Quick question from the wife...

Sebulba · August 11, 2021, 10:50:17 AM

Hello all,

So, I have the enviable situation to have a wife who is completely on board for getting into this bus crazyness.

So, I'm telling her about and 89 MCI that I'm looking at and I mention that the guy selling it says it airs up in 5 minutes. I say that's good, which I think it is.

But, my wife, being smarter than me says "what is normal when the bus was new"

All I can do is say that I don't know. But that is a good thing to know if I'm actually going to say 5 minutes is good.

So what was normal when this bus was brand spankin' new?

Thanks

Seb

Melbo · August 11, 2021, 11:02:37 AM

My 78 MCI takes about 12 minutes or so.

I don't know what it was like new.

HTH

Melbo

Utahclaimjumper · August 11, 2021, 11:57:41 AM

What's the difference,, it's NOT new..>>>Dan

richard5933 · August 11, 2021, 02:07:02 PM

My 1974 GMC 4108 is about as close to new as you'll find one of these vintage buses with only 58,000 miles on it.

This past week we were camping up north and I had to air it up mid-trip so we could sleep level. From 0 psi to 120 psi took about 4 minutes.

(I have a slow leak on a front suspension - air bags will be changed next month and the leak fixed. Until that happened it would hold level for over a month, and it would stay above 90 psi for a few days easily.)

chessie4905 · August 11, 2021, 03:33:49 PM

another question to your question. How long till air pressure drops from 120 to 60 with engine off?

Nova Eona · August 11, 2021, 04:11:26 PM

Yeah I'd be more concerned about how quick it loses air over how quick it gains it. If gains drop too much, rebuild the air compressor and it's not that big a deal. Quick losses indicate a potential systemic issue, the standard DOT test calls for less than 2PSI/minute while holding the brakes down (after the initial loss obviously).

Sebulba · August 11, 2021, 09:25:57 PM

Quote from: chessie4905 on August 11, 2021, 03:33:49 PM
another question to your question. How long till air pressure drops from 120 to 60 with engine off?

That is certainly another valid question.

Both indicators of the air system condition.

Seb

Seb

Sebulba · August 11, 2021, 09:27:41 PM

Quote from: richard5933 on August 11, 2021, 02:07:02 PM
My 1974 GMC 4108 is about as close to new as you'll find one of these vintage buses with only 58,000 miles on it.

This past week we were camping up north and I had to air it up mid-trip so we could sleep level. From 0 psi to 120 psi took about 4 minutes.

(I have a slow leak on a front suspension - air bags will be changed next month and the leak fixed. Until that happened it would hold level for over a month, and it would stay above 90 psi for a few days easily.)

Nice. That certainly is satisfying to have system in that condition.

Thanks

Seb

Sebulba · August 11, 2021, 09:29:51 PM

Quote from: Nova Eona on August 11, 2021, 04:11:26 PM
Yeah I'd be more concerned about how quick it loses air over how quick it gains it. If gains drop too much, rebuild the air compressor and it's not that big a deal. Quick losses indicate a potential systemic issue, the standard DOT test calls for less than 2PSI/minute while holding the brakes down (after the initial loss obviously).

Ok, the DOT test is a good thing to know. That will get put in my notes for future reference.

Thanks

Seb

RJ · August 11, 2021, 11:09:39 PM

Quote from: Sebulba on August 11, 2021, 09:29:51 PM
Ok, the DOT test is a good thing to know. That will get put in my notes for future reference.

Seb -

The DOT test is referenced here near the bottom:

http://busnut.com/forum/index.php/topic,3259.0.html

Every bus owner should follow this checklist (or one that they've added their own checks to be done over and above this generic list) before moving their coach for the first time every day. Professional drivers have to do it as it's required by law. Just because private owners aren't, doesn't mean they shouldn't.

It's pretty obvious in a campground watching Class A diesel pusher owners who simply start the engine and drive off that they're completely clueless about a thorough pre-trip inspection - especially the air brake check.

One of my pet peeves. . . but the political pressure to not require a pre-trip for private owners overwhelms any efforts to reverse that mindset.

FWIW & HTH. . .

richard5933 · August 12, 2021, 05:28:10 AM

Quote from: chessie4905 on August 11, 2021, 03:33:49 PM
another question to your question. How long till air pressure drops from 120 to 60 with engine off?

Great question. Right now with the slow leak in the front suspension the bus will go from 120psi to about 90psi in 4-5 hours. After that it will take overnight to go to 30 psi. Up till recently it took a couple of days to go to 90psi. This will be addressed shortly.

The pre-trip air brake test is something I've never seen anyone do in a campground besides me. Wish more would do it.

buswarrior · August 12, 2021, 06:39:29 AM

I would not do an air system check in a campground.

Just another noisy, stinking, smelly reason to ban buses from entering.

Do your check "out there" somewhere, away from pissing off the other campers and owners...

What matters is that you stay current and observant of the vehicle's condition, not the time of day you do formal evaluations.

Lunch time is good, then go get washed up?

Happy coaching!
Buswarrior

oltrunt · August 12, 2021, 09:02:02 AM

I agree with buswarrior. Besides if I went through the list that RJ Long set out I'd have to pay another day's space rent--not that I disagree with his list. I do an abbreviated version including lights, mirrors, tires and leaks.

I made up a little magnetic sticker with a list of things to check that are specific to my bus and the kinds of trouble I'm likely to get into right away if I ignore them.

While my bus has vacuum over hydraulic brakes it does have pneumatic over hydraulic toad brakes and passenger door operation. This thread made me curious so I timed how long it takes to fill my air tank to 60 psi the required operational pressure. 2 min 58 seconds. The system seems to leak flat in about 8 hours. Dual pressure switches turn the pump on and off within a 4# range and a LED flashes as a reminder to me that the pump is on. I don't start my drive until the pressure is up and the light is out. Jack

The sticker:

.

Tedsoldbus · August 12, 2021, 12:02:55 PM

I am guessing many of these buses are like us. Several years ago, they didn't leak at all.....

dtcerrato · August 12, 2021, 12:46:20 PM

Since our 2019 AK road trip and attending the Blytheville rally on the way back home the bus has been in the air conditioned bus barn getting more upgrades, renovations, maintainance & TLC than I have. We have a feel for our bus especially after 42 years so when it's time to go into gear - it's ready by all accounts...
Then as we drive it we know where we are and monitor everything so clear motoring ahead...