MC-8 Fan (Blower) Belt

DavidInWilmNC · July 18, 2007, 11:50:42 AM

Before my last trip, I replaced the radiator fan (blower) belt. There was nothing wrong with the old one, but I wanted a spare and thought I'd use the new one on the bus. I noticed that one of the fuel lines has a rubbed spot on it from the belt. Part of the outer covering of rubber was gone and I can see the metal braids underneath. I covered the area of fuel line with an old piece of garden hose to protect it for the way home and to insure that it wasn't prior damage and something that I was noticing for the first time. The belt tensioner seems to work fine. As soon as there's any air build up, the slack disappears. There sure is a lot of belt flapping before the tensioner takes care of it, though. I'm not sure how much play there should be in an untensioned belt. Is there a manual method of tightening the belt somewhat? It's possible that the fuel line needs to be strapped to the engine a bit better, too. Have others had issues like this with their fan belt? Thanks for any input.

David

Stan · July 18, 2007, 12:15:57 PM

The only issue I had with those fuel lines is that the book specifies the exact length and people who make up replacement lines tend to make them just a "bit" longer to be sure. The result is that the lines have a hump in them and they either rub on the engine or the belt hits them. My guess is that if you are able to tie the lines back to the engine, that they are too long.

Busted Knuckle · July 18, 2007, 04:13:08 PM

Also there is a way to avoid the slop in the belts at fire up! It's called pre-air the bus from shop air or do like many have an add a small compressor on the coach specifically for this job! FWIW

BJ

Devin & Amy · July 18, 2007, 05:10:18 PM

David,

BK is exactly right(as usual). If you air up the bus before firing it up you will have the added benefit of being able to turn it off quickly in case of an emergency, speaking from a fuel line experience. It also makes for a better neighbor policy.

Just plumb it in to the lower air line draincock in your RH engine bay.

Besides you may want to leave someplace real quick, don't ask.

Devin

Tony LEE · July 18, 2007, 07:06:12 PM

Is there a manual method of tightening the belt somewhat?

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There is a spring inside the tensioning cylinder to provide some belt tension when airing up, but there is no other adjustment possible.

Probably intended that the engine should not run above idle until the air pressure has built up enough to tension the belt. The bus AC and the alternator are protected against loading up with slack belts but there is no way to do it with the fan belt.

DavidInWilmNC · July 18, 2007, 07:16:41 PM

I generally do air up with a compressor. I'd rather it work correctly, nonetheless. I doubt Trailways aired up the bus before starting, and I'm sure the church that last owned it didn't either!

I'll check the fuel lines to see if I can secure them better.

David

Busted Knuckle · July 18, 2007, 07:23:48 PM

Quote from: DavidInWilmNC
I doubt Trailways aired up the bus before starting, and I'm sure the church that last owned it didn't either! I'll check the fuel lines to see if I can secure them better.

David

David you asked and I answered! All of the buses I've been around in revenue service that have that set up all flop when started until air pressure is built! With the exception of the ones we currently have in service! 98.5% of the time we pre air them as it is just so much nicer! (except when they are out on the road! As we don't have access to air then! But that may soon change too!)

BK