Loss of indicated oil pressure

[paddy]

Driving to work today, the oil gauge at some point - not sure when - went to zero and stayed there. I only noticed when I arrived.

Before then the engine seemed to be running fine, the dipstick indicates half-way between min and max, the line to the oil gauge seems intact with no unusual leaks evident anywhere.

I guess the possible causes are:
- genuine loss of oil pressure - a failed pump maybe?
- faulty gauge.

Before I take any risks with it, are there any suggestions as to the most likely problem, and a quick diagnostic check I can do in the car park (with no tools ...).

For example, if I take the oil cap off and I get a shit load of oil coming out, would that make me confident enough to drive 5 miles home?

Paddy

[SADLOTUS]

...any nasty noises?

[paddy]

...any nasty noises?

No noises, temperature normal, nothing abnormal at all. Running very nicely in fact.

Paddy

[types26/36]

a quick diagnostic check I can do in the car park (with no tools ...).
Paddy

Enforcing the need to carry at least a basic toolkit but that aside I think I would be inclined to beg,borrow or buy a spanner to loosen the oil pipe fitting to check if it is pumping oil.
Paddy do you have breakdown/recovery on your insurance? if yes why not use the service.

[john.p.clegg]

Hydraulic or Electric gauge?

If electric,has the wire come off the sender-if not,take it off and connect to the block-full deflection on the gauge shows all wiring and gauge O.K.

John

P.S Just re-read your post and it mentions leaks....ignore above...

[paddy]

Thanks John, mechanical gauge.

Thanks Brian - yes, grandmother and eggs .. I usually have a set of tools but today I don't.

Recovery back home is a last resort; I would probably forfeit the right to use it for domestic taxi journeys with the children

I think I'm walking to Halfords at lunch time. I'm guessing the oil pipe union nut is 7/16.

Paddy

[types26/36]

Recovery back home is a last resort;
I think I'm walking to Halfords at lunch time. I'm guessing the oil pipe union nut is 7/16.
Paddy

7/16 on my Sprint (original) but 13mm on the S2 .... non original

[paddy]

Thanks Brian.

I went out the car and started it, and the oil pressure jumped up to normal

I'm pretty sure now that the problem was the combination of:

1) loss of pressure on long RH turns: this can happen when slightly below half full for me;
2) pressure takes a long time to return after that happens (maybe 20 seconds or more at idle).

I don't know why it takes so long - after a normal stop the pressure comes back up immediately. I guess that when the engine is run without any oil for a few seconds, the pump completely drains the filter, and pumps air into the galleries, so it then takes a long time at idle to fill up again. After a normal stop the filter remains more or less full.

Panic over and ignominious trailering home averted.

Thanks for the replies.

Paddy

[Galwaylotus]

Thanks Brian.

I went out the car and started it, and the oil pressure jumped up to normal

I'm pretty sure now that the problem was the combination of:

1) loss of pressure on long RH turns: this can happen when slightly below half full for me;
2) pressure takes a long time to return after that happens (maybe 20 seconds or more at idle).

I don't know why it takes so long - after a normal stop the pressure comes back up immediately. I guess that when the engine is run without any oil for a few seconds, the pump completely drains the filter, and pumps air into the galleries, so it then takes a long time at idle to fill up again. After a normal stop the filter remains more or less full.

Panic over and ignominious trailering home averted.

Thanks for the replies.

Paddy

I'd be panicking if I was driving while waiting for "pressure takes a long time to return". I've experienced the loss of pressure on RH turns and did a check to see where the correct volume of oil registered on the dipstick. Following an oil and filter change, the level after running the engine to circulate the oil, came to just over the letter "F" in the word "FULL" on the dipstick (at the 45mm mark on the scale). That was with 3 3/4 litres of oil compared to the 4 litres spec! I now never let the level drop below the full mark and I don'r have the loss of pressure issue on right turns.

[paddy]

Yes, I know I have a dipstick calibration problem. When the RH turn problem happens I fill it up. It still takes you by surprise sometimes

Paddy

[bcmc33]

As a matter of interest during the assembly of my new engine I wanted to know where the top of the dipstick tube should be in relation to a full sump. To this end I put 4.25L of water in the sump and measured where it was to the sump/block line. Doing all the necessary sums I work-out that the length of the dipstick tube should be 3.25" long to match the full mark on the dipstick.
I aways had some doubt about my old engine with a dipstick tube length of 3", but as I deliberately ignored the amount of oil that would be in the filter, I guess my old engine was not all that far out.

[neilsjuke]

The tube on the front cover may have been moved and will give a false reading drain the oil and put in 4l and see were that comes too.
Neil