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 Sitting coach - How to get functioning againJump to page : 1 Now viewing page 1 [25 messages per page] | View previous thread :: View next thread |
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BigRabbitMan |
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Expert   Location: Cottage Grove, OR | The following is a copy of a post made by Eddie Huffstetter in the Yahoo group forum. I have reposted it here for future reference by others. Stephen and all, | ||
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| BigRabbitMan |
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Expert Location: Cottage Grove, OR | The following is a followup post by Eddie to a comment on the Yahoo site. Kjetil, I learn from here, from everyone. Thank you for the kind words. My post intended like always to simply state that for those inclined to do their own work, this work is quite doable without the expensive shops and associated labor costs. Your are of course correct, that simple vacuum hose issues are extremely important to any booster operation. This and all engines depend upon good intake manifold vacuum to run properly, and many engines that don't idle, idle poorly, over heat, accelerate with various delay, and just won't run properly all depend upon various vacuum hose and components integrity. Simple dirty PVC valves, a little vacuum hose to the distributor, any tiny vacuum hose, or that large hose to the booster really can mess up how an engine operates and idles. Nowadays modern engines depend upon the integrity of the air cleaner to intake large hose integrity which with just a single small crack, will make the engine run just horrible. That simple large usually accordion-flex hose must maintain a controlled Mass Air Flow environment that is sensed by a Mass Air Processor. That MAP sensor tells the Electronic Control Module what to do with data for all engine operation including Oxygen Sensors, Timing, and many more operations of the engine. The ECM is no less significant than the Central Processor Unit of every computer. Every car you own that is 10 years or newer and mostly from 1983 and newer, has a ECM and that air cleaner to engine intake hose is so terribly important and so overlooked as is a dirty air filter which affects all that mass air flow. Luckily, our FMC's don't have that, but if you have a Electronic Fuel Injection upgrade on your FMC, you do have this issue to monitor. That is why simple things like a clean air filter element is so important. Additionally the fancy smancy upgrades on a modern car or truck to aftermarket air filters of various name brands may be a very bad idea. So I have talked about mystical terms we all see, MAF, MAP, O2S, ECM, CPU, and unmentioned ACT, PA1, PA2, and other sensor-gadgets on engines the techs would have you stay mystified, yet these really are simple, easy to understand, and things you can easily identify, repair, and replace without all that expense. Most of these components are not that expensive. All vehicles use some form of PA1 valve which nowadays is the idle mixture control, no idle set screw nowadays. The thing gets dirty. If you clean it, you would be amazed at how much better all operations of a modern vehicle are restored. The techs do not want you to know this. It is just a stepper motor that lets air bypass the throttle body butterfly plate. Clean it and the throttle body at the butterfly, and you get a big bang for your efforts. The only caution is that the whole throttle body and PA1 valve is Teflon coated. Solvents destroy that so never spray a carb cleaner in any of this. Just like the magical things above you are not supposed to learn or understand, the brake system is also quite user serviceable. My post sure could have been better written, but the point is that you do not need to be more than a person who can understand a garden hose connected to a faucet, know that only air compresses and fluids do not. So if you methodically think it out in your mind, you simply get the air out and you don't need special tools. You could substituted any fluid, but brake fluid is used as it is designed not to boil at the hot wheels when brake is applied. It is just a different specialized use hydraulic fluid and nothing more. DOT 3 is used because the seals are not pure rubbers that need the DOT 4 or other fluids. If you have some types of cars, especially European, you must read which fluid to use as DOT 3 can destroy some of those systems. FMC's use DOT 3. Most of that understanding for FMC's and trucks is to realize that although the brake booster is a marvelous thing just like the power brake booster on you car, it does not and cannot have a reservoir to feed it like your car does. More similar to your car booster than not, it has no reservoir, but rather has a line from the master cylinder up at the front of your coach which does have the reservoir. That line works and feeds the booster all the way at the back. That line is your direct connect from your foot to that booster, which is not mounted up front where you are and connect by a rod to the pedal to push that boosters piston. You step on the pedal, the fluid from the master cylinder that is connected by a pedal and rod to the master cylinder up there where you are, moves the emote booster piston, which assisted with engine vacuum to that big large rubber diaphragm inside that big black metal housing, pushes the fluid which pushes the piston at the wheel being supplied. It is just that simple, but knowledge that the booster piston has very little travel is important because once it travels within the booster cylinder, it will simply bottom out. That is why it is back there closer to what it activates, and not up front by you. All movement is completed. There is no more travel, and you could have a nice hard brake pedal, but no brake applied. The booster piston ran out of room to travel. Any air before the booster, or after the booster, causes this malfunction. Brake shoes with too much travel because it simply needs adjusting out being too loose to the drum, also causes the booster piston to bottom out, but that is seldom the case with self adjusting shoes, and brake rotor pistons all self adjust as they do not use a return spring. It does not matter how many boosters are on the vehicle. Put as many as you like. They are all fed by a master, and all are slaves. It is hard to find a hardware store that does not sell clear vinyl tubing. This can be a helper slipped over a brake bleeder, but do realize that when you loosen a bleeder, the threads allow a sloppy connection that will allow air to get by them. It is very important to understand you can push on the brake pedal, prop it with a stick or device since you have no helper, go loosen any bleeder, watch the flow, then re-close that bleeder BEFORE leaving it and BEFORE letting up the brake pedal. You do not want to introduce air. If you goof up, you have to start over. Gravity bleeding: We all know that if you had a leaking wheel cylinder(s), all the brake fluid would run out from that wheel. That would be all the fluid from the Master Cylinder, the booster, and any line to that one wheel. When you have folks who would argue and chastise that you cannot just gravity bleed the entire coach, they are wrong. You can. You could actually keep the MC filled, open any bleeder, and just wait. It will eventually bleed all air until the fluid in the reservoir runs out, introducing more air. No one has such patience, but you get the idea of what you can do and what to expect. Depressing the brake pedal with sequence of timely opening and closing a bleeder simply hurries up the process of getting all air out. Brake fluid will remove paint. Keep it off of things you don't want to rust and corrode. Clean up of brake fluid is best done with soap and water. Brake components cannot be washed in solvents, which just makes a messy jelly goo. No, it won't hurt your hands and the smell/fumes will not hurt your lungs unless your deliberately huffing it. You might be surprised at how many wheel cylinders that are stuck can simply be removed and clean, put back into service with attention to adjusting the brake shoe to get the slop out and reduce the travel. There is a brake grease available everywhere. The cleaned piston, cylinder, and it's seals will resist the typical rust frozen corrosion that is found when FMC's sit up when you use that grease when reassembling. The grease is designed for use with brake fluids. It really helps stop rust from the raw metal cast cylinders which really attract moisture. It really helps with the bi-metal issues of cast cylinders with the typical pot metal piston inside it. My thoughts and successes are to simply bleed that air from the master cylinder, to the booster(s). You will be pleased with the gain you get from removing just one little air bubble in that line. I hope that any of this helps someone. -Eddie- Houston, TX | ||
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| Bair |
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Regular  Location: Santa Cruz, Calif. | This is an addition to the previous post. It is written in Word.doc format, so I hope it transfers. I belong to another group of antique motorhomes, the Aero Cruisers. http://www.aero-cruiser.fl-ink.com/index.htm The following is a repost of an artical I wrote for them. All fluid driven systems use the same info. Brake Fluid Explained Abbreviated from a TRD article by James Walker* This is just a brief run down on Brake Fluids, their designations and applications and maintenance. First, let’s understand DOT ratings. DOT stands for Department Of Transportation. The DOT (sometimes referred to as the Dotties) write characteristics for brake fluid. They do not say what it’s composition is, just what it should do. If you can get maple syrup to meet the specs, then it is good. All of the DOT ratings must meet 4 specs: 1. It must not solidify. There is no low end number for this but since -40°F is fairly common in the USA you know all fluids must function below that. 2. It must not vaporize. Again, there is no specific number given by DOT, but since 400°F can easily occur at the cylinders, we can expect a fairly high evaporating number. 3. It must be compatible with rubber seals. 4. It must not be excessively compressible. So the one fluid that meets all of the above and is yet reasonably easy to make and cost-effective is a glycol-ether based fluid. However, glycols have one very undesirable side effect, they love to absorb water. This is why brake fluids come in sealed containers. Once it has been opened, the water absorbing process begins. In a sealed system, like our brake lines it’s a small problem. But for a half empty container without a seal sitting on the shelf, the amount of H2O grows rapidly. Even with the cap on tight, the container is “breathing”: Getting warm during the day and cooling off at night, air with moisture is seeping into the container and being absorbed by the fluid. When you use this container of half full brake fluid, you are adding moisture to your braking system and rust will start to occur. It also lowers the boiling point of the fluid and raises the freezing point. This is where it gets kind of weird. The colder it gets, the lower the ability of the glycol to hold water, so pockets or bubbles of water can form which then freezes. So the point is, buy smaller bottles of fluid to keep on hand sealed and discard the remainder after it is opened. Now, realistically, water is everywhere and will eventually find its way into everything, including your sealed brake system. The point being made here, is not to help it along any further. Besides, if you flush your system at regular intervals, the old fluid will also flush any water it has absorbed. Discard half full shelf bottles. So as brake systems got more intense, DOT started upgrading their specs. The oldest spec you can still buy is DOT 3. The Dotties also decided to list the specs as “dry”, that is 0% water content, and “wet”, which is 3.7% water content. Beyond 3.7% water content the fluid is considered unuseable. DOT 3 – is still a basic glycol-ether fluid, but must a have a 0% water content boiling point of 401°F, and a 3.7% water content boiling point of 284°F. (As Mary Poppins would sing: “Just a little bit of water makes your stopping distance go down”.) DOT 4 - starts seeing the addition of borate esters which helps resist water. The 0% H2O boiling point of DOT 4 is to be above 446°F, and the 3.7% boiling point is 311°F. Yet the borates will degrade with time in which they start absorbing water and make the boiling points go down below those of DOT 3. So it is recommended that you use DOT 4 only if you are religious about flushing and changing your brake fluids. DOT 5 – Is the only really different brake fluid as it is Silicon based. It’s 0% boiling point is 509°F and it’s 3.7% boiling point is 356°F. Also, it is a thinner fluid making it more freeze resistant. So is this the Grail of brake fluids? Well, there’s 2 downsides. The first is that because of it’s larger molecules, air molecules can fit in between and resistance to compressibility goes down. Two is that all the fluids listed here DOT 3,4,5.1 are all intermixable. But DOT 5 stands alone, it cannot be mixed with any other fluid. Another advantage is that DOT 5 is less corrosive to paint than the others. Currently only one manufacturer supplies Dot 5 as OEM fluid: Harley. Finally comes DOT 5.1 – So finally manufacturers came up with a glycol formula that matched the DOT 5 silicon based characteristics. Since the two were not compatible and DOT didn’t want confusion, they called this new formula 5.1. Sometimes manufacturers refer to this as 4+ or Super 4. It is pricier. There is no magical formula as to which is better. Somewhere between price and performance is what you will settle on. The two big notes here are flush your system at regular intervals as prescribed by the vehicle manufacturer and don’t keep opened bottles for use later. Buy big bottles for the actual flush and keep a little sealed bottle for topping off if necessary. *James Walker is a brake specialist who has worked for Delphi, TRW, GM, Bosch, and Ford. He is currently an engineer for Carr Engineering and a freelance writer. | ||
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| wheelsweep |
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Contributor | Thank you for clearing up wheelcylinder mysteries. Always willing to benefit from valued experience of the "Chosen Few"(FMC owners). My FMC #1038 is in Solvang, off hwy 236/Refugio, behind a red barn in the grass. can I turn the front wheels without a running engine? Hoped to muscle the coach around to the front of the barn to clean dry ground for brake bleed without spilling a drop, of course. Shoud be there through the weekend, weather permitting. Gung ho!! Always ready to travel wheelsweep! | ||
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| BigRabbitMan |
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Expert Location: Cottage Grove, OR | [QUOTE]wheelsweep - 2010-03-04 9:50 PM My FMC #1038 is in Solvang, off hwy 236/Refugio, behind a red barn in the grass. can I turn the front wheels without a running engine? The answer is "yes" with some conditions. I have driven mine without a power steering belt and others have driven theirs with failed power steering units - it's called "muscle power!" I only went a short ways, but some others have gone through multiple states without power steering. To turn the wheels you will have to have the coach moving a little. If one person is making the coach move and another person is "Muscle powering" the steering wheel, you should be able to move it to a better location. You need to get #1038 running so that you can join us the next time we stay at Flying Flags RV park in Beullton. See the pictures in the Album section. | ||
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| denshew |
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Veteran Location: Canton, (Sixes) GA | Muscle power? I always thought this was called "Armstrong Power Steering" <G>....Denny | ||
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| 59ona64 |
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Contributor | Another way to turn the wheels w/o the coach running or moving at all is to jack up the front end and turn the steering wheel hard. This worked on a Revcon I was looking at to purchase--all batteries dead, no action on the jump tries and the battery installs in front of the wheel well on the passenger's side. Used a 2.5 ton floor jack, but b/c the jack wasn't very hefty, I left the wheels in contact with the ground, but it got lifted enough to take the pressure off the tires and turn them. Good luck! | ||
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