Leaking oil pipe

I have my first oil leak and it's a very slow drip. Part#8 GU06159300. Is a slow drip a big concern? How do you inspect the hose itself under that heat wrap? I'm trying to avoid removing tank and more importantly, avoid the cost and search for that pipe. All the other oil pipes have been replaced last year including the bellow bag cap. That pipe is on a 2013 with 76000 well maintained miles.

Is it a continuous flow pipe that can blow and coat my back tire while running?[You must be registered and logged in to see this image.]

That's the blow by tank return hose. Oil drains back into the sump from the tank. It's slightly pressurised by blow-by pressure in the sump, so if it did fail, oil would come out under blow-by pressure.

It's a known leak source, but not a high failure rate, I think.

Given that it's only fastened to the tank by a hose clip (clamp?), I'd be inclined to think the pressure is rather low, so cut the offending hose from the fitting at the sump, and replace with a suitable hose.

But, I'd like to hear if Mr. Roper approves.

The problem is that usually leaks from that pipe come from the crimped end where the hose meets the pipe that goes to the sump. Now if it is loose enough to leak it may suddenly fail catastrophically and if that happens the oil from the sump will blow back up and out and you will indeed end up with a dangerous amount of oil all over the rear wheel and brake.

The thing is the hose is pretty crap to be honest but the solution is pretty simple. You need to drain the sump but if you are desperate enough and the oil is new you can always just drain it into a clean container and re-use it. Then you have the embuggerance of getting the tank off but once that is done you can just disconnect the pipe, with hose, from the sump and the condensor box up behind the steering head and wriggle it out of the bike. Note it’s routing for when you reinstall it.

Then take the offending POS to your local hydraulic hose repair/manufacturing shop and tell them to replace the hose with a decent, oil resistant, silicone hose. They will probably do it while you wait or tell you to sod off to the bakery over the road for a cup of coffee and a slice of cake and by the time you get back they will of crimped you up a nice, and much superior, hose onto the pipe for probably a fraction of the cost of the shitty Piaggio part that will likely not be available and have to be shipped by bullock cart and trireme from Pontadera or wherever Piaggio keep their inadequate spares stock! It would probably take six months to get to you and there’d be a good chance it would be wrong anyway!

When reinstalling the new hose make sure its routing doesn’t interfere with the throttle linkages, refit tank. Refill with oil. Go ride.

Very well then. I'm due for an oil change soon anyhow. Thanks for guidance Gents.

I made my own with appropriate oil/fuel resistant hose, and included a non-return valve to keep the pressurised sump from forcing oil into the blow-by box.


If you reckon there's not much pressure in the sump, remove the dipstick and start the engine with your hand over the hole. The combination of blow-by and windage at idle is impressive..so imagine what it's like at 4000 RPM!

Yup. There is a whole lot of shit going on in there. Remember if there is only 2% blow by and the engine is 1000cc, (Most Grisos are bigger.) and every turn of the crank releases a lot of pressurised gas past the rings into the sump? Even allowing for rapid cooling and contraction of that gas in volume terms at 6,000 RPM there is a power stroke 3,000 times a minute. You do the sums. No I don’t know how to calculate the gas shrinkage, which will be big, but there will still be a fuck-tonne of pressure there even considering the drop off in VE as crank speed rises.

It's worse with the 1400. As you know, I've got to great lengths to reduce the pressure in the sump.

Yup. Crankcase volume is the same, basically, as the LeMans III of 1984! But the swept volume had increased to nearly 1400cc! From 850! The fucking thing is trying to blow itself up like a balloon!

Thanks for the tutorial!!! I was only considering that since the top of the hose seemed to be secured only by a clamp, then the same fastening method would suffice at the lower end as well.

I understand the Oiteker clamp and how it is a size to fit clamp that is non adjustable. I'm interested to know how the oil hose connects to the pipe at the sump side of assembly. Simular or the same as a hydraulic connect as Pete had in tutorial recommendation. I won't attempt it but am interested to find out how it's done at the shop I will source.

Update and new question....after long ride and steady run at idle tell me what I think I already know Pete. Not a leaky pipe that's the main bearing seal blown..??[You must be registered and logged in to see this image.]

That whole area was degreased and cleaned less than 10 miles ago.

What year is it?

2013

OK, that makes it too late for it to be a likely candidate for the leaky flange issue.

If there is oil coming from the bell housing slot then something is leaking in the bell housing. It could be rear main seal, it could be the idler shaft cap, it could be the flange itself.

Thing is that if the oil return pipe is leaking there is a lot of air turbulence in that area when you are moving along and the oil may be getting blown and splattered in that area. I’d suggest doing the hose first and then cleaning and degreasing the whole area thoroughly and making sure it is actually leaking from the bell housing before proceeding further because if it is coming from there it’s a gearbox out, clutch off job to fix.

You are sure it’s engine oil? Not gear oil?

I will investigate more tomorrow. The oil is old so its dark and due to my loss of sense of smell I can't tell by that method. Sump bolts coming loosened could be a possibility too I suppose. It's just gonna be a search and find mission. All the avenues that you mentioned will help me solve this. Thanks Pete. I'll keep my progress updated.

Old school..... clean it well and blow a bit of corn starch or baby powder at it. See if you get a clue from that. If not, start it for perhaps a minute and repeat. Good luck.

I use an aerosol product called developer from Magnaflux when chasing origin of oil leaks.
I get it from "Aircraft Spruce". The whole magnaflux crack detection kit has three components however the developer spray is the only item needed to display origin of leak.
Start by cleaning and drying the area, spray on developer and wait until it dries to a crusty powder, start engine and stand by watching for oil to appear.
In addition to Ricks household products suggestions, an aerosol deodorant may work.
Either way, the trick is to stand by watching for first sign of leak, not ride away and come back to it.

After due dillagence, and utilizing tips, once again another problem solved. Apparently, I had a mishap a while back and my stand came loose underneath and bike got away from me almost. In that process of idiocy on my part the drop out v on stand hit the pipe at an angle and the fastener came unsealed. Note: it was tight just came unsealed. The turbulence that occurs down there as Pete mentioned slung the oil all over down there. After discovering that the oil leak was probably there I reseated the pipe by pulling outward while tightening to assure a flush seal. Wollla! No more leaks of oil. At a cost of zero dollars. Sometimes it's best to start with the simple things first I guess. And never quit on these bikes. Thanks again for tips.[You must be registered and logged in to see this image.]