Oil light comes on when hard braking

[tfs08SWtC]

Not sure if this is the right section to be posting this, but I figured I would give it a shot. This hasn't happened to me before, not really sure why the light would come on only during hard braking then turn off as soon as I let off the brake.

Any suggestions? Could it just be the oil moving around in the pan away from the sensor since it is close to oil change time? Seems odd that it would shift around that much...

[navylife59]

Are you getting a red "oil can" light on your combination gauge? It sounds more like the common problem seen as a brake warning light when the brake fluid reservoir is a little low. Have you checked the oil level on the dipstick on level ground about an hour after the motor has run? If it checks OK and you are sure that the dipstick is inserted completely in the dipstick tube, you might be having some other issue in your oiling system. Any lapse of oil pressure puts strain on your bearings and journals.

[tfs08SWtC]

Are you getting a red "oil can" light on your combination gauge? It sounds more like the common problem seen as a brake warning light when the brake fluid reservoir is a little low. Have you checked the oil level on the dipstick on level ground about an hour after the motor has run? If it checks OK and you are sure that the dipstick is inserted completely in the dipstick tube, you might be having some other issue in your oiling system. Any lapse of oil pressure puts strain on your bearings and journals.

It turns out the oil was a little low... not sure how it is that low with a month left before I need to do an oil change. I added a quart and the light doesn't come on anymore, but it still seems a little low on the dipstick. Might have to do an oil change sooner than expected. Any reason why oil would be burning up that much? First time I have had this issue.

[navylife59]

You should not loose but a trace amount of oil per oil change. Very tiny amounts of oil are allowed to squeeze past the oil control ring to provide a thin lubrication for the upper cylinder during piston travel. The 2AZ-FE is a close tolerance OEM engine. Cylinder wear under normal operation should not be an issue till way past 120K miles. There can many causes to premature wear from poor oil, poor performing air/oil filter, defective or poorly installed piston rings. Overheating, poor maintenance, F/I, and NOS can damage piston ring lands, skirts, out-of-round cylinders, cylinder wall glazing.

The oil light is an oil pressure switch. The ECM activates the light on the Combination Gauge when the sensor detects a low press situation. A low volume of oil can cause the oil pump gears to cavitate which would provide for the a temporary low press situation. Any loss in oil pressure is bad on the rotating assembly and the cylinder walls. Enough times of this situation can lead to premature wear of the cylinders and loss of compression. In the dark old days before OBDII vehicles, the oil pressure sensors failed alot and sometimes the wiring harness would get a short in it. OEM's seemed to be doing alot of trial and error development like Microsuck. Put your untested product in the field and let the users figure out the issues. Do you know that once the engine is warmed up, that the oil press at idle is only around 7 PSI? The oil press sensors Mazda used in the 80's had a weep (witness) hole to let you know the internal seal of the sensor had failed much like the hole on mechanical water pumps that show a failed bearing seal. Problem was, once that internal sealed failed, oil would spray out that hole at what ever the oil press of the motor is at that moment. Not very smart.

Note: This is not blow-by which is an inverse product of a poorly sealing compression ring in a cylinder that flows into the crankcase during compression.

[tfs08SWtC]

Yea, I have a feeling something might be wrong... there is no reason why the oil would be that low on the dipstick with only 3800 miles on this oil change. Especially when it is right at the full line when the oil change is fresh. Maybe I should take it in to the dealer? I waited about 20 min after I got to work to check it and it was below the fill line on the dipstick... that just doesn't seem right.

[navylife59]

Just to rule out any possible Homer Simpson "Doah!" scenarios, you are reading the bottom line as the low-level and the top line as the full, right? Had a neighbor's wife ask me if I could jump start her car. Her husband left her with some instructions to put oil in the car every other day. The dipstick was dry and there was no sign of oil on the ground. When I told her that there was no oil in the motor, she promptly pointed to the cap that she removed to put the oil in. Problem was, it was the power steering reservoir!

[tfs08SWtC]

LOL yes, the bottom line is the low level and the top line is the full line. And yes, the oil has not be put into the steering reservoir either. I'm doing an oil change this weekend a little early and I'm going to keep an eye on the level every week to see progression of this issue. If I notice the level changing quickly, I'll be taking the car in I guess. Reason #1,452 to really dislike Toyota... not even 4 years old and the car is burning oil at a pretty rapid pace.

[connman429]

Just because the oil level is low doesn't mean you are burning it. If it's consumption, at that high of a rate you should notice smokey exhaust. There is a much higher likelihood that one of the main seals is leaking by. If it's the rear main, you may not get the puddle underneath, since it's draining into your bell housing.

Another possibility: drain your coolant into a clean bucket and look for oil on top after you are finished. If you have a leak path through your head gasket, that's where the oil will be going. If the coolant is clean, pour it back in and you've lost nothing more than an hour of your time

[navylife59]

Do you see any white to blueish smoke coming out of your exhaust?

If it is at idle, that is usually an indication of a worn valve-stem oil seal. At idle, the oil pressure is about 7PSI so oil tends to puddle up around the valvetrain. At higher engine speeds, the faster moving valves generate more friction against the oil so less gets by.

If it is at 50% to WOT, it is probably a bad oil control ring on a piston. It could also be an excessive worn cylinder round-out or a crack.

Another possibility could be a blown head gasket. Blown head gaskets usually do one of two things;
1. Pressurize the crankcase or water jackets during the compression stroke. Pressurized crankcase will push oil/oil mist thru the PCV system back into the intake system. Pressurized water jackets can rupture radiator tanks, hoses, pop off the radiator cap or blow out the seal in the water pump. Besides dropped oil levels, the intake will be full of hydrocarbon build up for oil.
2. Create a vacuum in those systems during the intake stroke. This can draw water and oil or both into the cylinder where it enters the exhaust as a combustion by-product.

Alot of different engines out there have water jackets in the intakes. The seals/gaskets can fail allowing water to intrude directly in the intake tract. We do not have that issue on the 2AZ-FE as there are no water jackets in our intake manifolds, The Throttle-Body does have a small water jacket to aid in severe cold weather run-up for the Idle-Air Control valve (IAC). It is machined in with no gaskets to leak. The water is fed externally by two hoses. Because of this, oil in the water or vice verse is a sure sign of a blown head gasket. An compression check can usually pin-point as to which cylinder is compromised.

[tfs08SWtC]

I would know if it was a blown head gasket... my first car had one and the oil looked "soupy" in color because of the coolant. It definitely isn't that. I'll look at the exhaust at idle, I haven't noticed any smoke coming out lately when I have been letting it warm up so maybe connman429 is right about the main seals. Again, there is no puddle underneath the car either. So it has to be going somewhere.

[navylife59]

If the head gasket had failed around an oil gallery drain back orifice, you could be having oil consumption w/o any contamination into the engine coolant. This is not so prevalent as with it failed head gaskets around the water jackets. An oil control ring on one or more pistons could be the culprit as other tell-tale signs are not showing.

[tfs08SWtC]

Thanks for the help navylife59... I'm just not THAT knowledgable about cars. I would have no idea how to check for all of this stuff. I think unfortunately I'm going to have to suck it up and take it in and get raped by the dealer just to check it out. But for now, I'm going to change the oil a little early and then keep my eye on it for awhile and see when the level starts to change.

[connman429]

Another thing that will happen if the oil is bypassing the rings is oil fouling of your spark plugs. If you pull out your spark plugs, the business end should be a little discolored, but clean. If they are black and grainy-looking, or black and shiny, you've got too much oil in the combustion chamber.

[navylife59]

Back before we had a Tech Article section, I had posted information in a thread on reading spark plugs I can't seem to find it now. You can just Gurgle "How to how to read spark plugs" and you will get a plethora of sites. The quick down and dirty can be had by selecting the Images results in Gurgle and you will see the picture chart. This is an old, old practice and still very much relevant with today's engines.