Modern Vespa

Friends - I need some help please.

The other day, I noticed a puddle of oil under my Vespa (2012 GTS 300). The center stand and underbelly were covered in grimy gunk. I cleaned and degreased everything to identify the source but still cannot tell.

Here are some thoughts:

1) The oil filter was a bit loose so I tightened it. Still leaking.

2) The oil pressure light is on. I checked the oil level and it was high (max). Could the light go on if there is excess oil or does it only come on from low oil?

3) I drained off some oil today and the dipstick is now slightly below max. Seems to me there was excess oil in the bike (I did an oil change 2 weeks ago, but didn't experience any issues until yesterday).

4) There is a little spout under the water pump. I'm curious what that's for. I circled it in one of the pictures. Could it be for oil overflow? That might explain things.

Anyway, please see pictures and let me know your ideas. I do have a Digitek diagnostic tool (although I don't have a clue how to use it). Perhaps it would help me read the error code.

Thanks in advance.

The oil light is on when the engine is running?

If the oil light is on with the engine running, that is potentially serious! Do not run the engine until you know more about the problem and the cause. You most probably have overfilled your oil when you changed it out. Or, you may have a rising oil level caused by either gas or engine coolant getting into the engine sump. Does the oil smell of gas? Can you see coolant in the oil?

If the oil light is on with engine running, did the engine knock or make other loud mechanical noises? If not, it may just be that you have knocked off the oil pressure sensor connector on the engine. Indeed, the whole sensor may be loose causing the oil leak.

The circled item in your photo is an engine coolant drain pipe. It allows condensation to drain from the water pump area and coolant to drain if the water pump seal starts leaking. This can give early warning of a failure allowing you to fix it before it becomes serious.

We need more info really. Can you see oil coming from the top end of the engine for example? Don't ride it untill this is resolved.

Thank you for your response! Much appreciated. Please see my answers below.

Does the oil smell of gas? NO, I poured some off and it seems perfectly fine.

Can you see coolant in the oil? NO

If the oil light is on with engine running, did the engine knock or make other loud mechanical noises? NO, scooter runs and rides as perfect as always

If not, it may just be that you have knocked off the oil pressure sensor connector on the engine. Indeed, the whole sensor may be loose causing the oil leak. Where is this sensor located? I'd love to check.


We need more info really. Can you see oil coming from the top end of the engine for example? NO. Everything looks perfect from the inside (under the seat) and elsewhere. Only sign of oil is in the area I photographed. All other areas are spotless.

And yes, oil light is ON with engine running.

The oil light on while the engine is running means no oil pressure in the engine - very very bad. Do not run the engine and bring it to a shop asap.

On the last picture that you posted there appears oil dripping from the oil filter gasket area, if sufficient oil squirted out while you were riding it could have splashed back to the underside of the engine, maybe!

Looks to me like someone used a big pliers to tighten the oil filter. It appears slightly crushed. Also damage to the paint near the end of it.

Is it possible the original oil filter seal was left behind and you've installed an oil filter on top of it? If the oil filter seal is still leaking that's an indication this is possible. That, or the whole works was warped with some pliers....

Generally speaking, oil filters should be installed by hand torque only. Tools should not be used to tighten them down. For this filter, perhaps a large flat bladed screwdriver would be appropriate, but that's about it.

Yes, after rechecking your pictures, I agree with Madison. It does look more likely this is an oil filter leak issue. If the oil filter seal has been damaged during installation (quite common if the seal wasn't lubricated with oil before tightening the filter), then oil will tend to spray out as engine revs rise and the oil gets hotter. Often this will only happen when your are riding. It could account for the oil light staying on as pressure is being lost. Or as Madison is saying, you may actually still have the original filter seal stuck to the engine and perhaps have installed another seal over the top of that. It will lower you oil pressure and almost certainly leak. Yours does appear to be leaking.

Photo's can be a bit deceptive, but it does look as though your filter is distorted. If that's the case you must replace the filter. Only hand tighten it firmly to start with, and then give it a tiny extra small turn with a flat metal blade of some kind (large screwdriver maybe) to finish off. Do not ever grip the body of the filter with water pump pliers or filter removal chains etc to tighten it. It will damage the filter and cause it to leak.

TO CHECK THE OIL PRESSURE SWITCH CONNECTOR...just look slightly above the oil filter and just a little to the right. You will see a black rubber/plastic boot covering the switch connections. Carefully pull that back and make sure the wire is connected to the terminal. If it has come off the switch the light will remain on. NOTE: The oil pressure light on the dash will also come on if the oil pressure falls below 0.3-0.6 bars. So although you motor may not be knocking, the oil pressure could be very low and the motor could fail if you continue to use it. I'd check this connector first before anything else if you haven't already done so. Then get a new oil filter and carefully check the seal situation to make sure you get the old seal/s off. Lubricate the new filter seal and fit the new filter hand tight and then just nip it up a tiny bit more as above. Good luck!

It seems like a botched oil change job. Based on all the diagnoses done by the members already it maybe best to do a new oil change. This time don't use the oil filter that Piaggio uses, better to get one that has a 17mm nut on it and you can tighten it by hand first and then put a socket on it and wrench it snug.
These guys make good oil filters https://www.knfilters.com/oil-filters/piaggio/vespa-gts

Drain the oil out, I would lean the bike over off the center stand and drain as much oil you can. I use a 1/2 gallon milk carton that I cut one side out and use that to catch the oil in and then transfer to a container for disposal.
Get your self a quart container with markings like this https://www.homedepot.com/p/HDX-1-qt-Multi-Mix-Pail-2M3/202264024
Use it to measure out how much oil you need and use a funnel to pour it in, you wont go wrong overfilling it.
I do oil changes on my Vespa twice a year once in the summer and once before thanksgiving.
I hope there is nothing wrong with your oil pressure sensor etc, cuz that will be a bigger job to deal with.
I think the members have diagnosed correctly for you.

In fact, the oil pressure sensor is quite easy to replace so no worries there. But it all costs money which is what baba is probably referring to.

I add ... after having removed the filter, check that there is no waste inside the part with the screw attached to the motor body and that it has not been damaged.

So, for those of you who are curious, here's what happened ---

The initial oil leak came from the loose oil filter (which I tightened by hand + 1/4 turn with the pliers) but apparently it had somehow become loose

When I went to clean and degrease the area to examine what happened, in all my enthusiasm and OCD-ness, I must have banged up the oil sensor with the brush (pic).

The damaged oil sensor started to leak, but I couldn't tell where the leak was coming from because it was being contained by the rubber boot that fits over the oil pressure sensor wire.

Today, I received a new sensor, replaced it, cleaned everything up and all is right in the world.

As Madison Sully correctly pointed out, I did scuff up my oil filter with the pliers because I couldn't get a good hand grip on it, but the damage is purely cosmetic. I ordered a backup filter just in case and will keep it handy.

If you have to start doing do-it-yourself maintenance you have to start buying the right tools, they will save time and money; you can start with the key to remove / install the oil filter:



You can also get yourself a maintenance program where, on the cards you have prepared before, make a list of materials and tools needed; then describe the correct procedure to carry out the operation. If you do not have it, look for the workshop manual where the part numbers are also available.

While using a tool to remove an oil filter is fine, and usually necessary, you should NEVER need to use a tool to install an oil filter.

Oil the O-ring (or whatever shape the seal happens to be), and get it as tight as you can by hand.

If you can't get it tight enough, find someone who can give it that final nudge.

About the only exception to this is if an oil filter is recessed so far you can't get a grip, but in my experience this is very rare. But regardless, Channellock type pliers are a really bad idea.

If you have trouble getting a grip on the filter to tighten it, go to Home Depot or Lowes and buy some Gorilla Gloves. They will give you the grip on the filter you need to get it snugged up.

Buy the oil filter with the nut molded to it versus the other one that requires a strap wrench or special tool to loosen/ tighten. You've got the other style filter on your scoot.

Thanks for all the tips

It is clear that it should not over tighten, for anything with a screw, in theory there should be a tightening torque but better than the clamp with which it has damaged the sensor is the strap wrench.
It is true, the original filter has the hexagon for the key but even in that case doing too much force can damage ...
Torque wrench in that case and proper tightening torque.
And ... yes, you can also tighten it by hand but it depends on how strong you are ... if you are a weightlifter it is worse than doing it with a strap wrench.