Low oil pressure caused by oil filter?

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So I noticed the oil pressure gauge on my '94 Subaru Legacy seemed to be reading low. After I replaced the oil filter, the problem went away.

It was taking about four seconds after startup for the oil pressure light to go off, then the oil pressure would very slowly rise. But it would never go above 25 psi.

After replacing the oil filter, the pressure now climbs quickly to about 65psi after start up, which is what I expect (this is with engine cold).

So what's up with this oil filter? Was it defective? It was a Amsoil eao34, says Made in Mexico Jul0209. I checked the ADBV and it didn't seem to be stuck. I guess maybe I should cut it open and see if anything is funky in there?

It really irritates me that it seems like it was the oil filter, because this is supposed to be a premium oil filter, and here I was running the engine for a week or so with highly suboptimal oil flow.

At first I thought it was the pressure gauge was bad (Sunpro I had just installed). So I replaced the sender and gauge, but it did the same thing. So next I tried the oil filter, and that seemed to fix it.
 
I had the same thing happen to me on 2 different AC/Delco filters. ZERO oil pressure at start up until you rev'd the engine and then oil pressure rose. I changed the filter and problem gone. I've never used another AC filter since. Been using Bosch the last 2 years and never had the oil pressure issue again. It was the filter.
 
Hm that's interesting. I wonder what it is about the filter that can cause it?

I had the oil pump off while doing the timing belt. I noticed on the first startup, the pressure did climb to around 65psi which I was happy with, but that was it. After that it never went above 25psi again until I changed the filter.

I know some cars can have trouble getting the oil pump to initially suck the oil out of the pan through the pickup after this kind of job though I've never had it happen.

I replaced it with a different Amsoil eao34 and it seemed to be fine. I've been using this filter for many years on several Subaru's but never had this problem before.

The other thing that really bothers me about this, is that without an oil pressure gauge, I would never have known about this problem. I had noticed increased engine noise for the first few seconds after startup which didn't seem quite right, along with the oil light taking too long to go off, but after that I wouldn't have known without a pressure gauge.
 
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it could be i had a problem like that using a pureone my oil pressure took longer to build up changed that and everything was back to normal that was on a dodge ram 250 with a 5.2 litre 318
 
Originally Posted By: porcupine73
Hm that's interesting. I wonder what it is about the filter that can cause it?

I had the oil pump off while doing the timing belt. I noticed on the first startup, the pressure did climb to around 65psi which I was happy with, but that was it. After that it never went above 25psi again until I changed the filter.

I know some cars can have trouble getting the oil pump to initially suck the oil out of the pan through the pickup after this kind of job though I've never had it happen.

I replaced it with a different Amsoil eao34 and it seemed to be fine. I've been using this filter for many years on several Subaru's but never had this problem before.

The other thing that really bothers me about this, is that without an oil pressure gauge, I would never have known about this problem. I had noticed increased engine noise for the first few seconds after startup which didn't seem quite right, along with the oil light taking too long to go off, but after that I wouldn't have known without a pressure gauge.


Keep the oil filter and give Amsoil a call ASAP.
 
I had a flaky oil pressure problem with a Amsoil Ea filter and a 94 Camry. Replaced the filter with another brand and no more problems. Sent filter to Amsoil who said it was full but not defective. I am not sure what to conclude, except that filter in that condition caused a problem.
 
Originally Posted By: GMBoy
I had the same thing happen to me on 2 different AC/Delco filters. ZERO oil pressure at start up until you rev'd the engine and then oil pressure rose. I changed the filter and problem gone. I've never used another AC filter since. Been using Bosch the last 2 years and never had the oil pressure issue again. It was the filter.


Were they the 'new' AC Delco filters? E cores. I stopped using AC Delco filters and now buy NAPA silvers. Same price.
 
Originally Posted By: GMBoy
I had the same thing happen to me on 2 different AC/Delco filters. ZERO oil pressure at start up until you rev'd the engine and then oil pressure rose. I changed the filter and problem gone. I've never used another AC filter since. Been using Bosch the last 2 years and never had the oil pressure issue again. It was the filter.


Was this the initial startup after an oil or filter change, or afterwards? Did you autopsy the filters? Two defective filters in a row is bizarre.
 
Originally Posted By: Jim Allen
Originally Posted By: GMBoy
I had the same thing happen to me on 2 different AC/Delco filters. ZERO oil pressure at start up until you rev'd the engine and then oil pressure rose. I changed the filter and problem gone. I've never used another AC filter since. Been using Bosch the last 2 years and never had the oil pressure issue again. It was the filter.


Was this the initial startup after an oil or filter change, or afterwards? Did you autopsy the filters? Two defective filters in a row is bizarre.




I had posted about this when it happened but beings it was so long ago I could not find it. But, anyhow yes it is strange, but true.

This happened each time about 1000 miles into the OCI, it was not related to a fresh oil change. I threw the first one away but I sent the 2nd to AC DELCO but never got a response. Mind you, these 2 filters were purchased several months apart so I doubt it was the same lot.
 
Originally Posted By: rshaw125
Originally Posted By: GMBoy
I had the same thing happen to me on 2 different AC/Delco filters. ZERO oil pressure at start up until you rev'd the engine and then oil pressure rose. I changed the filter and problem gone. I've never used another AC filter since. Been using Bosch the last 2 years and never had the oil pressure issue again. It was the filter.


Were they the 'new' AC Delco filters? E cores. I stopped using AC Delco filters and now buy NAPA silvers. Same price.



I'm sorry but I don't remember. It was 2 years ago, not sure exactly when ecore came along but I "think" the number on the box did not have the "E" after it making it the original style.
 
Only way a filter could cause a low oil pressure reading on a sending unit located after the filter is if the filter got majorly clogged somehow and didn't allow oil to flow. This would cause the oil pump to increase output pressure and eventually hit its max pressure relief setting, and shunt most of the oil back to the sump.

Even if the media was totally clogged up, it's possible depending on the bypass valve design, that the oil flow could be choked down significantly enough due to a restricted bypass valve flow area that would cause a low oil pressure reading. Or it's possible the bypass valve didn't operated correctly, thereby causing a large restriction when the filter needed to bypass due to clogged media.

Really need to dissect any filter that is suspect of causing a major lack of oil flow.
 
Thanks for the info. So I cut the filter open (Amsoil eao36 [not eao34 I had the wrong #]) this evening to see what was going on in there.

What I found was the media slightly collapsed, but not overly so. There was some amount of a sludge like slightly gritty black material over most of the filter media. I assume it came from my engine.

I don't think I see a bypass valve in this filter? It had a spring and solid end cap. I thought this filter was supposed to have a bypass? Unless I'm just not recognizing it.

So it appears what happened is the filter media got quickly plugged up with this sludgy stuff and then could not pass much oil, especially since it had no bypass.

That would explain that I did see around 65 psig the first time I started it up. There must have been a bit of junk in the pan that got pumped into the filter right at startup.

So I will need to keep an eye on the pressure now, since maybe there is more junk in there that will plug up the filter quickly again.

Between the pleats the filter was pretty clean, but the pleats were pretty packed together.
 
I need to open an Amsoil EaO20 that I suspect to be 'full', possibly. That or my oil pressure switch was faulty, replaced filter and switch no more oil light. No actual gauge, though...
 
The filter should be changed with another one exactly the same to verify it is the filter design, or a defect, or a lot closer to verifying. Always possible to get two bad ones in a row but not likely.
 
I think AC Delco got out of the filter business around 2005 or 2006. That's when the ecore's began to appear. Along with the complaints.
No point in really using one. They are 3.97 at Walmart. NAPA has the silver for 3.99.
 
PF47E and PF52E found at Wally's are e-cores made by Champion Laboratories. The same filters without the E suffix are conventional construction, but I don't know who makes them. I've bought PF52s (no E) at AutoZone recently, so I know they're still available.

Although I'm not completely sold that the e-core is as bad as some claim, I still prefer the others when I work on someone else's car. Power of suggestion...peace of mind...whatever.
 
So far the new filter I installed is not having the low pressure issue. So I was a bit hasty to complain the oil filter was faulty. It actually did a good job of catching whatever that junk was that clogged it up so fast. Still a bit confused on the bypass though, this filter had no bypass, and I thought it did. (Amsoil eao36).
 
Originally Posted By: porcupine73
Still a bit confused on the bypass though, this filter had no bypass, and I thought it did. (Amsoil eao36).


You got photos of it cut open? Hard to believe it doesn't have a bypass valve if you Subaru requires one. I've never heard of any Subaru having the bypass valve in the engine block like a GM V8.
 
I still have the filter, so I can shoot a pic of it.

Now this filter, however, is not the part # they suggest for Subaru. Right, Subaru's don't have a bypass in the block. There is one in the oil filter but not to bypass the filter, just to limit the pump output pressure.
 
Originally Posted By: porcupine73
I still have the filter, so I can shoot a pic of it.

Now this filter, however, is not the part # they suggest for Subaru. Right, Subaru's don't have a bypass in the block. There is one in the oil filter but not to bypass the filter, just to limit the pump output pressure.


The pump output pressure is never controlled by the oil filter. The engine's oil pump should have a pressure regulator valve built into it.
 
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