Stuck throttle cable

Pete 57 4104 · January 24, 2021, 11:41:22 PM

Throttle cable on 4104 is really stuck. Section in engine compartment completely stuck. Haven't gone forward from firewall yet. Have tunnel open in middle bay, but no clue which copper tube has cable. Any suggestions? Thanks

dtcerrato · January 25, 2021, 03:18:19 AM

@pete
Sounds like you're getting into the bowls of the ole' bus - that's good! Lol
Don't think there is any clear info in the manuals (Maintenance or Parts) showing what your asking for in general.
My suggestion is to follow the throttle cable tube between the engine & bulkhead and see what position it penetrates the bulkhead.
As you can see in the photo - all the lines run parallel w/o crossing so once you determine the position of the line in the raceway - it will stay in that position all the way through.
Once you have a bearing on it's position, with the bus secured on blocks so there's no danger of getting crushed, get under in front of that bulkhead and look up against the bottom of the plywood floor - you'll be able to see all the lines in the open before they enter the raceway. Once you have the throttle cable tube location it should be a no-brainer to locate that same tube farther forward in the raceway.
That's the best I could do for you on that one & the way I would proceed with your issue at hand.
Good luck & keep us posted.

chessie4905 · January 25, 2021, 04:54:07 AM

Quite common for the cable to wear through the curved section at the very end in the rear bulkhead before engine. The tubing is brass and over time, wears through on that curve. We replaced the curved section in ours with steel brake tubing. If I recall anymore, connected new curve to old tubing with compression union. Grease it good there in new piece. Worked for 200,000 after repaired and probably still ok.

richard5933 · January 25, 2021, 04:59:45 AM

Have you disconnected the cable from the clamp to be sure it's the cable and not the governor?

I had a throttle cable on my 4106 which was really (REALLY) stiff when I bought the bus. After I got it home, one of the first things I did was pull the cable from the housing to clean the cable and flush the housing.

All went really good until I went to put the cable back in - it would only go about 9 feet before hitting something really firm in the housing. It came out easily, so this was really confusing.

In the end, what happened is that the cable had worn through a small section of the copper housing as it made a gentle curve. When it did this, there were thin edges of the worn area. When the cable was reinserted, it caught one of the thin edges as it went around the curve and jammed it into the copper.

The solution was to cut out the damaged area of copper and replace it with a new piece using compression fittings.

My point? Once you figure out which copper tube is the cable housing, do your best to put your hand or eyes on as much of it as possible to inspect it for any worn or damaged spots before pulling the cable.

The copper may or may not be wrapped in a canvas cover, so you'll have to follow Dan's advice for following it where it goes through the first bulkhead.

If you've got the bus blocked so it can't come down on you, you should be able to follow the lines leaving the engine as they go over the rear axle and into the tunnel with a good flashlight.

luvrbus · January 25, 2021, 05:30:23 AM

Some times it is not worth the effort,I have seen the throttle casing where people have arc the casing some how and you were not going to get the inner out used air throttles from transit buses are cheap

chessie4905 · January 25, 2021, 06:16:42 AM

Cliff, that's only on rusted out Eagles and MCI's that improper procedures are followed when doing all the welding.🤭

luvrbus · January 25, 2021, 06:25:05 AM

Quote from: chessie4905 on January 25, 2021, 06:16:42 AM
Cliff, that's only on rusted out Eagles and MCI's that improper procedures are followed when doing all the welding.🤭

Eagle and MCI never used that cheap setup they spent a few extra bucks $:-\$

6805eagleguy · January 25, 2021, 07:34:19 AM

Quote from: chessie4905 on January 25, 2021, 06:16:42 AM
Cliff, that's only on rusted out Eagles and MCI's that improper procedures are followed when doing all the welding.🤭

Why is everyone so hard on eagles?

luvrbus · January 25, 2021, 07:40:52 AM

Quote from: 6805eagleguy on January 25, 2021, 07:34:19 AM
Why is everyone so hard on eagles?

They never owned one lol in it's time the best bus built,still the classy bus out there

chessie4905 · January 25, 2021, 06:22:05 PM

Thats because never had a 4905 Cliff.😁

dtcerrato · January 26, 2021, 06:38:57 AM

That "cheap" GM mechanical cable throttle is oem in our 67 year young 4104 and still smooth - cheap? No more than the rest if it's dinosaur mechanical beauty.
Lots of bus nuts make the mistake of heavier springs &/or wet grease/lubricant that creates increase pressure & drag that causes premature (68 years!) conduit failure. Dry lube & oem spring tension are your friend...

luvrbus · January 26, 2021, 06:49:54 AM

Quote from: dtcerrato on January 26, 2021, 06:38:57 AM
That "cheap" GM mechanical cable throttle is oem in our 67 year young 4104 and still smooth - cheap? No more than the rest if it's dinosaur mechanical beauty.
Lots of bus nuts make the mistake of heavier springs &/or wet grease/lubricant that creates increase pressure & drag that causes premature (68 years!) conduit failure. Dry lube & oem spring tension are your friend...

Morse cables work better and easier to maintain,GM stopped using that setup and went to air throttles that setup wasn't to bad on the 4104 with the 6L-71 but a real PITA on the 8v71 in the 4106 lol it is cheap Dan a piece of wire in a 1/4 inch tube but it worked for GM

richard5933 · January 26, 2021, 06:54:01 AM

Throttle cable vs. air throttle...

One of those cases where sometimes simple is better, as long as it's maintained it can work for a long time without problems. Not that an air throttle is all that complicated, but it does have more moving parts than a throttle cable. Of course, both are really simple compared to the new drive-by-wire systems out there today, but let's see how many of those are still running in 70 years.

luvrbus · January 26, 2021, 07:18:21 AM

Time marches on how many old buses with the 2 strokes last a million or million and 1/2 miles with the original engines ,back years ago car and pickup engine lasted around 100,000 now that is not high mileage a gas engine will last now 3 or 400,000 miles.You seldom see trucks broke down on the road anymore like you did in the 60 to the late 80's the diesel rigs don't even blacken the exhaust pipe anymore and are getting up to 10mpg grossing 80,000 lbs lol you have electronic buses 35 years old still running the highways so they are 1/2 way there

chessie4905 · January 26, 2021, 07:44:12 AM

The only thing I don't care about the air throttles is the more difficulty to modulate.