Modern Vespa

I took the fine advice of those who responded to my brake fluid question a couple weeks ago and posted that I'd done it and everything worked well.
It didn't! Now there is a tiny, tiny seep of fluid around the bleeder threads. It is so small that if I wipe it off it doesn't show up again for several hours, but it is there.
I've tightened and retightened the bleeder, I even put a cheater on a 1/4" ratchet, but I'm afraid I'm going to break it. Do I tighten it more or is there something else I should try?

Either the bleeder has not been tightened down enough or you're going to have to remove it and wrap some teflon plumbers tape around the threads and screw it back in. You'll have to bleed the brake again but it will solve the leaking problem if this is the problem.

Do NOT over-tighten - those bleed nipples crack apart really easily. PTFE tape and a re-bleed is indeed the answer.

+1 +1

Could I get away with putting on the tape and just squeezing a little fluid out, tightening the bleeder and call it good, without having to go through the whole procedure? It doesn't seem like any air would actually be introduced into the system except right where the bleeder screws in. (Just trying to get out of removing the windscreen, mirrors, and headset cover if I don't have to.)

When you remove the bleeder screw, it's going to allow air back into the system. Depending on how much air gets into the line depends on how much fluid you'll have to bleed to get all of the air out so you can try it but you may have to remove everything again.

I think you really need to do the full bleed, in that I think you need to push enough fluid through that you'll want to replenish it at the reservoir.

Sounds like the seat on the bleeder valve is either damaged or these a piece of crap on the seat keeping it from sealing. Take the bleeder out and look at the seat. Im sure a imported car parts place will have these in stock.

+2

You should not have to tighten a bleeder like you did. I'd check the seat and replace the bleeder.

FYI there is no sealing capacity engineered into the bleeder valve threads. The seat is the only thing that seals the system.

I've heard of people using speed bleeders on motorcycles, but no experience on Vespa's. If you going to have to remove the valve anyway, maybe something to think about. Anyone have any experience with speed bleeders?

But Teflon tape would work as a patch and cheaper than caliper replacement.

My advice:
1) order a new screw from the dealer, cheap and only want to do this once.
2) remove old screw completely and attempt to clean bore. Swabs?
3) replace with new screw and re-bleed.
4) still leaking? 2 wraps of Teflon tape on the screw or find a used caliper.

I find it very convenient to have the tape on anyway, as it stop that inevitable tiny amount of air being drawn through the threads, which often complicates bleeding. Plus it helps ensure the nipples don't corrode in place, then snap when you try to open them. You only do that once!

Just use some brake hose clamps nearest you can get to the caliper and that will stop the whole system emptying. You can then extract the bleed nipple, wind round ptfe and reinsert. Remove the clamps once the nipple is tightened adequately. Usually makes bleeding much more straightforward.

Jegemba

As others have said the threads do not seal at all. The seal is in the seat. IMHO no ammount of sealant is going to work for long. Maybe you gat a piece of grit between the bleed screw and the seat and scratched it. Hopefully just the needle is damaged and not the seat in the caliper.

Never EVER Use a hose clamp to crimp a brake hose. You are compromising the hose itself and could cause a failure down the road.
They are meant for fuel lines not brake lines.
And I know, people do it all the time and have never see a problem. They can fail, trust me I have seen it happen.

Agreed. Don't clamp a brake line. They're not meant for that kind of abuse.

So the reason I use teflon tape here is that I've found it impossible to bleed the brakes without it. With the bleed nipple loosened enough to let fluid out of the hole, fluid also escapes via the threads, and air goes back in via the threads.

I'm not really sure how you're supposed to get the brakes bled without it.

+1
I've used it for years for the same reason.

The way I do it is to close the bleed nipple as I am getting to the end of the stroke of the lever. The lever must never be on its return stroke with the nipple open or air will be drawn back into the system via the threads.

+1

Cost me £100 for a new caliper when I did it...

Well, last night I put the LX back in the workshop and went at it again.
First I removed the bleeder screw. The fluid pretty much came to the top of the threaded hole in the caliper, so I don't think much, if any, air got into the line. I carefully cleaned the screw and wrapped a few turns of teflon tape around the threads. I know, they aren't actually the seal. But, I figured it can't hurt and it might help prevent future seize-ups. Also, might help with future fluid changes.
Next I took a good quality paper towel and used its corner to swab the threaded hole and seat.
I replaced the bleed screw and put my bleeder hose with one-way valve on it. I cracked the screw open and squeezed the handle. Without releasing the handle, I closed the screw. I then repeated this two or three times. Pure brake fluid started coming through the hose with no air bubbles.
Then, I checked the window in the reservoir. Yup, Jess was right, I had to add fluid. So, apart came the windscreen, mirrors, and headset again. Topped up the fluid and put everything back together.

Now, the bad news. Apparently when I took the screw out fluid ran down onto the pads. When I tried a test ride the brakes squealed horribly and jerked to a stop. So, off to WalMart to get brake cleaner I went. Came home, removed front wheel, removed pads, cleaned pads and disc. Then put everything back together.

And, the good news. No leaks!! I went out a few times today and pumped the brake to make sure there was plenty of pressure in the system. Not even that tiny, tiny seep I had before.

Thanks for all the good advice!!

Glad to hear you got it fixed.

Danny,

Your attention to detail, perseverance, and wisely taking advise from those more experienced will keep your scoot running well and you safe. Well done! I hope to have half as much discipline when the time comes to venture into my own do-it-yourself maintenance.