Help, help! My baby's drowning

Craig R · November 20, 2006, 10:28:05 PM

Twice in the last couple of months one of the three air cleaners on my MC5c has turned up sopping wet. Of course, this has been accompanied by a marked decrease in power and marked increase in black smoke. I'm told that the position of the air intake allows rainwater to flow down into that canister if the bus is allowed to sit in a downpour. The fella says it's not a problem when you're underway with the engine running.
Can anyone shed any light on this situation? Is this guy right? Need I look no further than the sky for a source of the water? Can a traveller do anything short of seeking shelter to prevent this?

jjrbus · November 21, 2006, 12:47:57 AM

I've had my 1979 5C For 6 years. I have the original 3 filter set up and have never had this problem. The bus has set in FL for many heavy storms. I have been on this board for 6 years and never heard of anyone having this problem. Not much help, but it would seem that it is not a common problem and not a design flaw. but something else. I would open the door to the radiator compartment and inspect the floor for holes or cracks the could let water into filter area. I'm not an expert at this only my experience. HTH

Stan · November 21, 2006, 05:12:27 AM

I am not familiar with the 5C air cleaner but assume it uses the same basic construction as the 5A.

Inside the air box there should be a flange around each air cleaner mount that projects about one inch inside the boz. Twenty five years of use may have filled up the bottom of the box with dirt to the point where any water going in the intake louvers can run directly into the air cleaner instead of out the drain.

It is a very dirty awkward job to remove the box and clean it but it can be done.

jjrbus · November 21, 2006, 05:02:15 PM

Went and looked at mine today. I am assumeing it is the same air filter that is filling up with water each time? At the bottom of the filter houseing is a black rubber triangular or funnel shapped thing. The name of which is the black rubber thingy. there are 4 one on each filter and one mounted on the ceiling above the filters. Check the one on the ceiling and the one on the filter that is getting wet for blockage. These would allow moisture to be expelled from the filter and plenium. Stan may be onto something also. but the black rubber thingy should let the water escape. Let us know how you make out!

Stan · November 21, 2006, 05:13:52 PM

I didn't mention it in the previous post, but it was MCI tech service that put me onto taking out the air filter box to clean it. Apparently it was a fairly common problem with that vintage of bus if they were run in dusty conditions. The rubber thingy does drain the bottom of the box but is not effective if the dirt is built up higher than the flange around the top of the filter letting water run directly into the filter.

jjrbus · November 21, 2006, 05:42:47 PM

How high is the flange? It must be quite a challange to get the air box out. There must be an eaiser way?

Craig R · November 21, 2006, 08:12:07 PM

Thanks, guys, for all the swell info. I'm having a hard time visualizing where the air box draws air from. However, after snaking my hand up through a filter housing into the air box and having a feel around I'm thinking that air enters through a broad, narrow duct running up the outside wall of the bus to who knows where. I am further thinking that water is being sucked into that duct through the gap (left by deterioration of caulk) around a CPVC pipe that vents the fresh water tank and passes through that duct to the outside world. If I'm right, I wonder how much vacuum the intake produces to suck in rainwater (or vented "fresh water") as I drive down the road.
Thanks Again,
Craig R

RJ · November 21, 2006, 10:03:36 PM

Craig -

The engine air intake is located high up in the front portion of the driver's side radiator intake.

IIRC, I think there's an exploded view of this area in the parts book. . .

Not much, but HTH. . .

Stan · November 22, 2006, 05:21:11 AM

Craig: You are correct in that the air comes down the wall in a rectangular duct from the intake beside the radiator screen. If this is an oil bath cleaner, how did you get the filter out, or is it a dry cleaner?

jrbus: It is hard to remember what I had for breakfast and thinking back about 25 years, I would guess about one inch. Its sole purpose is allow space for dirt and water to accumulate before you drain it out. While talking to MCI tech service I said I thought it was impossible to do with the engine in place. He assured me that their mechanics do it frequently so I took mine out, with difficulty.

jjrbus · November 22, 2006, 04:36:46 PM

I looked at mine and it seems like it would be a VERY difficult job to r&r. What would be the prcedure on this? remove all the rivets on the bottom of the box, remove bottom, clean and replace? If I was forced into doing this, I would look into just cutting it all out and replaceing the filter system. I have acces to 2 MCI 7's here that this has been done to. While more costly, and I do not know how much. It might be the easy way to go!

LUKE at US COACH · November 22, 2006, 05:02:12 PM

Hi Craig R and Folks:

If I understand what you are saying is: Somehow the "House" water system is connected to the air intake for your engine. Is that correct?

If so, you may have put your finger on the problem.

We have numerous customers who come through our shop with the original 3 dry air cleaners and I have never seen the problem you describe.

Again, if I correctly understand what you are describing, then you are a victim of some very "Creative Engineering" gone wrong!!!!!

Please provide some additional insight so that those of us reading may be able to HELP!!!

Happy & SAFE!! Bussin' to ALL.

LUKE at US COACH

Craig R · November 22, 2006, 09:41:47 PM

Thanks for taking an interest, Luke & the rest of you guys. This is not a case of creative engineering; the house water system is not connected to the air intake -- they simply intersect. The fresh water tank is beneath the bed and the vent tube runs straight from the rearmost point of the tank through a built-in nightstand then out through the left (driver's side) wall. I now believe that this tube passes through the interior paneling, then the inner then outer face of the air intake duct, then the exterior skin of the bus. It is my hope that water has begun entering the air intake duct through the hole in the skin around this tube because the caulk is breaking down and no longer seals the gap. I hope this description sufficiently illuminates the situation.
Wish me luck.
Craig R

Stan · November 23, 2006, 05:33:20 AM

Craig: Lots of water enters the duct from the air intake on the side of the bus. That is the reason for the 'sump' in the bottom of the filter box and the drains on the box.

If the vent line is broken inside the duct it would be possuble to overfill the water tank and run water into the duct. It is easy to check the pipe by pulling it out and looking at it.

Although it is not the best idea, there is really nothing wrong with running water lines or electric wires inside of air ducts as long as they remain isolated from each other.