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This has been asked before but I didnt find a logical answer.

So I've bought this turboed na6 and since the brake pads were down to nothing I didn't dare take it for more than 50m down the road... Anyway. I got it cheap. I've fixed the pads and now registered it...just... Aside from pissing out oil from the cas seal there doesn't seem to be any crazy leaks from it. Warm idle on my other na6s have been just below 2 (stock gauge) this one is halfway between 1 and 2... More worryingly it doesn't get above 3 or so before holding that pressure. No idea on oil used (although it looks very clean) just yet but just wanted to know a) if that gauge is accurate is it bad for the engine, b) is it most likely a faulty spring in oil pump, ') or is it caused by the way the turbo feeds been run and huge oil cooler piping.

My knowledge is little in fluid dynamics but surely hose length and turbos would cause restrictions making higher pressure?
I kknow a photo would be helpful but it's so messy currently I dint think it'd help.


I will be removing all turbo gear and returning to stock shortly. I want to know if I need to replace oil pump while motor is out, or entire motor.

It will be oil probably. That's the same sort of pressures I get with my 0w-50, maybe a bit low at the high pressure. Memory is a bit vague.

From a fluid dynamics point of view think of it as electricity. Your adding another circuit in parallel with a turbo.

Oil cooler depends is your lines to the cooler bigger or smaller then the stock passage. Like a cable length increases resistance unless a larger hose/cable is used.

Cooler is many small passages in parallel. Is the parallel resistance of the tubes in YOUR cooler less then the hose supplying it?

I would imagine you would see a pressure drop over the oil cooler as it's being fed at pressure and returning to "0" pressure in the sump (eventually). But as your pressure (voltage) sensor is upstream (for memory) of the filter / cooler loop it should only see the same pressure or higher depending on the resistance if the cooler.

Appreciate the input. The lines are used are large, but long, probably 3m of extra piping... I want to assume it's always been like this since install, not something wrong. Multiple people have thrashed it and it's still got the stock VLSD too...I guess I'll get the real answer when I add to my known working setup.

The cooler and turbo feeds may raise or lower the pressure depending on how they are set up, your presupposition is that all of the oil system is in series, however much of it is in parallel and any extra parallel circuits such as a turbo oil feed despite being restricted and hence low flow is still an extra parallel circuit allowing easier and more flow through the system.

Dann

Yep. Simple and consise. Love it. I've built a car ground up but this is a whole kettle of fish more than the previous PO syndrome.

none of it sould really matter.

a a pre 98 b6, bp, bpt pump are all the same, they have different length engines, some have turbo, some dont. but all use the same pump and oil pressure sensor.

if you are getting pressure issues, then it shouldn't be the add ons causing it.

if it has a turbo...then chances are that the air con has been removed. Double check that the long bolt that goes through the oil pump housing that normally secures the air con bracket to the block has been replaced with a shorter one. you MUST replce that bolt or your oil pump will bleed pressure internally OR externally.

look at the front of the engine down by where the air con was and see if theres any "holes" that should have a bolt in them