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oil sender switch replacement

K

K_Claire

New member
oil light sometimes comes on after starting and stays on.

Seen an earlier post saying that it is likely to be the oil sender that is cause of problem.

How do I locate it and replace it if it is? seems to be a common problem from previous posts.

Kul
 
Oil light comes on for what reason? I think that the oil light comes on EITHER if there is low oil pressure OR if there is a low oil level.

The pressure sender is (I believe) a VW part, and is underneath the engine (mine has a slight oil leak on it, as I spotted at MOT time, but not bad enough for me to sweat over.) It has two contacts - one of which drives the oil pressure warning light (i.e. the ouput is 'High' or 'Low'), the other of which drives the oil pressure gauge (i.e. has a linear output). If the gauge is reading normally but the oil pressure light is misbehaving, it could be that the sender is half-duff (IYSWIM).

Either way, check the output from the gauge with an AVO meter before replacing it, if you can.


Oli.
 
what year is the 944?

When was the belts last changed and by who?

What does your oil pressure guage read when the light is on?

If your 944 is a post 87 model, is it the light at the bottom of the oil pressure guage that comes on, or is it the oil level indicator on the left hand side of the instrument cluster that comes on?
 
As Jon alludes there is a low level light (in oval dash cars) that is triggered by a float in the sump - they commonly fail. The other light is low pressure and is the bottom of the gauge, triggered as described above by Oli (I assume - never had an issue with that myself). Both will also light the large red warning lamp and for the level sender it will remain lit until ignition off regardless of subsequent change in the level or response of the sender if it is a bit dicky. In other words I believe the sender is read only at startup for oil level, probably to prevent the light flashing on and off during enthusisatic cornering.

The 964 has a button in the centre console to cancel the big warning light - shame the 944 didn't get the same.
 
ORIGINAL: Fen

As Jon alludes there is a low level light (in oval dash cars) that is triggered by a float in the sump - they commonly fail. The other light is low pressure and is the bottom of the gauge, triggered as described above by Oli (I assume - never had an issue with that myself). Both will also light the large red warning lamp and for the level sender it will remain lit until ignition off regardless of subsequent change in the level or response of the sender if it is a bit dicky. In other words I believe the sender is read only at startup for oil level, probably to prevent the light flashing on and off during enthusisatic cornering.

The 964 has a button in the centre console to cancel the big warning light - shame the 944 didn't get the same.
Click to expand...
Now that is interesting Fen - thanks for that post. I knew there was an oil level sensor somewhere, but didn't know where it was (other than in the sump, somewhere - doh!) or how it worked. If it works on a float system, that will explain why mine comes on when the sump is still 2/3 full - I expect that the float doesn't float as well now as it would have done when new, giving a slightly pessimistic view on the oil level.

I did also guess that it only took a reading when the ignition was turned on, as I have had an experience where the level light is off when I start the car, drive it briskly for a while, stop, turn the ignition off and on again within 5 minutes and the oil level light comes on. However, when the car is stopped again and left with the ignition off overnight, the oil level light doesn't come on when the car is started again the following morning despite there being no new oil added. This is presumably because the oil has now settled again in the sump, rather than being spread around the engine.


Oli.
 
I am assuming the oil sender switch is miss behaving reading previous threads.

The symptoms are that when starting, the light comes on as normal and then doesn't go out unless stop engine. If afterwards you start the car again, the light behaves normally and switches off after starting and remains off.

The light only comes on about 10% of starts approx. Oil pressure reads 5 bars-so pressure good. Dip stick reads oil level halfway between max and min.
 
car is 1988, new dash and is a lux. Oil pressure reads 5 bars when engine on, even if oil light is on. The light that comes on is on the left dial and looks like a '?' and also a light (warning bar) on middle dial.

The belts have been changed at 48,000 as per handbook and car has now done 80,000 but that was about 10 years ago. (Do you suggest I need to change belts now anyway irrespective of oil light).
 
hello again Fen, (another question)

I think it may be oil sender switch as previous thrteads suggest because light never goes out after it is on and light only comes on at start when I pressume the car is checking itself before starting.

Kul
 
Sounds like the level light, but it should light up the words "oil level" if it is. Maybe a bulb blown in the warning light?
 
ks claire, yes gets the belts changed if you dont know when they were last done, even though they have probably been done since last metioned in the book, its cheap insurance against damaged valves or more.
 
Got a similar thing on my 85 oval lux. Pressure rears 5 on startup and drops to about 4 as it had a new oil pump about 5 years ago, but after driving for 20-30 mins the light at the bottom of the pressure gauge and the main large ! red light will all start to flicker on and off. After another 10 mins it will start to stay on. Pressure is fine, oil level is fine.

It goes off when going uphill....
 
Just for info the oil pressure switch is mounted on the water cooled oil cooler unit mounted to the dreivers side of the engine block towards the front of the engine. It is just underneath the oil filter. There are two wires connected to it so it is easy to spot. They cost about £50 and are easy to fit but a real pain to get access to.
 
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