Car has about 200k miles on it. 2 days ago the light came on while idling but went away as I drove around my apartment complex, until I stopped on a slight incline. Went away again and only flickered when I went over bumps. The next day I changed the oil( preplanned before the light issue) the light came on again and has been on since. Also, with the engine running on idle and the oil cap loose, the cap sort of rocks and hops, and I think I saw oil bubbling around.

What are my options? It seems like this is more than a bad sensor switch, especially when I figure the oil cap. Due to the car's age, I'm thinking of replacing the oil pump and related piping, and the pcv. I'm also going to add aftermarket gauges for better information. Are there any other possible causes I can investigate? Are the alternatives any easier or cheaper to deal with? And are there any tips for a first timer trying to work from a Haynes manual and remove the oil pan for the pump?

 

I had the same issue on a '93 240 a few years ago. Unfortunately, I learned that light only comes on if the pressure is scary low. So address it now. More info will help as well. I'm not sure what the aftermarket gauges will tell you that the car isn't already. The 'rocking cap' seems to indicate that pressure is present but is not being contained.

Start with the basics. Are you using the right weight of oil for the hot summer weather?

Next, replace the oil cap. It's your first best, and cheapest step.

Are you losing oil? If not, and pressure is low, remove the oil pan and you will see a screen. If it doesn't look like a screen, or is dirty at all, clean it, and that should make an impact.

If you are losing oil, obviously gaskets and seals are likely to blame. Clean the engine (carefully, and with the right stuff), then run it for a day or 2 and look for the evidence of leaks.

If you are burning oil, things can get more complicated. Check for a blue-ish color in your exhaust. If it's there, or you have coolant and oil mixing, you have a bigger problem and will need to start swapping gaskets asap.

 

Thanks for the advice. The only oil I can think I've ever lost has been from the oil filler cap itself, but not recently. I haven't seen any oil+coolant mixing in the coolant tank, and haven't seen any signs of it either, as far as the film or even the residue on the oil dipstick.. What I'm hoping is that once this is dealt with, any decreases in pressure over time will be caught before it gets so low, as I'll have the gauge giving me a constant readout.

Have you dropped the pan before? Is it a long process?

 

The wire for your oil pressure switch is grounding itself out. Its gonna be bad where it runs under the front of the engine. I got five on it!

 

I...like your optimism. I think that was the cause of the light coming on about 6 months ago after an oil change. the light only came on after hitting some bumps, then would go off after hitting another. I'll definitely play with it in the morning to see for sure..

 

the oil cap hopping suggests your PCV is flugged up. clean your flame trap and oil seperator box, ensure all that plumbing is in good shape.

the intermittent low oil light could very easily be the sensor wire as Revolv suggests. the oil pressure sensor on a redblock is near the oil filter, under the exhaust manifold, and I believe the wiring is bundled with the alternator harness.

 

Think of it this way:

The oil pressure switch wire is always live with the ignition on. When oil pressure is low the switch is closed and it completes the circuit to ground (block) and then the light comes on!


A flickering light over bumps means bad wiring.


I hate to admit it, but I know I am exactly TWO quarts low on oil when the oil pressure light comes on when braking to a stop. It happened to me today and I took care of it immediately with two quarts of fresh oil without even looking at the dipstick. Then I pulled the dipstick, and it was right there at the top.


I will now explain which THREE WIRES are in that wiring harness that goes across the bottom-front of the engine:

1. A rather large red wire! But what does it do.....? It goes over to the starter. But why? But to charge the battery via large positive cable also connecting to the estarter.

2. Small guage red wire. It stimulates the alternator and also works twofold as a circuit that will make the low battery warning light illuminate during a low charge situation. If this wire is failed, probably is about to fail also, your alternator wont charge!

3. A small black wire= This is your guy! It is shorting out to the thin red wire and completing a circuit to ground that way, OR it is chaffing against the block or the alternator. Time to get greasy!!!! The wires fail from oil leaks that have been ignored.


To be honest, it's not fun digging that wiring harness out. There is a shortcut. I did it on my 240. It involves about 10 feet of wire, 4 red wire splices, and about 5 minutes of time. OR, you could spend a couple hours getting nice and greasy. Do you want me to inform you on how to perform this easy shortcut?

 

Damnit folks, I think we have a winner. The wire's completely severed from the sensor. Looks like it's been flopping around down there for...well, I'm not sure how long it's been like this.

 

REVOLV for the win... Well played

 

REVOLV,

If you've got any advice, I'd love to hear it.

 

Go bojangle a new wire lead from a junkyard car, or buy one from IPD and fix it! Oil pressure sensor light it CRUCIAL. If I didn't have mine hooked up, I wouldn't have known my oil pressure was going low coming to a stop, cornering, accelerating=low fluid level!

I blew the ol pushrod B20F engine in my 1975 245 because it consumed oil and I didn't have the oil pressure light wire connected! It started knocking on the freeway and I just say FUG IT and kept on going till it spewed coolant, chunks of block, oil and steam all over the road. It was quite dramatic and entertaining. I did it on purpose because I was planning on pulling that engine, but the new engine swap never happened and I sold the car due to rust issues.

Oh, LINK!!!:

Individual Harness Repair Wire GENUINE VOLVO 102603 3523813

 

or just go to a local electrical supplier or generic autoparts store and buy some oil resistant auto grade hookup wire, remove the plug from the oil sensor, take the plug apart, and splice on this new piece of wire, cut the old wire back to where there's enough left to work with, but past the grotty mangled section, trim the new wire to a suitable length, splice on the new wire to the old, and plug it in. drink beer!

 

If it doesnt have the rubber and the plastic clip (reusable. Snaps open) it will just pull back out if you bump into it or it could vibrate out.


I also suggest you keep an eye on your battery voltage like I said. Next to go is the thin red stimulator wire.

 

Reading this for the second time I think you are assuming the old pin is still good. It probably wont be. The wire inside the crimp will likely be shot, and the rubber will be GONE!


Hey, it's not rocket surgery. It's just a single wire circuit. Glad I could help point ya in the right direction. Nobody was born knowing this ****.

 

Guys, I really appreciate the help. I've been wanting to add more gauges to the car for some time and after discovering the faulty wiring here this morning, I've decided a new oil pressure gauge is the 1st one that needs to come in. Being able to establish a baseline and track the changes before the critical low point is much more useful that the warning light near critical failure.

 

add more guages, eh?

You need to start with making just your oil light work.


If you want to make both a guage and your Dummy Light work you will need a new sender that is compatible with the guage and also has a prong for the Dummy Light. What were you hoping to install?


Ok here is more info. You could use a VDO two prong sender and matching VDO guage. http://www.jegs.com/i/VDO/918/360-00...FRdsfgodXU4Kww
The issue is, the B230F block uses a much bigger thread than that sender. You will need an adapter also.



Is this topic about a 740!? In THAT case it is simply just a single wire inside insulation going across the front of the engine!


1: Make sure BOTH support brackets for the wire are there
2: Inspect it well for any breaks under the front of the engine

 

Yeah REVOLV, it's an 87 740 model. the wire is broken at the sender, like someone cut it right there. The wire dangles pretty much underneath the sender, on the bare metal there.

This is the gauge I'm considering: http://www.amazon.com/gp/product/B00...ilpage_o00_s00

I may be wrong, but figured I could go to a hardware store and pick up a brass adapter for it. I'm not concerned with keeping the dummy light functional.

This is what I walked outside to this morning BTW:

 

i recently fixed the oil pressure gauge sender wire on a benz, the connector was still on the gauge, the wire had broken just beyond the connector, so I cut off the bad stretch of wire, took the connector apart, soldered new wire to the pin clip, reassembled connector, soldered other end of new wire onto old wire, shrink wrapped, and voila, good as new. the benz has a gauge instead of a idiot light, which should be pegged at 3 BAR at anything above idle, hot idle might be as low as 1.5 BAR.

 

a hardware store is quite unlikely to have the right metric tapered thread adapter to fit into the volvo block.

 

but this aint a Benz! Volvo put a rubber down there by the exhaust manifold. Design flaw!

You are wrong. They won't have what you need.

Dummy Light has that name for a reason. My buddy blew the engine in my powerboat by not watching the oil pressure guage. Without a bright red light or audible alarm, I guarantee you will NOT notice the moment your oil pressure goes low. You will be looking at the road. It really is that simple.