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Starting flat-head 6 after rebuild question.


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Posted

I have a 48 DeSoto 3w coupe with a rebuilt engine. Trouble is it was rebuilt in the 80s but never started. It still turns over when I put a 1 13/16" socket on the crankshaft bolt. I've been told to go ahead and start it up, but a friend of mine said that it is essential that the camshaft bearings are greased before you start it. They were greased with lithium lube, but that was 30 years ago! Should I disassemble the engine to re-lube this area, or is there a way to deliver oil to these areas by turning the oil pump with a drill to produce oil pressure before first start up? Thanks, Marc.

Posted

I made up a primer oil pump by grinding off the gear teeth so I could install it in the engine and spin it with a long flat bladed screw driver in a drill. Primes my rebuilds easy and fast. The one shown is for a straight eight Chrysler.

You just need to find an old oil pump!

Posted
if ya feel the engine was stored well enough that no corrosion has build up on the sensitive areas, then disconnect the ignition and crank the starter to build oil pressure before startup. Otherwise, disassembly + cleanup + assembly lubrication may be in order.

If you pull the spark plugs out there won't be any compression and the load on the bearings will be very low while you are cranking it over getting some pressure to show on the gauge. And there will be less load on the starter too.

Posted

Or, you could pull the oil pan and look in there to see how rusty/lubey cam and lifters are.

How about a preluber made from a garden pump sprayer?

Posted

Perhaps you have a new oil pump too . Vintage Power Wagons recommends completely submerging the pump in clean oil and turn the shaft by hand until there are no more air bubbles . Then crank the engine until you have pressure on the gauge .

Posted
I made up a primer oil pump by grinding off the gear teeth so I could install it in the engine and spin it with a long flat bladed screw driver in a drill. Primes my rebuilds easy and fast. The one shown is for a straight eight Chrysler.

You just need to find an old oil pump!

OK, I've got an old pump. So, if I understand you, after grinding off the gear teeth, you bolt up the pump and then come at it through the distributor hole. Correct? Does it matter which way the drill spins?

Posted
OK, I've got an old pump. So, if I understand you, after grinding off the gear teeth, you bolt up the pump and then come at it through the distributor hole. Correct? Does it matter which way the drill spins?

Yes. You should spin it the same way your see the distributor rotor rotating. The other way would try to pump oil from the engine and put it into the pan.

Posted
Yes. You should spin it the same way your see the distributor rotor rotating. The other way would try to pump oil from the engine and put it into the pan.

Clockwise, right? Thanks...

Posted

If you're going to try priming-you've got to spin the engine while doing it or you'll just hydraulically bind up the pump-unless your bearings are badly worn. The staggered oil passages need to line up in order for oil to pump through the engine. You can do this with a breaker bar on the crank pulley, or if you've got the spark plugs out-probably grab hold of the fan and turn the engine from that. Mike

Posted

Don't the main bearings have grooves around them to quickly get oil to the crankshafts drilled oil holes sending it on to the cam and rods? Also the pressure releif valve could dump excess pressure if there was any.

It is a good idea to turn it over a bit to also line the front cam hole up with the timing chain nozzle to get oil on the chain if your'e concerned enough. A oil pressure gauge should be part of the priming procedure to check the oil pressure.

Posted

This is a very timely discussion, as I will be starting my fresh rebuilt engine next month.

As long as all the rotating parts are coated with plenty of assembly lube, would it not be reasonable to forget the second pump and drill etc. and prime the pump and build up initial oil pressure by simply pulling the plugs and cranking over the engine — as Todfitch suggested upthread?

12-volts could be used for this brief time for quicker results.

Posted

Thats the way I'd do it.

Posted
This is a very timely discussion, as I will be starting my fresh rebuilt engine next month.

As long as all the rotating parts are coated with plenty of assembly lube, would it not be reasonable to forget the second pump and drill etc. and prime the pump and build up initial oil pressure by simply pulling the plugs and cranking over the engine — as Todfitch suggested upthread?

12-volts could be used for this brief time for quicker results.

Yes with a fresh rebuild thats the way to go. If I had an ancient rebuild like the original poster I might try something extra. The engine in my truck is in my truck instead of Dads 51 ply because it only lasted 172 miles after a rebuild which had sat around the resto shop for about a decade.

Posted

mine built pressure almost immediatly, and pushed 35psi after about 10 rotations. I don;t think you will have a problem as long as pressure starts to show on the gauge. If you don;t see it start to build, then don't crank it until you find the problem.

But do spin it with the coil wire out of pull the plusg so it doesn't want to start on 9.

Posted
mine built pressure almost immediatly, and pushed 35psi after about 10 rotations. I don;t think you will have a problem as long as pressure starts to show on the gauge. If you don;t see it start to build, then don't crank it until you find the problem.

But do spin it with the coil wire out of pull the plusg so it doesn't want to start on 9.

It took me a while to find the issue with mine not showing pressure on the gauge... After pulling, checking and replacing lots of parts I found that the one piece of tubing on the entire car I had not replaced, the line from the firewall to the dash gauge, was clogged. Engine had plenty of pressure it just wasn't showing on the gauge.

Don't need to pull the coil wire if you've pulled all the plugs to eliminate the compression so the dry bearings have no load on them and the starter has an easier time of it.

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