Topic

Hi all,

I bought my MG TF 1.8 around 3 weeks ago, and unfortunately I already have a concerning problem with it...

I don't have a trusted mechanic (the one I had closed down...), so before I take the car to a new one I'd like to have your opinion on what might be going on.

The problem
When the engine is hot (oil temp higher than 90°), the oil pressure light starts flickering when the engine is idle. If I rev it even slightly, the light goes away. If I turn off the engine for a few minutes, allowing for the oil to cool down, the light stays off. No weird noises when turning on the engine and no other signs of something not working properly.

Some background
Right after I got the car I went for a very long drive (obviously!) and had no problems at all. The next day, with cold engine, I checked the oil level and noticed that is was very low, below the Min mark. I then topped it up with some 10w40 oil I had at home and the oil level now sits between the Min and Max markers.

I started having the oil pressure light problem only after I topped up the oil. As a side note, something bad must have happened to my oil dipstick in the past, since it looks "clamped" around the Max marker and the marker itself is not clearly visible.

Possibile problems
I have some ideas on what might be wrong:

1) I might have topped up with a different oil from what was already in the car, even though I used the oil specified in the user's manual.
2) I might have overfilled and when the oil gets hotter and expands it messes up with the oil pressure sensor. The oil level looks fine on the dipstick though.
3) The oil pressure sensor might have some problem and needs to be replaced.
4) The oil pump is slowly dying. In that case though, I should get the oil pressure light on even with a cold engine.

Any ideas of what is going on here?

Thanks!

lorenzo wrote: wrote:

Hi all,

I bought my MG TF 1.8 around 3 weeks ago, and unfortunately I already have a concerning problem with it...

I don't have a trusted mechanic (the one I had closed down...), so before I take the car to a new one I'd like to have your opinion on what might be going on.

The problem
When the engine is hot (oil temp higher than 90°), the oil pressure light starts flickering when the engine is idle. If I rev it even slightly, the light goes away. If I turn off the engine for a few minutes, allowing for the oil to cool down, the light stays off. No weird noises when turning on the engine and no other signs of something not working properly.

Some background
Right after I got the car I went for a very long drive (obviously!) and had no problems at all. The next day, with cold engine, I checked the oil level and noticed that is was very low, below the Min mark. I then topped it up with some 10w40 oil I had at home and the oil level now sits between the Min and Max markers.

I started having the oil pressure light problem only after I topped up the oil. As a side note, something bad must have happened to my oil dipstick in the past, since it looks "clamped" around the Max marker and the marker itself is not clearly visible.

Possibile problems
I have some ideas on what might be wrong:

1) I might have topped up with a different oil from what was already in the car, even though I used the oil specified in the user's manual.
2) I might have overfilled and when the oil gets hotter and expands it messes up with the oil pressure sensor. The oil level looks fine on the dipstick though.
3) The oil pressure sensor might have some problem and needs to be replaced.
4) The oil pump is slowly dying. In that case though, I should get the oil pressure light on even with a cold engine.

Any ideas of what is going on here?

Thanks!

In any engine as the oil gets hot the oil viscosity thins and the pressure reduces.

Overfilling the engine with oil will not give low oil pressure but is harmful and will cause other issues.

Using the correct oil is very important, the wrong oil can cause premature wear and reduce engine life (also the service interval)

The oil light being on at any time when the engine is running (hot or cold) is very bad, don't use the car until it's sorted.

The bottom end on the K series is normally bullet proof; the first you need to do is change the oil (min speck 10-40 semi synthetic) and fit a new filter, then give it a try. If the low oil pressure light comes again fit a new switch as they are cheap and easy to fit.

If you are still having issues you will need to fit an oil pressure test gauge and measure the oil pressure with a hot engine at idle.

Brian.

i would drain the oil and refill with 4.5 litres of the correct oil...insuring a new filter is primed and fitted.......this should be around the max.......if not the dipstick is giving a false reading...................have you any pictures of the dipstick........its not uncommon for people to cobble these up,even use one from another car............i overfilled a engine with oil when i was a lad......gestimating it i called it has the street lights were out that night and my car was leaking badly........the result was that i overfilled it.................the car was like a smoke machine.......the streets were left in a blanket of smoke with people pointing towards my car.....i looked in the rear view mirror and could not see behind........my car also struggled to go up hill without a bigend rattle........this was a silly mistake ive never forgotten..........but this didnt cause low oil preasure.........i have heard a case of overfilling with oil and the crank thrashes the oil ...which in turn aireates the oil causing low oil preasure......but without some further investigation diognosis is tricky............like already mentioned you need to check the oil switch......................oil preasure at idle should be between1.7bar-3.5bar.................oil relief valve opening preasure 4.1bar

Idiot lights and pressure switches can give false readings, to have piece of mind, you need to have an oil pressure test done.

Once the crankcase is filled to the correct level with the correct oil.
The oil pressure switch is removed and a proper calibrated test gauge is fitted, readings taken, test gauge removed then depending on the results.
If the test indicates good oil pressure then the switch should be replaced with a new one.

The oil pressure at idle should be 1.7 to 3.5 bar.
The oil pressure switch should open at 0.3 to 0.5 bar.
The relief valve should open at 4.1 bar.
And the maximum pressure at 6500 rpm is 7.0 bar @ below 40 deg C.

Thanks all guys. I just got the oil and filter replaced, but I still get the flickering oil pressure light when the engine is hot.

I guess the next step at this point is to have the oil pressure checked and hope it's a false reading or a defective oil pressure sensor.

In the event that it's actually a problem with the oil pump, I suppose that's a very expensive job, is it?

Invalid or non-existent item ID.price of the oil pump cheap enough ......fitting one depends on the mechanic you choose.......the relief valve is simple to access as this screws out from the side of the pump........in any case until the electrical side is tested first i would not even think about the oil pump scenario........oil preasure can be lost even when oil pumps are healthy...........pick up pipes ,bearings ,relief valves can all contribute low oil readings .........oil sensors only being around a fiver im suprised you havent tried one in yet