[Mk2] [Turbo] Low oil pressure at idle

[gazrev1tubby]

Hi guys, what would cause low oil pressure at idle, when at full operating temp?

Also, what would be deemed as low pressure - can you post what you typically see, if you have a gauge installed?

Oil in my car Is 10w 40 semi, castrol gtx magnatec. Engine was rebuilt 2 years ago, and a brand new oil pump was fitted. In that time, the car has probably covered circa 6000 miles

[Slarty]

Mine would be just under 2 bar when fully warm, which I think is about right? It would be a little lower than that once the oil was old and then come back up again with fresh oil.

Generally low oil pressure when at temperature is a sign of a worn engine.

Edit: Where do you measure your oil pressure from? Mine was from the OEM location on the cylinder head...

[gazrev1tubby]

Yep mine is also being measured from the cylinder head, via a small braided line, with a twin adaptor on the end. The stock pressure switch, and gauge sender are in the same adaptor.

My engine is only two years old, and was rebuilt throughout with forged rods and pistons. I'm getting good pressure when cold, and whilst driving, but at idle when hot - it hovers between 2 and 7psi!

No knocks or rattles that shouldn't be there.

Admittedly, the pressure was fluctuating all over the place the other night, so it could be a duff sender?

[Peter Gidden]

8-10psi is about usual hot, at idle.

[gazrev1tubby]

Thanks Pete, was hoping you'd drop in

That's set my mind at rest a bit, I did read up that typically 10 psi per 1000 rpm is considered within tolerance, so that rings true with what you've said

I'm going to move the sender, as it currently sits by the turbo - and I've read that heat and vibration can makes the senders go a bit scatty. Also, it's a cheap one, so I'm not convinced it's totally accurate

I'm sure that if it was only 2psi, it'd be knocking by now?

[Slarty]

I guess at idle, as there's little to no loading on the bearings there's not a big need for high oil pressure, as long as there's sufficient flow to keep the bearings lubricated....

[Magic Beans]

Out of interest what's the normal oil temps when warm?

[Slarty]

Out of interest what's the normal oil temps when warm?

You can't really define that as what's warm? I used to define "normal" as a safe temperature above which I considered the engine to safe to fully use which was above 80 degrees C. Motorway blasts would see over 100 degrees C, around town about 90 degrees C, so which is "normal"?

[Magic Beans]

Interesting

I'll monitor mine in more depth once it's on the road again, after this winter has finally passed.

Last time I was out in it was early December and it hit no more than 76 degrees, even after about 30 mins of driving, with a couple of spirited runs.

[gazrev1tubby]

Mines much the same, whilst driving it normally hovers around 70-80 degrees centigrade, but when sitting idling, it often climbs to around 100.

Thats measuring from the sump, via a sump plug sender jobbie.

[bobhatton]

Out of interest what's the normal oil temps when warm?

Oil should be 100c plus, around 110-115c would be about right

[Magic Beans]

Lower temps would indicate..?

This was just a 30 minutes shakedown run on a cold day, however I would have expected the oil to get warmer than that.

[ashley]

From my understanding, as a general rule expect oil temps to be ~10 - 15c above water temps. I've read that you want your oil temp to exceed 100c each time you run the car to avoid it sludging up with water, by exceeding the boiling point of water you help any condensation evaporate out.

Low oil temperature means your obviously not running enough boost, or not running your car hard enough

[ashley]

How have you got your oil system set up Phil? Remote filter, oil cooler, grade of oil??

[gazrev1tubby]

The problem is, whilst cruising, my oil temps don't climb above the 70 degree range.

This must be due to the cold air acting on the sump, and it may well be a completely different story in the summer - if we ever get one

The only time my oil gets anywhere near 100, is when idling in traffic.

[greeny]

Personally I'd be getting a little concerned with only 8psi at idle when warm, especially on a refreshed engine.

The stock low pressure switch, switches at 7psi iirc.

Have you noticed the pressure getting lower over time?

[calum4492]

gaz get rid of the cheapy gauge mate i had 1 from ebay and it red about the same as ur saying so i got abit worried and phoned nathan from century, so with a bit of advide from him i swapped my old gauge out for a new greddy 1 and the pressure sits exactly where it should now

[gazrev1tubby]

Personally I'd be getting a little concerned with only 8psi at idle when warm, especially on a refreshed engine.

The stock low pressure switch, switches at 7psi iirc.

Have you noticed the pressure getting lower over time?

Ive had the gauge fitted for ages, but only fitted the sender a week or so ago. But, the stock oil light goes off as soon as the engine starts, and it's never come on whilst running.

gaz get rid of the cheapy gauge mate i had 1 from ebay and it red about the same as ur saying so i got abit worried and phoned nathan from century, so with a bit of advide from him i swapped my old gauge out for a new greddy 1 and the pressure sits exactly where it should now

That's probably more like it bud, it is only a cheapo one !

Because the 3 gauges in my centre console match, I might get another one for boost or narrowband or something, to replace the temp gauge, then get a better quality temp one for another location in the car.

I bloody hate gauges, I find I spend more time looking at them than I do where i'm going ! They also make me paranoid

But at the same time, at least I get some idea of what's going on, and hopefully an early warning should a problem arise

[Magic Beans]

How have you got your oil system set up Phil? Remote filter, oil cooler, grade of oil??

10W40 with stock oil set-up.

It was only around 5 degrees outside and it wasn't a hard run at all, mainly due to it lighting the wheels up, so I'd need to check it all when I finally get it out on the road again.