Technical MOTOR, Awakening a slumbering engine and making sure its still good!

You guys know how it goes. You find that cherry ride in a barn that has been sitting since Elvis was in diapers. Maybe it’s the real deal – an old hot rod. Rode hard and put away wet back in the day – and not started since. Well kimosabe, there are a few thing you really need to know and check before trying to re-fire that old mill.



First off is the history of the engine in question. Was it running good when parked? When was it parked? Where was it stored? Inside, outside, buried under hay, or in the corner of a nice dry warehouse. What is the milage and overall wear on the car. Is it the original motor? Has it been rebuilt? Is it stock? Why was this car parked? Is there any obvious problems? Is there oil in the motor? What’s it look like? Same for the coolant.



The big question is – is this engine any good still?



These are all questions you should know and can usually be either guessed or answered just by carefully inspecting the engine. If the engine looks complete and unmolested, and ran fine when parked all those years ago, you are halfway there.



After checking out the history of the motor, you need to know if it’s stuck from sitting or not. Is she seized up?



First you have to see if the motor will even spin. Remove the plugs. Take some light oil in an oil can and pump about a teaspoon onto the cylinder wall towards the lifter valley on a V8, or on the far wall in a straight 6. Then leave it for a while. Gravity will pull the oil down the wall, and onto the rings, where it will continue down until it hits the lowest spot. This will ensure your rings are oiled all the way around. Make sure the clutch releases and none of the accessories are seized. Removing the belts is a good idea



Now take a breaker bar on the crank bolt and try to spin her clockwise. Make sure she turns over smoothly, and will spin over at least 2 complete turns. If you have an engine line this - pull the distributor cap while you spin the engine over, making sure that the rotor spins. If it does, mark the block where the breaker bar is currently point and start slowly rotating the engine in the opposite direction as before – note how far the bar moves before the rotor starts to move again. This is timing chain or gear slack. If the engine turns over smoothly, and you have less than 10 degrees of slack- you are looking pretty good. If the rotor does not turn – you have problems.



Sometimes you will encounter stiff spots but the engine still turns over relatively smoothly. These are usually caused by a “witness mark” from slight bore rust where water has condensed on the bore by way of an open valve. Usually just working the engine over by manually spinning it will get rid of these spots. Put in a little more oil to make sure the entire bore is oiled and just spin her over by hand.



Other times the engine will only turn a little each way, but grinds to a stop. This is caused by more extensive bore rust usually. You can usually free up the engine by pouring diesel fuel or penetrating oil into the cylinders. Use at most a cup of the stuff. Let it sit for a few days and retry. Make sure you turn it over with the plugs out and rags over the sparkplug holes since the diesel or penetrating oil is going to be coming out! This will also usually loosen up stuck rings. You might have to do this several times to get the engine spinning over smoothly. Usually an engine with bores this rusty will use oil once it is running. You will probally want to rebuild this one.



You can also have an engine that spins over smoothly then suddenly stops and won’t go any farther. Spinning it the other way produces the same results. Sorry folks, but you either have a stuck valve that is hitting a piston, or worse. Check the accessories one last time to make sure that its inside the engine. If it is, you are at least going to have to disassemble the engine to find the problem. Might as well go through the entire thing.



Worst case scenario is that she doesn’t move at all. FILL the cylinders with diesel fuel and let it sit for a few days. Remove the carburator and the exhaust pipes. With all the plugs out, try rocking the engine back and forth with the breaker bar. If it doesn’t move at all after a few weeks – you are just out of luck. You have major problems with that engine. If it does start moving, keep at it until is spins over nicely. This can take several applications.



I have seen this technique used to unsieze a Cat D9 that had sat in the bottom of a lake for three years after it went through the ice. Luckily it wasn’t running when it went for its swim. If it can unseize that – an engine that has been sitting above water should not be a problem.



I can almost hear the next question - “Well – now I have a nice spinning engine….what do I do next?”



Now you get to change the oil and filter to get out any crap sitting in there. Don’t be worried if water comes out of the pan, then oil. That’s just years of condensation. Be worried if what comes out looks like a chocolate milkshake or mayonnaise. That means the engine has been running while there was water in the crankcase. That is bad in two ways. First off, water does not lube bearings very well. Second off, the water had to get in there somehow. That somehow is a problem. Do not refill the engine and leave the oil drain plug out so it can drip and drool into a clean empty pan after the



Drain the radiator if it still has coolant in it. Pull the bottom radiator hose and run the rad through with water for a few minutes to make sure you wash as much crap out as possible. Then pull the thermostat housing and thermostat and run water through the block to wash out as much sludge as you can. Sometimes the sludge is thick enough that it hides leaks like rusted out core plugs and cracked blocks and heads. Leave the thermostat out for now, but check the hoses and replace as nessisary, and reinstall the thermostat housing.



After a good flushing with water, refill with water and leave the cap off. You might notice leaks now. Top it right off and leave it overnight, checking the level regularly. At this time I usually go and rebuild the carburator and replace the fuel pump. Check the next morning. If the water level stays up and there is no water coming out of the oil drain plug, fill her with fresh oil. If you have water leaks – fix them now. Don’t worry about adding new parts to an unknown engine, since if it runs and is in good condition you will have to replace these parts anyways, and if you get it rebuilt – you will have to replace the parts anyways.



Now we get to check to see if the starter is still on the job. 6v or 12V starts will both work fine with a 12v battery. Clean the wiring and look for any obvious problems. Make sure you have a good connection at the battery, starter, and that you have good solid grounds. Remove the coil wire and make sure the plugs are out. Hit the key and see if she turns over with the starter. If not, find out why since you know the engine is not seized at this point.



As soon as you get the engine spinning over merrily, lets see if it builds oil pressure. Take a simple cheap mechanical guage and plumb it to the oil guage port and place it where you can see it. Spin the engine over until you have pressure. It should take under 20 seconds of spinning. Do not hold the starter on for more than 20 seconds at a time since it will overheat, especially if running a 6v starter on 12volts. You might have to spin it several times before the oil pump primes and gives pressure. Remember, if you put anything other than oil into the bores, it will come shooting out the spark plug holes when you turn it over with the starter.



After it has finishes spitting out the sparkplug holes, and is turning over happily with oil pressure – its time for a compression check. Do each cylinder and check against the book values for that engine. Remember that oil has been squirted in the bores and that values will be higher than they usually are. You are more interested in consistency instead of looking for a certain number. All cylinders should be within 10% of each other. If you have a cylinder that has low or no compression – find out why. This is probally going to require digging into the engine.



By now you either have an engine that is waiting to be rebuilt or a spinning engine with oil pressure, and good compression. At this point you are 90% there. While you were waiting to see if there was any water going where it shouldn’t have been, you should have been rebuilding the carb and replacing or rebuilding the fuel pump. Trust me – these are two things that you want to do now. Replace the carb and fuel pump and any rubber line that exists from the pump to the carb. Blow out the hard fuel lines with compressed air and replace the filter. Have a couple spares on hand if you plan on using the stock fuel tank for fuel right now. I recommend using a piece of new line from the fuel pump to a jerry can of fresh gas when getting ready to start the motor.



Now its time to set the timing and do the ignition tune up. Using a piston stop, find true TDC and mark it on the balancer. Line up the #1 cylinder ignition wire on the cap with the rotor. We will set the timing pretty much at TDC to start it up, then set the timing using a timing light. Do a major ignition tune up to the engine – plugs, cap/rotor, wires, and coil. Spin the engine over and make sure there is spark. If not – find out why and fix it! We are ready to start the engine.



Now is time to prime the carb through the carburator vent. Gasoline in a ketchup bottom like used in restarants works great for priming the carb. Hook up the jerry can with fuel in it. Make sure the battery is fully charged. Make sure all tools and rags are clear. Pump the gas a few times, and turn the key! The engine should turn over a few times and light off. Check for leaks. Go and set the idle speed and mix screws. Grab the timing light to set the timing. Watch the open rad and top it up as the air bubbles out of the engine. There should be little or no bubbling after a few minutes. Let it run up to temp and listen for noises, and check everything to makes sure its working. Turn her off and reinstall the thermostat and restart it.



At this point your engine has been tested as good and should be running pretty good. I would change the oil after a few hours running to get any sludge or crap that is floating around in the engine. Then I would not worry about it.



Anyone see any problems or have anything to add? I have done this on a couple old cars and quickly found out if the engine was hurt or was a good runner.

 

Thanks for the tech. Stuff I knew already but have been trying to revive a 303 olds motor and it has a valve stuck. Handy to go over this as a mental checklist.

 

Excellent Post!

I love the everyman tech, something I can sink my teeth into and is applicable for everyone on the board.

Well Done!

 

If you take off the rockers, sometimes you can tap the valve with a hammer and knock it loose.

 

BTTT. Great post.

Cheers,

Drewfus

 

Nice little piece. I'm sure I'll use that in the future.

Woody

 

I've bought cars that sat for over 25 years and if there was gas in the tank... it had turned into "Gellitan Varnish" !

However... the "Worst time to find out that your gas tank leaks is after you put a sizable quantity of gas in the tank and you notice that the floor is getting mighty wet...!!!

And for these reasons I'd use an old outboard gas can to fire it up safely!


They come with a gas gauge, pickup, hose and a "Bulb Pump" (for priming!)

These things are all over the joint in Wisconsin and I often see them at Rummage sales for a "Dollar" and some Marina's will give them to you... especially if you buy the hose from them.

Play it safe until you can properly check your entire fuel system...!

 

Thanks. I saved a copy for future use. I currently have a 350 Chevy that won't turn. I'll give some of this a try.


Bill

 

Thats a very useful article for future use. It'll be nice to have for a "checklist".

 

Good to know, thanx........

 

bttt for a friend..., "Pay attention" this time...!

 

thanx, i will make sure to print this out and put in plastic and put in the garage, good to keep in mind!, heck man you might save a couple of engines of being awakend the wrong way..