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Old 11-21-2014, 01:35 PM   #1
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Lehman Fuel Injector Replacent

Recently, I purchased a set of rebuilt fuel injectors from American Diesel, and took them with me to La Paz, Mexico, where I keep the boat. My Lehman has 4000 hrs. on the meter now, and although it was running ok, with just a bit of smoke at startup, and a bit of fuel sheen on the water, I figured it was time to replace them.

Bob Smith at AD was very helpful in an MTOA post, explaining the steps and suggesting techniques to make the job easier. Three of the more important suggestions he made: remove the 2 bolts holding the secondary filters and move them out of the way, to provide access to #6 injector. If you don't do this , it would be VERY hard to remove #6; remove the injection tubes as units and invert them in the overturned valve cover to prevent loss of fuel and easier priming when finished; and also to pressure test the fuel return rail connections to check for leaks after reassembly.

Having a rebuilt set of injectors before commencing work was very beneficial. The new set had very small copper washers (1/4" OD) that seal the fuel rail slotted bolts and banjo fittings to the injectors. I knew that I would drop at least a couple washers down a pushrod tube or other inaccessible location, so I stuffed paper towels into all the holes. Amazingly, nothing was dropped! But, I did discover that the previous installation, whether original or by a previous owner, DID NOT include these copper washers! Why the connections did not leak I don't know, or maybe they did, but such a small amount as not to be noticed in the pan oil level. Hence, Bob's suggestion to pressure test the connections after reassembly.

I found that the easiest way to remove the injectors after disconnecting everything, was to use a 7/8" or maybe it was 1" socket, to turn the injectors gently back and forth to break the carbon accumulation on the tip inside the head. Then, wiggle them with a pair of channel locks until they could be lifted out. Each came out with it's old copper sealing washer attached. Don't think they could have been removed by prying with screwdrivers.

Installing the new injectors was straight forward. Each got a new tip copper washer, and 2 return fuel banjo fitting washers. All fittings were torqued to the specs in the Lehman manual. It wasn't necessary to remove the valve pushrods because access was adequate to remove and install all components.

To pressure test the fuel return connections, I attached a bicycle pump to the fitting on the outside of the head and pressurized for a few minutes.

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Old 11-21-2014, 03:50 PM   #2
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Greetings,
Mr. BT. Nice job and good tutorial. Thanks.
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Old 11-21-2014, 04:59 PM   #3
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What model FL?


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Old 11-21-2014, 07:45 PM   #4
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Mr. BT nice job. Do you still have smoke at start up and is the sheen still on the water?
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Old 11-21-2014, 09:13 PM   #5
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Very nice, thanks.
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Old 11-21-2014, 09:55 PM   #6
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Good tutorial - that should also put to bed forever the notion you need to remove the valve train/rocker arm to get the injectors out. If a yard tells you they need to come off they are screwing you.

Also, the new injectors will not stop the smoking or the sheen because that's what Lehmans do, but the engine will be smoother and idle better. You will have less smoke at cruise. Take the old injectors to a tractor shop, not a marine store, for a rebuild so you have a set of good spares.
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Old 11-22-2014, 10:45 AM   #7
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Good article, very nice pix. I have been proven wrong about having to remove the rocker shaft. Now I'm glad I didn't offer any wagers.
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Old 11-22-2014, 02:37 PM   #8
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Thanks for the feedback.

I forgot to mention that this engine is a 1979 Ford Lehman 120.

It was hard to tell about the smoke at startup. It seemed to be a bit less, but maybe that was only wishful thinking. The engine definitely idled smoother afterwards.

The bolts securing the injectors in the head are partially behind the valve pushrods, so you need a u-joint or "wobbly" socket to get to them. I used a 1/4" drive socket wrench.
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Old 12-16-2014, 01:06 PM   #9
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Good article Steve! Now I know who to call when it's time to do mine!
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Old 12-16-2014, 01:50 PM   #10
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Apophyge,

I'm sorry sir, you must have mistaken me for someone else!
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