FORD LEMAN 120 Maintenance

Hi, I am new to this Forum. I have a 36' MMC Trawler (Taiwan) with a Ford Lehman 120. the Boat is a 1982 and is in great condition. I bought the boat 5 years ago and have kept up with fuel and oil changes etc. but now wondering what to anticipate in terms of preventative maintenance. The engine has 2300 hours.

Thanks! Curt R

Curt, I have a Lehman 135 and I can send you the maintenance recommendations for it which should be pretty much the same. Send me your e-mail in a private message.

If you do not have an operators or parts manual for the FL120 you can get them on the GB owners forum in the Manuals section. You have to join the forum to access the manuals section but joining is free. The operator's manual describes most of the maintenance tasks like changing injector pump oil, coolant, adjusting valves, etc., etc., etc. I don't know how the FL120 compares with the FL135 in terms of maintenance and adjustments but they are based on two different Ford of England engines so what applies to one may not apply to the other. Best to get a proper set of FL120 manuals if you can.

Marin said:

Best to get a proper set of FL120 manuals if you can.

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I have all my original FL120 Manuals and many others. Shoot me an email and I can share them in PDFs.

- mike

somesailor@gmail.com

For those interested, I've placed a bunch of PDFs I have of my Ford Lehman FL120 Manuals on a server that people are welcome to grab here:

Index of /CHB

There are some older Espar manuals in there too. Hope it helps.

Thanks Somesailor, the Manual PDF is useful.
I`ve an overheat problem with my port Lehman 120. Since we got the boat the temp gauge read low, and like there might be no thermostat. Eventually I got a thermostat and installed it. Meantime we reconditioned the raw water pump and replaced all heat exchangers so hoped I fixed whatever caused a PO to remove the thermostat. But it got hot, so the thermostat,which tests ok in hot water, came back out.
Looking further, grabbing the pulley for the FW pump produces slack lateral movement (unlike the stbd one,) and I see a line of grease like material getting sprayed in a fine line on the hose adjacent to the pulley wheel which could be from the pump bearing, so I suspect the FW pump. The operators book says coolant "flows by thermo-syphonic action, assisted by a pump".. Also when we removed the new thermostat after short usage it was surprisingly dirty. Coolant level is well maintained.
Am I right to suspect the pump? If so, do I really need a puller to get the pulley wheel off the old pump to fit a new one as the Manual says.
The Manual says there is a repair kit, I think I`d replace the pump, oddly there is one offered online here. Or I`ll get it from AD, or Fredwarner1 on Ebay.
As far as I can see the pump is a standard Ford part not a Lehman marinising one. Anyone able to confirm that?
Any help or comment appreciated, especially from anyone who has been there.

Thank You Somesailor, I hope I never need them but they are nice to have.\

Don

Bruce-- Rather than ask a bunch of people who probably can't answer your question spring for a long-distance phone call and ask a couple of guys who probably can. Call Brian or Bob Smith at American Diesel. Bob designed much of the marinization kit for the FL120 when he worked for Lehman in New Jersey.

Running without a thermostat can make the engine run hotter! I discovered this years ago with an old car, but what happens is the water runs through the cooling system too fast to actually cool down. Sounds like you need to use a radiator flush to clean the FW cooling system out, then replace with a proper mix of anti-freeze and distilled water, and put the new thermostat back in.

Also, take a manual temperature reading on your engine. Use a thermometer in the open tank if you can do so, or use an infrared thermometer. You'd be surprised at how far off some temp gages are. Mine reads 10 degrees F higher than the actual engine temp.

Am I right to suspect the pump? If so, do I really need a puller to get the pulley wheel off the old pump to fit a new one as the Manual says.

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You do NOT need a puller to remove the pulley. A couple of light taps with a plastic mallet will get it off. (I just replaced my pump last winter as a PM item.)

Keith said:

Use a thermometer in the open tank if you can do so, or use an infrared thermometer. You'd be surprised at how far off some temp gages are. Mine reads 10 degrees F higher than the actual engine temp.

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Keith:

It would appear that I have the same problem. My temp reads 192 degrees at the panel. I've changed the gauge, sender, thermostat and pulled and cleaned (radiator shop) the heat exchanger. (One at a time, not all at once.)
With my infrared gun, when focusing the beam on the thermostat housing, I get a reading of 178-182 while the panel gauge says 192. Nothing and no one (including Tony Athens @ SeaBoard Marine) can explain this. (I also read that if any kind of sealant (tape, putty, etc) is used on the sender, it will result in an erroneous reading at the panel. (I have not checked that one out yet.) The interesting thing about it is the Cummins spec sheet (330B) says that the operating temp range for my engine is 182-203 degrees F. All my previous engines (different makes) operated at around 180 degrees. While searching for an answer, I read that the new diesels operate at higher temps for a more thorough fuel burn. (This certainly would not apply in your case but is interesting, nevertheless.)

I have a single Lehman that ran 'hot' one summer. Two things come to mind:

You MUST run the genuiine Lehman thermostat for the engine. Any old thermostat of the correct size, shape and temp will not work. Don't know why. Just don't do it. Get the real thing from American Diesel or North Jersey Marine (973) 546-6377. It's complicated.

Is the engine really overheating? Get a candy thermometer and check the coolant directly while the engine is running. You may just need a sending unit for the gauge (or the gauge). The sending units and the gauges have to be matched by brand and type to read correctly. None of the off the shelf sending units will work correctly with the installed gauges. Again, North Jersey Marine can supply sending units, gauges or a package of both. I've used them when I spent a summer chasing ghosts in the engine room.

I think I will run the issue past American Diesel.
The thermostat is a genuine AD one, it tests ok in a saucepan on the stove at home.
I think the temp gauge reads ok. Without thermostat, it is slow to rise,and temperature engine speed sensitive, getting to 150F without thermostat, exceeding 200F with it, at cruise. With no thermostat, my manual bilateral digital heat survey (a hand on each manifold) shows the port engine appropriately cooler than stbd.I don`t have a heat gun.
Play in the port pump shaft, combined with what looks like a fine grease spray from the pump (?bearing) onto the hose below, and overheat, leads me to the pump itself.
A flush of the FWC side is a good suggestion too, messy but necessary. I read somewhere to use dishwasher machine detergent which won`t foam much, followed by a clear flush, before a proper refill, does that sound ok?

BruceK said:

I read somewhere to use dishwasher machine detergent which won`t foam much, followed by a clear flush, before a proper refill, does that sound ok?

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The detergent flush is for an engine that has had components changed which are in the jacket water circuit. It is intended to remove grease and oil that would otherwise create hotspots on the liners. It doesn't do much to remove scale or other deposits.

Whatever you do DON'T use dish soap or you will be flushing foam for the rest of your life.

For that you need to use a cooling circuit cleaner intended to remove deposits.

Anyone have instructions on the best way to fully flush the system? I have the expansion tanks off to install overflow tanks and replace the thermostats. Seems like a good time to flush but I've never done it before. So far I removed the hose from the heat exchanger to the manifold and vacuumed out what I could. Nasty! Time to flush it good.

My mechanic approves the use of automotive radiator/cooling system flush products, maybe not everyone will. The system holds 20 quarts, you probably need 2 packs of any product.
According to American Diesel, sediment can accumulate at the back of no.6 cylinder. There is a "rear freeze plug" on the block you can remove to check for it, and probably drain there as well as other places.
Inside the expansion tanks there is a metal tube which leads to the overflow. This can get sludged and blocked, if so the overflow does not happen, the engine gets pressurized and finds places to vent pressurized coolant.
We fitted Mercruiser recovery bottles, it saved shipping the modified units from USA.
Check your expansion tank caps too, they degrade, maybe you get new ones with the kit from AD and the existing just gets capped off, if not best renew them if they look tired.
Although I engage a mechanic, I take an interest in what gets done.
A drift while we are talking FL120, there is a circulated view the FL120 requires the injector pump oil changed every 50 hours, leading to comment the engine is "high maintenance". I checked my 1978 Lehman Manual today, the period is stated as 200 hours, I suggest doing it with engine oil changes, it only uses < a pint.