Wake Up Call for a Long Dormant RV

Dear Car Talk

Dear Car Talk | Apr 23, 2015

Dear Car Talk:

I have a V-10 engine in an RV that has not been started in four years. Can I start it, and what type of oil would I use to put on top of the pistons to overcome any rust that might have formed in the cylinder walls?

-- Jack

I've always been partial to McEvoy Ranch Extra Virgin Olive Oil, Jack.

Just kidding. You're going to use regular old motor oil. But your first task -- and it might not be an easy one -- is to get the spark plugs out. If they've been sitting there for four years, they might need some serious convincing. But be very careful not to break one off in the cylinder head. That'll add six extra steps, an extra day or two, and at least $500 to this project.

Start by trying to remove the spark plugs. If you can get them out, then squirt a quarter of an ounce or so of oil into each spark-plug hole (you can use a plastic syringe, extended with a piece of rubber or plastic hose if need be), and then throw those old spark plugs away.

Next, disable the ignition system. You need to unplug all of the coils, not just from the spark plugs -- you need to unplug the connector that provides power to each coil. You're going to have gasoline and oil shooting out of those spark-plug holes when you crank this thing, so the last thing you want nearby is high-voltage spark -- unless you've got a very good insurance policy and are looking to upgrade this rig.

Next, you're going to crank the engine. With the spark plugs removed, the engine won't start, obviously. But by using the starter motor to crank it, you're turning the engine at 100 rpm instead of the 2,000 or more rpm it turns at once the engine starts.

That should allow the piston rings to more gently scrape off any rust that may have built up on the cylinder walls. It also gives the oil pump a chance to build up pressure around the bearings before the engine runs at speed.

Keep in mind that cranking the engine is going to make a mess. The oil that you squirted into those cylinders is going to come flying out like a Texas oil well. So protect anything nearby that you don't want Jackson Pollocked.

Once you've cranked the engine for 30 seconds or so, put in your new spark plugs, reconnect the ignition system and, if there's room in the tank, put in a few gallons of fresh gasoline. Of course, I wouldn't invest in too much gasoline upfront, just in case, Jack.

And then start it up. It'll belch blue smoke until that oil you squirted in there is all burned up, but that should clear up in a matter of minutes.

And if it turns out you can't remove the spark plugs, then just cross your fingers, skip steps 1 through 8, and just start the thing. It might be fine. Good luck, Jack.


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