1938 Primus 991, help needed

Hi there, this is my first post on here so bare with me on pressure lamp terminology.
Basically i've inherited a Primus 991 with a few issues that need sorting out before I can get it working, the main one being no glass lens (?) And the pump washer being worn. I've seen how to make a new one but if there is somewhere I can get one while getting the glass that would be great.

Is there a guide on stripping down or just use common sense? Oh and the top nut has the old thread broken of in it.

Any help would be much appreciated. Dom

 

Hello Dom and welcome aboard!

The Swedish members should have good advice for you, Jeff.

 

The only glass I can find is an old ruined Primus on Ebay with a replacement glass, I'd rather get a new repro if such a thing exists. Can I use any mantle?

 

The original glass can be difficult to find but a none branded replacement glass should not be too difficult. The size is 89 mm in diameter and 106 mm high, same size as the more common Optimus 200 and 1200. Same for the pump leather as I guess you mean. Same as Optimus but almost any 18 mm will fit. Unfortunately I can't help you with retailers outside Sweden so I guess you have to continue to Google around.

 

Hello Dom, that old Primus lantern on Ebay may be useful for parts and the build quality is good, so they will usually restore.

Check out the link below to see how well they restore and that is a 200 cp., lantern, so that is the size of mantle to fit, Jeff.

http://0flo.com/index.php?threads/2699

 

Thanks folks, lightbringer can you give me Swedish contacts? I could see what the chances of getting parts sent over are? Thanks again, be back soon.

 

In Sweden you generally think about Fogas when searching for parts to pressure lamps.
They will probably have the right glass, and other stuff, and will ship abroad.
Just pop a question in a mail to them.
It's Conny you want, so the e-mail is:
conny "at" fogas.se

There's also a German shop I like myself that got most parts you need, and they pack well.
The glass is to be found here.
They should have pump leathers too.

But I think Base-Camp might have a suitable glass too. And pump leathers.
Just give them a mail.

 

You have been given some good advice by the others, so I won't repeat any of that. As for the top nut. It is not uncommon for the screw to seize in the nut and shear off when trying to remove it. If I remember correctly, the thread is 3/16 Whitworth. I'm not 100% sure about the size but it is Whitworth. The remains of the screw will have to be drilled out and the thread cleaned with a tap. Best done on a lathe.

 

Thanks for all the advice/help, how can I remove all the dried up paraffin from inside the lamp base? Dissolve with fresh paraffin?
I'm also a bit confused about the controls and tank openings, one is obviously the pump, one the filler with pressure release but what is the Screw opening for?

 

It's just a fitting for an optional pressure gauge.
Normally you should have a blanking screw there.

I often use acetone to loosen up old dried in residues from paraffin. It generally works well.
Sometimes the sharp thinner used for two component car paint does the job better.

Let it sit over night and see if it has dissolved the goo.
You can speed up the process with the aid of a handful of nuts in the tank together with the cleaning fuel and give it a good shake now and then.
Use only magnetic nuts, i.e. not stainless or brass. That way you easily can pick out those last stubborn ones with the aid of a small magnet.

 

Nice idea, I will do that. Hopefully that will un jam the regulating knob which is stuck tight

 

If the regulating wheel is stuck, you might also have some problem with the cleaning needle rod and driving pin (they work as a rack and pinion).
I have seen their gears being sort off corroded together even if they are out of brass.
If you not already has removed the vaporiser, I suggest you do that first, and then remove the cleaning needle rod in order to free the gears from the cleaning needle mechanism and see what they look like.

 

Think I know what you mean, i've taken the tubes of to reveal a rod, does that just pull out?
Is there a guide anywhere on here to disassembling

 

When the wheel is free and does rotate, the rod often do come out by just pulling it.
But since yours is stuck, you probably must help it by both pulling the cleaning needle rod and trying to force the wheel. It rotates clockwise to lift the rod, so a good clockwise turn at the same time as you pull, or jiggle, the rod should do the trick.

I never seen any guide for disassembling these. It's a very simple and straightforward lantern to work on, so it comes by itself once you start to fettle.

.

 

Ok, so the rod part is a cleaning rod? it has a small point on the top but only very short should it go through the jet to clean? Thanks again for your help

 

Yes, you got it right.
The thin point at the very top goes through the hole of the jet to clean it out every time you make a full turn clockwise and then back again on the wheel when operating the lantern.
In top position-that's when the wheel is to full stop in the clockwise position-you should feel the needle protruding through the jet, but just barely.

The actual cleaning needle is only the tiny part at the top. It is screwed into the top of the long cleaning needle rod, which ends with a rack at the lower part.
Some images to show better. The last one show how I just lifted the rod out of the lantern and the grips of the pinion (the inner end of the shaft of the control spindle).
The needle of yours might look slightly different. Some cleaning needles has a four sided head in brass that holds the tiny needle (shown here. Not for a 991, mind you, but they look similar).

 

ah that's brilliant thanks, I think mine may need a new needle because the top is very rounded. So is a Pricker used just to clean stubborn deposits

 

You could say that.
Oh, well... perhaps not stubborn deposits. Rather small disturbances that always will occur when burning paraffin.
Sooner or later a tiny piece of carbon or other soot particle will partly, or even fully, obstruct the tiny orifice of the jet.
Even if it's not totally shutting the jet off, it will disturb the performance of a lantern, so a quick cleaning now and then will be necessary.
Not very often when all is clean and in good condition, but more often as the lantern get several hours of use and some carbon deposits will start to build up inside the vaporiser.

As a little side note, I might add that the control wheel only is for pricking the lantern. It's not meant as a shut-off valve or to dim the light.
Its normal position is to the fully left.
It's just for the short pricking it quickly turns to the full right, and then back again. (Perhaps a couple of times.)

 

Ok thanks. I can't free the rod from it's gear at all though.

 

Can you determine why it's stuck?

Usually it's sticky paraffin residues, but sometimes the gears has been sort of corroded together, and in that case it will take some more violence, and the teeth will most likely be shot.

If it's the gooey stuff from old paraffin, it should dissolve by pouring acetone down the hole where the removed vaporiser sat.

 

Done it! It was the control knob shaft that was gummed up.

 

Stupid question, I know, but I assume that you did loosen the box nut before?
If it's over tightened, it can "grab" the spindle surprisingly hard.

 

Yeah I had that of too, just a good wiggle and a soak in acetone worked

 

Nice!
Now you just have the fun parts remaining, and soon you will have a well working and nice little lantern.

How about some pics?

 

Yeah not far from a runner! The enamel is pretty poor on the top unfortunately. Do I need a 164 mantle?

Pics to come soon, how are they uploaded on here?

 

Dom, have a look at this page.
It should explain how you do this.
If you still run into problems, just ask.

No you shall not use a 164 mantle.
That one is open in both ends (two-tied).
What you need is a "sock-type" mantle that's only opened in one end.
The lantern is rated 200cp, so that's the size you should use theoretically.
But I prefer to use 250-300. E.g. Optimus No.4 is good for lanterns this size.

 

Well after a few months of occasional fettling i've got it lit and producing a good light. I do have a small query though, I bought a cleaning needle from base camp part no. p6347 which from my research on here should be the right one but it's thread is too large for my cleaning rods. Is there a chance they had more than one size?

 

6347 is correct for the 991.
Perhaps Base-Camp got the needles mixed up?
Or did you get the needles in the original capsule so you're sure they are 6347?
The threads are just one for this lantern, but it is different for some other lanterns, e.g. the 1020.

 

They weren't in the original capsules so I can't be sure they are the correct ones. The one I removed was an old steel one and was very corroded but even then it is obvious the replacement is too large to fit. I'm guessing they've sent the wrong ones then. I'm impressed with the light it gives off though, I want another lamp to play with now

 

That sounds strange. The thread size should be larger for the 991 than the 1020. The 1020 needles have a thread diameter of 2.1mm. I don't know at the moment what the 991 ones should be. The thread used for the 991 is also used for the 980, 981 and the table lamps based on the 991 burner.