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Author Topic: Minimum oil pressure  (Read 9833 times)

Offline bobby_fodge

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Minimum oil pressure
« on: January 16, 2020, 01:27:31 pm »
Hi, I now have an in car oil pressure gauge. Does anyone know what the minimum the pressure should be when on the move?


Offline GVK

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Re: Minimum oil pressure
« Reply #1 on: January 16, 2020, 09:55:20 pm »
At least 2.0bar (30psi) at 2000rpm when hot.

Offline bobby_fodge

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Re: Minimum oil pressure
« Reply #2 on: January 17, 2020, 03:17:35 pm »
At least 2.0bar (30psi) at 2000rpm when hot.

Hmm. My oil gauge can show as low as 20psi when engine is fully warm and revs are 1.5k.

Offline GVK

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Re: Minimum oil pressure
« Reply #3 on: January 17, 2020, 03:55:27 pm »
What happens if you increase to 2k rpm?

Offline bobby_fodge

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Re: Minimum oil pressure
« Reply #4 on: January 17, 2020, 03:57:49 pm »
What happens if you increase to 2k rpm?

pressure goes up. Being a DSG and leaving it in drive means the car chooses to stay in gear when the revs are 1.5k rather than change down.

Offline GVK

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Re: Minimum oil pressure
« Reply #5 on: January 17, 2020, 04:01:17 pm »
Does it increase to over 30 psi? If it does i'd be ok with that.

edit - just saw it's still giving you low pressure warnings on the oil cooler thread.

sad face...
« Last Edit: January 17, 2020, 04:03:54 pm by GVK »

Offline bobby_fodge

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Re: Minimum oil pressure
« Reply #6 on: January 17, 2020, 04:06:31 pm »
Does it increase to over 30 psi? If it does i'd be ok with that.

edit - just saw it's still giving you low pressure warnings on the oil cooler thread.

sad face...

What are you thinking? Dying engine?

It's not blocked pickup pipe as they was replaced at Xmas as was the oil pump.
 

Offline GVK

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Re: Minimum oil pressure
« Reply #7 on: January 17, 2020, 04:15:03 pm »
If you've had the oil pump etc changed then sadly it's got to be a clearance issue on the base engine (crank journals etc)

I have read before that a failing TFSI HPFP seal can dilute the oil and cause this issue.

Offline bobby_fodge

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Re: Minimum oil pressure
« Reply #8 on: January 17, 2020, 04:16:15 pm »
At startup pressure is 70psi then drops down to 35/30psi when idling at a steady 800rpm.

Will driving it with the pressure at 20psi do harm to the engine?

Offline bobby_fodge

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Re: Minimum oil pressure
« Reply #9 on: January 17, 2020, 04:19:18 pm »
If you've had the oil pump etc changed then sadly it's got to be a clearance issue on the base engine (crank journals etc)

I have read before that a failing TFSI HPFP seal can dilute the oil and cause this issue.

Oh poop. What engine work is needed to fix that or is it new block time?

Offline GVK

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Re: Minimum oil pressure
« Reply #10 on: January 17, 2020, 04:22:27 pm »
I'd say the harm is already done if you're getting oil warnings.  :sad1:

How many miles is on it?

To rectify would be done a couple of ways like new bearing shells poss a crank grind, or a replacement block.

Offline bobby_fodge

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Re: Minimum oil pressure
« Reply #11 on: January 17, 2020, 04:27:40 pm »
I'd say the harm is already done if you're getting oil warnings.  :sad1:

How many miles is on it?

To rectify would be done a couple of ways like new bearing shells poss a crank grind, or a replacement block.

Just under a hundred, I've had it since 60k, oil and filter changes every 3-5k. I might source a block and get it reconditioned. Is there any way of 100% veryifying the damage without taking the engine apart?

Offline pudding

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Re: Minimum oil pressure
« Reply #12 on: January 17, 2020, 04:29:31 pm »
At startup pressure is 70psi then drops down to 35/30psi when idling at a steady 800rpm.

Will driving it with the pressure at 20psi do harm to the engine?

That sounds normal for cold pressures.   So when it's hot, it drops to 20psi at 1500rpm, but pressure increases with revs?  If that's the case, the oil pump is working as it should but I can't find the oil pressure specs for the GTI engine online, so can't tell you what numbers you should be seeing when hot.

Regarding the above, oil pressure is created by the resistance to flow, i.e. rod/main bearing clearances, cam bearing clearances, and the little holes that feed tappets and tensioners etc.  If any of those things leak or wear out, oil pressure can reduce.  You would know if you had worn out con rod or main bearings though as the engine would have a few death rattles......but having said that.....engines suffering from sudden oil pressure loss (such as blocked pick ups) can massively accelerate bearing wear.

Yeah, you would need a rebuild or new engine if the above is the case  :sad1:







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Offline bobby_fodge

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Re: Minimum oil pressure
« Reply #13 on: January 17, 2020, 04:32:45 pm »
At startup pressure is 70psi then drops down to 35/30psi when idling at a steady 800rpm.

Will driving it with the pressure at 20psi do harm to the engine?

That sounds normal for cold pressures.   So when it's hot, it drops to 20psi at 1500rpm, but pressure increases with revs?  If that's the case, the oil pump is working as it should but I can't find the oil pressure specs for the GTI engine online, so can't tell you what numbers you should be seeing when hot.

Regarding the above, oil pressure is created by the resistance to flow, i.e. rod/main bearing clearances, cam bearing clearances, and the little holes that feed tappets and tensioners etc.  If any of those things leak or wear out, oil pressure can reduce.  You would know if you had worn out con rod or main bearings though as the engine would have a few death rattles......but having said that.....engines suffering from sudden oil pressure loss (such as blocked pick ups) can massively accelerate bearing wear.

Yeah, you would need a rebuild or new engine if the above is the case  :sad1:

Do i have to stick with the AXX block? I don't want to buy any ancillaries to work with a different code engine. I need the car on the road for as long as possible hence me thinking of getting the block and then swapping it with my current one.

Ta for all the help with this, it's bad news but I just want the oil pressure issue sorted.

Offline pudding

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Re: Minimum oil pressure
« Reply #14 on: January 17, 2020, 04:35:05 pm »
I'd say the harm is already done if you're getting oil warnings.  :sad1:

How many miles is on it?

To rectify would be done a couple of ways like new bearing shells poss a crank grind, or a replacement block.

Just under a hundred, I've had it since 60k, oil and filter changes every 3-5k. I might source a block and get it reconditioned. Is there any way of 100% veryifying the damage without taking the engine apart?

You'd need to plasti-guage the crank and rod bearings to be sure, but that's a massive faff of a job.   As a rough check you can drop the sump and oil pump and see if there's any play in the rods.  You'd definitely hear it when revving the engine if they were shot though.

I can't see it being fooked at 100K though.....but if it is, any other engines take your fancy?  CDL, Audi 5 pot, 7R engine?  :happy2:


2007 ED30 | 2009 TDI 140 | 2016 BMW 330D