Oil pressure intermittent warning

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Digger65
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Oil pressure intermittent warning

Post by Digger65 »

Hi forum
1988 T25
Dg1.9 petrol
20-50 mineral oil


Did have a look over the forum but couldn’t find an exact match to my issue
Of an intermittent oil pressure warning that goes off once engine warm

Lasts for a few seconds and goes off and returns a few mins later then goes off again.

Engine sounds fine and no smoke, temp seems fine and doesn’t rise, oil looks good, no contamination

Will book it for a pressure test as a priority.
It hasn’t had an oil or filter change for a while so will have that done too

Will it be ok to get it the 5 miles to the garage?

In meantime will check wiring to sensors inc wiring blocks, earth and behind inst cluster
Thanks
D

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Mocki
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Re: Oil pressure intermittent warning

Post by Mocki »

Hi
welcome to the forum
looks to me like you already know the answers 

Visually check the wiring in the engine bay , pay particular attention to the twin white plug and socket With the two brown wires from the two oil pressure switches , near the thermostat housing just above the LH Head, they are known to go a nasty corroded green colour on the contacts 
also check the insulation on this wiring has not been damaged by either heat or chaffing 

replace the oil pressure switches 

change the oil ( 15w40 mineral ) and filter ( Mann W719/12) and if non of that solves your issue , a pressure test . 

 
Steve
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1989 2.1LpgWBX HiTop Leisuredrive Camper

Digger65
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Re: Oil pressure intermittent warning

Post by Digger65 »

Thanks for picking up on this

In peoples experience is the nature of the fault being intermittent an indication of a faulty sensor, wiring issue or even oil degradation I wonder?

Logic would suggest if the fault were mechanical it might be a continuous and regular alarm sounding.
Rather than Occasional sounding?
I will start with suggested actions and go from there, updating the thread in turn
Many thanks
D

KeithB
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Re: Oil pressure intermittent warning

Post by KeithB »

Following this thread with interest! I had a new exhaust and oil pressure switch fitted yesterday - now I’m parked up on the Peak District trying to find an answer to the very same problem 🙄

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AngeloEvs
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Re: Oil pressure intermittent warning

Post by AngeloEvs »

KeithB wrote: 19 Sep 2020, 12:21 Following this thread with interest! I had a new exhaust and oil pressure switch fitted yesterday - now I’m parked up on the Peak District trying to find an answer to the very same problem 🙄

The oil pressure switch you need to locate is in the region of the water pump and Pulley.    This is the switch that will activate the Buzzer,   it should connect to chassis with the engine running.   If the wire to this switch has become disconnected then the buzzer will sound.    The spade terminal needs to be checked where the wire is crimped as the wire can break at this point. If this is the switch that was replaced it needs to be checked to make sure it is the correct type and normally open circuit, once the engine is started ith should connect to chassis.

The other oil pressure switch close to the pushrod tubes is for the oil Pessure LED.

 
1987 DG Karisma LPG with remodelled interior

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937carrera
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Re: Oil pressure intermittent warning

Post by 937carrera »

When you say the warning goes off, does that mean the light and the buzzer ?

The "high" pressure switch is only functional when the revs are over 2000 rpm, oil pressure is lower when the engine is hot, and will rise when revs are higher, so maybe it is only going off in the 2000-2200 rpm range for example.

Couple of simple things you can so as part of the diagnostic

Firstly locate the "high" oil pressure switch, what colour is it. This "should" tell us what rating is currently fitted.
Secondly, remove the electrical connection and put it to earth - there is probably a spade on the dizzy. If the warning no longer goes off, then it's either the switch or actual low oil pressure.

Moving to a 15W40 oil will likely reduce oil pressure a little from what you have today, everything else being equal. Many people use / recommend that. Personally I use 20W50 and have also seen a 15W60 being recommended by ajsimmo

It's also possible that it is nothing more than a poor connection onto the spade on the switch (as Angeloevs suggested), so clean the connectors and give the connector a little nip before you replace it.
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine

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