oil pressure at idle
 

hi all just wanted to check something.

I have fitted prosport oil pressure and temp gauges to my newage bugeye hot idle is upo 7 bar and when it runs its always good oil pressure always above 5 bar, warm idle say 80 degrees C oil temp is about 2 bar or alittle more, hot oil pressure at idle say at 90 to 100 degrees C is 1.6 bar

oil is millers 10-60 I think has done 5,000 miles so due for a change soon, does this sound ok? lots of oil in it and i dont suspect any issues just interested.

Don't know in bar, but mine is about 20 psi at idle when warmed up, and between 60-70 psi when moving.

Quite a wide range on pressure there tbho from 80-90'c and 1.6 is a little low for hot idle but not a problem yet I wouldn't have thought.

Sounds ok. Mines just a tad under 2bar at idle and 6 bar with the oil at 80 or above

I also use prosport gauges. My oil temp sits at 90, oil pressure on cold idle is around 110psi, warm idle is around 60/65 psi and normal driving sits at 90 psi.

20psi at warm idle is pretty low...

its about 23 psi to 25 psi at hot idle. I take my pressure from the original sensor position and even with a slight deviation in earthing I know the pressures can be all over the place. when I first fitted the gauges I earthed them behind the stereo but when I turned the lights on the pressure went down and the temp went up!

Mine is around 1 bar at idle when warm 85-90*, its been like that since I fitted a second hand engine 2 years ago.
The presure is taken with a hks mechanical gauge.
It goes up to around 5 bar at 3500rpm.
Not given me any problems as yet ( touches nearest piece of wood).

25psi warm idle
110psi ish cold idle
90psi normal driving

prosport gauge at original pressure sensor location.

Personally I wouldn't use 10w60 tho.

Interested to hear your reasons

oil grade makes a difference to pressure,
those readings are fine

I've had these pressures since the API rebuild last year.

Mine is at just over 1Bar (14.7psi=1BAR) at idle when fully warm at about 80'c showing on the Prosports. 90psi at idle when cold. perfectly normal as the take off is at the top of the block.

It does make you wonder how inline 4 cylinder engines get by at idle when cold. I've seen old Fiesta 1.1 HCS engines with the cam covers off started up after valve adjustment checks and it's nearly a minute before you see any oil seeping up, and that's fresh oil too!

Really good quality Synthetic oils cling on so you have oil where you need it before the pressure comes...crucial. No wonder such a large % of wear occurs at start.

While I'm whinging- Who starts their cars with the foot on the clutch? Remember if you do that you are pressing the crank against the thrust washer and increasing wear if you do. Not ideal.....

I also see 1 bar of oil pressure once the car is fully warmed up, worries me a little, as soon as the revs increase I have good pressure though.

I also have an oil temperature gauge (cant remember the make) but it take along time to see oil temps of 80. In fact I only see that temp after a decent drive and I let the car idle for while, once im on the move again the oil temp drops back down once again to around 70.

Didnt realise pressing the clutch in when starting was a bad thing, ill stop doing this now!

some impreza you have to press the clutch in to start them

Didn't the STi 6 have an over-ride where you had to depress the clutch to start it ?

Shaun

one minute late........

Shaun

60psi at warm idle is not normal!!!

2.1 - 2.2 bar is roughly what i get and would seem the normal sort of figure at warm idle.

4.2 bar at warm idle is alot!

That's because the old Kents engine are pushrod - they don't really need oil at the top end, the rocker arms are basically drip-fed. Most OHV pushrod engines are like this. These engines were never renowned for good oil-flow anyway (flow NOT pressure - there is a huge difference) - which is why when Ford switched to softer metals on the Endura-E versions for the cams/followers they wore out much quicker (Ford KA), whereas an old Kent from a MK1 Fiesta would last much longer (harder metal surfaces wear less and are more tolerant to lack of lubriation via poor servicing which are common with these kind of cars).

However, there is stll alot of flow through the bottom end; If you removed the oil filter and started the engine, you'll note it will nearly empty the whole contents of the sump within 5 seconds! (don't ask how I know this :o ).

The biggest restriction is not the pump, nor the oil...but the size of the oilways and bearing clearances. An engine with worn bearings will show lower idle oil pressure at the same temperature with the same oil as one with tight bearing clerances. However this difficult to compare with other people's cars as tehy all have different levels of wear, and mesurements are taken at different temps with different oils. So there is no hard and fast rule of what exact figre it should be - what you need to keep on eye on is how stable it ramains, for eample if one day its lower than usual in the same operating conditions, you need to check things out.

However as a rough rule of thumb 20psi is acceptable on a hot engine at idle, the oil will be thinner and therefore flow will be much higher, the consequence of such is lower pressure (due to less restriction). Flow is good, remember this, as this is the primary cooling for the bearings (coolant just does the cylinder heads bores and turbo housing). If it ever dips lower towards 10psi, you have an issue. Be it worn bearings, sticking relief valve or the pump backplate has come loose - using a thicker oil may mask this, but it should be borne in mind there maybe an underlying issue and the thicker oil is just hiding it,

The exception is if the oil really is getting too hot on a regular basis (upwards of 120 degrees C ) or there is a fuel dilution issue. But this is where change intervals and grades need to be considered, as well as the state of tune in consideration to the manner the car is driven.

I have always worked on 1.2 bar at hot idle being a minimum for oil pressure. 60 PSI sounds quite high, would expect that at cold.

With regard to pushing crank against thrust washer, isn't this no different to putting your foot on the clutch to change gear? I am pretty sure pushing against a thrust washer at 2-3k rpm is worse than at cranking speeds ;)

As above on the oil pressure and the clutch in at startup.

Have always dipped the clutch to start. A cold gearbox can be a massive load for the starter and battery, especially if either is weak. Can make the difference between starting and not starting on freezing mornings. And also prevents the "oops I left it in gear" incidents LOL

By the way I have always left my car in gear. Have never fully relied on the handbrake since my old mans Citroen rolled away at Rocamadour in France, with my sister still on board. Heading for the cliff edge I threw myself through the (open) drivers window and jammed the brakes on with my hand. Bit incomfortable until my old man turned up and stuffed it in gear. Lesson learned LOL




:)

I get around 2Bar onces up to 80. On a cold start i see between 6 and 7 bar depending on how cold.

Quote:
Originally Posted by DonNedly http://images.ibsrv.net/ibsrv/res/sr...s/viewpost.gif
Personally I wouldn't use 10w60 tho.

Mainly because it takes longer to warm up but also Subaru don't recommend it, thicker oil is harder work for the engine on start-up and it can mask other problems.

I know everyone has opinion on it and many people run 10w60 but personally unless heavily modified i'd stick with 40 or 50.

Commence the off-topic flame-war!

Not gonna flame, but it doesnt take longer to warm up, the 60 simply means at a preset temperature it wont thin any more than a 60 single grade oil, it will warm as fast as any other oil but not thin out as much as a 50 oil at higher temps (210 degrees F/100 C iirc).

10w-60 oil is no harder on startup than 10w-50 as the first number indicates how thin the oil is at cool temperatures, W=Winter (or rather how thin it appears to be).

If you want an oil that is better from cold start you would go with a 0w-XX oil.

However, I would tend towards a 5w-40 or 5w-50 oil unless I was driving my car hard, like say on a track day, just because the extra protection afforded by the 60 grade would be wasted and cause addtional drag on the engine at most speeds, leading to increased fuel consumption.

In essence I agree with your decision, and not really off topic, as the end result of using 60 grade oil could lead to increased oil pressure, as the oil wont thin as much as say 10w-40 at normal operating temperatures.

(for clarity in this post I use the word thin to describe a less viscous oil)

Been out in the car tonight to re-check all my facts and figures.

On initial stone cold start up the oil pressure peaks at 125 psi and quickly drops down to 115 psi. This is ever decreasing as oil temp increases.
Once oil is up to temp and under normal driving the oil pressure sits at 90 psi, oil temp sits quite happily at 90 also. At warm idle the oil pressure is showing approx 57 psi.
The car has had these figures since ownership, runs absolutely perfectly. Paul has worked on the car and never mentioned any issues whatsoever and certainly hasn't mentioned anything regarding the oil pressure.
Oil is changed every 4 months no matter the mileage (covered just 2K in the last 12 months) using millers fully synthetic. Am currently using 10W40 but changing to 50 shortly.
Engine consists of 30K 2005 JDM STI Spec C bottom end joined up to STI 3 heads.

These readings seem high compared to above posts. Why is this ??

thats really strange matt, i have never heard of a reading of around 4 bar hot idle!

Some engines do show high oil pressure especially those with uprated oil pumps and relief springs.

90 psi seems very high for a warm idle mind you and could mean the tolerances in your engine are very tight.

A possible explanation could be, if electric, a mismatched dial and sender unit (ie a 0-100 psi sender and a 0-150 psi gauge)

standard o4 sti

about 7 bar cold and 2 when hot, running millers 5w 40 oil.