40EL75 Rebirth

[oldrem]

Before I spend too much on parts, I was hoping to get a compression reading on the cylinders. I replaced a bad neutral safety switch, but found the solenoid to also fail testing. I first tried to compression test by using a rope to manually crank the engine, but this old fart can't pull fast enough to get a reading over 60 psi
(single pull).

I tried running jumper cables directly from the battery to the starter, but can't even get it spinning as fast as I did with the rope.

The battery is a 6 month old 625 crank amp marine battery with full charge.

Next, I yanked the starter and ran it on the bench. It runs full bore like it should, though I know it's not load testing.

I'm figuring my next step is taking the battery to get a load test. If that passes, where go I go from here? I was hoping to not invest in a starter unless I know compression is good. Catch 22?

 

[jbuote]

Still pretty new here, but do you have a known good battery you could jump the starter with? (While installed on the engine)

Load testing the battery is the next step I'd take too, since most auto stores would do it for free.. LOL

Either way, if a known good battery (yours load tested or another one) still can't turn the starter properly, then I'd be suspect of the starter..
Would removing the positive lead on the starter (from solenoid) before you jump it make a difference?
Not sure it would, but just a thought off the top of my head...

 

[oldboat1]

Battery or connections, sounds like. For compression testing, remove both plugs. Pull it over until the needle on the tester stops rising (4 or 5 pulls or so), make a note of the number and move on to the next cylinder. Kind of a big puppy -- need a solid stand for pulling it over, or on the transom of the boat.

 

[oldrem]

Thanks for the input. I'll take the battery in for testing tomorrow. If it tests good I'll pick up some new jumper cables (the ones I was using are about 40 years old and have some corrosion I tried to wire brush off), reinstall the starter and give it another go. I'll also try multiple pulls with the rope.

Meanwhile, I had noticed the pinion was a bit sticky, so I inverted the unit tonight and did some degreasing and re-oiled with some 3-in-one. That part is much happier now and works freely like it should. I'm leaving it inverted overnight so no excess oil can get into the motor.

 

[F_R]

Must have tool for diagnosing that kind of stuff = a multimeter (voltmeter). If you don't have one, get one. If you don't know how to use one, learn. You also will learn a lot about electricity as you do. They can be bought for less than you've already spent on parts that might not even be bad.

 

[oldrem]

Must have tool for diagnosing that kind of stuff = a multimeter (voltmeter). If you don't have one, get one. If you don't know how to use one, learn. You also will learn a lot about electricity as you do. They can be bought for less than you've already spent on parts that might not even be bad.

Yep, I have 4 of them. That's how I found the bad neutral safety switch and solenoid. Invaluable tool. I own a small computer shop and use them almost daily.

 

[oldrem]

OK, here's where I'm at.

1) had battery tested at O'Reilly and told it was good
2) picked up new set of solid copper 4ga cables
3) thoroughly cleaned all contacts and applied light coat of Noalox
4) applied light coat of white lithium grease to the gears
5) reinstalled starter motor
6) applied power and it spins beautifully
7) ran compression tests

I'm not looking for great speed from this motor. Can I get by with compression readings of 88 and 89? (at least both were consistent), assuming my cheap compression tester is accurate.

I tested the coils and both tested bad. Lord knows how much more I'll be finding as I go, but want a decent running motor when I'm done.

 

[jbuote]

Hmmm...
Not a pro, but 80 and 89 sounds low....
I think compression on a 40 of that year should be at least 100, but closer to 130-140 is better...
Not positive on the upper range....

Pretty confident that your numbers are low and you may want to check out why... Could be rings, or cylinder wall scoring...
But please don't think the worst from what I mention.

One of the more experienced folks here will be along soon I'm sure, and will let you know for sure what the real deal is... (and I could be wrong...)
I'm going to follow along though, and keep learning myself..

Hope it helps a little... lol

 

[flyingscott]

Do you have spark? If So Put it in water hook up the gas and see if it runs. If it starts make sure you are pumping water.

 

[oldrem]

Do you have spark? If So Put it in water hook up the gas and see if it runs. If it starts make sure you are pumping water.

both coils failed testing - no reading from ground to the spark plug wire, plus there was rust inside both boots. So put simply, no way to test ignition at this point

 

[flyingscott]

Put a spark tester in the boot and see if you have spark. Clean the points and re-gap them and see if you have spark. A small round wire brush and penetrating oil to clean the inside of the boots. The fact you have rust in the spark plug boots tells me the motor sat for a while lube the cylinders and let sit overnite and re-test the compression.

 

[oldrem]

Put a spark tester in the boot and see if you have spark. Clean the points and re-gap them and see if you have spark. A small round wire brush and penetrating oil to clean the inside of the boots. The fact you have rust in the spark plug boots tells me the motor sat for a while lube the cylinders and let sit overnite and re-test the compression.

The spring in one of the boots was rusted tight to the plug and broke when I pulled it off. I stuck the probe deep into the wire stub when I ran the ohm test. I can try cleaning the other next weekend. I will try an overnight soak of the cylinders. Is Blast ok to use? How long can I let it soak - would a week be ok?

My son-in-law is going to lend me his better compression tester next week to see if my cheapy is reading low. It sucks still having to work 6 days a week at my age

 

[flyingscott]

You are only going to make sure that the piston rings are going to be lubed with the oil. You want oil in the cylinders to do a proper compression test. You have to let it sit overnite to let the excess oil drain out or you will get a false compression reading. It wouldnt hurt to spin it over a couple times to clear the excess oil also. Have you looked at the points and condensors you have the low tension magneto they are notorious for no spark with dirty or incorrectly tapped points. To do a spark test on the broken wire strip the insulation back 1\4/ " and wrap that around the spark tester. Proceed with the test.

 

[boobie]

Edit....

 

[hardwater fisherman]

If there is rust inside the plug boot ,then probably the other end of the lead inside the coils are in poor shape. Those coils are pretty hearty. And not likely to both fail at the same time. If you twist and pull out the plug wires from the coils, and then test them directly from the pin inside the coil then you might find them to be okay. I am by no means an expert but I found the same thing while testing the same coils. If the coils test okay as I suggested cut back the lead on both ends. Or better yet get some new 7mm copper core plug wire. I have 4 of the same coils and two of them failed the ohm test at the plug boot and where ok at the pin inside the coil. And after I put new leads they both passed the ohm test at the plug boot. I agree with flyingscott that most often with that ignition,loss of spark is due to the points. If you choose to remove the leads from the coils just twist them while pulling. And to reinstall just push them in and twist. After you have installed them just gently pull them without twisting. And if they stay then they are installed correctly.

 

[oldrem]

If there is rust inside the plug boot ,then probably the other end of the lead inside the coils are in poor shape. Those coils are pretty hearty. And not likely to both fail at the same time. If you twist and pull out the plug wires from the coils, and then test them directly from the pin inside the coil then you might find them to be okay. I am by no means an expert but I found the same thing while testing the same coils. If the coils test okay as I suggested cut back the lead on both ends. Or better yet get some new 7mm copper core plug wire. I have 4 of the same coils and two of them failed the ohm test at the plug boot and where ok at the pin inside the coil. And after I put new leads they both passed the ohm test at the plug boot. I agree with flyingscott that most often with that ignition,loss of spark is due to the points. If you choose to remove the leads from the coils just twist them while pulling. And to reinstall just push them in and twist. After you have installed them just gently pull them without twisting. And if they stay then they are installed correctly.

Crap, wish I'd had that advice before lol. I pulled both coils Monday night and did a bench test. One was totally dead at the plug wire so I tossed it - recycling center has it now (they picked up today). The other tested marginal, so I kept that one. As you stated, probably just needs a new wire? Is that available at an auto parts store?

I will need to get at least one anyway now. I already ordered new points and condensers.

Hopefully I'll be able to run another compression test late Saturday or early Sunday to either confirm or hopefully void the first tests. Either way I'm going to pull the head in a week or two, so I'll get a good look at the cylinder walls. I ordered a new head gasket in hopes of the best.

 

[flyingscott]

If those are the original coils you cannot replace the plug wire on them as they are part of the coil assembly. The newer style coils have replaceable wires.

 

[hardwater fisherman]

I am pretty sure that the original coils can have the wires replaced. Because I was able to replace them on one that I know is not a replacement. And the one in the photo is a dead coil that is apparently the factory coil. You can see the screw that accepts the plug wire. If you are correct then I have 2 coils that are bright blue with black painted frames . And I have 2 faded blue ones with flaking green paint. But they are all replacements? EDIT I have another old one like in the photo with a new plug wire that I have tried and works. I keep it as a spare. But I cant find it at this moment.

 

[flyingscott]

Somebody ground those out either you or somebody else. But they were epoxied in as part of the coil very seldom does a solid core wire go bad. Usually the coil will fail internally or the exterior is cracked..

 

[hardwater fisherman]

Then the screw that holds the plug wire is just for show?