filter .

When I was playing with L20B fours back in the late 80s I had that bypass removed and plugged , I was using a remote filter as well . Note that L20Bs use a larger Z115 style filter std .

I don't think oil filters magically clog up , if you are prepared to change your oil and filter at reasonably regular intervals you should never have a problem that a filter bypass could solve .   

Agreed! You seem to have made two great points to keeping it yet removed it? In your opinion, what are the positives to removing it? 

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joshuaho96 Veteran

joshuaho96

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On 4/15/2022 at 6:28 AM, TurboTapin said:

After taking the night to think about it, I could see a lot more positives then negatives to removing the plug and fitting in a bypass valve.

I center punched, drilled and taped the plug M8x1.25. Used a plate and a bolt as a puller and it came right out. After lots of cleaning with a magnet, shopvac with a small vacuum hose and brake cleaner; I gently hammered in the new bypass plug using an appropriately sized socket. 

Pretty sure this is the correct thing to do if you know that there will be no downstream relief valve. Looking at the RB20 housing I don't see anything like the relief valves in the RB26 housing.

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TurboTapin Rising Star

TurboTapin

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On 4/15/2022 at 8:40 PM, joshuaho96 said:

Pretty sure this is the correct thing to do if you know that there will be no downstream relief valve. Looking at the RB20 housing I don't see anything like the relief valves in the RB26 housing.

Agreed. The RB20 housing does not have a bypass/relief valve. That's why RB20's have the bypass valve in the block. Cheers. 

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Butters Experienced

Butters

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Amm this is why you buy a nice greddy oil filter re-locator, they have the bypass built in at the filter re-locator. Also thermostat for the oil cooler.  Much easier than messing with the block.

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