Oil light slow to turn off from cold

[genie45]

Evening all.

I've been trying to understand what could be causing my oil light to stay on and after googling, searching this forum and looking through the various manuals I'm non the wiser.

When first starting the oil light comes on and has been gradually staying on longer and longer each time I start up, the last time I drove it it stayed on for about 20 mins, once it goes out it stays off.

The engine sounds fine and after having a few people ( with much more knowledge than me) check it over I was advised to change the oil pressure switch but it is still the same, I am reluctant to drive it as it is, does anyone have any advice please?
It's a stock 1600 (1970) and the oil level is half way between the lines on the dipstick 20/50 oil.

Any advice would be very much appreciated.

Genie

 

[rlepecha]

Sounds a bit odd that.

Do you have a multimeter?

If so, disconnect the wire to the switch at the engine block.
Set the meter to continuity, start it up and put one lead from the meter to ground and the other to the spade on the switch.
Does it beep or read short 0.00? If so then the switch is definitely reading low oil pressure.

The only other thing I can think of is a bad ground or just unlucky to get a bad switch again.

This is the only reason I use an oil pressure gauge, because the switches are pretty poor and I can see exactly what sort of pressure I have.

Is it an original dipstick? I've heard of some of the aftermarket ones being marked up incorrectly? So maybe not enough oil, can take some measurements for the markers if you need them.


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[StuF]

If you disconnect the king lead from the coil and cold crank the engine does the oil light go out after 10 or so seconds?
I always do this to build oil pressure after an oil change or strip down perhaps you need to change your oil and filter for some fresh
Maybe get a pressure gauge so you have more of an idea whats happening inside the engine incase the pressure is low

 

[Moseley]

When the oil light does finally go out, does it begin to flicker before hand, or just suddenly switch off? I would suggest that if it was actually related to oil pressure, you'd get to a point where the light began flickering before it went out, but even then, oil pressure should be highest when cold, and higher again as the engine revs increase. It sounds like something else is at fault to me with the sensing system.

 

[ozziedog]

Just a thought from the khasi, I'm not sure how to check this so an oil change may be required. I'm thinking if it's not an electrical problem and what we're seeing in reports from your sensory system is correct. Is it possible that the oil is being contaminated with fuel or water even ? I run 20/50 also from Halfords,. So my idea is to do an oil change with warm oil to get as much out as possible. When you refill with oil, do your final level check on a cold engine, a couple of hours should be enough. But make the cold oil level be exactly on the top line. Whenever you run the engine , do your oil check before you start the engine. You should then know if anything is adding to your oil and contaminating it. Getting a good sniff of it may tell you if it's fuel leaking but if it's something else or only just starting. Have you checked your venting system? I once ran a pipe to a bottle in the engine bay and the pipe (wrong type) expanded and made a weird vacuum and that caused all sorts of problems. I still vent like that but with a proper pipe and a vented bottle. :roll: keep us informed please.


Ozziedog,,,,,,,,, how old is the oil ? :mrgreen:

 

[georgeyv]

Ozziedog could well be onto something! A good oil change I think is in order - Have you changed the mesh above the sump plate recently? It could be badly gunked up and blocking the oil from getting through properly until it's nice and warm and can fit through the smaller gaps. I'd get some oil and gaskets and give the mesh a clean in petrol or thinners and re-install with fresh oil and see how you get on.

 

[genie45]

Thanks guys, will work my way through your ideas and report back on my findings..... I guess I am due a oil change as have clocked 2,000 miles since it was done, maybe that is the simple answer...fingers crossed

 

[dustrat]

If as you say you can be driving for about 20 mins before oil light goes out I doubt that it is oil pressure problem as your engine would be making lot of noise. The oil pressure switch is actually fitted into the main oil gallery so it sounds as if you have switch or wiring problem. First take switch out and poke a bit of wire in hole to see if it is blocked then put some rag beside oil pressure switch hole, disconnect positive feed from coil and get some one to turn engine over and see if oil come out OK. If good flow of oil replace switch,replace positive terminal to coil and fit a test light from switch to positve terminal on battery and start engine, test light should go out,if not you have a falty switch problem. If light does go out stop engine and replace oil pressure warning light wire and start engine again. If it does not go out you have a wiring problem.The warning light is activated by positive feed going through warning light and earthed though switch and oil pressure breaks the earth contact and light goes out.
Robert

 

[genie45]

A couple of people have said it sounds fine don't worry about it...... Can't accept that and defeats the object of me having the camper and wanting to learn how to fix and maintain it, it's still early days for me so my practical skill are limited but I intend to work through all the ideas above on Saturday to try and identify the problem.

rlepecha, I think I have the original dipstick,  but the measurements would be great to confirm if you get a chance.

Cheers guys. [GRINNING FACE WITH SMILING EYES]

Genie



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[genie45]

Thanks to all you guys for the advice, It would seem that the wire from the pressure switch to the dash is the cause of the issue.

I removed the pressure switch and wire to the coil and a good amount of oil came out when the engine was turned over, I then replaced the switch and borrowed a test light and as soon as I turned the engine over the light went out.

So I now I have to replace the wire....what grade/type of wire would I need and best place to buy please

Cheers
Genie

 

[dustrat]

Pleased you found out the problem. The wire from switch to warning light does not carry a heavy current so go to your nearest auto accessory shop and explain what you are doing and they will fix you up.Buying more wire than you need is better than not having enough. :idea:
Robert

 

[genie45]

A little update on my quest to sort my oil light issue.

After running a new wire from the pressure switch to the warning light and starting the engine the light out...yay.......BUT the generator light did not come on at all...........ha ha.....after all my efforts to find the problem, that problem was not actually the one I had....my warning lights were in the wrong position on the dash ( not sure who I can blame for that [WINKING FACE])

So after more advice and very grubby hands from removing and testing the dynamo and regulator it looks like I will be replacing the regulator tomorrow.

It all makes sense now and as frustrating as it has been getting to the bottom of the problem I do feel I have learnt loads about how it all works. [GRINNING FACE WITH SMILING EYES][GRINNING FACE WITH SMILING EYES][GRINNING FACE WITH SMILING EYES]

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[ozziedog]

Well, that's a new one on me. I can see exactly what s happened and how. Amazing how things can gang up and complicate issues . :roll:

Ozziedog,,,,,, everyday is a school day :mrgreen: