My oil light comes one - what's up with that?

[scoobie]

It's a 1995 Mitsubishi Colt, 1.5l. When it's warmed up and idling, the oil light comes on. If I rev the engine slightly the light turns off. If the car is in motion, the light goes off.
Only on when idling. The dipstick shows oil is full, right to the Max. The oil and filter were changed 3 weeks ago, I'm running 5w25 synthetic. -is this anything to worry about?- thanks.

 

[JHZR2]

low oil pressure... pump is shot? Sender is bad?

 

[StevieC]

Bad Sending unit... Dad had a colt before he was in an accident with 300,000KM and it did the same thing... He replaced it about a week before he had the accident. Guess that was a waste eh?

Replace your Oil Pressure Sending unit and you will be fine...

 

[scoobie]

thanks, Stevie, I thought everything was o.k. because engine sounds real nice, and there is no oil gushing out anywhere.

 

[StevieC]

You can't kill these engines... I would almost guarantee that the sending unit is bad, because you would have to have badly abused this engine for it to be the oil pump or something else... (Dad's a Mechanic of 35 years, so you can sleep easy!)

Depending on the mileage I would switch to a 5w30 or 5w40, these engines seem to like a slightly thicker oil... Not that I think this is causing your oil light, but just as a side topic.

BTW: The sensors are pretty cheap and you can get an after-market no-name one cheap.

 

[OVERKILL]

Good advice in this thread.

If the new sending unit does not fix the problem, pick up a mechanical gauge to verify how much pressure you are seeing.

Low oil pressure is a sign of worn bearings. Typically an issue with the oil pump presents itself as complete pump failure, which is obviously not the case here.

 

[Donald]

First - the best answer is to check with a mechanical gauge. But the inexpensive gauge sets do not cover all cars and you need a more expensive set from MAC or similar (on EBAY).

I had an unexplained oil pressure problem and narrowed it down to the filter that proved odd results. Now the engine had 180K at the time so that could have been part of the problem.

But after I switched oil filters and did two Auto-Rx cleanings I have never seen the problem.

Actually the problem went away (via mechanical gauge) when I switched oil filters.

I sent the filter to Amsoil and they said it was working properly but was full, but only had some 6K on an Amsoil filter.

 

[youdontwannaknow]

Originally Posted By: scoobie
The oil and filter were changed 3 weeks ago, I'm running 5w25 synthetic. -is this anything to worry about?- thanks.


anything different about this oil change ? different filter ? different oil ?

 

[Zaedock]

Originally Posted By: youdontwannaknow
Originally Posted By: scoobie
The oil and filter were changed 3 weeks ago, I'm running 5w25 synthetic. -is this anything to worry about?- thanks.
... different oil ?


Scoob, have you considered that the 20 weight you mixed in is too thin at operating temps?

 

[Crashbox]

I agree with OVERK1LL that it could possibly be worn bearings, hopefully it's just the sending unit.

I once had a '66 Chevelle which apparently only had aboot 5 psi at idle, yet the idiot light never glowed... Even better than replacing the sending unit IMO is replacing the light with a genuine gauge if it's affordable and reasonable to do.

 

[scoobie]

I'm going to take it in next week, and let my mechanic look at it.
I now have a pretty good idea about what needs to be done - check the oil pressure, and if low, check the oil pump and check the bearing. if oil pressure is good, replace send unit, or install true oil pressure gauge. I don't think the oil is too thin; this is Canadian Tire Formula 1 synthetic made by Shell Canada, and the blend I made should still have a hot cSt of close to 10. Hopefully it's the send unit, because the engine runs really smooth and strong, but you never know; from what I read elsewhere it's not good to ignore the oil pressure light, because it's possible to seize up the whole thing.

 

[StevieC]

The sending units used my Mitsubishi are built with Fail-Safe in mind... The sensors have a part inside that weakens over time/heat and when it wears out it leave the light on or partially like you describe because its better to be cautious than not know at all. Most likely this is your problem... But good suggestion by OVERK1LL to have the oil pressure tested, just in the off chance you have a bad pump.

GOOD LUCK!

 

[Spykem4e]

I had the exact same problem with my intrepid. When oil was warmed and then, on a stop or a redlight, the oil pressure light would flickered or stayed on and then, when i pressed the gas pedal, it would go away. It cost 25$ for the oil pressure sensor and wire. I changed it and never had problem anymore.

 

[gsnod]

Likewise -- I have the same issue with my 2003 Mitsubishi Outlander, and I'm trying to locate the Sending unit. It was suggested it was by the oil filter, but I can't remember anything resembling the unit being around the filter area....

Any other ideas where the sender unit is located on this 03 Outlander? It's a little cold now to be laying on the creeper looking for it...but I'm game!

 

[StevieC]

It could also be on the back of the engine... Rare times I have seen it mounted on the back of the blocks too...

 

[Donald]

I would throw on a new Supertech filter for all of $3.00 and rule out the filter. Your mechanic will almost certainly throw on a mechanical gauge and see if the sender is the problem.

For your bearings or oil pump to be toast, they would have to be really bad as the oil light does not come on until the oil pressure is very low like 5 PSI.

Thus I love cars with oil and voltage gauges.

 

[mechtech2]

By all means, get a new sender. It won't be much.
You will fix it or find out if the engine is a little loose.
But it's probably the sending unit.

 

[scoobie]

sending unit cost 25$ and another 25$ to install. everything is perfect now. my mechanic told me that the sound of the running engine sounded fine to him.

 

[StevieC]

Told yah! Drive Happy my friend, those are good engines!