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How to prepare a motorhome which hasn't been run for long time

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When first approaching a vehicle that has sat unused for many years, it can be tempting to just stick a hot battery in it, and a bit of gas, and try to start it. But doing so without checking things out properly can be not only damaging to the vehicle, but possibly eve...n dangerous.

First, give the vehicle a very thorough visual check. Look everywhere underneath, under the dash, in compartments, under the hood, etc... watch for things like rats nests, eaten thru or rotten wires, rotted hoses, rust, squirrel damage, etc... Be careful too, of other "residents" that might be calling it Home... snakes, rodents, even raccoons are known to hide in, under or around dead vehicles. Wasps and bees too. Don't stick your head, or hands in places you cannot see without first probing around a bit with a stick. Over the years, I've had everything from hornets, to stray cats and rattlesnakes pop out at me.. I've learned. I

f you see that the wiring appears to be intact, you can check the fuse box and battery cables for corrosion and blown fuses. On a motorhome, don't forget that it has a separate electrical circuit for shore/genset power, along with a normal 12v. circuit. You must check these circuits out separately, In the breakerbox in the coach, make sure the breakers are set for the coach to be on normal 12v. service. Usually, they are clearly marked with "Shore Power" or ""Genset". There will be one larger amperage breaker that is the "Master". Make sure it is set to the "On" position. I prefer to set the other one to "Shore Power" to prevent damage to the genset electrical circuit in case of any unexpected problems. Just make sure the power cord to the coach is unplugged.

Then you can do a "Safety Check" on the power. I like to remove all of the fuses first from the fusebox, after making a drawing of their positions, and then hook up a fully charged battery. That way, I can add in the fuses one at a time, ensuring that there is no problems with that circuit before adding the next. If all of the fuses go in without any failures or smoke,flames,etc... Go thru all of the lights, switches, and other power circuits. Try the headlights,blinkers,brakelights,gauges,warning lights etc... You want to make sure that all of the engine related circuits are operating correctly. Temp and oil gauges, warning lights, the fuel selector switch, the battery selector switch, are all going to be needed before you crank the engine over. If they appear to be non working, you need to fix these first.  Usually, electric gauges will move a bit when you turn the engine switch to the "On" position. For mechanical gauges, they won't do anything until the engine is started, so just look for damaged lines or sending units unplugged or corroded. Warning lights should come on briefly as a check when the key is first turned on. If they do not, look for bad bulbs in the gauge panel.

OK, now we have done an initial assessment, did a thourough safety check of the electrical systems, and successfully got power to all of the electrical circuits. Now, we can move on to the mechanical parts, and get her fired up!

First, do a visual check of the engine. Look for rotten vacuum hoses, coolant hoses, and belts. Look to see that there is nothing that appears to be rusted thru or weakened, like brackets, braces, mounts,etc.. Check the coolant level and look at the radiator. Is the coolant clean looking, or does it look like it has oil in it? Does the waterpump have any play in the bearings? Bear in mind, things like hoses,belts,and such will have to be replaced regardless later on before you actually drive it... you just want to see if it is safe to run it a bit right now. Now check the oil, make sure it is fairly clean and doesn't appear to have rust or water in it. An engine will condensate internally as part of normal heating & cooling, this water will build up over time in the oil.

Before actually starting the engine, you need to plan on changing the oil and filter, and then again after it has been ran for a few hours or a few miles. But you can see if the engine will turn over first.

Now, get out your tools and pull out each sparkplug. Look at it and watch for excessive rust that indicates a lot of water getting into the cylinder. They shouldn't ever have more than a light hazing of rust on the electrode ends. Any more than that, indicates that a cylinder is likely heavily rusted and the engine cannot be turned over without severe damage. If the plugs all look OK, Use a syringe to inject about 1 ounce of "Marvel Mystery Oil" into each cylinder. I use an old Meat injector that you can get at any grocery store. Put the plugs back in and make sure the plug wires are clean and tight.

Take the distributor cap off and look at the points if it's not an electronic ignition. Look at the inside of the cap and the rotor button. Make sure that they are not worn out or burned. Light sanding can clean them up.

Now, remove the air cleaner, make sure a critter hasn't built any nests inside the air filter or duct work.

Dirt daubers also love to build in carburetors, look to see that everything looks clean & normal. Remove the fuel line and check for rust inside the line, check the filters for rust or clogging. On mechanical pumps, theres a short section of rubber hose that connects the pump to the line attached to the frame. This allows the engine to flex as it runs, look to see that it isn't cracked or dry rotted.

Right now, we are not actually going to run the engine off the fuel tank, so concentrate mainly on just from the pump to the carb. If all appears OK, Use a large socket on the main crank bolt at the front of the engine and with a large breaker bar, try to gently turn the engine by hand back & forth a bit. You are looking to see if the rings are stuck to the cylinder walls, be very gentle, they break easily & will mean a rebuild if you do. If you feel any hard resistance beyond what it takes to turn it normally, (it helps if you have access to another identical running engine for a reference, or just by experience) Stop and allow the Marvel Mystery Oil to soak for a couple days. Then try again.

Once you think it is turning over back & forth normally, you can prime the oil pump. This is vital on an engine that has sat a long time. If oil pressure isn't built up regularly, lifters can collapse and oil pumps can even lose their primes as the oil eventually drains back into the pan.

Remove the distributor, after making reference marks on the distributor and engine block, and rotor button, so you can replace it later exactly. Use a special tool in a drill, or cut a large flat blade screw driver handle off, and use it in the drill, down in the bottom of the hole where the distributor was you will see a slotted rod sticking up. Make note of its position, as it locks into the bottom of the distributor shaft & must line back up later. Now, use the drill to spin the rod for at least 5min. Have an assistant verify that the oil pressure builds up on the dash gauge, or that the oil light goes off, with the engine switch turned on. Now, replace the distributor, ensuring all the original markings line back up exactly. Distributors rotate as they go in, back up one tooth at a time as you insert it, until the marks line up when it's fully seated.

Unbolt the carburetor, carefully remove the vacuum hoses, and slowly lift the carb. up. You can reuse the base gasket for now, if it releases cleanly. Now, slowly flip the carb. upside down. Listen carefully for the sound of the floats moving. If you cant hear them, it means they are stuck and would flood if you applied fuel. Gently tap on the bottom of the carb. while holding it upside down, and see if you can get them to loosen up. You should be able to hear them moving as you flip the carb. back & forth from right side up, to upside down. Now replace the carb. Use a small bit of gasket sealer (I use a spray type from Permetex, available at any parts store).

For now, you don't want to run the engine off of the fuel tanks, remove the line going to the fuel pump from the frame, and fashion a temporary hose going to a 5 gal. or smaller gas can. Attach this to the fuel pumps intake line, where the hose would have been. Leave the line attaching to the carb. off, have a mason jar ready to catch fuel as it comes out, you want to first catch any trash or rust that might come out, before it gets into the carb. Think of it as flushing out the line.

Now for the moment you have been waiting for!! With you watching the engine and ready to catch the fuel, have an assistant try to turn the engine over briefly. The first attempt, you just want to make sure the starter engages and rotates, the engine seems to be turning over normally, the oil pressure seems to try to build, and theres no unexpected suprises going on.

After you turn it over enough to get a steady pulse of fuel coming out the line, stop and attach it back to the carb. Now turn the engine over again, without pumping the carb. so it can fill up the fuel bowls. Brief 5 sec. tries a couple times should do it. Now, have them pump the carb. once & look to see if you see fuel squirt out of the accelerator pump jets located in the center of the carb. butterfly holes. If you can't see it, try turning the engine over a couple times again & try again. If you see fuel, the bowls are now full & you can try to see if it will run. Crank the engine with the assistant giving the carb. a couple pumps at a time. You can flood it easily if you aren't careful. If you smell raw fuel, hold the pedal to the floor while it's turning to clear the fuel out. If needed, be prepared to rotate the distributor a bit to get the timing exactly right, remember, you had it loose earlier.

Once the engine fires up, don't rev it above a fast idle until it warms up. Keep the rpms varied a bit to allow the lifters to reseat and fully pump up. Look for any oil or coolant leaks. Make sure all of the other systems that are attached to the engine are also functioning normally, like the power steering pump, and alternator.

Is it now running? Congratulations!

 Now you can move on to the next part, the drive train. Check the transmission fluid and ensure it is full, doesn't smell burned, and looks fairly clean. You will want to change the fluid & filter later, but if it is smelling badly burned, you might need it checked out by a shop before trying to drive it far. Lube the grease fittings in the universal joints, and make sure they seem secure and have no play. Remove the oil filler plug and use a pinkie in the hole to check the oil level in the rear end. If you can't touch oil, it's low.

Brakes: Warning! Always assume that brakes over 5 yrs. old will need a full rebuild of every component made of rubber. This includes, Wheel cylinders, caliper seals, flexible lines, master cylinders, and possibly even the booster. Also, springs weaken with age, regardless of how good the appear. Assume they are weak & replace them. Inspect every inch of the metal lines and fittings from the master cylinder to the wheels. I cannot stress enough how critical it is to have safe brakes. I have personally experienced a total failure of the brakes in our 27' Winnebago going down a mountain on our way to Gatlinburg. It was due to a rotted flexible hose going to the front caliper. These coaches are extremely heavy, and a failure could mean your life, or someone Else's. Don't scrimp on cheap parts, & don't take a chance that the hoses or parts will be fine if you don't replace them. Do not attempt to move the motorhome until you know the brakes are 100% safe and capable of stopping you.

Tires: Tires dry rot. Period. If you see large cracks in the sidewalls, they need replaced or they will fail. If they hold air and seem OK, be prepared for flat spotting from sitting up. Drive very slowly for a couple miles to give the rubber a chance to loosen back up & return to normal. If the thumping doesn't go away after a few miles, you likely will need to replace them.

Wheel Lugs: Check the lug nuts to make sure they are at the proper torque, especially on the rear duals. It is normal for them to loosen up over time as the wheels rotate. Check them again after the first 50 miles, and then again at 100 miles, then every few hundred miles thereafter. This is done before every trip.

Spare: Is it OK? Does it have air? Is it dry rotted? You might need it one day, make sure it's in good shape.

Wipers: Check the washer bottle for dry rot, replacement universal bottles are available, as are washer pumps. Check the hoses to the squirters, check the blades for damage. Using dry rotted blades can scratch the windshield. Make sure the wipers work on low & high.

Genset: As for the engine itself, the same basic principals used to start the coaches engine apply here as well. Assume it's locked up & proceed from there accordingly. Once the engine is running, you can let it warm up & then try to switch the breakers in the coach over to "Genset" and see if it makes power. If it doesn't, it might need repair.

Anything Else: Just take it slow & easy, especially the first drive or two. Check things often & watch out for cooling or oil problems. Valve covers are something that are bad about leaking if they have been sitting, as are oil pan gaskets & crank seals. These may go away after the coach has been driven a bit. If not, you might need to freshen up the gaskets & seals.

Keep a close eye on your warning lights & gauges, and be ready with tools available if you have any problems arise. Watch the steering and suspension for odd behavior, and be ready to repair them as needed.

This guide was intended to take you from a "locked up" to a running point. I assume before actually using the coach on a regular basis, it will receive a full tune up & all belts, hoses, fluids,filters etc... will be flushed out or changed. Failure to do so may cause problems. I am assuming that you have reasonable mechanical skills and access to a full set of basic tools, otherwise, you shouldn't attempt a project of this scale alone. Take advantage of the wealth of information an reference guides available in repair manuals. Also, read thru any discussions or topics related to your issue to see if anyone else has experienced, and more importantly, solved the problems you encounter. Be sure to seek advice and recommendations from seasoned mechanics, or friends who have experience.

Good luck with your project & Thank you for preserving just one more piece of Motorhoming history!

A little "Seafoam"(r) down the carb while running it doesn't hurt either, then pour the rest into the tank..


I have been told that I should purge the fuel system prior to starting the motor as it has been sitting for 5 years. Do you think this is necessary? Do you know of an easy way of doing it other than removing the tank, fuel pump and filters?

Absolutely!  Get as much fuel out as you can.  You can do this with an electrical pump.  Don't be surprised if you get rust and gunk from the bottom of the tank though.

It may be wise to take out as much as you can and stop if you start getting crap in what's coming out.  If you do, you'll need to clean the tanks.  Not fun, but definitely necessary.

Once you have put in fresh gas, replace the filters.  They will be gummed up and not likely to become clean like new just by running seafoam or Lucas or other cleaning agents through.

Which leads me back to that.  Use seafoam or Lucas, or other quality cleaning agents, in their correct amount (don't skimp) in the fresh gas.  You should also spray down the carb with carb cleaner.

5yr old gasoline is likely closer to being turpentine, than it is gasoline. In addition to the above recommendations, you can also add 1 quart of transmission fluid to about 10 gallons of fresh gas once you get the worst of the junk out and are ready for your first fresh fuel. The transmission fluid is an excellent cleaner, as well as being a very good lubricant for the entire fuel system to help with any internal varnish or gum buildup in the carb. After startup it might smoke a bit until you use that tank up... that's perfectly normal.


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