Belt Replace

[russsh]

Ok, traveling in KS, everything normal with our bus FE BB, 97 5.9 12v engine. Have aftermarket temp gauges on it, working great, coming from wisconsin, we had a panel blocking the radiator a bit to keep the engine up to temp.

As you know, when that fan comes on, YA know it, loud! but working as it should. Until it didnt, it came on, then off, then on, then nothing, no fan. Engine temp started to rise so we pulled over and took off the panel over the radiator, back on the road, engine temp good, actually kinda cool for the 5.9.

Another hundred miles, almost to our overnight destination, engine temps started to rise but not overheat. Knew something was wrong. Yep, lost the serpentine belt....belt just gone, a few parts here and there. NAPA had a belt, just got it on now, and didnt have to tear the front off the bus off. Kudos to my awesome wife helping!

Questions: what caused the fan to stop, and what caused the belt to disintegrate, did one cause the other?

Test running now, looks good, however the belt tensioner seems to be jiggly a bit, not side to side like bearings, just up and down inline with the belt, that normal?

Thanks in advance!

russ

 

[brokedown-SKO]

Your fan is belt driven with an electric clutch. When the temp sensor reaches its target temp, it turns on a relay which engages the fan clutch. It's abrupt and obviously you know how loud the actual fan is. The same belt also drives your alternator and water pump, and passes through a tensioner. The fan engaging when the engine is running at speed is pretty intense, so a marginal belt might fail quickly if that starts happening often.

Your electric fan clutch may have failed, maybe more likely your temperature sensor that engages it failed. Mine did that recently and I replaced it with a manual switch and haven't been bothered enough by it to fix it more correctly.

The belt itself, it's a wear item and they don't last forever... Often times a wire or zip tie or something else will maange to make contact with it and it doesn't take long to disintegrate.

I carry a spare serpentine belt. I also worked out a great way to move the tensioner using a strap and the steering column... Yeah I've done that a few times.

It is possible that your tensioner has gone bad. THey don't last forever. It's a common failure on T444E in fact.

 

[Brad_SwiftFur]

Questions: what caused the fan to stop, and what caused the belt to disintegrate, did one cause the other?

Test running now, looks good, however the belt tensioner seems to be jiggly a bit, not side to side like bearings, just up and down inline with the belt, that normal?

1: Belt being 20+ years old might be a good reason. We have no way of knowing how old the previous belt was. *GET A SPARE BELT!* If the new one fails anytime soon, then you have other problems which need addressing.


2: Yes, the tensioner will move "up and down" with the engine running, just a little. Completely normal.


Next time you have the belt off, check for freedom of movement of everything that turns. Things should spin (relatively) freely but not have any wobbling or end-play - the obvious exception being the crank pulley.

 

[russsh]

Your fan is belt driven with an electric clutch. When the temp sensor reaches its target temp, it turns on a relay which engages the fan clutch. It's abrupt and obviously you know how loud the actual fan is. The same belt also drives your alternator and water pump, and passes through a tensioner. The fan engaging when the engine is running at speed is pretty intense, so a marginal belt might fail quickly if that starts happening often.

Your electric fan clutch may have failed, maybe more likely your temperature sensor that engages it failed. Mine did that recently and I replaced it with a manual switch and haven't been bothered enough by it to fix it more correctly.

The belt itself, it's a wear item and they don't last forever... Often times a wire or zip tie or something else will maange to make contact with it and it doesn't take long to disintegrate.

I carry a spare serpentine belt. I also worked out a great way to move the tensioner using a strap and the steering column... Yeah I've done that a few times.

It is possible that your tensioner has gone bad. THey don't last forever. It's a common failure on T444E in fact.

Thanks for the quick reply! the fan connection, seems theres just 2 wires going to it right? Thought about doing a switch, also thought about disabling it for now, and add a couple of aftermarket fans infront of the radiator and turn them on manally when needed. Had the bus for almost a year before that fan kicked in, scared the crap out of us! We were in Pecos TX, stuck in traffic, in Dec, so not hot, but warm enough to heat up the engine.

Any way of testing the fan electrical, just wire in a switch and turn it on? im sure we could hear it click. Would the fan engaging when running cause my belt to come apart?

 

[russsh]

1: Belt being 20+ years old might be a good reason. We have no way of knowing how old the previous belt was. *GET A SPARE BELT!* If the new one fails anytime soon, then you have other problems which need addressing.


2: Yes, the tensioner will move "up and down" with the engine running, just a little. Completely normal.


Next time you have the belt off, check for freedom of movement of everything that turns. Things should spin (relatively) freely but not have any wobbling or end-play - the obvious exception being the crank pulley.

Thanks! We did check for loose or wobbly pulleys and such, seemed ok. And ya, who knows how old that belt is/was. The fan and the clutch both turned ok, just wondering if when the clutch engaged to run the fan, it killed my belt?

 

[Brad_SwiftFur]

Well, considering the "shock load" when the fan engages and a questionable belt, it's entirely possible. My bus has a hydraulic clutch so the fan engages much more slowly and smoothly but when it's engaged, I *KNOW* it. Good thing about mine is - no electrical gadgets to fail.