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Old 11-18-2013, 09:17 PM   #1
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Slow cranking lehman 120

I have two Lehman 120 engines with 12 volt starters. Both are rebuilds and crank very slowly even with two batteries.

I series the batteries on one engine to get 24volts and it turned fast enough to start the engine. Any wisdom before I burn up the starter.
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Old 11-18-2013, 09:25 PM   #2
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Check (in this order) batts, connections, cables,. Don't forget to check the connections at the switches. Check for heat, indicating a bad connection after cranking.

Really check the batts. perhaps a load test if you can.

You have low voltage getting to the starters, check what it is while cranking (at the starters).

Luck
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Old 11-18-2013, 09:29 PM   #3
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The engine I am trying to start is not back in the boat yet. I trying to discover any issues before opening the boat to reinstall.
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Old 11-18-2013, 09:31 PM   #4
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I was just admiring your Pilgrim 40 in another area of the forum, really classic look, very nice.
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Old 11-18-2013, 09:55 PM   #5
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Thank you.

I would then have the starter gone over by a rebuild shop, it's a truck motor after-all so take the starter to an auto starter shop to check it out. It will be a bunch easier now then after installed.
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Old 11-18-2013, 10:02 PM   #6
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Quote:
Originally Posted by SCOTTEDAVIS View Post
Thank you.

I would then have the starter gone over by a rebuild shop, it's a truck motor after-all so take the starter to an auto starter shop to check it out. It will be a bunch easier now then after installed.
Ditto here. If it checks OK, then next would be to see if the battery cables are "dropping voltage" under a load- I'm sure the batteries have been checked? PM me if you want some direction on the voltage drop test. New rebuild. Just one engine? When you got it started did it run OK? Just wondering about crank bearings too tight, etc.
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Old 11-18-2013, 10:09 PM   #7
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The first engine started and ran fine and is back in the boat. The second has yet to fire up, I was planning the 24 volt kick tomorrow to get it started unless someone talks me out of it. I bought both starters new as part of the rebuild.
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Old 11-18-2013, 10:59 PM   #8
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Welcome aboard Bryan,
If you're sure the battery is top line and the leads are all good?, the I'll 2nd Forkliftt, a rebuilt motor is probable tight, Lehman's are slow to crank at the best of times.
Now when I was a youngster... back when Pontius pilot was still a first officer!!
we used the old fix of heating up the oil, you could try that!, it's amazing how fast it will crank over when the oil is hot...ok guys so I'm old, but don't discount the old methods
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Old 11-18-2013, 11:02 PM   #9
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how did you heat up the engine oil?
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Old 11-18-2013, 11:13 PM   #10
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Well for the big radial engines on the aircraft we had a tank with a heater element, for the smaller motors we just drained the oil pan and warmed it up on a stove...don't let your wife catch you!!
My last tractor, a Ford 8000, had a Lehman..well basically the same thing, I wouldn't even bother trying to start that on a cold day unless the block heater had been on for a couple of hours, after that, one touch of the key and away she would go.
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Old 11-18-2013, 11:15 PM   #11
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Bryan,

I have 2 Lehman 120's on my boat & the Port side was slow to crank since I bought the boat. I load tested the batteries they were fine. I checked all the wiring connections and discovered a bad connection on a small wire to the solenoid. Fixed the loose connection and she cranks like a dream. Good Luck!
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Old 11-21-2013, 08:13 AM   #12
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Battery cables can be VERY deceiving...meaning they can look pristine, but have a bad connection/solder job inside a lug, and drop a large amount of voltage. I was troubleshooting a similar situation once. Put my meter on the batt post, measured 12.5v to ground. Other end of the cable, 7.5v to ground. What the heck?
Took the cable off, wiggled the lug really good...and the dreaded white powder indicating corrosion came out. New cable, good to go.

For heating up the oil, place a small 1500watt space heater so that it blows onto the oil pan for a few hours.

Jim
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Old 11-22-2013, 05:36 AM   #13
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One of those heat guns will help find every bad connection.

Crank for 30 seconds , and shoot every connection from the batts to the starter..

Clean the hot ones.
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Old 11-22-2013, 11:38 AM   #14
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I would suspect what you have done to hook them up out of the boat. The batteries need to be large enough (not some spare car battery. The cables need to be 2-0 size (no jumper cables). Tha battery needs to me fully charged and all connections need to me made properly. I like the ground cable to go right to a starter mount bolt.
I looked at a boat once the cranked so slowly that the owner kept a can of starter fluid in his drink holder... It only took us 2 hours to correct the problems so it would whirl over and start. Unfortunatly he had already blown the head gasket w/ the starting fluid.
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Old 11-23-2013, 03:08 AM   #15
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I would not hook up MY 12V starter to 24V.
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Old 11-23-2013, 05:31 AM   #16
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>I would not hook up MY 12V starter to 24V.<

This is done all the time with hot rods with very high compression .

A kit is made to only do the connection when the key is in start , and it seems not to bother the starter a whit.
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Old 11-23-2013, 06:38 AM   #17
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Cable size is a function of length...if the battery is right next to the starter anything thicker than 6 ga will be fine for normal crank times....on a Lehman with a 2.8kW starter.

Good connections are key...

If one is rotating so slow it isn't starting and you have swapped starters and cleaned up properly sized cables...it may not be in the electrical side of the house...
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Old 11-23-2013, 09:56 AM   #18
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How is the one you started running and starting? Will it start with 12V only now?

I suspect since they are new rebuilds something is too tight with the engine and the starter is doing it's best. This isn't uncommon with rebuilds either. I'd try spinning the engine by hand and compare it to the other engine as to tightness. It might save a starter.
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