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Discussion Starter · #1 ·
I have a 1968 Chevelle Nomad with the original 327. The car and motor have 80k miles, however it has not ran in nearly 10 years. My great Grandfather bought the car originally, and it has just recently come into my possession. On with the problem. This past weekend I got the car back running, but an odd thing happend. Within 10 seconds of running the oil filter seal blew out and it dumped nearly all the oil before I could shut it down. Thinking I had somehow picked up the wrong oil filter, I got another one, verified it was correct, and installed it with more oil. Same thing, it blew out the oil filter seal. We're talking about a geyser, not a trickle and it's instant. From there I removed the filter and "hub" it screws onto. I cleaned up the hub, checked for obvious problems and reinstalled it with the filter and new oil. Again, it blew it out. I fear I have a blockage in an oil gallery just beyound the filter. Does this sound plausable to you fella's? Can anyone think of anything else that would cause this problem? If it is a blockage, is there anyway to clear it short of a rebuild? Thanks for your help.
 

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When you say its blowing the seal out be a bit more descriptive. Is it a spin on filter or the old "can" type?

Is the gasket actually being displaced or is the seal not complete and its just leaking?

In any event the relief valve in the oil pump should limit pressure such that the pressure never exceeds that of the capability of the filter to retain its seal. I would be looking at just how tight you have to crank that filter to get the seal you need. Something is wrong with either the style filter you are using OR the mount you are attaching it to.
 

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Discussion Starter · #3 ·
If I crank the filter as tight as i can, it blows the oil out, and displaces the seal, with great pressure. I've been messing with small blocks a long time, and I've never encountered anything like this. It's a screw on filter and the AC-Delco number is pf454. The little by-pass valve that is built into the "hub" seems to be in working order. I may be totally wrong with my logic, but it appears to me, that whether the oil bypasses the filter or not, it can't get much beyond the filter. The seal is the path of least resistance and the pressure is released there. Does this help more?
 

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66 El Camino 57 Chevy pickup 2004 Tahoe
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make double-dead certain there's not an old filter gasket stuck in the mount.
 

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Dale,

The first two thoughts that come to my mind are:
1) Are you sure the seal area is clean? There aren't any old oil filter seals stuck up against the block, are there?
2) You say you cranked the oil filter as hard as you could. Maybe you are over tightening it which would cause the filter to distort a little.
3) Have you tried to prime the oiling system with a primer through the distributor? You can always start at a low speed and work your way up higher. Plus, in case she gushes, you can stop very quickly.

Hope it helps...
Bill

*EDIT - Dang... Tom is faster at typing than I am... lol *
 

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I've had the seal from the old gasket stay stuck to the block. The second seal on the new filter just slides out and leaks. Get a flashlight and check once you have removed the filter. Like the other guys said, odds are pretty good that there is old rubber up in there.
 

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66 El Camino 57 Chevy pickup 2004 Tahoe
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>>And sorry to say...been there and done it.<<

that's the value of experience, you're able to quickly recognize the mistake as you're making it again..... :)
 

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Discussion Starter · #9 ·
Thanks for the response. I am absolutely positive there is no seal remnant at the mating surface. I cleaned it with a wire brush after I removed the hub the filter screws onto. I only screwed the filter on as hand tight as I could get it. No filter wrenches. What I haven't done is primed it. What is the best way to prime it? Removing the distributor and using a drill on the oil pump shaft?
 

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The seal does not seat against the part that you removed from the block. It seats against the machined area on the block itself. Check that area real close, sometimes it is hard to see if you aren't paying close attention.
 

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Discussion Starter · #12 ·
I don't have the original owners manual, and any factory stickers have long since deteriorated, but the filter is what the AC-Delco book called for for a 1968 327 in a Chevelle. As far as the Mating surface, it's clean. If we assume that the filter is correct, and the machined mating surface of the block is clean, can anyone think of anything else that might cause this problem?
 

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yes, I heard of a few issues with that in the past. Could be a tolerance stack-up deal like shallow mount, deep adaptor. what does it feel like when it tightens up? it should tighten up gradually as the rubber compresses, not hit bottom and stop.
 

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Can you, post a pic of the filter adaptor you're using?
 

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Discussion Starter · #16 ·
It tightens gradually. It actually feels no different than any other oil filter as it tightens. I can watch the seal as it compresses, and everything looks totally normal. I had it on my lift checking it out thoroughly, and it's blowing my mind. I compared the adaptor to another one I had off a mid 70's 350 in my shop. It's exactly the same. I think I might try installing that adapter on my motor and see if it does the same thing. I got to thinking, and if some of the threads on the adapter are stripped, it might let the filter drop down a thread or two under pressure, thereby resulting in a leak. I can post a picture, but it won't be for a day or so. Doesn't the flow of oil go through the filter first, and then to the rest of the motor?
 

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Pull out the oil pressure switch put in a test gauge and see what the oil pressure is when cranking the engine. I had a Chev and it also had been sitting for many years and had the same problem with the oil filter. Put a gauge on the engine and had 75 lbs oil pressure on the starter. Changed the oil pump and all was fine. The pressure relief valve in the pump was siezed in the housing and wouldn't relieve excess oil pressure.
 

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I was thinking the same thing. The engine has been sitting for so long that the pressure is getting to high and blowing out the easiest spot it can find. I seen this once on a late 80s 3.8 Oldsmobile once.
 
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