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.

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.

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.

Ken

Greetings,
Welcome aboard.

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!
Regards,
Nick

Have you talked to Brian at American Diesel? He is the guru.

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?

N97746 said:

Where did you have the throttle at start up?

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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.

Regards,
Nick

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.

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.

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.

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.

I agree bleed the injectors. Sounds like air in the system someplace

Does the engine have a glow plug?

Perhaps the cold start controls the glow plug?

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.

Comodave said:

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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What does your mechanic say about your problems?

OldDan1943 said:

What does your mechanic say about your problems?

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The only problems I have now is Covid and a poorly cooling refer. We sold the boat with the Lehmans in it last year.

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?

N97746 said:

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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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.

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.

I would suggest bleeding at the IP outlets then at the injectors. These old gals are a bit temperamental about air in the lines. Also make certain that there are no leaks ahead of the lift pump, anything there and you are fighting a losing battle.

The cold start is actually a form of fuel enrichment. On the old style manual systems you would advance the throttle to full, pull the cold start knob to activate then put the throttle back to it's normal starting position. Tried that a few times but it was just as effective to advance the throttle during startup.

Can someone help me better understand this cold start device? I haven't heard of such a thing before, but I also have no experience with Lehmans.


With a governed engine, which I presume the Lehman is, wouldn't the governor be calling for full fuel, or at least increased fuel while starting, without any need for assistance from some other device?


And of course the whole fuel/air mixture/richness things is different with diesels vs gas engines. More fuel makes it go faster, but doesn't change the mixture in a way that makes it more or less explosive as it does with a gas engine.


So curious to understand it, and whether it's unique to Lehmans, or if other engines have such a thing. I've heard of intake air heaters, of course glow plugs, and even ether injectors. Also engines that start on gas, the switch over to diesel. Not a pony motor, but an engine that burns both gas and diesel, but gas only to get it initially started. I used to run an International tractor that worked that way.

My old 1991 Dodge/ Cummins pickup had an enrichment device that would inject fuel during start up. It would always have a small puff of blue smoke at startup.
It also had an intake air heater that would turn on for ambient temps under 50 F 2 separate systems.
I never used a cold start on my Lehman not sure if it even had one.

twistedtree said:

With a governed engine, which I presume the Lehman is, wouldn't the governor be calling for full fuel, or at least increased fuel while starting, without any need for assistance from some other device?

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This exactly my doubt, too.

I would love to dismantle one of these injection pumps to see exactly what this little button actually does.

I can't say exactly what the injector cold start button does but, since finding out about it here, I use it almost every time. It has become part of my ER check list. Before starting the check, I put the helm throttle all the way forward. As I do the ER check, one of the things I do is push the button. Then I leave the throttle forward to show me that the ER check was completed. Bothered me at first seeing the throttle left balls to the wall, but I got used to it now that I know it is telling me something.

The cold start button seems to do something similar to a full throttle start, but also seems to be a quicker start and accurate at throttling back. When starting, I set the throttle just a bit above idle, push the start button, and the engine instantly fires at about mid-throttle and drops back to just above idle without any input from me. No need to time when to throttle back. Perfect every time. Maybe it's magic.

I have cable cold start and what it appears to do is increase the idle set point. As said, throttle forward, pull the cable and return throttle and the rpm is higher on start.
Frankly after determining that I just push the throttles to approx. 1000 rpm position and they start on 2nd or 3rd turn. (sometimes I am at 1500, throttle back to 1000)
I guess the button activates a solenoid which moves the idle position.

Soo-Valley said:

I guess the button activates a solenoid which moves the idle position.

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No solenoid - the operation of the button is entirely mechanical.

It sounds like the throttle advance for starting a chain saw.

Nick F said:

No solenoid - the operation of the button is entirely mechanical.

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Not on our last boat with Lehmans. The cold start button was on the flybridge and when you activated it you could hear a click in the engine room.

Ford Lehman's do not have glow plugs. The cold start button is pressed in, hold it in while pulling the fuel stop lever on the injector pump towards the right, and then all the way back again (towards the gearbox end). The cold start button will thus stay in.

There are two bolts on the face of the injector pum, at opposite ends. Crack these open. Pull the throttle lever towards 3/4 open.

Crank. Fuel with air bubbles will emerge from the two bolts. When it's more fuel than bubbles, tighten the bolts as you continue to crank. The engine will fire up, give it a couple of seconds before backing off the throttle.

In 16 years I've never ever touched the injector lines to bleed. The two bolts on the injector pump is always enough to do the job.