Disasters, averted

[jelmore]

We're at Prevost Ft. Worth for annual service. After the OKC rally and such a good showing by United Engine, I was going to have them do the service. i had a last minute change of heart. A couple of things needed additional attention.

The muffler was blown out, picture attached. I would have thought I would have noticed a loud exhaust, but really nothing unusual. The coach next to us here for service let his blown muffler go too long and it burned up his Webasto, all the wires to it and his circulation pump.

And then, the brakes. All four caliper slide pin boots on the disc brakes were cracked and needed replacement. Should have gone in for that chassis service at 6 months instead of letting it go for a year because those boots are a minor replacement. Three of the pins had mild surface rust and were saved by dressing them. One of the tag pins was seized and had to be replaced.

My lesson: regular service and inspection is serious business. And Prevost's schedule is probably a minimum schedule, especially as our coaches age.

I think this was an expensive service.

[Jon Wehrenberg]

Jim,

I don't know how others schedule their routine maintenance but I think the lube schedule currently called for by Prevost is 6250 miles up from the 5000 miles specified for my first coach.

I use 5000 miles and I have to say while it seems like I get about 3 or 4 trips between service intervals, it is worth the extra work because I am under my coach and all over it looking at everything. There have been several times the fact that I was under there doing a service and inspection that I averted an expensive event.

I have found hoses installed by the converter that looked good starting to fail and it was a drip of anti-freeze that alerted me. The hoses were junk and ready to let go. I have spotted hub seal leaks and fixed them before my brake friction material was oil soaked or my bearings run dry.

I have found the big baffle which directs cruise air cooling air flow ready to fall off due to broken bolts. There are too many little things I can no longer recall. The point is the cheapest maintenance is that which I do not have to do because I am doing the underchassis lube and inspection probably far more often than I need to.

In your case you need to have someone that is actually capable of doing more than greasing fittings, and that someone has to understand you want eyeballs on all areas of the underside.

You did not realize the exhaust was loud because it did not happen all at once. It started to fail and the noise gradually increased so it sounded normal. I had to replace the one on my other coach and I saw the problem and did not hear it either.

[jelmore]

I think for those of us on the road, there's enough Prevost facilities around the country to stop by every 6,000 miles for a lube and inspection. That $200 expense will probably save thousands.

[sawdust_128]

Thank you for the heads up.

[Jon Wehrenberg]

For those that drop their bus off at a service facility and walk away you should really, really take the time to stand right behind the technician and watch the entire process. It is amazing what can happen between service intervals and how those subtle changes can have an impact.

We have a lot of grease fittings. If one fails to take grease and the technician is not very conscientious you have a future problem. If you keep returning to the same technician there is no assurance he will spend the few minutes it takes to replace the fitting if he was willing to ignore it the first time. Ditto for those fittings that have a bad check and will ooze grease.

What about the mechanic or tech that does not check the level of oil in the hubs? The back of the wheels will clearly show if there is a leak in the seals. But what if the guy is too lazy to deal with it, or chooses to not even look for things like that. It isn't the cost of a bearing you will be facing if the bearings start to run dry. It's even worse if the bearings on the drive axle are dry because the differential lube level is too low.

Is anyone looking to see if the shocks are showing signs of failure by seeing if there is any oil on them? How about the shock bushings?

When you are under the bus it is the perfect time to listen for air leaks. That's not a real sophisticated way to check for leaks, but it is one way. At the same time it is good to drain the air tanks and if done in the right sequence it is also a way to verify the check valves are OK. When is the last time anyone drained those tanks? If you get moisture in the suspension system your entire Norgren valve train is going to get really screwed up.

Your air dryer is your first line of defense in the air system. Is anyone keeping track of when it was changed. The wet tank is a way to monitor it's effectiveness and so is looking around where it spits to see if there is an oil film on the chassis in that area. If there is you have gone far too long between cartridge changes.

You can see and inspect the tires from the outside, but how often do you get a chance to look at the inside sidewalls? I once found a nail in the inside sidewall of a tag axle tire. Wouldn't have seen that if I wasn't looking for the condition of my tires from the side I can't usually see.

Is everything dry under the coach? If not where is the oil, transmission fluid, fuel or coolant coming from. Is the leak something that can turn serious?

When is the last time you or the technician looked at your air lines going to the brake chambers? Of all the hoses under the coach these move up and down with the suspension travel. Are they rubbing on anything? How do they look? Are they cracked or brittle? If one of these fails you will have issues. While you are under the bus that is the ideal time to have the parking brake released so you can listen for even minor leaks in the parking brake chambers.

Are the air bags OK? any signs of anything rubbing on them? How are the front shocks? They are what limits up travel on the front suspension and it is possible to pull the top ring right off a shock.

This was a quick list and is probably not complete, but it should illustrate how much we should be looking at or having someone look at when under the coach. A lube job, even with all the inspections doesn't take very long so it is really worthwhile to insist whoever is greasing the underside should also be looking for any indications something requires more attention. If all you are looking for is a cheap lube it may turn out to be very expensive in the long run.

[truk4u]

All good stuff, but I think most will find a little oil around the dryer discharge, it's the nature of the beast and doesn't necessarily mean your dryer is at it's end of life cycle. How much oil is too much, you have to know your bus and determine what is normal.

[Jon Wehrenberg]

I don't have any oil in evidence on the body around the dryer discharge, but I have seen coaches where oil is dripping off the chassis.

As Tom says you have to know what is "normal" before you know what is a sign the dryer needs to be serviced. I use a two year cycle on the dryer.

[phorner]

Just as a side comment, I have found that the majority of technicians don't mind my hanging around and watching/asking questions.

I try to stay out of their way so that I'm not hindering their work and let them know that I'm interested in how my coach works and want to learn as much as I can from them. I try to be an extra set of hands when they need it and be generally helpful if I can.

I think that most appreciate that I have taken an interest in their work, I'm not afraid of getting my hands dirty, and I'm not just dumping the bus off to get "whatever" done.

[jelmore]

This was a quick list and is probably not complete, but it should illustrate how much we should be looking at or having someone look at when under the coach. A lube job, even with all the inspections doesn't take very long so it is really worthwhile to insist whoever is greasing the underside should also be looking for any indications something requires more attention. If all you are looking for is a cheap lube it may turn out to be very expensive in the long run.

It is reassuring to me to see several Prevost techs under my coach with flashlights and pry bars poking around and taking notes, answering my questions, pointing things out to me. I get some peace of mind knowing that people are looking it over that see it daily and know what things should look like.

[Pete]

Just had my shocks changed at Prevost in Ft. Worth on the way to OKC.
Of 8 shocks changed only 1 showed any evidence of leakage (oil). As the tech removed the shocks, he manually compressed each shock before laying them on his work cart. Of the 8 shocks changed, only 2 came partially back to their normal position, sort of.
So the moral of the story is: Shocks can be bad without showing evidence of oil leakage. The change made a world of difference in the ride.

[jelmore]

Pete,

A couple of questions ... these shocks can be compressed by hand? That doesn't seem like much resistance. Perhaps I don't understand they way shocks work. Can you describe your ride before and after the new shocks?

I hadn't noticed my muffler being loud (sounds about the same with the new muffler) so maybe I don't know what my ride should be like.

[Jon Wehrenberg]

A shock absorber resists movement. When you hit a bump, if the shocks work properly they work against the air bags or springs to try to keep them from compressing, and then they also work the opposite direction to limit the rebound.

Without shocks our buses and cars would bob up and down like the bobble headed dog in JDUB's rear window.

When they are worn out you can compress and extend them easily by hand like you would a bicycle pump. When they are new you can still compress and extend them only it takes a lot of energy and the movement of the shock is very slow.

An oil leak is only one way to check their condition. The only other way I know is to remove them and try to compress them by hand.

[Kevin Erion]

I found that the shocks on our bus have very little if any compression force (in) but lots of rebound (out). You can go to the Koni web site and they have a chart that shows the amount of rebound and compression of there shocks. It makes sense because the air bag does all the work going down and the shock controls the speed it returns.

[Gary & Peggy Stevens]

Pete what was the Cost of your 8 Shock removal / replace?

Gary S.

[lonesome george]

Kevin, Where did you purchase the Koni's you installed? And if you don't mind my asking, how much did they cost.

[Kevin Erion]

Just for the front, from Prevost Mira loma and ONLY $130.00 each!