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Confused by warning lights.

Posted: Fri Jan 11, 2019 9:31 pm
by Berk
Right, I've been through my 1212 with a set of crimpers and a pocket full of cables, and everything now works as god intended. (Almost)

When the engine is running, the Engine oil warning light (green) comes and stays on (But not until the engine is running) the light also comes on if I unplug it from the oil filter housing and ground it to the chassis.

The engine has the correct amount of oil, and doesn't appear to be suffering at all.

I was originally considering cleaning the oil pump wire filter, as per service task E, but I'm not sure it's needed, given the unexpected behaviour of the light.

Anyway, getting to the point.

I reckon I've probably got a Normally Open oil pressure switch, where a Normally Closed one should be used.

Does this seem likely, or do I need to go sump and loom diving?

Re: Confused by warning lights.

Posted: Fri Jan 11, 2019 11:06 pm
by db2d
The light should come on when the cable is grounded. Change the switch, but to be safe check the oil pressure with a gauge

Re: Confused by warning lights.

Posted: Sat Jan 12, 2019 9:31 am
by TEZB
I have seen this before on a 990, It turned out that someone had put a brake light switch on instead of a oil pressure switch, new switch soon sorted it

Re: Confused by warning lights.

Posted: Sat Jan 12, 2019 10:26 am
by Scooby
Get a pressure gauge on it. It's not difficult and you will learn quite a bit about the engine if you play around with the revs. It may indeed be only a duff switch but for peace of mind get a gauge on it. Plenty of gauges about, even one off a sprayer will do it with a bit of plastic piping but don't use a pneumatic gauge.

Re: Confused by warning lights.

Posted: Sat Jan 12, 2019 10:33 am
by Berk
Thanks both, that was my assumption.

If the light is on, it has some oil pressure at least, so that's good.

Re: Confused by warning lights.

Posted: Sat Jan 12, 2019 10:34 am
by Berk
I'll definitely have a look for a gauge when I have an hour, need one for another acquisition anyway.

Re: Confused by warning lights.

Posted: Sat Jan 12, 2019 12:09 pm
by SteveCollett
I had exactly this when I did up my little 770. Absolutely do get the pressure checked, it literally is 2 minutes, thankfully mine was fine, as I expect yours is. Good luck

Re: Confused by warning lights.

Posted: Sat Jan 12, 2019 4:20 pm
by Scooby
Berk wrote:
Sat Jan 12, 2019 10:33 am
Thanks both, that was my assumption.

If the light is on, it has some oil pressure at least, so that's good.
Exactly the opposite !!! The light should come on when you turn the switch. When the engine fires it should go out. In a worn engine sometimes the light doesn't go out until a certain level of revs. has occurred. Likewise, when an engine has been worked very hard and the oil is very hot it will sometimes comes on at low revs, meaning that there is some wear somewhere.

If your light is on when the engine is running it will either be the switch or very low or non-existent oil pressure. I wuoldn't even run that engine until you've set up some sort of gauge arrangement and checked the pressure. Yes, it is usually the switch but I would never ever chance it.

Re: Confused by warning lights.

Posted: Sat Jan 12, 2019 7:38 pm
by rid54
Scooby wrote:
Sat Jan 12, 2019 4:20 pm
Berk wrote:
Sat Jan 12, 2019 10:33 am
Thanks both, that was my assumption.

If the light is on, it has some oil pressure at least, so that's good.
Exactly the opposite !!! The light should come on when you turn the switch. When the engine fires it should go out. In a worn engine sometimes the light doesn't go out until a certain level of revs. has occurred. Likewise, when an engine has been worked very hard and the oil is very hot it will sometimes comes on at low revs, meaning that there is some wear somewhere.

If your light is on when the engine is running it will either be the switch or very low or non-existent oil pressure. I wuoldn't even run that engine until you've set up some sort of gauge arrangement and checked the pressure. Yes, it is usually the switch but I would never ever chance it.
I think the comment refers to the fact that a pressure-sensitive switch which makes contact when there is pressure (like a brake circuit switch), actually indicates pressure if it closes the circuit. The pressure level is of course not indicated so proper investigation is needed, but something obviously happens to the oil pressure as the engine is started.

Re: Confused by warning lights.

Posted: Sat Jan 12, 2019 8:28 pm
by Berk
As Rid54 said, my assumption is that everything is working, as until there's oil pressure, the light is off, once the engine is running, the light comes on. So it's working as expected, just with the light on when it should be off (and off when it should be on)

As such, until the switch appears in the post and I lay my hands on a gauge, I'll not panic.

Re: Confused by warning lights.

Posted: Sat Jan 12, 2019 8:36 pm
by Scooby
That is entirely up to you of course and it does indeed point to a switch problem since it appears to be working back to front but I still wouldn't run the engine until I knew for sure. How do you know if there is sufficient oil pressure to send it all round the crank, little ends, etc. etc ? All it is telling you is that there is some kind of problem just at the point where the switch is. Oil goes to a lot more places within the engine than that.

Re: Confused by warning lights.

Posted: Sat Jan 12, 2019 8:57 pm
by Berk
Well, it's been running fine for just over a year with me with no major issues, I'm not about to panic because I plugged a light back in.

Of course, you're absolutely right that it does need a proper looking at, but I'm not gonna flap for the sake of it.

Re: Confused by warning lights.

Posted: Sat Jan 12, 2019 9:30 pm
by Scooby
I bought a few 1212s new and don't forget that there was a period when cranks cracked, but usually under warranty. I had one ! What age is your 1212 ?

Re: Confused by warning lights.

Posted: Sun Jan 13, 2019 12:04 am
by Berk
Reasonably old, v5 says first registered 1974.

Re: Confused by warning lights.

Posted: Sun Jan 13, 2019 8:21 am
by Scooby
I used to buy a new tractor every August 1st when the registration letter was changed and it was the '74 model that suffered the cracked crank. I had a decent bloke ploughing with it at the time, would have been September-ish, and he took the rocker box off it because he thought it was a noisy tappet but it turned out to be a cracked crank. It would only have had a few hundred hours on it. Yours will most likely have a few thousand hours on the clock and it's either been back under warranty and been fixed or if it hasn't then it isn't going to be a problem.

I seem to remember that it was only a small batch of tractors that were affected but it has been discussed on this Forum a long way back.