Author Topic: Jensen 20G Rebuild  (Read 118 times)

krypto31337

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Jensen 20G Rebuild
« on: May 27, 2019, 10:12:04 am »
First off, I would like to say "Hi" and I'm glad to see this new forum.  Although I never posted at the old place, I did read plenty of posts and I'm glad to see a lot of familiar names here.  Learned plenty from the posters so I thought I would finally post a project or two of my own.

Here's a Jensen 20G I bought a few years ago that needed some TLC:

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It was dirty with lots of 3-in-1 oil everywhere.  The power cord was in two pieces.  The firebox was discolored from water leaks.  The boiler had calcium stains.  The steam box was almost ready to fall off the engine.  Somehow the generator was in the wrong place (driven off the pulley not the flywheel)?

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Anyway, nothing that big a deal as it was all superficial damage.  I won't bore you with the details, since many of you have done these repairs more than a few times, so here's what it looked like after some work:

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Big improvement.  These Jensen toys are really tough and can absorb a lot of abuse.

And here's a short video of it running:

https://youtu.be/_uIgGnqEZ2U

It has a bit of a knock, possible just from wear with use, but it's still a strong runner that's easily capable of keeping the generator running along quite happily throughout an entire boiler-full of water.
My Workshop Blog:  http://doug.sdf.org/

classixs

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Re: Jensen 20G Rebuild
« Reply #1 on: May 27, 2019, 11:01:03 am »
The Jensen 20 is a firm favourite here, and your´s certainly turned out to be real gem in the end.

Well done !


As far as the knocking goes...
If you can´t find any obvious slop in the various connections causing it, try adjusting a bit on the screws holding the crosshead guide to the cylinder.
On more than one occation, i´ve found that minor adjustments there, making the crosshead run completely true, has eliminated a knocking sound on these.
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Stoker

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Re: Jensen 20G Rebuild
« Reply #2 on: May 27, 2019, 01:55:58 pm »
Jensen 20's are fine engines without a doubt. Real workhorses when put to the task.

Nice that you took the time to bring that one back to better condition, there are years of fun ahead for this engine now that you've done your work on it!
Information is not knowledge, Knowledge is not wisdom, Wisdom is not truth, Truth is not beauty, Beauty is not love, Love is not music:
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St Paul Steam

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Re: Jensen 20G Rebuild
« Reply #3 on: May 27, 2019, 02:22:35 pm »
A very nice Jensen 20G, the workhorse of the Jensen line.
Bruce
St. Paul Indiana , USA

dadstoys

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Re: Jensen 20G Rebuild
« Reply #4 on: May 27, 2019, 03:43:09 pm »
The Jensen 20G is a splendid engine and you have done a great job on bringing the engine back to its original condition.
Keep on steaming

Kevin

IndianaRog

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Re: Jensen 20G Rebuild
« Reply #5 on: May 27, 2019, 03:55:52 pm »
Hi Krypto....welcome aboard.  Your restoration turned out great, glad that poor, abused engine ended up in your capable hands.

As for your minor knock...I would suggest what is a very easy fix.  Remove the front end of the cylinder and do the same on the rear (rear includes cross head guide). Clean all surfaces of residual gasket material...sometimes all sorts of sealants have been found which cause piston to hit an obstruction (or the cylinder end caps themselves), resulting in a knock.  The tolerances were very tight when engine was made.

My favorite replacement gasket is to use a dollar bill and with a fine pencil, trace the front end cap on the bill four times...resulting in two new gaskets for the front and two for the rear.  Trace the screw holes and before cutting gaskets from the larger bill, drill out the screw holes for a cleaner hole.  Then with a sharp pair of scissors...cut the ID and OD of each gasket.  You can oil the four pieces that result to make them seal a bit better, then hold two of them in place and re-screw the end cap and do the same with the rear (crosshead guide end) using two gaskets on each layered on top of each other.

This will hopefully eliminate the problem with knocking.

cheers,
Roger
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Jim

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Re: Jensen 20G Rebuild
« Reply #6 on: May 27, 2019, 06:05:28 pm »
Hello and a big welcome to the forum!

The firebox looks great painted black.

What a fantastic and organised workbench you have.

Thanks for posting the photos and the video of Jensen 20G restoration and hope the great advice in regards to finding and eliminating the knock that you have received gets that sorted out for you.
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Jim
South Coast of New South Wales Australia

krypto31337

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Re: Jensen 20G Rebuild
« Reply #7 on: May 27, 2019, 07:55:11 pm »
Thanks guys!  :)

When I was testing fitting the engine, the piston was definitely running closer to the crosshead guide end, so perhaps a bit more gasket material on that side will give things a bit more breathing room.

Hey Rog, I've been visiting the indispensable Temple of Steam for years now.  I doubt there's a Jensen in my small collection that hasn't benefited from one of the tips mentioned in the Restorer's Toolbox.  Thanks for the info!
My Workshop Blog:  http://doug.sdf.org/

oilfield_steam

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Re: Jensen 20G Rebuild
« Reply #8 on: May 27, 2019, 07:56:04 pm »
Nice work Doug.

All good tips from Jan and Roger.  Try them for sure.  It did sound to me that there was less of a knock after your switched your Stephenson Reversing gear?  Running at these speeds its not unusual to have a little knock.

Scott

krypto31337

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Re: Jensen 20G Rebuild
« Reply #9 on: May 27, 2019, 08:13:22 pm »
Perhaps the change in sound is from a slight difference in the valve timing from one direction to another.  I didn't tweak with that adjustment a whole lot.

Some of it is in the camera, as I have another video shot with almost the same setup and it sounds different.  I'll get it sorted out one way or another. 
My Workshop Blog:  http://doug.sdf.org/

Nick

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Re: Jensen 20G Rebuild
« Reply #10 on: May 27, 2019, 10:14:37 pm »
Welcome Aboard and Great to see you posting  ;D

Nice Work! Please share more of your projects with us  ;)
Nick

Jim

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Re: Jensen 20G Rebuild
« Reply #11 on: May 27, 2019, 10:41:40 pm »
Krypto, that's a very neat pressure gauge on the Jensen in the video.

Where did you source that from?
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Jim
South Coast of New South Wales Australia

krypto31337

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Re: Jensen 20G Rebuild
« Reply #12 on: May 28, 2019, 10:31:59 am »
Krypto, that's a very neat pressure gauge on the Jensen in the video.

Where did you source that from?

Well that adapter was someone else's idea that I copied from a picture in the old forum.  The small gauge seems to be very difficult to find now at that pressure range (0-30 PSI).  McMaster-Carr quit carrying them awhile ago but I was able to find a few on Ebay at some point.

It's a handy device because it's so easy to move around from engine to engine. 
My Workshop Blog:  http://doug.sdf.org/

Griffin

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Re: Jensen 20G Rebuild
« Reply #13 on: May 28, 2019, 10:57:06 am »
A nice restoration Doug. Also with the added bonus of the cast base #15.

Nice to see.
Steven

txlabman

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Re: Jensen 20G Rebuild
« Reply #14 on: May 28, 2019, 11:38:48 pm »
Very nice restoration. Thanks for posting the pictures and video you have gotten great advice already regarding the knocking from two of our Jensen experts.

Welcome to the Forum from the Great State of Texas. You also have the third subscriber to your YouTube Channel (me). 🤠

 

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