Motor has not been started in 8+ years, what precautions do I need to take?

I just recently purchased a 1995 Dolphin motorhome that has not been started in 8+ years. I have been advised by multiple people that I shouldn’t even try to start the motor before changing the oil and draining the gas tank or the motor will seize. Now these people are by no means auto mechanics or experts and I would just like a few other opinions. Do these people speak the truth? What should be done? Thanks for your help.


I am a professional mechanic

You would be a fool to try to start the thing on that gas

In fact, it’s not really even gasoline anymore. It has degraded to the point that it will in all likelihood not ignite.

There is a chance the fuel pump and sender have already been damaged by the crap that’s in the tank. I’m assuming the fuel pump is inside the tank, correct?

If the tank has a drain, use it.

The ideal solution would be to remove the tank, drain the crap and wipe out the sludge and varnish. Believe me, it’s in there.

If that’s not an option, siphon out the crap and fill with new fuel.

Change the oil and filter

Remove the valve covers and squirt some oil on the valvetrain

Remove the plugs and squirt a shot of oil in there

May as well change the plugs if in doubt

Then turn the engine over with a socket and breaker bar to free up the rings

Install a fresh battery

After all that, prime the fuel system a few times before attempting to start this thing

Good luck, and let us know how you make out

A lot depends on the storage conditions.

Where was it stored (in a garage in Florida or in Alaska?

The fact is you will need to tell us more. Also I would suggest that you have it checked by a good mechanic.

You must expect the gas in the tank to be bad. I’d drain the old fuel out of the tank.

Next, I would pull all 8 (assuming 8 cylinder motor) spark plugs. Shot some oil (about a tbsp) in each cylinder and turn the motor over by hand, meaning find a way to put a wrench on the crankshaft to turn the motor. With plugs out the motor should be pretty easy to rotate with 1/2 " ratchet or breaker bar.

Does this motor have a carburator? or is it fuel injected. Things differ quite a bit depending on which. But, mainly you have to assume all the fuel lines from the tank to the motor are also full of bad fuel. So, you need to rig up a temporary fuel supply with known good fuel before starting the motor. This is relatively easy on a non fuel injected motor.

Before you install the plugs you need to spin the motor using the starting motor and catch the oil that comes shooting out of the cylinders from spark plug holes. Now, install the plugs and with the known fresh gas supply see if the motor wiil crank over. After a few cranks it should fire on at least one or two cylinders. If there is no firing at all, then try some putting starter fluid or a couple of teaspoons of gas down the carb or throttle body opening. Keep back as there could be backfiring and be ready for some flames.

If all this seems beyond your skills, consider towing the vehicle to a mechanic for an evaluation on how to fire it up. Changing the oil and all the fluids should be done and the function of the brakes, steering and suspension all need to be checked before putting this vehicle back on the road so you will need a mechanic at some point. And yes, I’d drain and refill the oil before attempting to start it. up.

Thank you for all the advise.

The motorhome has been stored outside in Salt Lake City, Ut. It does get below freezing here in the winter as well as summer temps reaching well above 100.

I believe it is fuel injected but I haven’t seen the vehicle yet, I live in Montana. The motorhome was given to me for free so I am just trying to see what all needs to be done before removing it from my grandparents property

Since it is on your grandparents’ property, I would go ahead and get it running there, if you can

And then you can hopefully drive it away under its own power

If you get it running, it’s probably best to immediately replace the tires. They’re surely rotten by now

And make sure you don’t have any rusted, leaking, or swollen brake lines/hoses before you drive off

In Minnesota, when an engine has sat idle for many years, we find the cheapest oil there is and completely fill the engine with oil. Then we allow the engine to sit for a week with the oil. Then the oil is drained and the spark plugs are removed. Then we try to turn the engine over by hand at the crank bolt. If the engine turns over we reinstall the spark plugs and add the proper amount of oil.

If the engine doesn’t turn over by hand it means the engine is seized. So we don’t worry about the condition of the gasoline in the tank.


The only thing I will add to the advice that you’ve already been given is that if the motor home still has old gas in it then you should plan on replacing the fuel pump and filter as a preventative measure.

Quite often a fuel pump will die after being exposed to old gasoline even if the engine appears to run well at first on fresh gasoline.
It’s best not to discover this kind of problem on the roadside a few hundred miles from nowhere.

Old motor homes can also be somewhat similar to old boats; always something going on with them.

In addition to the other advice do this: If you find that the motor is free and can be turned with a tool at the end of the crankshaft, leave the plugs out, ground the spark plug wires and spin the motor with the starter for about a minute. If the dash has an oil pressure gauge, you might see a little oil pressure. There will be residual oil on the bearings etc but this ensures a fresh supply. As compared to starting the engine, spinning with no plugs is a light load for the bearings, etc.

Lots of great advice. And as someone mentioned the location of the vehicle allows some freedom to take the time to hopefully save the engine. A few ounces of oil in each cylinder, then turning the crank by hand, followed by cranking the engine with the spark plugs out until oil pressure is registered would likely be of great benefit. Good luck.

thank you everyone for the information, I will repost and let you know how it turns out

Just don’t put too much oil in each cylinder, that could damage the engine. A tablespoon or less is enough.

It sounds like Tester and Texases are talking about two different approaches.

If I understand Tester correctly, he’s saying to completely fill the engine with oil - till it won’t hold anymore. Which means the cylinders will have whatever oil they can old (without spilling out the exhaust valves).

Yes, I wasn’t talking about Tester’s approach, which makes sense. I was talking about the ‘put some oil in the cylinders before you crank it over’ approach. If the spark plugs are left out that’s fine, but if the spark plugs are in with too much oil it could hydrolock. Unlikely, I know.