Suggestions to get whistle to work on older tinplate set.

With the transformer disconnected, try to get the whistle relay of operate using a D cell.  Start right at the whistle relay and then work your way back to the track and see if you can tell where the power is being lost. The heavy wire to the rollers will cause truuble, start with replacing that with 22 or 24 gauge super flex wire. Other problems could be dirty wheels or rollers, poor ground between truck and tender frame, or the roller shafts could be dirty or worn. 

Service Documents for Lionel Whistles and Tenders:

http://www.olsenstoy.com/searchcd2k.htm

While the 263 isn't explicitly listed, the actual whistle components are pretty much the same across the Lionel spectrum and there is a "generic" whistle document:

http://www.olsenstoy.com/searchcd31.htm?itm=708

My money is on the whistle relay needing some TLC. 

Make sure your polarity is correct in your track wiring. I had mine reversed and the bell button sounded the whistle. Also, does the whistle spin freely? I needed to clean mine and add a drop of oil. I also used a small screwdriver to spin the whistle manually to get it started the first time.

George

Another thing to check is the springs under the rollers replaced several on some old postwar tender trucks and it worked.

Jsulli21 posted:

Hello all,  I acquired an old 263-e steamer with a whistle in the tender. It will not function when I put on track. I removed the tender shell and used jumper wires and it works perfectly. only when I put on track it does not work with the transformer. Now I have used the mrc 270w transformer and an old postwar zw transformer. I tested both with a postwar whistle and it worked. Could it be the wiring on the pick-up rollers. The previous owner used a heavy (too heavy IMHO) to connect the rollers to the whistle.  Any suggestions would be appreciated as I really love this engine. Thank You. 

When you say tested with jumper wires, do you mean you used jumpers to power the whistle by bypassing the relay contact or did you keep the relay contact in the circuit?  If you bypassed the relay, and it ran, but it will not run through the track and relay, the relay contacts may need a cleaning or a-tweaking.  or there is possibly an open in that trail. Sometimes they can be a bit finicky...  As others said too, the oversized wires to the rollers are trouble.  Too stiff and will reduce the free movement of the trucks and rollers and possibly keep the rollers from making good contact.

A Thank you to all for replying to my post..I tried putting power to the rollers and grounded the truck and it worked, so I decided to rewire the trucks and get rid of the heavy gauge wire. I rewired with some old black flex wire I acquired years ago and bingo, it whistles like a champ. ran around a loop and each time she sang a good tune....Thanks again for all your suggestions and assistance..  yes...