Preping a rebuilt engine for storage.

[White70C20]

Hello all,

I recently finished rebuilding the 250 inline 6 out of my grandfather's '70 C20. I am going home over the summer, and I don't have time to completely install the engine back into the truck before I leave. I was wondering if anyone had ideas/recommendations on how I should prep the engine for storage. The engine hasn't run since it was rebuilt.

Thanks!!!

[71Dually]

It will depend how long you plan to store it. Assembly lube can dry out if left to sit. If the lube dries then disassembly, cleaning, new assembly lube and reassembly will be required.

At a minimum I would break in the cam and get oil circulating throughout the engine. When it comes time to shut down the engine after cam break in run it out of gas. This will prevent unburned fuel from sitting inside the engine in storage.

Gasoline will dissolve the oil on the cylinder walls and leave them suseptible to corrosion. Pull the spark plugs and squirt a little oil in the cylinders. Rotate the crankshaft by hand 1 turn by using a socket or wrench on the crank pulley bolt to lube the rings and cylinder walls. After rotating the crankshaft put a couple more squirts of oil in each cylinder for good measure. Put anti-sieze on the spark plug threads then reinstall the plugs and tighten them.

Some folks will run plain water during cam break in. If this is done then prior to final shut down run 50/50 mix coolant thru the engine so the plain water will not cause rust in the engines internal cooling system. Drain the coolant from the block thru the blocks drain plugs. Replace the drain plugs then seal the coolant inlets and outlets.


Then remove carb and seal the intake manifold with a gasket and a flat steel plate to prevent debris and moisture intrusion.

If the exhaust manifold is rusty inside remove it as rust never sleeps and can migrate to the engine internals. Personally I would remove the exhaust even if it wasn't rusty and seal up the ports like the carb flange on the intake manifold. On your inline engine it may be easier to remove both intake and exhaust manifolds and use a strip of uncut gasket material and a single piece of 1/4" cold rolled steel flat plate to seal all the ports at once.

Leave the distributor installed as that makes one less hole to plug. Leave the spark plugs installed for the same reason. Seal any remaining holes like PVC system etc... Leave the oil in the crankcase to prevent bleed down of the oil pump.

After all that get some dissectant packs to absorb moisture and throw about a dozen of them in a large garbage bag and seal your engine in a few layers of heavy duty trash bags. Get some plastic stretch wrap from a packing supply store and wrap the engine (inside the trashbags) throughly with plenty of stretch wrap to prevent moisture intrusion. Store the engine indoors in a temperature stable room to prevent condensation formation.

When you are ready to place the engine back into service pull the spark plugs and squirt about an ounce of Marvel Mystery Oil in each of the cylinders. Reinstall the plugs hand tight, you will be pulling them again prior to fire up. Let the MMO sit in the cylinders for a couple of days. After the cylinder walls and rings have marinated well change the oil and oil filter. Don't neglect to fill the filter with oil.

Pull the spark plugs to prepare for the next step. Get an oil pump primer tool and remove the distributor. Install the pump primer and start circulating oil thru the engine for a little over a minute. Put a ratchet and socket on the front crankshaft pulley bolt. Continue to run the pump primer tool and begin to hand rotate the crankshaft. Watch the spark plug holes for the pistons to spit out MMO. If no MMO comes out after a half to 3/4 of crank rotation stop and squirt some MMO into the cylinders to keep the cylinder walls/rings lubricated as you continue to circulate oil with the pump primer tool and slowly rotate the crankshaft by hand. This should prepare the oil system for bringing the engine out of mothballs.

Reinstall everything to fire the engine up. One thing to do is make sure the carb float bowl has fuel prior to cranking. That will prevent excessive cranking filling the carb with the fuel pump. Let the engine run at no less than 1600RPM for the first couple of minutes to get plenty of oil to the cam lobes.

The above procedures should get you safely thru storage. Ideally the engine should be fully broke in (500 miles) prior to any extended storage but this should be acceptable if a full engine break in is not possible. I would not store an unfired rebuild any longer than 6 months with assembly lube alone. Assembly lube is a specialized grease compound and grease does dry out over time. Dried grease has no lubricating properties. If you start a new unfired engine using dried assembly lube then you are highly likely to start wiping cam lobes, spinning bearings and seizing piston rings to cylinder walls.

[myyamr7]

I've bought rebuilt engines in the past that had never been started and had sat for a few years, with no issues. In my opinion only a few steps are needed.
...Try not to store it in a moist environment. Condensation is the biggest cause of corrosion.
...Prime the engine with oil, fill the pan, put the filter on, pull the distributor and turn the oil pump with a prime tool and drill for a few minutes.
...Seal off any access holes to the motor, intake, exhaust, sender units, breathers, etc. Make sure what you put over the larger holes, can't be chewed through by rodents. A simple trick I have seen, a piece of the old metal window screens taped over the holes with duct tape.

[Hawghauler]

If it's out of the truck, and you're only going to leave it for a few months, Just plug the holes, stuff some rags in the exhaust, and leave it. I've never seen an engine suffer from a few months of neglect. I would assume carb is dry since you haven't fired it yet. If not, you should empty the carb. Otherwise it won't hurt it to sit for a few months. If you have it out of the truck, it won't have water in it, so it won't hurt to freeze it. As long as you're not leaving it out in the rain, you shouldn't have any issues. If you are leaving it out in the rain, put a cover over it, tie the cover tight around the motor, and call it a day.

[White70C20]

Thanks guys!