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New Engine Build And Now Getting 120 Psi On Oil Pressure

Started by postve , Jun 29 2025 10:04 AM

Best Answer Spider , 29 June 2025 - 06:51 PM

I think your gauge is wrong and leading you on a goose chase.

The Oil Filters are only rated to 100 PSI. At around 120 - 130 PSI the can deforms and will eventually rupture. Even at 100 PSI, you can feel it ballooning. I'd say here too that the 120 PSI is likely all that the sender will allow and if it was able to measure the problem - assuming there really is one - then the pressure will be higher.

If you have a high oil pressure problem, a very common cause for it being this high is the plug on the front of the block has been fitted too deep and it is blocking off the vent port at the back of the Oil Pressure Relief Valve. This one has a slot head plug fitted, but depending on your engine, this is usually a brass plug or a blind pop rivet

If that is in too deep, it will block off the passageway behind it and your oil pressure will be sky high, way over 150 PSI. At these pressures it's a race between the oil filter can blowing up, the oil pump gasket blowing out or depending on the oil pump, the drive for it shearing off.

One test for this is to leave the engine for a day or 2, so the oil will drain back, then remove the spark plugs and crank it over, at first, it will crank quickly, but wehn it gets 'wet' again, it will slow to a crawl, like hitting a brick wall.

BUT

I suspect your gauge is leading you up the garden path here.

Try a known mechanical gauge first before doing anything else. See what that's showing and we can do some more fault finding before going too far.

If you need to change the Valve, as Nick has mentioned do not use the Ball type, they are not suitable for road use;-

https://www.theminif...huttle-vs-ball/

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61 replies to this topic

#1 postve

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Posted 29 June 2025 - 10:04 AM

Hey guys

I have the following head scratcher

- new 1310 build
- digital oil pressure gauge - I have two of them
- originally oil pressure looked fine
- now when I fire it up and let it sit, hits 120 psi and does not move
- tried the other digital gauge and displays 150 psi???

I am wondering if the gauges are pooched or possible oil not flowing?

Changed the oil filter yesterday I did notice not a lot in the filter and praying the oil pump is not the issue??!! Thoughts!??

Edited by postve, 29 June 2025 - 10:05 AM.

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#2 nicklouse

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Posted 29 June 2025 - 10:08 AM

What do you mean by not a lot in the filter?

should be full of oil.

relive valve stuck?

It should allow oil to pass at 60/70psi as standard.

The only way to increase the pressure it passes oil is with a longer/stronger spring so it opens at a higher pressure.

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#3 postve

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Posted 29 June 2025 - 10:11 AM

Nick, with a digital oil pressure gauge is there a relief valve and forgive my lack of knowledge. I simple installed an electronic digital and it has worked before?!

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#4 Ethel

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Posted 29 June 2025 - 10:25 AM

The relief valve is in the engine. It should bleed surplus pressure off back to the sump. It's under the big hex headed plug near where the oil pressure sender/gauge attaches. The pressure is sampled from the end of the main gallery, so it'd have to get there via the relief valve & oil filter.

The oilway drillings do cross one another, so I wonder if it could be pressure locking the valve from behind???

Rogues gallery???

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#5 postve

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Posted 29 June 2025 - 10:30 AM

Ahh got it and I swapped to a flex line so maybe pull that off today and take a look at the valve spring setup - kinda makes sense as was working initially and now just sits at 120psi - I am terrified to drive the car until resolved. Let me send a picture to make sure I am clear

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#6 postve

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Posted 29 June 2025 - 10:40 AM

Just testing a link , one moment

https://imgur.com/a/Ey7Iydh

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#7 postve

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Posted 29 June 2025 - 10:44 AM

Okay meant this link and you mean here right?

https://imgur.com/a/Ey7Iydh

Again when I checked filter little to no oil in there and agreed it should be full

Edited by postve, 29 June 2025 - 10:52 AM.

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#8 postve

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Posted 29 June 2025 - 10:56 AM

Okay went online and found location so thinking is this could be the problem folks?

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#9 imack

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Posted 29 June 2025 - 11:12 AM

If you're showing pressure then it won't be the pump. Sound like you have a blockage somewhere between the pump and the filter. Oil filter and feed pipe should be full of oil. Don't run the engine until you've found the issue, you've got no oil feeding the bearings, cam or anything else in the engine. I'd start by removing that flex pipe and inspect. That gallery goes directly to the pump.

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#10 postve

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Posted 29 June 2025 - 11:17 AM

Agreed 100% imack and relief at not being the oil pump and logical - maybe for starters I might just swap back in the OEM connection pipe as from my limited understanding possible could be the source of my issue but scratching my head as to how that would happen - give me a few as having my morning coffee at star bucks - and old/new pic for viewing in the meantime - my 78/21 JCW

https://imgur.com/a/Ey7Iydh

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#11 Ethel

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Posted 29 June 2025 - 11:20 AM

The oil pressure is measured after the filter.

I'd say investigate the relief valve. If it was a restriction from the transfer pipe/hose it ought to cause the relief valve to open.

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#12 postve

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Posted 29 June 2025 - 11:22 AM

Thank you Ethel and all, sound advise and I will investigate all this morning and with a DHL strike might take a while to get a new relief valve but let me pop off and show you M8’s, don’t have to drain oil to do it I hope!