07-02-2025, 09:51 AM
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#1
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Registered User
Join Date: Jun 2010
Location: spain
Posts: 73
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The oil pressure drops above 3000 rpm
Hello, I have a problem with the oil pressure. After replacing all the hydraulic lifters for a tic-tic noise with some of them, the noise stills.
The problem is oil pressure is low when rev the engine over 2500 rpm (driving highway for ex.), so the hydraulic lifter is discharged. Do you know where is the possible causes of a low oil pressure?
I have red that the chain tensioners charge with oil pressure and if they aren't hermetic can loose oil for it and pressure decrease.
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07-02-2025, 10:48 AM
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#2
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Registered User
Join Date: Feb 2005
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I'd be looking at the oil pressure relief valve on the oil pump, possibly the pump itself.
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“Anything really new is invented only in one’s youth. Later, one becomes more experienced, more famous – and more stupid.” - Albert Einstein
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07-02-2025, 02:01 PM
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#3
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Registered User
Join Date: Jun 2010
Location: spain
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Quote:
Originally Posted by JFP in PA
I'd be looking at the oil pressure relief valve on the oil pump, possibly the pump itself.
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is the 25 and 26 parts?
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07-02-2025, 02:13 PM
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#4
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Registered User
Join Date: Feb 2005
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Yup........
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“Anything really new is invented only in one’s youth. Later, one becomes more experienced, more famous – and more stupid.” - Albert Einstein
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07-03-2025, 08:23 AM
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#5
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1998 Boxster Silver/Red
Join Date: Sep 2017
Location: 92262
Posts: 3,093
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Quote:
Originally Posted by JFP in PA
Yup........
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That's a quick easy update.
JFP... alternatively... could it be a bad/faulty sending unit? 
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1998 Porsche Boxster
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07-03-2025, 12:37 PM
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#6
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Registered User
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Quote:
Originally Posted by Starter986
That's a quick easy update.
JFP... alternatively... could it be a bad/faulty sending unit? |
Possible, but they don't tend to die that way, they just stop working completely. He could always substitute a mechanical gauge to find out if it is real or not.
The pressure relief valve on the pump can fail and blow open a soon as the pressure begins to build, suddenly dumping all the pressure.
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“Anything really new is invented only in one’s youth. Later, one becomes more experienced, more famous – and more stupid.” - Albert Einstein
Last edited by JFP in PA; 07-03-2025 at 12:40 PM.
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07-04-2025, 10:07 AM
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#7
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1998 Boxster Silver/Red
Join Date: Sep 2017
Location: 92262
Posts: 3,093
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Quote:
Originally Posted by JFP in PA
Possible, but they don't tend to die that way, they just stop working completely. He could always substitute a mechanical gauge to find out if it is real or not.
The pressure relief valve on the pump can fail and blow open a soon as the pressure begins to build, suddenly dumping all the pressure.
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Thank you.
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1998 Porsche Boxster
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07-04-2025, 10:08 PM
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#8
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Registered User
Join Date: Jun 2014
Location: LB, Germany
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I would also check the oil pump for wear.
And maybe also the net / filter of the oil catchup of the oil sump. Maybe it's clogged by old sealing material or something else.
Also make shure you run the right engine oil. 0W-40 is recommended from the factory. If you run a modern 0W-20 or 0W-30 that could also cause too low oil pressure. I think - they also have 0W-8 these days.
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07-06-2025, 04:04 AM
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#9
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Registered User
Join Date: Jun 2010
Location: spain
Posts: 73
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Quote:
Originally Posted by JFP in PA
Possible, but they don't tend to die that way, they just stop working completely. He could always substitute a mechanical gauge to find out if it is real or not.
The pressure relief valve on the pump can fail and blow open a soon as the pressure begins to build, suddenly dumping all the pressure.
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If after replace the relief valve continue the noise, next step wiil check the oil pressure in the head and after oil pump. The oil suction cup in the crankcase was checked and is ok.
In the case after replace relief valve and the oil pressure would be low, what could be the problem? chain tensioners loosing oil? oil pump gears with excesive wear?
I have to mention that this hydraulic lifter noise started after the engine was repaired of water-oil mixed through one of the brass plugs in the cylinder head that was corroded.
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07-06-2025, 06:20 AM
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#10
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Registered User
Join Date: Feb 2005
Location: It's a kind of magic.....
Posts: 6,649
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Quote:
Originally Posted by heiwaz
If after replace the relief valve continue the noise, next step wiil check the oil pressure in the head and after oil pump. The oil suction cup in the crankcase was checked and is ok.
In the case after replace relief valve and the oil pressure would be low, what could be the problem? chain tensioners loosing oil? oil pump gears with excesive wear?
I have to mention that this hydraulic lifter noise started after the engine was repaired of water-oil mixed through one of the brass plugs in the cylinder head that was corroded.
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I would two things: 1. Replace the pressure sender with a mechanical gauge and test the system again. If the problem persists, 2. I would next be looking at the oil pump itself for excessive wear or pitting on the gears.
__________________
“Anything really new is invented only in one’s youth. Later, one becomes more experienced, more famous – and more stupid.” - Albert Einstein
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07-06-2025, 09:30 AM
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#11
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Registered User
Join Date: Jun 2010
Location: spain
Posts: 73
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Quote:
Originally Posted by JFP in PA
I would two things: 1. Replace the pressure sender with a mechanical gauge and test the system again. If the problem persists, 2. I would next be looking at the oil pump itself for excessive wear or pitting on the gears.
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The pressure sender is located in one of the head? I think the screw is M14x1,5
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