Rusty Petrol Tank

[Carts]

Hi

I have a morini 31/2 sport 1980 model, about 2 month ago there was a petrol leak from the petrol tank, at the rear left hand side near the seat unit. Talking to a mechanic he think it has rusted inside at the seam. I know with modern petrol with ethanol rust is more likely if bike left for a while. So looking at my options, is this a common issue with 350, have looked at sealing but not had that much joy before doing this and if rust is in seam only think it will get worse if sealed over and in time will leak again ?

So are there any good quality tank out there, don’t want to buy another tank that could have same problems. Or is seam being rusty unlikely. Mechanic has looked at it with borescope. And sealing could work.

Cheers carts

[Steve Brown]

Hi Carts, Yes it is possible to seal a rusted tank but first you have to remove the rust with chemical treatments. I have used the kits from Frost Automotive/POR15 with success on four tanks at least. Only one was a Morini though.
Their kit comes with three containers. First is a degreaser that removes all the old stale petrol chemicals, wash that out with lots of water. Then use the rust remover/killer chemical, wash that out with lots of water and dry the tank completely. Then finally use the sealer chemical.
It all takes a long time, many hours/days and a lot of arm work rolling the tank around in each stage. It does work though!

There are other makes but I've only used the one mentioned.

[Ming]

As Steve says, sealing works if done properly. I use a product called 'Slosh' (https://www.rust.co.uk/product/slosh-pe ... k-sealer-7) which is OK so far. I also use cheap white vinegar for an initial clean, or electrolysis if the tank is very rusty. I used it on a 250C2 tank which had pinholes along the bottom outer of the tank (above the seam) where it had been left on a sidestand.

[AntietamClassicCycle]

Caswell is the only product I will use. Much easier prep and super durable.
https://www.caswelleurope.co.uk/fuel-tank-sealing-kits/

[3potjohn]

I have been using POR15 for years.On 3x BMW and 2 Morini tanks. If you get the Frost Motorcycle repair kit and follow the instructions, particularly with regard to drying the tank and leaving it to cure properly. Forced warm air circulation is best. Remove fuel taps and seal the holes somehow. I used rubber bungs.
Good luck
John

[Carts]

Hi all

Thanks for the positive feedback. I will look into the various product you’ve all used. Good to hear it worked, the mechanic I use wasn’t to sure if sealant would work as rust in seam.

Cheers again.
Carts

[Ming]

If you have no luck, I have a tank available. It was donated to me by Mr Brown in case I needed it, though it has dents and paint damage. I didn't need it in the end. The problem is it's in central France, so not readily available. I may be able to get it to Staffordshire, depends on family visits.

[Carts]

Thanks Ming

I’ll keep you in mind. Problem is I’m worried if I get another tank will I have same problem sooner or later.

[Ming]

...I’m worried if I get another tank will I have same problem sooner or later.

I don't think there's any problem inside the tank - it's the outside that might cost a bit! I would certainly try one of the kits available first.

[3potjohn]

Just to add, When I got my 350 in 2011 there was a weep of fuel at the left rear of the tank, which was covered by a small patch of duct tape. I then tried a product called Petro Patch. I then came across the Frost kit and used this. I think I rushed the drying process and so still had a vague ooze by a seam. I was then fortunate to get another tank which was sound. Subsequently though I also sealed this tank with POR15.
I then decided I would strip the old tank using Nitomors, which I hate handling,This did get the sealant out eventually to reveal about 30 pinholes especially around the fuel spigots.
So what I am saying is that I believe the POR15 is a good product if used properly.
John

[Ming]

Just to add, ... believe the POR15 is a good product if used properly.
John

On the nail. The inside of a thin steel tank part full of petrol and atmosphere is pretty harsh, any treatment needs careful application. I think any of the modern 'ethanol proof' kits should be OK if applied correctly.

[AntietamClassicCycle]

I used the Caswell sealer to line the gas/petrol tank on my Gravely garden tractor about 10 years ago. It had about a dozen pinholes, but no rust. Even though it sits year round with the 10% ethanol swill that passes for gasoline around here in it, there has been no degradation of the sealer. Looks the same as the day it was put back into service.

[Carts]

Thanks everyone for your encouragement, as you all seem to say getting the prep done properly is the key. The internet can show failures and makes them seem the norm when it may be just a few %.