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Old 07-03-2022, 06:19 PM   #1
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Reviving a comatose Lehman

A brief history first. I was told the boat motored out to it's mooring five years ago and would not start for the rest of the season. It was hauled out and sat on the hard for the last four years. That's when I came along.

On examining the engine I found that the line from the primary filter to the lift pump was plugged solid. Delaminated? I've replaced the primary filter set up, all fuel lines, new secondary filter. The lift pump "looked" OK, no tears in diaphragm that I could see so I reinstalled it. I also pulled the head, checked cylinder bores, new head gasket, checked valve clearances. For the trial start I bypassed the fuel tanks and used a clean five gallon jug. I used a priming bulb to bleed primary and secondary filters ending with a clean bleed of the IP. I was hoping I could bleed the injector lines with the engine cranking.

Here's where it gets a bit odd. I would do five second spurts with the starter and after about a minute or so you would get a couple fast spins like it was starting to catch. thought I might try the cold start switch. Pressed it in, manual no solenoid, and after a revolution or two fired right up. But it went to a full race, thought I had a runaway, then died in a second or two. without the cold start engaged it would not fire up, would only spit and spin faster. with cold start maybe idle for a half second then race and die. Throttle was at 1/4 to 1/2 open, stop control lever in full run position.
After the third episode of race and die decided to check the forum for answers.

Thanks in advance for any help.
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Old 07-03-2022, 06:43 PM   #2
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You may have an injector pump problem. First, check oil level in injector pump. Oil should be changed every 50 hours. Yours is probably way overdue. Your governor may also need to be tuned. Get the shop manual. Search for youtube videos on what to do.
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Old 07-03-2022, 06:56 PM   #3
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In addition, I would recommend manually bleeding each injector. Not only May it significantly help, but it will at the same tell if you if the injector pump is at least basically working.

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Old 07-03-2022, 07:12 PM   #4
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Greetings,
Welcome aboard.
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Old 07-03-2022, 07:18 PM   #5
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My engine (I have since sold the boat) would never start from cold without using the cold start button. Same as for you, the engine would start instantly and race. I would pull the throttle back quickly and the engine would then often die. On the second attempt I was usually able to keep it running. Once running, it worked perfectly.

I posted a question last year to the forum, asking what the cold start button actually does, but no-one seemed to know.

I suspect the cold start problem may be a priming issue, or a bit of air somewhere, but I have sold the boat and may never discover.

I know that some Lehmann owners do not have to use the cold start button.

Good luck!
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Old 07-03-2022, 07:21 PM   #6
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Have you talked to Brian at American Diesel? He is the guru.
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Old 07-03-2022, 08:32 PM   #7
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gsholz, I didn't mention but I did do an injector pump oil change before attempting a start. Also did an engine oil change while I was at it.
kchace, was hoping not to have to do an injector bleed unless all else fails. Sort of hate to undo all my nice tight connections. But if I have to ....
Comodave, Have spoken with Brian before regarding the top end overhaul. Tried calling him about this but keep getting a busy signal. Plus, after lurking on the forum quite a while I'm impressed by some of the knowledge right here.
Nick F, From what I've read, the cold start button adds extra fuel when activated but as soon as the engine fires up it snaps back to the off position. Early fuel injected cars had a separate cold start injector. Newer ones have it built into the computer program. Interesting that your old engine did the same racing routine that mine is doing. Where did you have the throttle at start up?
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Old 07-03-2022, 11:32 PM   #8
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Where did you have the throttle at start up?
I had it at maybe half throttle. You have to have it well away from idle otherwise the cold start button will not stay in.

I was also informed that the cold start increased the fuel quantity being injected - I dont understand why max throttle (without cold start) would not do the same thing. I also dont understand why the cold start is not required for a restart later the same day.

I wonder if the explanation could be that the injection pump is partly worn such that it does not inject properly at cranking speed, but does inject properly at engine running speed. This explanation would seem to fit the symptoms.

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Old 07-03-2022, 11:35 PM   #9
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You have to bleed the injector lines. If there's air in the lines, it compresses, doesn't move the fuel along, and the fuel in the injector never reaches a high enough pressure to overcome the spring loaded valve in the injector. So no fuel to the cylinder.
Just loosen all the tube nuts and bleed all at the same time. Place rags around the injectors. Dish soap and water will clean up the diesel later.
You bleed all at the same time so the pressure is too low for any injector to open. Doing one at a time may cause the engine to start with a tube open and a bigger mess.
As the pressure builds in the fuel gallery near the injector tip, it forces the needle valve open. There needs to be nearly zero air in the line. Otherwise the air just compresses, no fuel moves, no spray, no start.
You may need some heat, too. If compression is low.
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Old 07-03-2022, 11:44 PM   #10
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We never bled anything except the secondaries. Never bled the individual injectors. We would bleed the secondaries and then do a cold start and they would fire right up. We would push the throttles to full throttle, then push the cold start button, then return the throttles to idle and push the start button.
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Old 07-04-2022, 07:11 AM   #11
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Nick, When digging through the paperwork on the boat I found receipts for the IP rebuild. They were dated about 11 years ago, but the boat hasn't run for the last 5 years.
Lepke, Thanks for the great pic of the injector inner workings. However, not knowing much at all about these engines, I would think if air in the injector lines were the problem it wouldn't run at all. I would not get that rapid racing situation after using the cold start button.

Again, being a complete noob when it comes to this engine, I'm wondering if perhaps the IP isn't getting enough fuel from the lift pump? I have no reason to suspect this and don't want to go wandering down the wrong path throwing money at things that may not need to be fixed.
Didn't mention this and don't know if it will add any more information, but on one of the cold start button start ups, it started as a nice idle for 4-5 revolutions then with no throttle input went into the rapid racing scenario, then died.
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Old 07-04-2022, 07:36 AM   #12
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I wouldn't discount what Lepke says. bleed the injectors, cheap and easy. Experience like his is why you said you came here and posted.
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Old 07-04-2022, 11:14 AM   #13
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I agree bleed the injectors. Sounds like air in the system someplace
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Old 07-04-2022, 11:31 AM   #14
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Does the engine have a glow plug?

Perhaps the cold start controls the glow plug?
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Old 07-04-2022, 01:21 PM   #15
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No glow plugs. My understanding of the cold start is that it sets the engine to a fast idle, that is what the mechanic told me.
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Old 07-04-2022, 01:43 PM   #16
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No glow plugs. My understanding of the cold start is that it sets the engine to a fast idle, that is what the mechanic told me.
What does your mechanic say about your problems?
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Old 07-04-2022, 01:46 PM   #17
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What does your mechanic say about your problems?
The only problems I have now is Covid and a poorly cooling refer. We sold the boat with the Lehmans in it last year.
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Old 07-05-2022, 10:48 AM   #18
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Thanks to all that chimed in. I'm away from the boat at present but should be able to work on it next week. I'm thinking I will start at my temporary fuel tank and bleed everything up to and including the IP. Next I will do as suggested and bleed the injector pipes.
Question on bleeding the pipes. You back off the large nut that retains the oil seal, then loosen the small nut that holds the pipe to the injector. Will just loosening the small nut a few turns be enough? Where will the fuel that hopefully leaks out end up? Should I pull the valve cover to mop up any fuel or will it just run out external to the engine?
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Old 07-05-2022, 11:06 AM   #19
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Quote:
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Question on bleeding the pipes. You back off the large nut that retains the oil seal, then loosen the small nut that holds the pipe to the injector. Will just loosening the small nut a few turns be enough? Where will the fuel that hopefully leaks out end up? Should I pull the valve cover to mop up any fuel or will it just run out external to the engine?
Just loosen the small nut - maybe a quarter to half a turn. The fuel will leak out right there (outside the valve cover). Wrap a rag around the loose nut to contain the mess.
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Old 07-05-2022, 12:05 PM   #20
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That certainly seems doable. Boy I would love to have engine access as shown in your pic. I didn't mention that the engine in question is in a vintage wooden lobster boat. There is an engine box fairly tight on either side and the main bulkhead divides the engine with cylinders 1-3 down below in the cabin, while 4-6 are back in the house.
Look forward to giving this a shot and seeing what happens. Either way, will be reporting back.
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