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Author Topic: Air Compressor Failure  (Read 2801 times)
BlakeWright
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« on: July 21, 2014, 03:13:11 PM »

I am on the 401 (the Canadian 4 lane hwy take runs between Windsor and Montreal), I check the gauges, only 70 psi of air, I pull off at the next exit.  No leaks, but I am not making any air.  There are two truck garages at this exit, too busy to help.  I go to Home Depot, buy a small contractor's compressor, plug it into the inverter, run a air line out the back window, air up the coach and continue home.  Returned the compressor the next day.  Total cost, $30.00 for a taxi ride (we didn't have the toad with us).

This is a MC-7 with a 8V92.

At home, replaced the governor on the air compressor, still no air (Governors are cheap, a rebuild Bendix was $24.00, including tax at a local supplier).  I removed the compressor from the engine, it was seized.  The drive hub had sheared the key and was spinning freely on the compressor crankshaft.
On closer examination, it appears as if a piston seized in the bore, because the rods were loose on the crankshaft.

The question is WHY?  I don't want to put a new air compressor on and have the same problem.  There was lots of anti-freeze in the compressor, so it is being cooled.  The rods were OK, so it must be getting oil.  There is an alcohol system on the coach, would that wash to oil off the cylinder walls?

Any hints on re-installing the compressor i.e. aligning the drive coupling.

I have decided to install a small electric compressor in the coach as a backup to the engine compressor and to air-up the coach before starting the main engine.  Any ideas?
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BlakeWright
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« Reply #1 on: July 21, 2014, 03:17:51 PM »

The compressor is a Tu-Flo 700, Part #289915.
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luvrbus
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« Reply #2 on: July 21, 2014, 03:51:04 PM »

Anti freeze does not always mean cooling,on the 8v92 the compressor should have the in line coming from the water pump and out line goes to the back of the block below the head. Is the compressor air intake separate with a air filter or tied into the air cleaner? .  When those get above 400 degrees the piston will seize, all compressors should pass a little oil to keep your problem from happening I would make a guess heat killed it or it starved for intake air 
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mikke60
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« Reply #3 on: July 21, 2014, 04:01:44 PM »

All I have to say on the whole subject is SHAME ON YOU!
buying a compressor, knowing your going to use it and return it!!
Guys like me ,who have make a living, buying material and building, have to pay for people who abuse a good return policy!!
Mike smola
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bevans6
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« Reply #4 on: July 21, 2014, 04:26:29 PM »

Deleted.  Suffice it to say that I don't approve, in any way, for any reason, in airing up a bus with a cheap contractors compressor and driving it on one of the busiest multi-lane highways in North America.  Totally a criminal act, against many many laws.

Brian
« Last Edit: July 21, 2014, 04:43:24 PM by bevans6 » Logged

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« Reply #5 on: July 21, 2014, 04:43:14 PM »

Brian, wouldn't you call that a moral dilemma?   Will Canadian insurance cover an accident when they find out you have a A/C compressor in service? 
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bevans6
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« Reply #6 on: July 21, 2014, 04:46:59 PM »

I deleted my original post, however insurance law is that they will cover just about any malpractice you commit as far as liability is concerned. And possibly sue you to recover the payout to others if you were in an illegal act at the time.  Running an air-braked vehicle with inoperative service brakes is illegal.  Kind irrelevant, I think, if the worst had happened.  Which thankfully didn't.  

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
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BlakeWright
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« Reply #7 on: July 21, 2014, 04:57:40 PM »

The intake air comes off the manifold between the turbo changer and the blower.  What kind of air filter do you use if you use separate intake?
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BlakeWright
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« Reply #8 on: July 21, 2014, 05:02:11 PM »

Who said the service brakes were Inoperative, the little compressor had no problem maintaining 120 psi in the bus system.
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gus
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« Reply #9 on: July 21, 2014, 05:21:13 PM »

I agree with Mike, returning that air compressor was nothing to be proud of - shame.

You could have kept it as your spare since it worked once already.
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« Reply #10 on: July 21, 2014, 05:31:33 PM »

I was interested in this until I read that the compressor was returned.......
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eagle19952
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« Reply #11 on: July 21, 2014, 05:31:59 PM »

The drive hub had sheared the key and was spinning freely on the compressor crankshaft....

well that's going to cause more problems....
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wg4t50
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« Reply #12 on: July 21, 2014, 05:53:21 PM »

I am also in the camp about returning a perfectly fine compressor for a refund, sounds like a desperate bus wannabee. Embarrassed Sad
Seems most of us take the high road and glad I do.
Dave M
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Iceni John
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« Reply #13 on: July 21, 2014, 08:52:03 PM »

Go back to Home Depot, buy back that compressor, then install it in your bus connected to the accessories air system, not the brake system!   It is for inflating tires and running air tools, and for absolutely no more than releasing brakes enough in an emergency to pull off the road to a safe place where a tow truck can safely hook up to you.

Even a little rinky-dink cheapo compressor can produce 120 PSI, but not at sufficient volume to safely supply brakes.   That's why a Tu-Flo 700 produces umpteen times more air volume than a cheapo electric compressor.

John
« Last Edit: July 21, 2014, 10:48:55 PM by Iceni John » Logged

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Dave5Cs
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« Reply #14 on: July 21, 2014, 11:48:04 PM »

Brian, whats the CFM on the 700. IIRC BW said 11 0r 12 at 120 which is pretty high to keep up.
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