Fuel tank sealing

[rovermorris999]

The tank on my Daimler E20 is rusty inside, no leaks but some flaky rust which has caused a failure to proceed on two occasions by blocking the pickup pipe. It's definitely this as I've has a look inside with an endoscope. Not a pretty sight.
So time to remove the tank and clean and seal. There seem to be several different suppliers of slosh-type sealants out there, does anyone have first-hand experience of any?
Is it worth having the tank professionally cleaned first? Some of the kits do contain cleaners and surface preparation products but I would imagine a blast with a steam cleaner might be better.
All suggestions gratefully received unless anyone has brand new tank going cheap!

[72twink]

I had a similiar problem on my AC, after looking at the sealing options I chose to just get an ally tank made and galvanised the filler necks.

[rovermorris999]

An update: the tank is now out and it doesn't look as bad as I thought. The tank is, like I am often, baffled and from what I can see through the various apertures there is only a little surface rust, mainly staining. The endoscope made it look worse than it was as it was a bit blurry. Quite a few bits of crud in there but what I think stopped the car was a small cardboard disc, the sort you get inside the lid of a screwtop bottle. This was in the area of the pickup and my guess it was sucked onto the end of the pipe and held by the vacuum until I blew back down the pipe from the engine bay to clear it. The bits of loose crud look small enough to pass down the pipe and get picked up by the inline filter I've fitted. Certainly none of them look big enough to block the pipe.
So do I just rinse the tank out, dry and replace and keep my fingers crossed or is it worth getting it cleaned and sealed?
I suppose an alloy tank would be the way to go but not a cheap option but probably the best.

[droopsnoot]

From what I've read (and I stress I haven't tried this yet), most of the sealer kits come with enough stuff to coat the inside of the tank, and rely on you pouring it in and moving the tank around to get it to coat all the inside. I wonder how well that will work with the baffles.

As for the cleaning side, I have had molasses recommended to me - mix with some water, bung up all the breather holes and so on, then fill the tank and leave for a bit. Wash out, then seal if you wish. Quite a bit cheaper than using something like citric or phosphoric acid. Again, not yet tried it personally as my car isn't ready for a fuel tank.

[rovermorris999]

Regarding sealing, the baffles do worry me. I can imagine a big build up of sealer which might come off later. Molasses sounds interesting, tasty and sweet-smelling at least.

[davepen]

rovermorris999 said:

slosh-type sealants out there!

Some people are suggesting that the new ethanol petrol is attacking old sealant... but no first hand knowledge.

[droopsnoot]

Frosts seem to offer a tank sealer that stresses compatibility with increased levels of ethanol.

[sideways man]

Droopsnoot,thanks for the link to Frosts

I have a mk1 escort with an alimax aluminium fuel tank. While I wouldn't describe it as actually leaking,there is a whiff of fuel and the welded seams have fuel residue on them after a while. When the car comes back from the painters...long story....will try some of their sealant. At £11.82 its much cheaper than a new tank!

[droopsnoot]

Frosts have a good range, though I do find a lot of their stuff is very expensive. That price doesn't sound bad, actually, but some things like flap discs and wire wheels are hellishly dear.

[Mr_B]

Thread revival time. I've got both tanks off my car and they are almost perfect inside with only a tiny bit of surface rust around one outlet pipe.
I was wondering if its worth sealing the tanks given they've lasted 25 years no real problem. I was watching a bit on Jay Leno's garage and he was talking about these peeling away as a kinda rubber sheet when attacked by ethanol and causing more problems, but believe California has much higher levels than the UK. So has anyone done theirs and had any problems ?

[v8250]

I've used the POR-15 tank sealant from Frost a couple of times. It works superbly and is designed to be used with higher ethanol based fuels. Of note, good preparation is key to getting a good long lasting result. POR-15 Metal Prep/Metal Ready is the product to use.

http://www.frost.co.uk/por15-fuel-tank-sealers.htm...

[V8 FOU]

Just give them a very thorough clean with some clean nuts and bolts inside to rattle around and remove any crud. I would guess that the corrosion you have was caused by some water in the tank settling to the bottom.

Have tried selants on bikes tanks with varying success. Not a big fan, except of the fumes! Jeez, do they give you a high....
Ermmmmm

[52classic]

I have recently used 'Rustbuster slosh sealant' on MKII Zodiac. Followed instructions to the letter and it does seem to have worked insofar as the flakey bits have stopped arriving at the filter on the bulkhead. Tank has to be off the car to get 360 coverage and I removed the sender unit to get enough room for the tip of a pressure washer. Important to keep the outlet and the vent pipe clear throughout because the material is gloopy enough to block them!

[grumpy52]

We had a jag xj6 in that had been treated with a sealant in one tank .The sealant had broken down leading to the carbs getting blocked by tiny bits of sealant .We fitted an in line filter which catches it all now and has the element changed at each service .The car does less than 1500 miles per year .

[Mr_B]

You read quite a mixed bag on these. On reflection, I'm not sure my main tank is suitable for this as it has a narrow hard line on top of the tank and another that bridges both sides of the tank and could be problematic in application. The smaller much simpler boot mounted tank would be easier to do, but this tank is perfect and it was the main underbody mounted and most rust prone tank which I thought might have benefited.