Testing Oil Pressure

Steve777 · **Joined:** Fri Oct 16, 2015 11:31 pm **Posts:** 282

So before I dig into my CRD which presumably has a leaky/fallen lifter, I wanted to check the engine oil pressure since if some metal has been circulating around the engine and it needs a new oil pump, the time to do that would be while the tbelt and cams are off.

I searched this forum and the FSM for info or oil pressure specs but did not find anything, so I thought I'd ask here.

Getting the measurement seems pretty straightforward, remove the oil sender, screw in the appropriate threaded adapter from oil pressure gauge kit, and take some readings. (If anyone know anything else one need do, pls let me know)

Question I have is what are the expected pressure readings at what rpms, hot and cold. Anyone have any thoughts on this? I could just use generic ones but thought someone here might have some experience with CRDs.

TIA

TKB4 · **Posted:** Sat Jul 13, 2019 1:15 am

I have not seen anything particularly for the CRD or even diesel engines in general. What I have read somewhere in the distant past was that idle pressure should be at least 10 psi and possibly as much as 15 to 20 or so and the pressure should rise about 10 psi from idle pressure for each additional 1000 RPM. There will also be variation depending on oil used with higher weight oil resulting in increased pressure ( but not increased flow).

Judging from this with 0-40 or 5-40 I would expect a little around 15psi at 1000 rpm and 25psi at 2000 rpm etc But I would think probably a little Higher for a diesel I just don't know. Perhaps Geordi or others know by experience or research. I do believe this is a pretty robust oil pump though.

WWDiesel · **Posted:** Sat Jul 13, 2019 8:28 am

From the FSM:
Minimum Oil Pressure (Warm)
0.7 Bar (10 psi.) at Idle
2 Bar (29 psi) at 3800 rpm

rankom · **Posted:** Sat Jul 13, 2019 3:41 pm

on my mechanical oil pressure gauge i see 20psi idle and 50 psi driving down the road 2000rpms , 5w40 rottella, T6 , cold engine way higher

Steve777 · **Joined:** Fri Oct 16, 2015 11:31 pm **Posts:** 282

Thanks All. And thanks to WW, not sure how I missed the specs in the FSM.

Did a test this AM, saw 70psi cold (75F) at idle. At operating temp 24psi at idle and 76psi at 3000prm. So well above (like 2x +) the FSM numbers. I am running Rotella T6 5-40 oil. So looks like the oil pump and bearing are doing OK.

WWDiesel · **Posted:** Sat Jul 13, 2019 7:25 pm

This engine has a "Oil Pressure Relief Valve". This valve should dump oil pressure at a present pressure to prevent over-pressure.
The oil filter and oil cooler can only handle so much pressure.

rankom · **Posted:** Sat Jul 13, 2019 8:04 pm

good point ww about over pressure and relief valve . but in my case my engine is in excellent condition , when cold in winter time , mechanical gauge pegs over 100 psi so seems relief valve is set higher ,after few mins it drops down to 80 ish. itd be nice to know the exact limit.

rankom · **Posted:** Sun Jul 14, 2019 9:59 pm

according to tdi guys on 1.9 tdi VW engine maximum oil pressure is 7.0bar=103psi so im guessing vm 2.8 is the same.

joelukex4 · **Joined:** Thu Sep 29, 2011 4:54 pm **Posts:** 386

It says right in the schematic that the oil pressure relief valve opens at 94psi.

Testing Oil Pressure

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