I've been looking at a Conti Prestina on Ebay for some time and recently decided to buy it. The machine needs to be restored, but is in okay condition. I'm currently expecting to just replace the gaskets and clean all the parts properly, hopefully nothing important will break during this little project of mine.
So far i've disassembled the group and the pressostat from the boiler. It seems like the group have recently been disassembled before, perhaps by the seller, because all the bolts very easy to loosen and the the group smelled of WD40 or something similar.


As you can see in the pictures the group needs a bit of cleaning, but nothing is looking too bad. I was planning on just using soap and warm water to get the worst of the problems, followed by a overnight soaking in cafiza. I don't assume the cafiza will damage anything here right?
From what i could read in Garys Prestina restoration thread the piston can be unscrewed from the piston rod without the spring launching it into orbit right, because the spring looses tension before the piston rod lets go? I made this mistake with a Mini Gaggia would like to be sure that this won't happen with the Prestina.

The next problem is some umbraco screws(i assume that's what they're called) that wont budge. The ones on the group weren't a problem but those on the sight glass mount is stuck completely.

In the picture you can see the head of one key that broke of in the screw. None of my keys are strong enough to put the needed toque on those screws, so i need a recommendation for some tools suited for the job, something like a umbraco breaker bar? If you know what could handle this challenge then i'm all ears.

So far i've been using an adjustable spanner to get the bolts off but facing the boiler bolts and the group to boiler bolts i'm realising this won't be enough. I'm planning on getting myself a set of flare nut wrenches and together with a rubber mallet i'm hoping it will be enough to get the bolts off. I have a socket wrench set that would be perfect for most of these bolts, but the group blocks them from fitting on to the bolts, so i will need the flare nut wrenches, if only for the group. Anyone know a cheap brand of flare nut wrenches that will get the job done?


As you can see in the image one of the group bolts are missing. I know this won't be a popular option, but would it be possible to just replace the gasket and not cut new threading on the fourth one and replace the bolt? The seller send me a video of him pulling a shot on the machine so i know that it can hold pressure, even without the last screw. Perhaps it works and i've saved myself time and money and if it doesn't then i replace the bolt?

There are more things i need to fix on this machine but i thought that it would start this thread with just the most important problems. If anyone have some general tips or advice for tools i will need further into this project please do say so. Just remember that i live in Denmark so not all the specific brands of tools or sites selling replacement parts will be an option for me.

Nice find, I knew you'd get on to a commerical lever...

Try to be patient with those screws. Soak them with penetrating oil or WD40 for a few days. Then you can even a razor blade and work around where the screws meet the frame, and help to loosen them. Then soak them again. This often works. If you end up drilling them out you need to do it right (straight), then probably re-thread the hole.

Others have a lot more experience than me, but taking it slow is definitely a way to save time in the long run.

Magnus, congratulations on getting that Prestina. We PM'd about it behind the scenes, and I suggested that based on the eBay photos you would need to do a tear-down and rebuild. The condition of your bolts and other fasteners confirms this. Your Prestina will not need just a clean-up. Taking it apart and addressing the rusted bolts and other issues will be rewarding, though. I would not recommend operating a machine with hot water and steam under pressure without the factory spec bolts holding things in place. This isn't a popular or unpopular opinion. It is just basic safety, and it's how you treat a collectible machine in need of restoration.

You ask about whether the piston can be unscrewed from the lever assembly. I'm not sure why you are asking since I report extensively on my restoration thread from hands-on experience. In that thread I first built a spring clamp that did the job also but that was more dangerous than unscrewing it without compressing the spring.

Harbor freight is a good source for inexpensive wrenches, as is Craftsman at Sears on sale, Kobalt at Lowes and Husky at Home Depot.

You don't really want a flare not wrench for the nuts in your pictures, you want box end or combination wrenches. Flare nut wrenches are for fitting on tubing where you need more than an open end wrench.

Something like his if you can live with long handles:
http://www.harborfreight.com/11-piece-m ... 47067.html
Long handles are nice for leverage, but hard in tight spaces.

Or one of these if just want a more normal set of wrenches:
http://www.harborfreight.com/14-pc-rais ... 68807.html
http://www.harborfreight.com/14-pc-full ... 68790.html

I like the second set better, but I'm partial to polished wrenches, I think they feel nicer.

Those are about as inexpensive as you'll find a reasonable set of wrenches.

Here's a picture of flare nut wrenches:
http://www.harborfreight.com/5-pc-metri ... 68866.html

Ira

Here my homemade piston spring compression.

Motivated by writing my post i went at the machine again. This time i was able to free the boiler from the casing. I was able to remove 3 bolts on the boiler by first unscrewing the nut and then tapping the bolt back and forth with a rubber mallet. The condition of the bolts tell me that Gary is right here, the bolts will need to be replaced. My phone is having some technical difficulties with taking pictures so i can't show it right now, but the part of the bolt that is "inside" the boiler edge is very dirty and rusty.
Only 3 of the bolts on the boiler are actual bolts, the rest are threaded bars with a nut on each side. This is causing some trouble since the bolts where easy to loosen with a socket wrench and remove after that, while the bars are stuck. I've tried to hammer a bit back and forth with a rubber mallet but none of them are moving at all.
Since the bars are most likely in the same condition of the bolts i plan on replacing them after they have been removed. This makes me consider trying to simply hammer them out with a regular hammer instead of going through all the trouble of removing them gently by soaking them etc. before throwing them out anyways.

Ira, i don't know why i became so fixed on the flare nut wrenches, but i see now that a regular set will do just fine in my case. So far they haven't been needed, but i assume they will be at some point and getting a set at our version of home depot won't be difficult or expensive.

I read the part about the piston rod again Gary and i see now that the answer to my question is there. However, i'm having a bit of trouble understanding what you write about the unscrewing the piston. The spring won't send the piston flying that part i understand now, but what is it you are writing about using a vise grip plier and a screw in the piston hole? Maybe i'm making it more complicated than it is, but wouldn't a regular set of pliers and a metal rod be sufficient to unscrew the piston if the rest of the lever assembly is fixed to something?

Finally, i was actually able to get the umbraco bolts loose! Don't really know how to explain it but i found another tool that could apply torque that didn't risk breaking of a key. Now the only problem is the one screw that still has the broken key in it, any ideas as to how i could get it out?

By unbraco bolts, I guess you are referring to hex socket cap screws. The best way to work with them is a quality hex key socket, unless the space is too tight. Same with the other nuts and cap screws. A six point socket of the appropriate size will go a long ways towards preventing chewed fastener heads. The majority of box end wrenches are 12 point. A good quality socket set is almost a necessity on a project like that. Most come with a breaker bar, which can be extended with a length of pipe. Always buy the best quality tools you can afford as sometimes cheap aint cheap. When presented with rusted and corroded fasteners a good soak with penetrating oil before starting to wrench is a good idea. And if it's still stubborn, time for the torch.

Looking at the photo of the boiler with the mix of fasteners it seems you're not the first one in and I would find out what should be there and replace accordingly. As for the hex socket screw with the broken off key, think it's vice grip time. Go slow and use plenty of penetrant.

CoffeeBeetle wrote:Finally, i was actually able to get the umbraco bolts loose! Don't really know how to explain it but i found another tool that could apply torque that didn't risk breaking of a key. Now the only problem is the one screw that still has the broken key in it, any ideas as to how i could get it out?

Unbrako is a brand name, they make extremely high quality allen screws and keys. Had that been an Unbrako bolt and hex key, he likely wouldn't be having this problem. If you can, center punch the hex key and try to drill it very slowly with a left handed drill while pressing very hard. if you're lucky, the bit will grab the key and pop it free. If you have access to american, metric and a set of torx bits, find one that you can tap in with a hammer, the tighter the fit the least likely to slip. Other than that, as someone said before, it's time for a vice grip.

Ira

About unscrewing the piston: It has a couple of holes where a spanner wrench or similar tool can insert to turn it out. It wasn't hard to do so.