Dramatic air pressure loss, overheating (was No idea what happened )

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Dramatic air pressure loss, overheating (was No idea what happened )

May 14, 2012, 10:43:56 pm

Ok, well it's been a while since I've been on the forum and our coach has just been setting in the barn. Last week after a major interior / exterior cleaning, my 2 teenage boys and I took a 6 1/2 hour drive from Northern Michigan to Chicago. On the way down we ran on a full tank of fuel that sat in the tank since August of 2011. I know!!! That's a long time !! At the time of filling it up in August I put in a fuel additive knowing that I would be having shoulder surgery at the end of December and not able to winterize the coach. Also at that same time I carefully added a serving of anti-alge to the tank.

So, we hit the road and had no problems what so ever for the 6 1/2 hours down. The weather was nice, temps fair and every guage was operating just as they should. My trans guage usually shows about 150 depending on the outside temp and if running in hills or not. The radiator always stays real close to 180 but goes up a couple degrees and then back. The air pressure mostly stays between 90-100ish. I know there is a tiny leak some place because after setting for an extended period of time she drops in height. So, on this trip down all of these guages were fine and I had no surprises.

As we were leaving from being in a parking lot boondocking for Friday and Saturday, we got a horrible downpour of rain Sunday from 11am until about 1pm. We left the parking lot at about 12:45 and hit the road. About 15 minutes after we left the rain was not so hard but still was coming down pretty good and we had just gotten on the highway. I'm clipping along on a 6 lane highway and ended up to the far left and in only 1 lane from the cement wall. All of the sudden I notice that we started to slow way down. I'm thinking to myself, WHAT THE HECK!!! I look down and the air pressure was dropping SO FAST, the trans temp looked to be up about 20-30 degrees and the radiator was showing almost 200. But...the air dropped so low so fast that the air brake started to set. Well, I can tell you I was on high alert and freaking out. All I could do was panic and pray. I pushed in the brake button to keep it from locking up and got over to the wall lane at my first chance. It happened SO FAST and then we were doing about 25 miles an hour on the highway. I want to think that I actually stopped on the inside shoulder and had to restart the engine. Once back started I ran the shoulder for several yards until the traffic was a little less and shot over to the next lane then the next and so on.

About 2 miles up the road I got off at an exit all the time watching my guages which seemed fine for the most part. The air pressure was fine but my panic mode was still high. I pulled into a hotel parking lot and got out. I walked around the coach looking for anything out of the ordinary...leaks, hisses, everything. But there was nothing I could see. I got back in, looked at all guages and proceeded back on the highway. We were at about 1/2 tank of fuel leaning to the 1/4 tank mark. I drive for about another hour give or take and then fueled up. I estimated it would take about 75 gallons or 1/2 of my 148 gallon tank and it actually held 71 gallons from a good size truck stop where I knew they went through good fuel volume. We drove the rest of our 5+ hour trip and never had an issue with anything. Ladies and gentlemen....I'm leary!!

My neighbor is our county diesel mechanic and I asked his thoughts one day about it. His first comment was that things don't "fix" themselves. I told him I prayed over it and that left him just looking at me smiling

Then he said you probably had alge in the tank but I mentioned having put the anti alge stuff in it. He suggested that I replace the fuel filter and said that there would most likely be green slime in it. Well, I changed that and the fuel /water seperator filter today and found there to be nothing green or slimey at all. In fact, they both looked completely fine.

So, with all that being said, do any of you have any ideas as to what could have happened?

I will add one thing. When I got back to our town and dropped my boys off and then headed to the barn I noticed the belts really barking in the back. Last year a couple times they squealed pretty good to. I tightened them up good at that time but never had done anything with them on or before this trip. I wondered if in the rain and at the time having been going up a VERY SLIGHT to almost flat incline....could that have been an issue had I not heard them from the rain and road noise???

I've given everything I can think to give you for some knowledge and advice. We are planning a trip to Tennessee in August and it's going to be a fair haul. I will have my whole family , inlaws included and really don't want there to be any surprises.

Thoughts?

Carl Sandel
36' 1991 U280
3208T Cat w/ 130k miles
Northern Michigan

Re: Dramatic air pressure loss, overheating (was No idea what happened )

Reply #1 – May 15, 2012, 12:11:17 am

Put the clues together and see what you have. A known slow air leak, slipping belts (including I suppose to the air compressor), more slipping of belts in the rain, and loss of air to the point of the brakes applying themselves.

Get the air leak fixed and put new belts on it, you should be fine.

Re: Dramatic air pressure loss, overheating (was No idea what happened )

Reply #2 – May 15, 2012, 07:18:46 am

I could not agree more with Tom.
Former owner of a Fortravel 1988 ORED with Cat 3208T.

Re: Dramatic air pressure loss, overheating (was No idea what happened )

Reply #3 – May 15, 2012, 08:00:17 am

Carl, How long since the air dryer has been serviced ? If the dryer purge valve stuck open momentarily you would have the air loss symptoms that you mention. The very humid air in a rainstorm coupled with a dirty dryer could have caused this.
If I remember right on the 3208 the Compressor is belt driven, a wet slipping belt could cause the compressor to fail to turn but that is a stretch.
Check for the leak
service the air dryer
Tighten or replace the belts ( I know on a 3208 it is a b.....)
Good luck
Gary B

Re: Dramatic air pressure loss, overheating (was No idea what happened )

Reply #4 – May 15, 2012, 08:12:43 am

Sounds to me the guy upstairs was trying to tell you not to drive in pouring rain! Why do people ignore weather and insist to drive in poor weather? I would always wait for the next day to drive the next day when the sun is out. I have heard the best, I had to get home to mow the lawn!

Re: Dramatic air pressure loss, overheating (was No idea what happened )

Reply #5 – May 15, 2012, 08:58:16 am

I wish I had a choice not to drive that particular day but I had kids that needed to be home for school so there wasn't much I could do to wait a day on that one

Gary, yes the belts are a real pain to replace and there are 9 or 10 of them.
My air leak is very very slight, like "almost" nonexistent...but still there none the less. I will see what I can find out today if it is quiet enough from road noise today around my place.

So, about the air dryer and belts. First...can a person buy air dryer filters from The Filter Barn?
I ask this because it may help narrow down some information that could help with feedback from you all.

This July we will have owned our coach for 4 years. The first year we just spent cleaning it up, getting used to things and made some minor adjustments here and there. The coach sat in our driveway outside that year.

The second year we owned it I put on all new Gates belts and installed the new air dryer filter. ( I remember a large order from TFB at that time and think I may have gotten that air dryer from them...if not I picked it up locally BUT it was at the same time as belts. That year with new belts and air dryer filter she sat outside.

The last 2 years the coach has been in a metal pole building not heated but with no circulating air or outside elements.

I say this to get an idea from seasoned vetrerans as to whether or not I really need to change belts....I SO DREAD THIS CHORE and would the air dryer need a changing also.

So...Since the air dryer filter and belts have been installed from new, we have only put on 5000 to 5500 miles ( and 5500 is a huge stretch since we can track every time the coach has been out ) and of that time it has been stored indoors for 2 years.

Should those belts still be supple enough to simply snug and adjust?
And should that air dryer filter still be in decent condition with those few hours of use on it?

Thanks in advance

Carl Sandel

Re: Dramatic air pressure loss, overheating (was No idea what happened )

Reply #6 – May 15, 2012, 09:10:52 am

Carl, The belts should be fine, they will last years. If you have already serviced the air dryer you will have to look further and at this point I am just guessing without having the coach at hand.
In my Opinion there are no reasons for a coach to dump air other then , Air dryer stuck open, Or pressure relief valve on wet tank stuck open.
Both could be due to non use.
Sorry I cant help further.
Gary B

Re: Dramatic air pressure loss, overheating (was No idea what happened )

Reply #7 – May 15, 2012, 09:29:23 am

Thanks Gary, I will ask my neighbor if he thinks either of these can be lubricated some how ....and to help me find them.

Carl Sandel

Re: Dramatic air pressure loss, overheating (was No idea what happened )

Reply #8 – May 15, 2012, 10:36:02 am

Carl, No way to lube these. Look to air dryer, does it SPIT or POP OFF when you start engine, if so its operating. May have been dirt or other crap in valve. While you are at it drain all tanks, if ANY water in them you may have dryer problem. Again just guessing long distance.
Call me if you want 770-595-3891
Gary B

Re: Dramatic air pressure loss, overheating (was No idea what happened )

Reply #9 – May 15, 2012, 10:51:18 am

You could look at your air governer. It could have had a problem and not allow air to air up. Then your height adjustment and brake use would bring the pressure down. Check under te wheel wells for tread marks. You could have been riding on the tires and building friction but OT is the temp spike that is odd here. Can't figure how air pressure changes our temps.

Re: Dramatic air pressure loss, overheating (was No idea what happened )

Reply #10 – May 15, 2012, 11:12:40 am

Really difficult to call. One possibility I can think of is like John mentions with the air governor causing low air pressure with the result that the body dropped down and the rear tires started rubbing on the wheel wells causing more HP to be used resulting in higher engine temps. Other possibility would be a road debris momentarily blocking/moving the right height control.

My rear tires don't clear by much as is and when my airbag failed, they touched and left plenty of evidence.

If it happened once, it will probably happen again. Yes, check the rear wells for tell tail marks.

Pierce

Re: Dramatic air pressure loss, overheating (was No idea what happened )

Reply #11 – May 15, 2012, 11:26:09 am

Quote from: Carl Sandel – May 14, 2012, 10:43:56 pm

On the way down we ran on a full tank of fuel that sat in the tank since August of 2011. I know!!! That's a long time !! At the time of filling it up in August I put in a fuel additive knowing that I would be having shoulder surgery at the end of December and not able to winterize the coach. Also at that same time I carefully added a serving of anti-alge to the tank.

That is not a long time. I hauled the stuff bulk and could tell you stories concerning long time fuel storage that would raise the hair on the back of you neck. Algae requires perfect conditions to grow in fuel and is more predominant in coastal areas of the country. So that is the least of your worries.

Now the brakes, I don't have a clue. In all my years of driving over the road, I never had air pressure go down that fast. Had it not build pressure on one occasion, because the key got turned off. It had a manual fuel shutoff and would run with the key off. You say it was pouring rain??? Thinking the rain must have had something to do with it... I have had various different air valves mess up and need replacing. Need a mechanic for that stuff, and they often guessing and replacing valves. Just a piece of dirt in the air system will cause one to mess up. And one never knows for sure except the new valve "appeared" to solve the problem.

Re: Dramatic air pressure loss, overheating (was No idea what happened )

Reply #12 – May 15, 2012, 04:01:54 pm

Ok, I just got back from the barn and here's what I noticed and made notes of.
The air pressure was on zero after setting for the last week. I started to coach and looked at the time. It took 5 minutes to reach 90 on the air guage. At real close to 120 or just below, the air dryer blew off for the first time, this was 7 minutes from starting the engine.
The passanger side was down on the tires and the drivers side was up and looked almost like normal. This is when I went out and hadn't started it yet. The passanger side always rides and blows up slightly less than the drivers side. I would like them even if someone could share how to adjust it after I find the leak.

Would that mean that the leak is on the passanger side?

I have 2 needles on the air guage and don't really know what they mean. If someone could share that with me it would be greatly appreciated and I will make a note with that info and put it in the coach. The red needle is always about 5 lbs ( I assume the numbers are in lbs ) higher than the white needle.
When I got in the coach and started it I didn't release the brakes and didn't pump them or do anything that would use any air...I just let the engine idle.
After reaching the max air volume I noticed that it was dropping but it was a very very slow process. so much so that I had to really be still and not move my head and it almost played tricks on my eyes.
When the white needle was about 88-90 and the red about 95-ish, they started going back up and once reaching the max...the air dryer blew off again. This was at the 20 minute mark.

I closed up the barn and got under the front where it is basically wide open space and l listened. I am assuming that the leak will be a low volume hiss, but did not hear anything. While under there I did as Gary suggested and quickly opened and closed both air tanks. Not a drop of water or even a mist came from either tank. I did notice however that when closing the one one valve on the passanger side, it has a very slight window of being 100% closed. Just a smidge past that spot either way would then leak. As I adjusted it the air was off and there was no sound what so ever.
I want to mention that I have another guage which I believe to be an after market guage. It is on the lower left of my dash but mounted under so it hangs down. I "think" it says brake air or just air but I am not 100%. I DO know that it is air of some sort. When I was cleaning out my generator bay the other day I noticed ( and may have noticed this a year or so ago, but since everything seemed fine I haven't been concerned ) a very tiny air line that was broken in to. I tracked it to that guage under the dash. That guage by the way has never worked...duh!
I went to the back of the coach and tracked it to what looks like another air tank above the axle differential. Actually I was on the driver side rear tire shinning a flashlight and that's where it "looked" like it was going.
I didn't hear any leaks in front or rear, but realize that I need to get to the source of the other end of that broken line. So that brings me to another question. I have the coach setting on it's own now, meaning the support pipes are NOT under it keeping it up and giving me a peace about being under it. If I raise it up with the air bags and lower it back down to support it with the pipes...isn't that going to remove the opportunity to have pressure pushing air out?

If so, couldn't I raise it up PAST where the pipes would go and still put them in place incase something were to happen they would be a safety catch, and with the coach still being supported by air there would be pressure so I could check it out?

I was going to crawl under it not supported and with out the option .... but all I could hear was my wife.....who I love dearly

getting in my you know what about not having the pipes there. It's not a comfortable feeling knowing that there is no safty if you know what I mean and I knew I wouldn't hear an air leak over her telling my to be careful the whole time I was under there.

So I will wait to hear your thoughts about the pipes for support before I can give a report about any leaks near that rear tank or lines etc.

Lastly...if an air bag had a tiny pin hole, could you hear it or if that was the case would it just pop. I'm really trying to find this and remedy it once and for all.
Any other ideas I will gladly attend to. I seem to believe that my air dryer if fine.

Carl Sandel

Re: Dramatic air pressure loss, overheating (was No idea what happened )

Reply #13 – May 15, 2012, 04:57:08 pm

They leak, don't pop. Use a small hand sprayer (windex size) with a water/soap mix to search for leaks. When the air bag leaks, it will probably be in the direction of the tires as they seem to throw road debris against the bag so that is where the leak usually is. Will blow a lot of bubbles at the leak. Stick an ounce of liquid soap to 12 ounces of water so it's a nice rich mixture. Kids bubble soap works well also.

You did not say whether there were any tire marks at the top of the wheel well.

You can look at the wheel wells and spray water/soap mix on the bags without getting under the rig. Better safe than sorry so might be a good idea to let a mechanic under the rig if a quick look and spray does not find anything. It's really easy to get hurt in a split second underneath. You've seen the bumper jack photos.

Pierce

Re: Dramatic air pressure loss, overheating (was No idea what happened )

Reply #14 – May 15, 2012, 05:43:50 pm

Carl, The air gauge needles, One is the wet tank , the one you found at the rear axle, the other is the dry tank, these are under the front of the coach most likely. When you apply the brakes you will notice that one needle moves faster than the other, this indicates the amount of air pressure that you are applying.
Use your pipes to be sure coach does not come down while under it, place them between the frame members and then if you lose air the coach body will not drop on you.
Carl, It looks like you need to find someone probably in your area to get with you and go over all your coach systems to explain what they are and how they operate. If you get in the Atlanta are contact me and I will do it. For the most part the systems in our coaches are similar and not hard to understand how they work even if you don't have the space and tools to do repairs. The more you know about the coach the better able you are to diagnose problems and get repairs done more efficiently.
Gary B

Re: Dramatic air pressure loss, overheating (was No idea what happened )

Reply #15 – May 15, 2012, 06:32:16 pm

Pierce, Sorry I forgot to mention the wheel wells, there was a mark there from the previous owners and since I have had it I see nothing that would be new for me. I think I will hit it with a bit of black paint and that way "if" it ever does happen to rub, I will have a noticable spot to identify.
Gary, I already did lift the coach and put the 8 pipes in place. I have it a tad higher just so I know there is pressure on them. I found that air line that is broken...it goes to the exhaust brake, that BTW has never worked. I guess I can get some new line and repair that. Also, I did not hear any air coming from that area either, most likely due to not having the engine running. I may start it again to see if anything comes from there though. It really only appears that the broken line runs from that guage to the brake mechanism. I don't or should I say, I haven't found a source for where the air would actually come from to start with. There is no drain valve for that rear air holding tank, at least not that I found while under there. Maybe that is "drained" with the air dryer? I will be going back out shortly to look and listen again. I came in to grab a spray bottle as Pierce suggested since I'm not hearing anything at all.
Gary, thanks for the offer to help go over the systems. I am rarely in Atlanta but I will take you up on it if I am. I appreciate it

As mentioned earlier, my neighbor is the county road commission mechanic and works on all their diesel plow trucks. He has been a great source for quality American made parts at the counties cost. He is going to help me replace all 8 air bags sometime soon and mine are looking pretty rough and he's going to do some brake work for me also....again at cost!! So, I figure I had better take full advantage of that deal. He really knows his stuff so he's kinda my go to guy for mechanical stuff. I just really like to check with our forum for the technical stuff as there is SO much knowledge about our Foretravels. Sometimes he just looks at it and scratches his head

I'm hoping the spray bottle finds the leak....I just want to know where it is.
Now I have found that the little "catch" dealy for my shifter won't engage to lock it into place when shifting from one gear to another so I've been messing with that. We have had a couple times that the coach wouldn't start and after wiggling the shift handle it's fine. It just did it again and I was wondering if when the coach is raised as high as it will go, maybe there's a sensor that won't allow it. Probably not but I thought I'd toss that out there. I can see the part and have lubed some of the internal parts down in that little housing box the shifting cables are in.

Back later, Thanks again everyone

Re: Dramatic air pressure loss, overheating (was No idea what happened )

Reply #16 – May 15, 2012, 08:05:19 pm

Carl, There is a drain for the rear air tank, most likely it is just forward of the left rear wheel just inside the fibreglass body. It will have a petcock on it. A airline leads from the tank to the petcock.
Gary B

Re: Dramatic air pressure loss, overheating (was No idea what happened )

Reply #17 – May 15, 2012, 08:55:47 pm

When you find the rear tank vent: if you find water, you need to revisit the dryer. Since you're looking for a LARGE momentary leak, it's not a spray bottle kind of problem. My bet is on the governor. Since it would cause the symptoms you cite and is cheap, I'd replace it now. Many of us carry a spare just in case we encounter your problem.

Re: Dramatic air pressure loss, overheating (was No idea what happened )

Reply #18 – May 15, 2012, 09:11:18 pm

I'd sure like to learn more about the "governor"; like what it looks like, where is it, how does it work, what's involved in replacing it and what is typical cost of part?
(if this isn't the right thread, maybe split it out?)
Dick

Re: Dramatic air pressure loss, overheating (was No idea what happened )

Reply #19 – May 15, 2012, 09:17:25 pm

Here you go Dick:
Air Governor/ Air Leak

Peter

Re: Dramatic air pressure loss, overheating (was No idea what happened )

Reply #20 – May 15, 2012, 09:19:26 pm

And a couple of pics of the D2 governor in these posts:

99' U320 air brake high pressure

Low Air Pressure from Air Hose

Re: Dramatic air pressure loss, overheating (was No idea what happened )

Reply #21 – May 15, 2012, 09:45:47 pm

I have changed many sets of belts on the 3208 cats and yes they are a real job. Sounds like they are loose and the water from t;he rain let them slip. The most likely ones are the 2 belts that go from the crank over an idler pully that is the tensiion adjuster. It is on the p;assenger side of the engine and if they are not properly tensioned will slip very bad as they drive the alternator and also the air compressor. I made a tool from a 1/2 inch bolt that I could put between the crank pully and the idler to be able to tension the belts as there is no place for a pry bar. On the bolt I slip a 1/2 inch socket on the threaded part and then use the nu;t to force the pulleys away from each other. If you have a question you can call me at 813-215-3463, Ron

Re: Dramatic air pressure loss, overheating (was No idea what happened )

Reply #22 – May 15, 2012, 11:01:59 pm

Well, here's the skinny on what I found. I took out the quart spray bottle and quickly went through that with soap / water. I then brought out a gallon of same and only used a small amount before making a discovery. I sprayed every single connection I could find from front to back....EVERY SINGLE ONE

I sprayed every bit of the 8 air bags except for a tiny bit in a couple tough areas to contort myself to. I was thinking ...that will be the spots they leak, lol

As I found the drain valve Gary pointed out for the rear ( wet ) tank, I sprayed it and holy cow!! She was leaking!! I turned it on and off real fast and still leaked. Then I rotated it 180 and it was better but I noticed that the actual turn mechanism was a little loose and figured it is best to completely replace. So..leak #1 FOUND. QUESTION, is one style valve better to buy than another?

I made me way to the bay that holds the on board air compressor and found a leak just past the on / off valve for the extention air hose. I actually gave it a couple twists with a wrench and it is 100% tight. Leak #2 REPAIRED

Then I continued to spray the lines under the step, behind that section and behind the compressor and no leaks there. Then I sprayed all of the lines, connections, adjustment knob and pressure relief valve on the compressor and wouldn't you know!! The pressure relief valve leaked. So I pulled on it quickly and let out some air hoping to reseat it but it still leaked just a touch when I sprayed it again. QUESTION, Can I remove it and put in a plug with some Teflon tape so I don't have to worry about it again? If not, is there a good quality relief valve I can count on?
Leak #3 FOUND
I kept hearing something like tiny bubbles ( not the song, lol ) and when I looked just above the on / off valve for the air hose, I seen a small foaming glob and when I wiped it away I found a wear mark on the line!! Leak #4 FOUND ( I actually let out all the air from my lines and roughed it up with course sand paper and mixed a 2 part epoxy hoping it will seal it off. I will know tomorrow and if not I will have to cut and splice )
After adding up the tank valve, the compressor relief valve, the loose line for air hose and the wear spot it would equal the slow leak that allows the coach to sag and settle down over time when parked. It does not however address the fast leak I had momentarily the other day in the rain on the highway.

I checked out my belts this afternoon and found that the 2 that run the air compressor and the altinator are in fact loose. Loose to the point where I can wiggle one effortlessly about an 1"+ and the other about an 1". The rest seemed to be fair and I will check them again tomorrow, but the alt and comp should certainly be tightened!! Could that really have been a big factor with slipping in the rain that day on the highway?

Ron, I seem to remember about a 1/2" tention bolt off the top of my alt with an adjustment bolt and a set bolt. It looks like a pretty simple job to tighten. I can lift the bed and set right on the engine. I'll let you know if I find out different.

Brett, No moisture to speak of from any of the 3 tanks drained, so that's good.

Will the air governor be marked so I know exactly what part to replace it with... number, id tag, or something?

Thanks for the pics and links to that info, it will certainly come in handy tomorrow when I get after the replacement. I know it's not been done while I've had the coach and knowing who owned it before me, I'm pretty sure they wouldn't have thought about it.

So, that's how that went. I found one more issue but it will require another post to specify.

Thanks all

Re: Dramatic air pressure loss, overheating (was No idea what happened )

Reply #23 – May 16, 2012, 06:56:14 am

Sounds like the belts are slipping on the compressor, and while they may look good if they have slipped very much they will be glazed and need to be replaced. The air governor is usually on the back of the compressor held on with 2 bolts, they are not expensive larger NAPA stores may have them as well as any truck parts stores. Your air dryer has more parts than just filters(purge valve, unloader valve, pressure releaf valve, and so on) kits are avaliable you will need your dryer model #, and they are not hard to rebuild although they can be hard to get to, it's usually easier to remove it from the coach to properly clean and install the kits. Also one other thing you did not mention, was your low air alarm/light going off when all the problems happened? This alarm should be going off when air pressure drops to around 60-70 lbs so you know to get off the road, because as you know the parking/emergency brakes are going to come on real soon. It should be on when you start the coach if the air is down, if not you may want to look into that real soon, so you don't have another near heart failure.

Re: Dramatic air pressure loss, overheating (was No idea what happened )

Reply #24 – May 16, 2012, 10:11:22 am

I believe my air dryer to be fine since it is only 3 years old with not more than 5000 miles on it. I do believe that my belts are slipping and will be tightening them today I hope. I checked the belts last night and the condition looks great...like new and did not see any glazing or discolor. This low air alarm has my attention though. My coach is most always out of or very low on air due to setting for periods of time and I have never ever heard an alarm or seen a lithg of any kind to let me know this. Does someone know where I can find such an animal on my 91' 280? Perhaps Don Hay with your 92' or really anyone with that knowledge.
Well, back at it today. One day it's fine...the next I have a list of 20 things to inspect, adjust, replace and repair. Thanks guys

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