Lehman Filter Changes

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CharlieO.

Guru
Joined
Sep 21, 2020
Messages
1,670
Location
Lake Champlain Vermont, USA
Vessel Name
Luna C.
Vessel Make
1977 Marine Trader 34DC
Ford Lehman 120.

Changing all filters on the engine, fuel filters, Racor filter and oil change. Also changing oil in injector pump and have a new rocker box gasket to install.

This is my first time doing these tasks, anything I need to take into consideration before I start? I have one of those West Marine manual pumps for getting the oil out.

Thanks
 
I did it once with a manual pump. Then I bought a 12 volt gear pump - :)
 
I use a manual pump on mine. Warm engine a few minutes. Filter on mine is upside down and that sucks.
 
The secondary fuel filters have gaskets that look sorta like O rings but they aren’t O rings. Make sure they are not twisted. Also make sure you get the old ones off since they may stick up inside the filter housing. You don’t want 2 gaskets there because they will leak.
 
If you are going to change the valve cover gasket, do a valve clearance check while in there.
 
And don’t crank the valve cover down too tight, they are easy to bend.
 
The secondary fuel filters have gaskets that look sorta like O rings but they aren’t O rings. Make sure they are not twisted. Also make sure you get the old ones off since they may stick up inside the filter housing. You don’t want 2 gaskets there because they will leak.

AKA “square o rings”. Like the ones on an oil filter.
Another caution is to not tighten the oil plug on the injection pump too much. Snug is good as the housing is relatively easy to strip out.
 
The oil in the Minimec needs to be changed every 50 hours. It is not that complicated, but it is difficult to get to the bolts.
There is one bolt on top of the fuel pump, one on the side and one on the bottom. After many experiments we now take the bolt of and put a hose with a small funnel below when the bolt is out. About 4.5 cups of oil will come out and once it is drained you use just normal engine oil as the new oil. Go slow with filling the last cup. As soon as the oil comes out of the opening where the middle bolt is sitting, there is enough oil in the pump.
I would suggest to really stick with the 50 hours and not go to the 100 hours as sometimes is suggested.
 
Thanks all. I do have the original manual to read also and I ordered all my parts from American Diesel to be sure I got the right parts. I am looking forward to getting up close and personal with our Lehman.
 
I was in the last seminar that Bob Smith taught. As to the oil change interval on the injection pump, he said change it at 50 hours and see if it is diluted with diesel. If it isn’t then extend the interval to 60 and see if it is diluted. If not then try progressively longer intervals up to 100 hours. He didn’t recommend going past 100 hours. But if the oil isn’t diluted at a shorter interval then changing it isn’t necessary. He said each engine is different so you just have to see how your engine works. One member in the class said his 2 Lehmans were different, one he had to do at 50 and the other was fine to 100 hours.
 
The secondary fuel filters have gaskets that look sorta like O rings but they aren’t O rings. Make sure they are not twisted. Also make sure you get the old ones off since they may stick up inside the filter housing. You don’t want 2 gaskets there because they will leak.


They won't just leak. They will spray oil far and wide. Don't ask.
 
The oil in the Minimec needs to be changed every 50 hours. It is not that complicated, but it is difficult to get to the bolts.
There is one bolt on top of the fuel pump, one on the side and one on the bottom. After many experiments we now take the bolt of and put a hose with a small funnel below when the bolt is out. About 4.5 cups of oil will come out and once it is drained you use just normal engine oil as the new oil. Go slow with filling the last cup. As soon as the oil comes out of the opening where the middle bolt is sitting, there is enough oil in the pump.
I would suggest to really stick with the 50 hours and not go to the 100 hours as sometimes is suggested.
You mean like Bob Smith recommended?
 
The oil filter adapter is typically mounted to the engine with 2 bolts and has flexible oil lines connecting it to the engine block and oil cooler. If there is sufficient slack in the oil lines you may be able to unbolt the filter adapter from the engine and tip the filter horizontal when you change it. Put a paint can or coffe can under it to catch the oil. If you change the oil lines make the new ones long enough to mount the filter the right way for easy changes.
 
Pretty sure my fuel injection pump only took 16oz of oil....that might vary a bit but that's where it started coming out the side overflow hole/plug on mine. JLeonard is correct to be sure you don't strip the drain plug hole (don't think you can suck it out)...mine was bad when I first got it and had to tap it on the snowbird trail... a PIA.

That was one way to know if there was fuel dilution, increase in removed oil so the first time I drained it into a container and marked it with a sharpie.

That drain hole is easy to check anytime and the few drops that may come out can be "blotter paper" checked for fuel dilution if concerned. In my opinion, the fuel dilution issue was for high time injector pumps and a waste of time for many....as long as you are aware of fuel dilution and check for it. The 50 hour change "suggestion" I believe was for typical boat owners who neglect certain maintenance issues.
 
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I started at a 50 hour change interval but quickly went to 75 then 100.
I used a plastic measuring cup and marked a line at the proper volume per the manual(I forget what that was). Then when I drained the oil I could see if the volume was the same.
It always was.
I could also use the sniff test to determine if I thought it was diluted. I never thought it was.
When I refilled I would fill the measuring cup to the line I marked then put it in the pump.
And the used oil would go into a fuel tank unless I was changing engine oil at that time.
Right or wrong that worked for me.
 
Have a couple oil absorbing pads available and a really small funnel for refilling the secondary filters, you can use the lift pump but it is a slow process. Also have a couple gallon size ziplock bags available for when you change the racor filters.

pete
 
On our last boat I put the Racor priming pumps in the Racor filters. It made priming the secondaries a breeze. Change the filter and then crack the bleed screw. Push the ptiming pump button and in a couple of seconds it was bled. Close bleed screw and done.
 
I use a marked translucent condiment squeeze bottle to fill the injector pump.

Tator
 
And don’t crank the valve cover down too tight, they are easy to bend.

Take a metal ruler to the underside of the valve cover at the screw holes to find out if they have been overtightened. If so put it on a flat metal surface and tap the surface with a hammer to re-flatten it. The torque for those screws is only 22-INCH pounds.
 
My valve cover was a thick cork gasket, that can make up for a lot of sins when taking it off and putting it back on.... it had to be 3/16 to 1/4 inch thick.

Only had to hand tighten the screws holding down the cover.... not like there was liquid pressure against it.
 
A great improvement for the secondary filter is to replace the dual cannisters with a large single. Also to avoid the mess when changing oil is to punch a hole in the upper side of the filter. This allows the filter to drain into the crankcase. Then put a piece of tape over the hole and undo. A wad of bilge diaper around the fitting takes care of any drippage.
 

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All went well. Didn't make too much of a mess. I can see where the squeeze condiment bottles could come in handy for filling the filters and injection pump. I am now familar with the process of bleeding my fuel system.

One item checked of my to-do list, one item added to my to-do list.

Now to replace that leaking oil cooler line I found.

Seems like my to-do list never gets shorter. :)
 
If a valve adjustment is necessary, the heads must be retorqued first.

Why does this not sound like a good idea to me? I've been a master tech for over 20 yrs and admit very limited diesel work, especially engine mechanical work. But I don't know about touching the headbolts.

Of course there are engines that when you install a new head gasket there will be special instructions. One of them on very few engines is to assemble engine and run until t-stat opens and the shut down and tighten 90 degrees more.

But that is when new. After a few yrs,,,, leave well enough alone.

But I could be wrong. I hope I am. , i love learning new things
 
I adjusted mine shortly after I got the boat. Engine had around 3000 hours. I did not retorque the head. ( didn’t know I was supposed to)
14 years later it. was still running fine.
 
Why does this not sound like a good idea to me? I've been a master tech for over 20 yrs and admit very limited diesel work, especially engine mechanical work. But I don't know about touching the headbolts.

Of course there are engines that when you install a new head gasket there will be special instructions. One of them on very few engines is to assemble engine and run until t-stat opens and the shut down and tighten 90 degrees more.

But that is when new. After a few yrs,,,, leave well enough alone.

But I could be wrong. I hope I am. , i love learning new things

FL120 manual says retorque, FL135 I am told does not need to be.
One place to start is the service manual.
 
Changing oil in injector pump

The first time I drained the old oil it made an awful mess. If you have the (better) Johnson raw water pump on the engine the area around the drain plug is VERY tight.

I ended up installing a 12" hose on the drain hole with a cap on the end. This way the draining could be done cleanly. However, installing the hose required a banjo fitting which was difficult to find - I think I got it from a motorcycle parts supplier.

The only photo I have just shows the end of the 12" hose.
 

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For the calve cover gasket. As others have said, not too tight

My addition is to take a straight edge to the valve cover edges (that lie flat on the gasket) to make sure they are not warped from folks cranking down on them.

If they are bent, light hammer and dolly work to straighten out.
 
To get more clearance room to work , I loosen up the raw water pump and twist it out of the way a bit then tighten up again. This allows better control of the oil being drained from the injection pump. After completion, put back in its normal position.
Also instead of sucking engine oil out of the dip stick tube, while the oil is mostly out, replace the drain plug with one that you can now attach a hose that can suck out from the bottom with a small pump. I believe American Diesel supplied the part for me.
I second punching a hole in the high point of the engine oil filter and give it plenty of time to drain. Liked the idea to tape over the hole but never tried it.
Should be minimal mess if given enough time.
 
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