Oil warning light - odd circumstances.

[Offgrid]

Now that I'm on the home straight with the ignition and exhaust, I'm turning my attention to the routine maintenance stuff. First, a bit of background. The car is a 1990 745 with a B200E engine. I bought it over a year ago, and it's been on a SORN for that period. I've only driven it for about 5 miles, but I have run up the engine intermittently. Over the last few days, I've idled the engine for an hour or two each day. This is to clear the engine, and look for any problems prior to its MOT. It idles at about 600 rpm, and I'll adjust that when I've replaced the ignition leads etc. I think the previous owner had started to prepare it for an MOT, but gave up to turn his attention to the restoration of a Morris Minor. It looks as if it has a new air filter, and new very clean oil at the max level. However, the oil filter looks as if it has been repainted. For the last couple of days, the oil warning light has been coming on, and only goes out if I take the revs over 1,200. There is a new oil filter still in its box the came with the car.
What could be causing the warning, and what should I do about it? Obviously, I can't change the filter without changing the oil. The only causes I can think of are - blocked oil ways, a blocked filter, or a failed oil pump. My possible solutions are -

- Run the warm engine at 3,000 revs every day for about 5 minutes.
- Change the oil and the filter.
- Although the vehicle is now insured, I can't run it on the road without a valid MOT.
- Fit an oil pressure gauge, and check the reading at various rev ranges.
- Fit a new oil pump.

What would you do?

[SalvadorP]

Originally Posted by Offgrid

Now that I'm on the home straight with the ignition and exhaust, I'm turning my attention to the routine maintenance stuff. First, a bit of background. The car is a 1990 745 with a B200E engine. I bought it over a year ago, and it's been on a SORN for that period. I've only driven it for about 5 miles, but I have run up the engine intermittently. Over the last few days, I've idled the engine for an hour or two each day. This is to clear the engine, and look for any problems prior to its MOT. It idles at about 600 rpm, and I'll adjust that when I've replaced the ignition leads etc. I think the previous owner had started to prepare it for an MOT, but gave up to turn his attention to the restoration of a Morris Minor. It looks as if it has a new air filter, and new very clean oil at the max level. However, the oil filter looks as if it has been repainted. For the last couple of days, the oil warning light has been coming on, and only goes out if I take the revs over 1,200. There is a new oil filter still in its box the came with the car.
What could be causing the warning, and what should I do about it? Obviously, I can't change the filter without changing the oil. The only causes I can think of are - blocked oil ways, a blocked filter, or a failed oil pump. My possible solutions are -

- Run the warm engine at 3,000 revs every day for about 5 minutes.
- Change the oil and the filter.
- Although the vehicle is now insured, I can't run it on the road without a valid MOT.
- Fit an oil pressure gauge, and check the reading at various rev ranges.
- Fit a new oil pump.

What would you do?

My first thought was that I would fit an oil pressure gauge. But also, given that the filter itself looks sketchy and there was a new filter inside the boot/car, that kinda gives it away that either the filter really needs changing, or that the car was having oil related issues and the previous owner was trying to figure it out. Maybe he thought the filter just needed a makeover, and when that didn't work, he intended to change it

Either way, I wouldn't run the car without an oil pressure gauge and new filter/oil. I think measuring oil pressure should be the first priority here.

Just my 2 cents.

[john.wigley]

Good call re the pressure gauge, SalvadorP. The oil warning light switch itself could be faulty and nothing wrong at all with the engine. It is not unknown for the light to come on or flicker at idle especially with hot oil.and extinguish as the revs increase above tick over.

I'd be inclined to swap the switch for a gauge as you say to establish the actual value. I would then replace the switch if necessary - they are cheap enough - and also the filter, which can be changed without changing the oil. Offgrid will lose the contents of his filter (about a pint) and will need to top up the engine by that amount. It is also important to use a filter with an NRV - preferably a Volvo one.

Better still, why not fit a tee-piece and have a gauge in the car as well as the warning light?

Regards, John.

[Offgrid]

I've been looking at oil gauges, and I don't like the mechanical ones. The digital ones seem to be more suitable for me. Swopping the warning sensor, and fitting a gauge temporarily under the bonnet may be a good call. Then when I have resolved the problem, I can install the gauge in the saloon. That's the car I want to trick out and experiment with ( B230E engine). The estate is going to become my daily driver, and will probably be driven in the manner of a pensioner in a classic Volvo.

The flickering warning comment is a good call. I have variable readings on the fuel gauge, so I may have some earthing problems. Given the car has been left unused for a few longish periods, that seems likely.

[SalvadorP]

Originally Posted by Offgrid

I've been looking at oil gauges, and I don't like the mechanical ones. The digital ones seem to be more suitable for me. Swopping the warning sensor, and fitting a gauge temporarily under the bonnet may be a good call. Then when I have resolved the problem, I can install the gauge in the saloon. That's the car I want to trick out and experiment with ( B230E engine). The estate is going to become my daily driver, and will probably be driven in the manner of a pensioner in a classic Volvo.

The flickering warning comment is a good call. I have variable readings on the fuel gauge, so I may have some earthing problems. Given the car has been left unused for a few longish periods, that seems likely.

If you don't have one, you can buy a tester kit that also has tips for compression, besides oil. Some even have tips for fuel pressure testing. It's cheaper than buying different testers for each test, beccause the gauge is the most expensive part. I've had good luck with cheap ones from amazon.
I guess if you test the oil pressure in a few different situations and you see it's good, or it gets normal after changing the filter, there is no need for constant monitoring of oil pressure.

you can get one of those testers for as low as 20 quid, maybe even less, if on sale.

EDIT: Btw, in fact there are some that have a long enough hose that you could pass it through the firewall into the engine bay and monitor values from the inside, like a normal gauge. Those are the best. You can drive around a little bit and then remove it when you are done testing.

[Offgrid]

I'm starting to wonder about the oil that is in there. It looks like sunflower oil, and I would have expected it to darken by now. I must have run the engine fir at least 5 hours, and that should have created some discolouration. I bet the guy pinched some of his wife's cooking oil.

[SalvadorP]

Originally Posted by Offgrid

sunflower oil,

Holy Molly, not to say Holy F**K!

Anyways, having watched enough "costumer states" compilations on youtube, I am fairly confident in saying that if it still looks like vegetable oil after hours of runing, it probably isnt. Veggie oil at those temps and pressures becomes thick as glue. Here, a quote from google, but I'm sure I can find a video too:
"Due to the oil being so thick and sticky, it won't flow properly through the engine, and it will not burn efficiently. In turn, this will cause the oil to solidify and build up, damaging the engine and causing it to burn out or stall."


PS: i went ahead and looked for a video anyways and it took me 5 seconds. It's the beggining of this video: [YOUTUBE]https://www.youtube.com/watch?v=81KbmZjiGJE[/YOUTUBE]

[classicswede]

It is a common problem and easy to sort.

The most common issue is wrong oil filter causing the warning light to to take longer than normal to go out. If that was the issue then just changing the filter would have resolved.

With the light coming on at low RPM this is usually down to the wrong grade oil

I would fit correct oil filter and and correct grade oil 10w40 semi is my oil of choice for our climate.


The other possible is the seals on the link pipe from the oil pump to the block leaking but they only leak if they have been messed with. It could also be the pump worn but the pumps are fairly reliable and on a maintained engine without moon miles not likely to be the issue

[Forrest]

On most of the Volvo redblock engines it is perfectly feasible to change the filter without changing the oil. If you change it cold the bulk of the oil will be in the sump and you will only lose a small amount from the filter. That said, if you don’t know the provenance and age of the oil you’re better off changing that too as already suggested.

The correct filter will be a Volvo imperial filter 351785. These have a non-return valve that prevents the filter emptying when the vehicle is not in use. If your current filter doesn’t have that then that could be the problem.

The oil pressure switches can go wrong. If you have to replace it be aware that the electrical connector will be very brittle and may need repair if disturbed.

[Forrest]

Sorry, meant to mention in my previous post that if your car came with a new, loose oil filter and fresh oil but the existing filter looks artificially spruced-up then there is a good chance it is stuck on. Best use a good quality strap wrench or similar non-destructive method to try and loosen it before you drain the oil in case you cannot shift it.