Hard starting Lehman 120, again

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The long cranking helps by creating heat in the engine from compression. The cold start feature on my boat works by putting the throttles full open, press and release the cold start button, pull throttles back to idle and then start. By pushing the button I am setting the high speed idle, I think that is what it is called. If yours isn't holding then that may well be your problem. I would troubleshoot that first and see if that fixes it.
 
Red hook 98, the stop button is not at all the same thing. Comodave nailed it. Try that function for the next start and let us know how that works?

Good point about the stop solenoid, does it snap open when you start cranking? If not, it might be delaying the fuel.

Turning over an old clam-crusher like these Lehman’s produces plenty of heat immediately such that diesel fuel ignites immediately. That’s why your good engine starts right up, in fact almost all of them do! At least one cylinder is all it takes.

I think your issue is entirely fuel, there isn’t any getting in right away, there is a delay. If the cold start routine works I would start looking for an injection pump.
 
This is slightly off-topic but, I once owned a DeFever with a single 120 FL that was hard to start (actually would not start) in the cold PNW winter. My solution was to aim a hair dryer into the air intake while cranking. Worked every time. Unplug the shorepower cord and go.
 
Steamguy said:
This is slightly off-topic but, I once owned a DeFever with a single 120 FL that was hard to start (actually would not start) in the cold PNW winter. My solution was to aim a hair dryer into the air intake while cranking. Worked every time. Unplug the shorepower cord and go.
Click to expand...

Hmmm interesting cure. Your preheat glow plug did not work?
 
OldDan1943 said:
Hmmm interesting cure. Your preheat glow plug did not work?
Click to expand...


This was a FL 2715-E 6 cylinder. They had no glow plugs. The DeFever was a 1979 model. I miss that boat. :D
 
Steamguy said:
This was a FL 2715-E 6 cylinder. They had no glow plugs. The DeFever was a 1979 model. I miss that boat. :D
Click to expand...

Wifie bring me your hair dryer so we can leave the dock.
 
Pre heat

the described scenario is chillingly close to mine in that I rebuilt one of my engines after it got a gut full of sea water from the exhaust and it too was amazingly difficult to start so I fitted an air pre heater from a Mazda 3500 truck engine ($60Aus approx) and I press a button on the dash for 30 seconds prior to ignition ( you need to install a solenoid in the system and take the power for the heater off battery leads at the starter ) and it starts very well. Just to add another place to look in the mix, I was drawing a lot of amps on start up as well and the starter was a bit slower than it should have been and after checking all connections , changing batteries etc, I pulled the starter motor down and one of the brushes was jammed just enough for it to not be making contact so I cleaned all the brushes and guides and now it spins over really fast and with the heater never gives any trouble. Have you compared the spinning/cranking speed to the other motor at start up ?
 
Air leak

[
QUOTE=jleonard;857845]It also sounds like an air leak to me. I would check every fitting and connection by loosening and retightening.
FF's plan is a good one too.[/QUOTE]

Unless there is something your not telling us it’s very, very likely an air leak.
The aero start just kicks it along so rpm is enough to overcome.
It’s going to be nearly impossible to find as fuel probably won’t leak out.
Also when you have fixed it you probably won’t realise until it starts behaving normally.
 
Ford Lehman 120

Redhook98 said:
I know this is a beat to death subject, but I cant seem to find any good answers yet that have worked out. I have two Ford Lehman 120s in my 1979 MT. Both original and circa 1979. One has been completely rebuilt, including a new injection pump. The other is original with 2400 hours. The one with 2400 hours starts easily, no issues. The rebuilt one is the problem child.
The rebuilt one simply does not want to start when cold. Tried all different settings to the throttle lever, no joy. Removed the CAV filters and installed the adapters. Bled the system, no joy. Installed a Facet electric fuel pump in line with the lift pump, no difference. Bled the system again using the electric fuel pump. Again, no joy.
I do hear a slight tapping noise from the engine in question. Air trapped in an injector? Badly adjusted valve? Wouldn't the electric pump power me through any fuel leak issues? I'm stumped.....
Click to expand...
Once running, it runs great. Runs out to 2500 if I want it to and sounds smooth. Have to use a short spurt of starting fluid most times. No smoke (other than the normal amount of light smoke from a 40 year old motor). Restarts easily when warm as well.

Tapping sound is most likely a valve or valves. Easy fix. The starting issue could be anything. Have you called American Diesel and spoken with Brian? That would be my first start and then I'd go to a reputable local mech.
My Ford Lehman 120 is 36 years old, has 7600 hrs, never been rebuilt and runs like a charm (knock on wood).
 
Redhook98 said:
I know this is a beat to death subject, but I cant seem to find any good answers yet that have worked out. I have two Ford Lehman 120s in my 1979 MT. Both original and circa 1979. One has been completely rebuilt, including a new injection pump. The other is original with 2400 hours. The one with 2400 hours starts easily, no issues. The rebuilt one is the problem child.

The rebuilt one simply does not want to start when cold. Tried all different settings to the throttle lever, no joy. Removed the CAV filters and installed the adapters. Bled the system, no joy. Installed a Facet electric fuel pump in line with the lift pump, no difference. Bled the system again using the electric fuel pump. Again, no joy.

Once running, it runs great. Runs out to 2500 if I want it to and sounds smooth. Have to use a short spurt of starting fluid most times. No smoke (other than the normal amount of light smoke from a 40 year old motor). Restarts easily when warm as well.

I do hear a slight tapping noise from the engine in question. Air trapped in an injector? Badly adjusted valve? Wouldn't the electric pump power me through any fuel leak issues? I'm stumped.....
Click to expand...

I just this morning finished adjusting the valves on one of my FL 120s. I found that there was almost no lash in five of six cylinders. On start-up after adjustment the engine ran significantly more smoothly and with much less smoke out the exhaust which also cleared up very much more quickly. Start-up was quicker as well.

You say your engine was rebuilt. The manual calls for the head bolts to be re-torqued on a new engine after the first fifteen hours of running along with a valve adjustment. Was this ever done on your new engine? I talked with Brian Smith when I ordered new valve cover gaskets. He recommends re-torquing the heads and adjusting the valves every 500 hours. He also said that re-torquing the heads should be done before adjusting the valves. For FL 135 owners, the heads are never to be re-torqued. Tomorrow I will be doing the other engine. I will report my results.

As for your other engine, you would do well to torque the heads and adjust the valves. Below you will find the procedure for adjusting the valves. To torque the head follow the tightening sequence in your manual. Loosen each head bolt and re-tighten to 110 foot-pounds.

Valve Setting Procedure for Ford Lehman 120/135

Intake Valve Lash (120) - .012
Exhaust Valve Lash (120) - .015

Intake Valve Lash (135) - .015
Exhaust Valve Lash (135) - .015

Valve Sequence from Front of Motor:

Valve 1 – Exhaust
Valve 2 – Intake
Valve 3 – Exhaust
Valve 4 – Intake
Valve 5 – Intake
Valve 6 – Exhaust
Valve 7 – Exhaust
Valve 8 – Intake
Valve 9 – Intake
Valve 10 – Exhaust
Valve 11 – Intake
Valve 12 – Exhaust

To Set Valves:

Rock Cylinder 6, Set Cylinder 1
Rock Cylinder 2, Set Cylinder 5
Rock Cylinder 4, Set Cylinder 3
Rock Cylinder 1, Set Cylinder 6
Rock Cylinder 5, Set Cylinder 2
Rock Cylinder 3, Set Cylinder 4

Rocking Procedure:

Using a breaker bar and a 7/8 socket installed on the center bolt of the flywheel pulley, rotate the engine clockwise until the No.6 cylinder exhaust valve fully opens and the intake valve begins to close. The springs of both are at their highest at this point. Rock in both directions until both are not moving up or down. Then set the intake and exhaust valve lash on Cylinder No. 1.

Then rock 2, 4, 1, 5, and 3 in order. This will happen as the engine is continued to be rotated clockwise.

Note: The cylinder head on a Lehman 120 must be re-torqued (110 ft.-pounds) before setting the valve lash. On a Lehman 135 the head must NOT be re-torqued.
 
Good morning,
I had a hard cold start also.
You said after warmed up runs good. So, the line is pressurized.

I had a “pin hole” air leak, after sitting all night/ or day it lost pressure. So, it may not be a cold problem ,but a very very small pressure leak. I would go over every connection joint. Again.
Best to you
 
Capt Richard A. said:
Good morning,
I had a hard cold start also.
You said after warmed up runs good. So, the line is pressurized.

I had a “pin hole” air leak, after sitting all night/ or day it lost pressure. So, it may not be a cold problem ,but a very very small pressure leak. I would go over every connection joint. Again.
Best to you
Click to expand...


Brian at AD discounted the whole fuel thing. But I do think I am going to investigate that more. It does have an electric fuel pump installed now. I figured that would alleviate the non-pressurized line issue, if there was one.
 
Redhook98 said:
Brian at AD discounted the whole fuel thing. But I do think I am going to investigate that more. It does have an electric fuel pump installed now. I figured that would alleviate the non-pressurized line issue, if there was one.
Click to expand...
What did Brian at AD suggest?
the electric fuel pump gets the fuel to the injection pump but should not be able to pump past there. Air before or after injection pump needs to be bled, IP cannot pump air easily. IMO
 
IF you are certain that there is solid fuel after 24 hours of non use to the engine , and it only likes to start with help ,
my GUESS would be lowered compression from stuck rings.

An old injector set to accept an air hose can be used to do a blow down test that can show if its a leaky valve or bad rings..
 
Check for air in the fuel already. I suggested this a couple pages back with how to do it.

Leaky rings can be checked by comparing blowby flow to other engine. If rings are sealing poorly enough to affect starting, blowby flow will be huge.

Also check valve lash.

I doubt hard starting is compression related. Absolutely can do it, but rare. And there will be other symptoms.
 
I am looking into air leaks in the fuel lines now. No blow-by whatsoever. Valves were adjusted last week.



What is the best method for purging air from the hard fuel lines between the IP and the injectors?
 
Ski is suggesting, as I did earlier, that you check your valve lash. Again, were the heads re-torqued after the rebuild as required? I just re-torqued my heads and adjusted the valves on my two Lehmans. I found one engine to have almost no valve lash, the engine that did not start quite as quickly as the other which did have more lash but less than spec. Bottom line, the first engine starts more quickly although it really wasn't a problem. The point is, adjusting the valves made a difference. This should be done in any case so why not do it and eliminate this issue as your problem before worrying about compression in a rebuilt engine?
Ski in NC said:
Check for air in the fuel already. I suggested this a couple pages back with how to do it.

Leaky rings can be checked by comparing blowby flow to other engine. If rings are sealing poorly enough to affect starting, blowby flow will be huge.

Also check valve lash.

I doubt hard starting is compression related. Absolutely can do it, but rare. And there will be other symptoms.
Click to expand...
 
Sorry for my post. I saw afterward that you adjusted the valves. Did you remember to re-torque the heads? When I talked to Brian Smith last week about this, he said this must absoultely be done before doing the valves. This would especially be true for a rebuilt engine.
Redhook98 said:
I am looking into air leaks in the fuel lines now. No blow-by whatsoever. Valves were adjusted last week.



What is the best method for purging air from the hard fuel lines between the IP and the injectors?
Click to expand...
 
This is a two person job and may require lots of oil absorption pads.
First bleed the fuel pump then loosen the connection to each injector....one at a time. Turn the engine over and when fuel (no air) happens, tighten up that connection and move onto the next in line. Of course, I have forgotten which end of the rail you start on. I THINK you start on the first inline injector, chasing any air all the way to the last injector.
 
catalinajack said:
Sorry for my post. I saw afterward that you adjusted the valves. Did you remember to re-torque the heads? When I talked to Brian Smith last week about this, he said this must absoultely be done before doing the valves. This would especially be true for a rebuilt engine.
Click to expand...


Head was also re-torqued.
 
Redhook98 said:
Head was also re-torqued.
Click to expand...

The proper way to re-torque anything is to first loosen the nut or bolt and then retighten it to the proper foot pounds. This is done in a specific pattern, then when you think you are finished, go back over them to verify they are torqued properly.
Failure to do this properly may result in a blown head gasket and/or a warped head.
After a specified number of engine hours, check the head for proper torque.
Get a professional!
 
Last edited:
Old Dan, a professional is not required to retorque a head. A good torque wrench is. A wrench with a deflection pointer is not a good wrench. One that clicks when the set torque is reached is a good wrench. A good wrench will cost more but will be a good investment. Following the procedure you outlined will get a good result. But, I will say that I am a very experienced shade-tree mechanic. Anyone who is just learning their way around an engine room would do well to hire a guy and watch him closely for the next time or to do the second engine if one has twins.
OldDan1943 said:
The proper way to re-torque anything is to first loosen the nut or bolt and then retighten it to the proper foot pounds. This is done in a specific pattern, then when you think you are finished, go back over them to verify they are torqued properly.
Failure to do this properly may result in a blown head gasket and/or a warped head.
After a specified number of engine hours, check the head for proper torque.
Get a professional!
Click to expand...
 
A well calibrated beam torque wrench is often considered better than a click-type in terms of accuracy. However, a good quality click type is plenty accurate enough for engine work and also far easier to use correctly without a ton of skill and practice (which will give better real-world accuracy for most of us non-professionals).
 
catalinajack said:
Old Dan, a professional is not required to retorque a head. A good torque wrench is. A wrench with a deflection pointer is not a good wrench. One that clicks when the set torque is reached is a good wrench. A good wrench will cost more but will be a good investment. Following the procedure you outlined will get a good result. But, I will say that I am a very experienced shade-tree mechanic. Anyone who is just learning their way around an engine room would do well to hire a guy and watch him closely for the next time or to do the second engine if one has twins.
Click to expand...

Jack, I was a nuclear power trained machinist mate 1st class. There is some parts that are first torqued, to a specified amount and then additional torque, counting the flats of the nut or bolt as specified in the manual.
I agree on your choice of torque wrench but, it should first be certified as correct.
IMO, A good clicking torque wrench does not include a purchase from Harbor Freight.
SMILE I have long maintained, if I am tied to the dock, a professional can do it. Out to sea? Here hold my beer and watch this. LOL
 
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Redhook98 said:
The button on the cold start feature will not stay in. The other motor does, this one does not. holding the Stop button and cranking a little while seems to help (believe that is essentially the same thing)
Click to expand...

Redhook98 said:
Brian at AD discounted the whole fuel thing. But I do think I am going to investigate that more. It does have an electric fuel pump installed now. I figured that would alleviate the non-pressurized line issue, if there was one.
Click to expand...

Redhook98 said:
Head was also re-torqued.
Click to expand...
Red. Please understand, trying to help.

You re torqued OK done.
Brian told you it is not fuel problem based on an unknown (ours) conversation, OK, I will take it to mean no fuel problem as in no air.

The valves were adjusted after the re torque and they were done to specs.
I know how to do the valve adjustment, but indulge me and explain how you did it so I can rule that out.

Have you fixed the cold start? But do tell me that the cold start issue is fixed and how.

You are discussing multiple issues at the same time zny which can cause a start problem.
Now some are suggesting rings, all before you have convinced us that the other items are resolved.
 
Thank you Soo-Valley. I do appreciate the assistance. Here it is in a nutshell.


I bought a 1979 MT with twin 120 Lehmans. One has 2240 hours, the other was rebuilt. By rebuilt I mean new pistons, rings, bearings, injector pump, injectors, etc. Since it was rebuilt by the PO (who is a marine mechanic and quite well known in our area), it has been more difficult to start than the other motor. When cold out, it takes an awful lot of cranking, and sometimes would not start at all without ether. Started "ok" when warmer, but took a lot longer that the other. Injector timing was triple verified when it was installed.



That is my baseline when I got it from him. Over this winter, the motor would not start at all, again, without ether.


Seeking advice from others on this forum and reading back articles, I have down the following:
- Installed an electric fuel pump (in line with mechanical) - supposedly to assist with any air in the lines, ease of bleeding and reliability.

- Installed spin-on fuel filter adapters (for ease of changing and reduce chance of air entering system via CAV filter unit)

- Re-torqued the head (IAW the factory manual)
- Adjusted valve lash (IAW the factory manual)
- Installed new batteries (dual group 31 tractor batteries in parallel)

- Installed vacuum gauges on Racor 1000 filters (just nice to have to see if any fuel filter issues with that filter)
- Checked injector pump timing again, dead on.



Spoke with Brian during these steps. He brought up compression. His reasoning is that it started well when warm and thus had expanded and promoted better compression. I do not believe this to be the case, but did order a few block immersion heaters from HotStart for next winter anyway.



I checked blow-by. There is zero blow-by and no copious amount of smoke when starting or when first started. Slight tapping towards rear of motor in the valve train area. Adjusted lash did nothing for that. But this could also be my unfamiliarity with diesels. I have been building gas motors for boats and cars for 30 years, but am unfamiliar with the nuances of diesel noises. I do not believe this to be a compression issue.



When batteries were replaced, it did make the engine easier to start. This made normal starting a viable option, but still took 30-seconds or more of intermittent cranking.


No working cold-start option. No matter what the throttle position is, the cold-start button will not stay in. Pushing it in and holding it makes no difference when trying to start cold. Disconnecting the linkages for the stop solenoid and for the throttle and trying different combinations did not work. Button simply will not stay in. Other engine is fine. Push to full throttle, push button in, reduce throttle to 1/4 and it works great. I have no idea where to start on the cold-start issue.


My plans right now are for the following:
- Remove all fuel line from Racor 1000 to the electric pump and from electric pump to secondary filters and replace with A-1 marine fuel line. That will remove multiple potential leaking connections (I have loosened and tightened all connections already)
- Remove mechanical fuel pump from the equation entirely
- I may R and R the dual spin on filters and go with a single Racor unit there in its place.
- Install the block heaters like Brian suggested.

- Bleed the injector lines


Sorry for the frustration.
 
With the engine 24 hours cold , I would give a quick squirt of starting fluid, to see the results.
 
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