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L28 blowing oil. Literally.


MidnightRider

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I just did the first oil change on my rebuilt L28E. It's a stock block with an N42 head, schnieder street cam. The car started leaking oil at the filter the first time I took it out, the seal on the oil filter wasn't flat so I figured it was a defective filter. Put on another one in the garage, spewed oil everywhere. Put on another one, from autozone, reccomended size, the surface was clean. No the old seal was not there. Yes I put a little oil on the seal. Yes I tightened it enough. Drove it again.... same problem. Not only did I miss my exams but when I fired it up it was so low on oil that the engine was literally griding metal and moaning until the oil I added circulated.

 

Am I using the wrong size filter?

 

The ones I got from autozone were FRAM Tough Gaurd TG8A

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Yes. It screws on easy by hand, with no leaks.

 

Take the filter off and take a good look at the sealing surface and the threads on the filter mount. Remove the rubber gasket from one of your old filters and stick it on there to see where it sits. Someone in the past might have scratched the sealing surface, or buggered up the threads.

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There's not a whole lot to the oil filter and it's sealing surface. You just need to stick your head down in there with a bright light and see what's going on. The L6 has the most accessible oil filter mount and sealing surface that I've ever seen.

Edited by NewZed
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You can poke the check ball in with your finger or a soft tool with the oil filter off, I believe. EL-4 in the FSM describes service and replacement.

 

A comment from the logical thinking perspective - if the oil is not coming through the sealing surface, where is it coming from? Blowing out through a seam in the filter? Is the filter damaged? Why are you focusing on the filter if you don't think it's leaking at the filter seal?

 

Check the oil pressure gauge. Maybe you knocked it when you were changing the filter and it's cracked or broken at the base. A small hole at high pressure would spew.

Edited by NewZed
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Ok maybe I didn't put it very clear,

 

Old motor - oil came out of ever where but not the filter

Rebuild motor - Everything is perfect, no leaks.

Rebuild motor after first oil change - Leaks oil at the filter, tested several filters.

 

I tested the check ball, seems fine to me but maybe something is clogging it at certain times or at high RPMs. :hs:

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The only time I have ever seen the oil filter seal get blown out is from a bad oil pressure bypass in the oil pump. If this sticks closed the oil pressure will go way to high, at least when the oil is cold. Check your oil pressure.

 

This. My dad's dry sump oil pump had the bypass piston froze. Pushed oil pressure past 100psi with easy and bam. It literally pops though and sprays EVERYWHERE.

 

Note: This does it with a brand new filter, it doesn't matter if the seal is fine, it doesn't destroy the seal, it doesn't tear it, it just sprays oil, very quickly. Granted we have a dry sump so it likely goes a bit faster. This is likely your issue, check your oil pump itself.

Edited by ModernS30
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So that's two for the oil pump check valve.

 

So you two are saying that a good L6 oil pump will generate enough flow to overrun the oil filter relief valve with enough pressure to lift the oil filter off its base, blowing oil out, if the oil pump regulator valve is stuck or blocked? Or maybe so much flow is generated that the main gallery after the filter is a restriction, so the filter relief valve doesn't matter?

 

Just trying to learn something. That seems like a lot of oil and a lot of pressure. Sounds interesting.

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Edit - a blocked main gallery, after the oil pump, could also lead to high pressure, and take the oil filter relief valve out of the picture. Might also explain the groaning bearings.. The oil pump regulator valve should still hold pressure to ~80 psi though. Good luck.

Edited by NewZed
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Thanks for the advice guys, I went ahead and ordered a pump from autozone a couple of hours ago. NewZed asked a good question. All I know is the first time it blew, it leaked oil from the end of my neighborhood to the other side of town 30 minutes away. When my dad saw the oil on the street and called to tell me to check my gauges they looked normal. I pulled into a parking lot and sure enough there was a puddle underneath the car as soon as I stopped, and the dipstick showed no oil. Good thing my dad saw that because I would not have noticed those gauges because they are hard to see at night especially with oncoming traffic. Gotta get me some prosport evo gauges, they even flash red when there's a problem. B)

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So that's two for the oil pump check valve.

 

So you two are saying that a good L6 oil pump will generate enough flow to overrun the oil filter relief valve with enough pressure to lift the oil filter off its base, blowing oil out, if the oil pump regulator valve is stuck or blocked? Or maybe so much flow is generated that the main gallery after the filter is a restriction, so the filter relief valve doesn't matter?

 

Just trying to learn something. That seems like a lot of oil and a lot of pressure. Sounds interesting.

 

Exactly. The oil pump is a positive displacement pump with a 150 (or more) horsepower behind it. The oil filter bypass is not the issue. The oil pressure builds up in the oil system after the filter due to the bearing clearances and such. When the pump output volume exceeds the leak rate and raises the pressure to 60 PSI or so the (pump) bypass opens to allow some of the oil to bleed off before the oil system. If the bypass is stuck closed the pressure can easily be several hundred PSI. Something will fail at this high pressure.

 

A case in point: My father's Alfa Romeo packed a rod bearing and overheated the oil (or perhaps the other way 'round). When the mechanic put it all back together he neglected to check the oil pump (lame). At start-up they got 4 quarts of oil on the ground because the oil filter seal blew out. The mechanical oil pressure gauge was also damaged due to being over-ranged (100 PSI gauge). After some head scratching they checked the pump and found the bypass valve was stuck closed, presumably due having been overheated. A new pump solved the problem.

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