Slant Six Forum :: Oil Pressure

If the sender/gauge is accurate and the oil change doesn't fix the low pressure, where is the next step in diagnosing the problem?

My oil pressure has leveled out to about a static 25 psi, which makes me feel a little better but not fully confident. Still falls to about 20ish psi under throttle.

Also, correction again, oil pump is new. When the mechanic was installing my new oil pressure sender he said that the whole oil pump housing cracked. He replaced it for free, which is why it is not on my receipt.

So, advanced/autozone didn't have a oil gauge for me to rent. Planning on buying one but I think the issue is coming to a peak. Driving pressure is down to 8 psi. I switched to mobile synthetic but it didn't help. Calling the mechanic tomorrow, let him take a look. Taking the car off the road in the mean time. If it's the oil pump, hope it's under some manufacturers warranty (less than 500 miles). Guess I'll know soon enough.
Thanks for all the help and suggestions, I'll post an update once/if the issue is discovered.
Aspen76

It was a pro motive by Purolator.

replaced it with a Napa silver filter

True story: When I built my first performance engine (351C, 4 barrel heds, quecnh pistons, etc.), I was still young and poor. One time I got so broke I put a cheapo oil filter on. The engine had high oil pressure when cold, around 80 psi. (I did not know that you could shim an oil pump rellief valve TOO much!). One cold morning, a fellow serviceman borrowed it to get to base. He did not watch the oil pressure. The cheapo oil filter gasket blew out, and dumped the oil. He called me and said it 'did not sound good', and that he did not notice anything before it started making noise. That was an understatement.

It took a lot to get that fixed, maybe 300 times what I had saved on the cheapo filter.

Author:	mpgFanatic [ Fri Aug 01, 2014 8:52 am ]
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Quote: If the sender/gauge is accurate and the oil change doesn't fix the low pressure, where is the next step in diagnosing the problem? My oil pressure has leveled out to about a static 25 psi, which makes me feel a little better but not fully confident. Still falls to about 20ish psi under throttle. I have seen oil pressure get lower under throttle and then rise immediately as the foot comes off the pedal... the engine was extremely tired and my mechanic's theory was the rod bearings were worn to the point where engine vacuum made a difference in the vertical clearance of the bearing. But we never tore it down to test, because a $100 beater car offered a wonderful replacement engine. That type of wear is nothing which will appear suddenly, though, as you described this did. Quote: Also, correction again, oil pump is new. When the mechanic was installing my new oil pressure sender he said that the whole oil pump housing cracked. He replaced it for free, which is why it is not on my receipt. Well, I'm not the only one to experience the problem of cheapo imported replacement parts... ya know, where the factory part lasted 40 years and then the repair lasts 1 or 2.... Gosh I wish better parts were available. At any price. But again, don't let your brain dwell on that possibility, until you know what's really going on. - Erik

Author:	aspen76 [ Tue Aug 05, 2014 6:54 pm ]
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So, advanced/autozone didn't have a oil gauge for me to rent. Planning on buying one but I think the issue is coming to a peak. Driving pressure is down to 8 psi. I switched to mobile synthetic but it didn't help. Calling the mechanic tomorrow, let him take a look. Taking the car off the road in the mean time. If it's the oil pump, hope it's under some manufacturers warranty (less than 500 miles). Guess I'll know soon enough. Thanks for all the help and suggestions, I'll post an update once/if the issue is discovered. Aspen76

Author:	TonyPgh [ Tue Aug 05, 2014 7:28 pm ]
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Quote: So, advanced/autozone didn't have a oil gauge for me to rent. Planning on buying one but I think the issue is coming to a peak. Driving pressure is down to 8 psi. I switched to mobile synthetic but it didn't help. Calling the mechanic tomorrow, let him take a look. Taking the car off the road in the mean time. If it's the oil pump, hope it's under some manufacturers warranty (less than 500 miles). Guess I'll know soon enough. Thanks for all the help and suggestions, I'll post an update once/if the issue is discovered. Aspen76 Wow!! Don't forget to update us, and good luck. I just bought a set of mechanical gauges. I am afraid to hook them up now...

Author:	nm9stheham [ Wed Aug 06, 2014 8:58 am ]
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Quote: So, advanced/autozone didn't have a oil gauge for me to rent. Planning on buying one but I think the issue is coming to a peak. Driving pressure is down to 8 psi. I switched to mobile synthetic but it didn't help. Calling the mechanic tomorrow, let him take a look. Taking the car off the road in the mean time. If it's the oil pump, hope it's under some manufacturers warranty (less than 500 miles). Guess I'll know soon enough. Thanks for all the help and suggestions, I'll post an update once/if the issue is discovered. Aspen76 Ok, no doubt the right decision. BTW, the switch to Mobil1 (or any other synthetic) in this situation was not to raise the oil pressure, but just to protect the engine from damage while running the engine with such very low oil pressure.... important to do since you listed this as a daily driver. You were wise IMO to take that step for the sake of the engine.

Author:	oldskoolracer [ Wed Aug 06, 2014 3:21 pm ]
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What wieght of oil do you run? I recall you posting that you have in the range of 200-300k miles on the engine right? Chances are if your having these issues you may have excessive bearing clearances... It may be improved upon by running a heavier oil, and/or a high volume pump to keep the clearances pumped full of oil... Let us know what you find out after getting another gauge on there... An overhaul of that engine may be in your best interest if your really concerned and are willing to let it be parked for a few...

Slant Six Forum https://slantsix.org/forum/

Oil Pressure https://slantsix.org/forum/viewtopic.php?t=55883	Page 2 of 3

Author:	aspen76 [ Wed Aug 06, 2014 6:06 pm ]
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Hey guys, I'm glad to announce that the issue is fixed. Talked to my mechanic today and while he was almost certain it was bad bearings from the sound of it, he said that it could be collapsed oil filter. Changed the oil filter in 5 minutes and BAM, 50 psi again. Something so simple yet was the issue. I'm going to stay away from pro motive oil filters going forward. Yet again, thanks for all your help and suggestions, Aspen76

Author:	SlantSixDan [ Wed Aug 06, 2014 6:24 pm ]
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What brand of oil filter failed for you?

Author:	TonyPgh [ Wed Aug 06, 2014 8:47 pm ]
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Wow thats good news!! I double that question. What brand of oil filter was that??? I always run Purolator. Dan, is there a certain one you like??

Author:	aspen76 [ Thu Aug 07, 2014 3:59 am ]
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It was a pro motive by Purolator. Small thing too, replaced it with a Napa silver filter. http://www.promotiveautofilters.com/oil_filters.html

Author:	Charrlie_S [ Thu Aug 07, 2014 7:51 am ]
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In that link, you posted there is a "contact" button. I would do that and let them know about the problem.

Author:	oldskoolracer [ Thu Aug 07, 2014 9:07 am ]
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WOW! Glad you caught that! Ive definately seen that more than a couple times, dont know why it didnt cross my mind here...? I always run WIX filters on everything... Usually a couple extra bucks, but there a great brand of filters! The NAPA "gold" filters are just reboxed WIX just for NAPA distributors... Im a strong believer that youre oil and the filters you run should NEVER be a compromise, always use a well known, well trusted product... But thats just my opinion though...

Author:	SlantSixDan [ Thu Aug 07, 2014 1:25 pm ]
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Quote: It was a pro motive by Purolator. Looks like a "value-priced" line of filters with a bogus "size standardization" claim being used to explain why the ProMotive filter is too small for the application. A "ProMotive by Purolator" filter is not a Purolator filter. Those cost maybe a dollar or two more, and you'd be wise to spend it. Quote: replaced it with a Napa silver filter NAPA's "value-priced" (cheap) line of filters. Unless you are truly down to your last few dimes, I can't think of a good reason to buy less than the best oil filter. In the long run, good oil filters cost less than "econo-valu" ones.

Author:	nm9stheham [ Thu Aug 07, 2014 1:41 pm ]
Post subject:
True story: When I built my first performance engine (351C, 4 barrel heds, quecnh pistons, etc.), I was still young and poor. One time I got so broke I put a cheapo oil filter on. The engine had high oil pressure when cold, around 80 psi. (I did not know that you could shim an oil pump rellief valve TOO much!). One cold morning, a fellow serviceman borrowed it to get to base. He did not watch the oil pressure. The cheapo oil filter gasket blew out, and dumped the oil. He called me and said it 'did not sound good', and that he did not notice anything before it started making noise. That was an understatement. It took a lot to get that fixed, maybe 300 times what I had saved on the cheapo filter.

Author:	1930 [ Thu Aug 07, 2014 2:40 pm ]
Post subject:
Quote: True story: When I built my first performance engine (351C, 4 barrel heds, quecnh pistons, etc.), I was still young and poor. One time I got so broke I put a cheapo oil filter on. The engine had high oil pressure when cold, around 80 psi. (I did not know that you could shim an oil pump rellief valve TOO much!). One cold morning, a fellow serviceman borrowed it to get to base. He did not watch the oil pressure. The cheapo oil filter gasket blew out, and dumped the oil. He called me and said it 'did not sound good', and that he did not notice anything before it started making noise. That was an understatement. It took a lot to get that fixed, maybe 300 times what I had saved on the cheapo filter. If it were a slant six you could have just refilled it with oil and drove away!

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Author:	TonyPgh [ Thu Aug 07, 2014 5:52 pm ]
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I have been using some Purolator Gold one. I am a little worried now. I used to use Fram, but after getting a few that had bad threads, I stopped. WIX is nice. I don't think anyone near me has Wix on hand. My father use to use them. I think they are different than a paper filter, but I may be wrong?