Oil pressure and warning light :(

[wildejon 7]

Hey all,

 

I just took the 205 out for a run and just when I parked up, saw this beautiful combination of lights...

 

I'll first do a mechanical pressure test, although my guess is that if both lights are on, there really is an issue.

Question on the pressure test - I guess I should get different readings at cold and hot, does anyone know what they should be?

 

There is a small oil leak from the rear of the sump (I think), it seems relatively minor and I wouldn't have expected it to cause a low pressure.

 

I'll clean up the sensor connectors too, although as the lights are not on all the time and the pressure reading is changing, I guess they are OK.

 

The oil is maybe 2 years old, although it's done about 1000km since.
I'll likely swap it out too, just incase it has degraded.

[Tom Fenton 1,525]

Doesn't look too good. Check the bottom pulley bolt is properly tight as the oil pump is probably friction driven and not keyed.

[wildejon 7]

Thanks, will do.

Do you know the torque? I can't find it in the book 

[wildejon 7]

Also, for what it's worth, the pressure (at least on the gauge inside the car) sits around 2 bar when it's cold. So this only seems to happen when the engine is much hotter.

[Thijs_Rallye 86 4 Cars]

Pressure is too low imo. 180 kPa @ 120°C @ 1000 RPM.

 

From: https://www.205gtidrivers.com/applications/core/interface/file/attachment.php?id=33087

 

[stewal 7]

Didn't peugeot increase the sprocket size of the oil pump on later cars meaning lower pressure across the rev range?    Even so, assuming the switch is OK the light should never be on with the engine running. The stop light is linked to the oil pressure and high water temp switches so simply comes on with them as a more visual alert: it's not an extra sensor.

[DamirGTI 323]

Oil pump mainly just shifts volume , what really creates oil pressure is main and big end bearings clearances and clearances within all the engine internal moving parts (tighter bearing clearances - higher oil press. , loose clearances - lower oil press. , even oil/press. leaking out from the bearings/journals if clearances excessive , bearings and/or crank journals worn) .

 

If there's no strange engine sounds while running , I'd say it's wiring problem ..

 

Measure oil press. with manual mechanical gauge to verify if it's ok. or not .

 

D

[wildejon 7]

1 hour ago, stewal said:

Didn't peugeot increase the sprocket size of the oil pump on later cars meaning lower pressure across the rev range?    Even so, assuming the switch is OK the light should never be on with the engine running. The stop light is linked to the oil pressure and high water temp switches so simply comes on with them as a more visual alert: it's not an extra sensor.

Thanks, that makes sense. They flicker the same in the video. What are the 2 sensors behind the alternator then though? 

[wildejon 7]

48 minutes ago, DamirGTI said:

Oil pump mainly just shifts volume , what really creates oil pressure is main and big end bearings clearances and clearances within all the engine internal moving parts (tighter bearing clearances - higher oil press. , loose clearances - lower oil press. , even oil/press. leaking out from the bearings/journals if clearances excessive , bearings and/or crank journals worn) .

 

If there's no strange engine sounds while running , I'd say it's wiring problem ..

 

Measure oil press. with manual mechanical gauge to verify if it's ok. or not .

 

D

Thanks!

 

The engine sounds great to me.

 

I’ll check the pressure tomorrow, I had to order a gauge….

I guess it doesn’t matter which of the sensors I remove?

[pug_ham 240 3 Cars]

1 hour ago, wildejon said:

What are the 2 sensors behind the alternator then though? 

Usually the shorter fatter one is the pressure sender pictured below.

 

 

The other shorter / thinner sender is the low px switch.

 

g

[wildejon 7]

11 hours ago, pug_ham said:

Usually the shorter fatter one is the pressure sender pictured below.

 

 

The other shorter / thinner sender is the low px switch.

 

g

Funny, so the low P switch controls the red lights behind the 'stop' and behind the 'pressure gauge'
Thanks mate!

[wildejon 7]

OK, so: 

- Mechanical pressure gauge seems to suggest maybe it’s not all bad? It’s around 4bar at idle on start, dropping to around 1.5 bar (22psi) when warm-ish. I didn’t get it super hot. I wasn’t sure how low it could go before I should worry. The low warning is less than 1bar, right?

This IS lower than the 1.8 linked above though, which is concerning.

- The internal gauge never gets above 2bar so it’s either crappy wiring or a buggered sensor. The multiplug wiring looks crap, I’ll replace that first.

- New symptom, the stop light doesn’t come on with the low oil light. They are the same signal, right? (Might also be multiplug, the dash bulbs are all new FWIW).

 

I feel like I’m going in circles but at some point it must work!

[James1975 2]

I thought mine was low, from cold it sits just over halfway from 8 bar then drops to around 2 and half when hot, not sure if the gauge is entirely accurate, i put new big ends and main bearings in so i know its good for pressure, i learn to not worry too much, not sure if this helps.

[James1975 2]

On 6/27/2023 at 11:59 AM, wildejon said:

Thanks, will do.

Do you know the torque? I can't find it in the book 

Think its 130Nm

[wildejon 7]

I have big end bearings on order, just incase I need to do them (I’m due to sell it in a week).

The internal gauge seems

really inaccurate (max 2bar), although even the physical one never tops 4.

 

[wildejon 7]

I removed the brown multiplug, now it has nice waterproof connections, yay.

But…

 

Inside pressure reading is still 2 bar. I think maybe it’s always been this way.
It doesn’t seem to increase on revving.
(The mechanical gauge showed 4).
Stop light still isn’t working, I have no idea why or how to test it.
Neither pressure or stop light show before starting anymore, the pressure one did before I messed with the wiring.
Engine does maybe sound a bit rattly, especially after revving a little.

Video is at moderate temp at idle (900 rpm) not fully hot.

 

[DamirGTI 323]

1 hour ago, wildejon said:

Inside pressure reading is still 2 bar. I think maybe it’s always been this way.
It doesn’t seem to increase on revving.

 

It should/must've , rise as you increase the revs ...

 

Not looking good TBH , time to whip the sump off and have a look .. (i'd suspect big end bearings bust , too much clearance or worn crank journals)

 

D

[wildejon 7]

Thanks @DamirGTI 
The pressure does change though, check this out.

 

The internal gauge doesn't do a lot but I think it must have a wiring issue.

[DamirGTI 323]

7 minutes ago, wildejon said:

Thanks @DamirGTI 
The pressure does change though, check this out.

 

That is ok. then .. that second test - ok ! good press. and press. build up with revs .

 

Wiring and/or gauge problem then ...

 

D

[pug_ham 240 3 Cars]

The video of the external gauge showing 2 or 4 bar looks ok to me, even at idle the previous one isn't catastrophic or anything to really worry about too much imo.

 

You can test the wiring to a point by shorting the wires onto the block, iirc the oil pressure sender should swing to full pressure / top of the scale when earthed to the block and the stop light should (obviously) put the stop light on the dash on.

 

If the wires are crossed over on the senders, it might give you the problem you are having, I can't remember what happens when they are cross connected but it's been posted on here before.

 

Like I suggested in my pm, try running a fresh piece of wire to the plug under the dash from the oil pressure sender to eliminate the engine bay wiring.

 

g

[wildejon 7]

Thanks guys! 
I ran it to temp today and the video here shows the pressure. The dial never reads what the gauge does. It rises with rpm too (not shown in video). I think this points 100% to a wiring problem!

 

Note: oil temp sensor needs rewiring as the wire shattered when I replaced the brown multiplug.

 

I really hate wiring.

And I REALLY hate removing the dash, lol 

 

I’ll try what you suggested next and see what the dials do. Will have to wait until later as I need my wife or one of the kids to help me…

I guess if they don’t show a maximum (or ‘stop‘), either the wiring is shot or the sensors are (can’t be both sensors IMO) and if they DO show a maximum, the sensors are shot?

 

Thanks for the support!

 

 

[Thijs_Rallye 86 4 Cars]

Pressures with the mechanical gauge look good enough to me.

 

You don't necessarily need to remove the dash, run the wire from the sensor to the connector near the bottom of the a-pillar. If I remember correctly there should be a connector there with all the analog signals from the engine bay. I only don't remember if it is on the passenger or drivers side (which also depends on the model year afaik). If you find the connector with the 112 wire that is the one you are looking for. I forgot which one is for the oil pressure but the wiring diagrams on this forum can help you with that.

[wildejon 7]

Cool, me too 

 

Ah, that's an idea, thanks!
I super hate wiring, but fixing it is a good way to learn!

[wildejon 7]

Like an idiot, I forgot to test the wiring with just a plain cable (I had the voltmeter in the middle). I'll do it in the morning.

Oddly though I get 6V at the pressure sensor connector and 140mV at pressure sender connector

Also weirdly... the handbrake light is also now intermittent 

[pug_ham 240 3 Cars]

You only need  a second person to check the agues when you earth the wire at the engine but even then you could do it with a well placed video camera but to check it with a fresh piece of wire, all you need is a length with a spade connector on it for the senders on the engine.

 

Just contact the other end at the under dash plugs, they don't even need to be pulled apart.

 

As said, you don't need to take the dash apart at all.

 

g