Oil Pressure Drop Under Load

[mhyphenl 10 1 Cars]

Just changed the oil after 500 miles since re-build. Only changed filter and oil! Now when the oil is hot pressure seems to drop under load. This wasn't happening before!?

[erbs 42 1 Cars]

what oil filter brand did you use?

[mhyphenl 10 1 Cars]

Fiam!? About 7 quid!

[farmer 328 1 Cars]

Genuine Peugeot ones on trade are £3.25 each or so

[mhyphenl 10 1 Cars]

It's only when hot that it's noticeable, and mid to high revs. What's odd is that it drops even if your at constant speed and just lightly touch to accelerator, take your foot off the accelerator and it shoots up, lightly touch again and it goes down. Almost like touching the accelerator alters the current going through the sensor, although I'm pretty sure that's not possible!?

[welshpug 1,661]

certainly possible if the wiring is rubbing on something.

Edited May 2, 2016 by welshpug

[mhyphenl 10 1 Cars]

Worth a look I guess,

Any other ideas as to possible causes??

[Telf 224 2 Cars]

not being rude- you haven't got some rag/cloth etc jammed in the filter housing maybe?

 

have you got your old filter? drain it- refit - see if its still having an issue?

[Telf 224 2 Cars]

or maybe the new filter is damaged internally

[toolie72 67 1 Cars]

Knocked the wiring to oil pressure switch-maybe its engine angle ie power on/off moving back and forward enough to pull cable

Worth a wiggle (said the actress to the bishop finarfinar)

[mhyphenl 10 1 Cars]

Hmmm, so on the drive to work today, engine warm, going along at 60. Take my foot off the accelerator and the the pressure goes up, lightly put power back on (only enough to maintain speed) and the pressure goes back down, foot to the floor and no difference!? Accelerate from slow speeds and it behaves as you would expect apart from the fact that when you lift off to change gear the oil pressure goes up further. Wiring seems ok on quick inspection!

[welshpug 1,661]

you really shouldn't be driving it if you suspect the oil pressure!!!

[mhyphenl 10 1 Cars]

what's odd is that the oil pressure seems really healthy. When hot it idles on the first white line and at about 60 it's about 2/3rds. I know that the sensor isn't accurate to anything but it moves up with revs, it's just this odd behaviour at a constant speed!?

[pugdamo 111 2 Cars]

Is there any way you can get hold of an oil pressure test kit? Connect that up and drive it to see if it is actually the oil pressure or sensor/wiring issue.

[mhyphenl 10 1 Cars]

I actually purchased one when I had an issue a couple of years ago. Only problem is I cant get to the sensor without taking half the car apart, its got ABS and air con so there's all sorts of s*ite in the way. If I have to I will!

[large 33]

Does the red oil pressure warning light come on?

[mhyphenl 10 1 Cars]

no, it doesn't go anywhere near that low and the light never comes on. Apart from before you start it of course. For the sake of a few quid i'm going to put a Peugeot filter on just to make sure!

[mhyphenl 10 1 Cars]

Some interesting observations on this. The effect i'm observing seems dramatic as the needle drops from the third line to the second when warm. However if im going faster or slower than that the drop is tiny. Also when my oil pressure is between those lines it twitches about. It turns out that between those lines the sensor seems extra sensitive, it only takes small changes in revs to go from the second line to the third so it looks like the effect is being massively amplified by this. Is anyone else's oil pressure gauge very sensitive between these points?

[jackherer 543]

Does it change slowly or quickly?

 

If it's quick it isn't showing a change in oil pressure, the thick oil going into the sensor is inherently a damper so you will only see slow sweeping changes. If the needle is darting up and down it is an electrical fault.

 

Either way if you have any doubts about oil pressure you need to fit a mechanical gauge. e.g. https://www.machinemart.co.uk/p/clarke-cht712-oil-pressure-test-kit/

[ALEX 98 1 Cars]

Replace the spade connector on the oil pressure sender on the front of the block.