Ford Lehman 80hp - How easy or hard is it to blow a head gasket?

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jonahmulski

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Having blown two head gaskets on my Toyota trucks as a teenager I’m extra paranoid about overheating and blowing head gaskets. So when the four cylinder Ford Lehman in our sailboat overheated a while back I became worried that the head gasket might have been compromised. It happened when the end cap on the heat exchanger blew out. How this went unnoticed as long as it did is a long story. The short version is that it was one of those “one thing leads to another” scenarios that happens in the middle of the night while motoring around a notorious point (Point Conception, CA). It’s been over a year now so I don’t remember exactly how hot the motor got. I don’t think the temperature gauge needle was pinned but if my memory serves me right it was getting there. We shut her down and sailed a zig-zag track for ten hours to get twenty miles north to Morro Bay. We were able to repair the heat exchanger at a local radiator shop and the motor operated normal for the rest of the trip north to Moss Landing. Over the last year there have been a number of things that have kept the head gasket worry with me.
The exhaust has been getting whiter and whiter. The coolant has been leaking out the over flow more and more. There is dark fluid mixed with the coolant. It’s a little oily too. However, the engine oil does not have any water in it and she runs like a champ.
The guy who owned Orion before us did not use her much, she was a live-a-board. He did start her up once a month and run her till she was warm and did basic maintenance but nothing more. Now she has been running her for hours on end when the wind is light and we want to get north or south to our next destination (because this is a trawler forum I can say this without too much embarrassment). So these things could be the product of routine maintenance that needs to be done. White smoke – the valves need to be adjusted. Coolant leaking and having dark oily fluid in it – coolant needs to be changed and/or the exhaust elbow gasket is leaking (American Diesel’s suggestion) or the exhaust manifold is having issues.
Until now all my wrenching experience has been with gas motors. This is the first diesel I have owned and what amazing engines they are! These things should be everywhere! Back to me though… They are a combustion engine so I know the basics but I don’t know a lot of their specifics. How hard is it to blow a head gasket? Are compression tests normal for diesel engines? Any other thoughts on what could lead to the coolant leaking and having dark oily fluid in it?
I did adjust the valves. They were three or four thousandths loose. Is that a lot? But I haven’t yet warmed her up to see if the white smoke is still happening. It got too late. I’ll do that in the morning and post what I find. In the meantime any input would be much appreciated.
Oh, the motor has 1400 hours on it, 200 of which we put on in the last year and a half. Any other background needed?
 
I'm not a diesel mechanic by any means, but white smoke (make sure it's not steam which is not necessarily abnormal)) is usually a sign of coolant getting into one or more combustion chambers. A blown or bad head gasket can certainly be the cause of this.

If you're getting dark oily stuff in the engine coolant, it sounds like you are getting lube oil into the coolant, which can also be a head gasket issue.

If it's oil in the raw water side of the system, that can be coming from a failed and leaking (internally) oil cooler.

The base Ford of England diesel for the FL80 and 120 engines is susceptible to blowing head gsskets if the engines are overheated. The head is also prone to warping if a severe overheat occurs.

If we were in the same situation as you we'd be getting a reputable diesel shop with experience with these engines involved. Talking to the Smiths at American Diesel might get you some suggestions, but diagnosing a problem on the phone is an iffy proposition at best.
 
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Welcome aboard! I can't believe I'm up this early- be we opted for "one more night on the boat" and have to travel home for work at 8 "Central" time.
Marin made some great points and I'll throw in a couple of more thoughts.
A few thousandths on the valves is minimal, not enough to cause any real problems. I would remove the cap while cool- and start the engine. If you immediately see large air bubbles start to come out of the coolant that indicates you are introducing compression past the gasket (or a cracked head). I really doubt that will be the case since you are not seeing coolant contaminating the engine oil. This usually happens after the engine shuts off- coolant pushes into a cylinder and then seeps past the rings into the oil pan.
So far as "oil" in the cooling system- could it be possible some one grabbed a dirty funnel to pour coolant into an overheated engine about a year ago???
If no combustion gasses are obvious in the cooling system with the cap off, I would suggest removing the thermostat temporarily, running a good flush through the cooling system, then drain/ have HE checked by a competent shop and refill after adding a new thermostat. Then retest. Good luck!


1983 Present 42 Sundeck
Twin Lehman 135's
✌️
 
Welcome Aboard.

You didn't seem to indicate that the engine is running hotter.

I would certainly follow the advice of Brian at American Diesel and do the easy stuff first.

IF you are so worried about the head gasket, then I'd replace it at your leisure, before it becomes a bigger issue. I've also lost a head gasket on a gas engine, but it did what it was supposed to, fail and thus lose compression, so no other damage occurred.
 
White smoke is either unburned atomized fuel, or water. Put your hand or hold cardboard by the exhaust for a few seconds and see if it smells like fuel or not.

If it's fuel, the cause has to be one of these
Lack of compression
Water in the fuel
Air in the fuel
Defective injector
Leaking head gasket
Cracked cylinder head

If it clears up after warming up then likely compression. If it persists i would start by looking at the injectors first, once that's ruled out I'd move to the compression test.

I agree with coolant troubleshooting from American diesel. Lastly when was the last time your heat exchanger was serviced? It may be partially clogged again.
 
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The coolant can be tested for lube oil. I think a NAPA store or diesel shop will have the test kits. If, with the cap off, you see puffing or smoke or the coolant smells like diesel exhaust that is a clue of head gasket. A few thousands in valve adjustment is normal. There is also a test for lube oil to look for coolant test kits from diesel shop.


The most common cause of white smoke is steam meaning insufficient water flow. Did you check the pump impeller? Yes compression can be checked with screw in gauge. But I would work the simple stuff first.
 
I don't know the time-line but the "white smoke" might just be because it's winter and the air/water is colder?

You did not mention maintenance, if it was done by the PO or if you did any when you bought it?

The valve condition, while not a real problem, gives me a clue. Run it up as suggested and check for combustion gases in the coolant or other obvious failures. If negative, I would do an oil and filter change, change the coolant (old coolant can cause an overheat all by itself) take off the transmission and main oil coolers and either service or replace them, keeping the old ones for spares (much cheaper than the results if they fail), replace the raw water impeller (do you do that every year?) while you clean the intake strainer, servicing the shutoff to make sure it's not restricted (I found a couple of very smelly fish in mine once) and while you are at it, change the fuel filters. Does it have a Simms injector pump? If so, change the oil. In a perfect world, I would replace the injectors with my spare set. Change the air filter on condition. Check the belts, they are probably as old as the boat.

Transmissions need regular service too.

Now I would tie her tight to the dock and run it under load to warm it up, then run it at wot in gear for 5 minutes while I monitor with my infra-red heat gun. Flash your stuffing box too, and your gearbox. I would do this with a large tin can fitted and handy to place over the intake in case of runaway (a running engine can be extremely dangerous, eye and ear protection, no loose clothing etc etc).

That will tell the tale. Break a leg!
 
If it worries you enough to not trust it, change the head gasket.

Head gaskets can be compromised by heat. Nowhere near as sensitive as Toyotas with their aluminum heads, but still the gasket can be damaged from heat.
 
Great input!

Forkliftt, good call, I'll look for obvious air bubbles in the coolant reservoir today.

No Mast, I'll also do the exhaust test. Let me make sure I understand each of the potential problems you outlines.
::Lack of compression - This would be because the fuel does not burn completely or does not burn at all or a gradient depending on how low the compression is? I would think this would make the engine run really rough.
::Water in the fuel - Does this lead to a lack of fuel burning or vapor in the exhaust or both?
Air in the fuel - does too much air lead to a lack of fuel burn because the ration of fuel to air is not correct?
:: Defective injector - The fuel does not atomize correctly so some of the fuel does not burn?
::Leaking head gasket - Water is getting into the cylinder which leads to fuel not burning correctly? In my brain I can't see how the water would continue to get into the cylinder once the engine is running. Isn't the compression in the cylinder way higher than the pressure in the coolant system? Perhaps it would get pulled in on the down stroke? I think of this as leading to the air in the coolant situation.
::Cracked cylinder head - I imagine this leads to the same sings as a leaking head gasket?

Bayview, a coolant and oil test kit are great ideas. American Diesel suggested that the exhaust elbow gasket may be leaking exhaust back into the coolant. I imagine the exhaust has some engine oil in it too? If so, this test would tell me that oil is getting in but not the source? It will help me rule out the possibility of plain old dirty coolant.

Xsbank, That is a great to do list! I have done a good amount of maintenance, oil and filter changed (no obvious sign of water in the old oil), Simms oil changed, fuel filters changed, raw water impeller changed,
I have all new HE but have not put them on yet, I will. The belt needs to be changed. I don't have an extra set of injectors. Are they available? I held off on getting them rebuilt but with this issue I may end up doing that. Anyone know a good shop in the San Diego area?
What temperatures should I see with an infra-red temp gauge at the points you mentioned? You said you would warm the motor up and then run it at "wot" for five minutes?
And thanks for the safety protection gear reminder, I do love to see and hear!

On long trips (8 to 10 hours) the temperature gauge currently sits just above 180. She's not currently over heating.
 
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Wot = wide open throttle. The manual will tell you what your wot rpm should be. Your engine temps should be uniform and within tolerances, for example 190 degrees at all the cylinders, make sure none of the temps get too high, for example your stuffing box should be warm to the touch (don't be tempted to test it while it's turning). Your engine is rated at wot but it will sound like its angry and trying to eat your marina. It's quite alarming as you usually only use 1/2 "throttle."

If there is a weakness in your cooling system, wot will reveal it.
 
I forgot again (darn) there is a procedure to 'burp' your coolant system with the small valve on the top of the motor. I won't tell you how to do it because I can't remember if the engine is running or not, but make sure there is no air in the system.
 
Jonah,
Loss of compression could also be the result of blow by, etc but you generally get it I think. I know you had focused on the gasket. But you'll be best served by troubleshooting it methodically. Like I said if the white smoke is caused by fuel, check the injectors first. Then if they are ok I would do a compression test next.
 
Thanks RT! It's fading, but the important parts still work!
 
Thanks No Mast, that's good advice.
I ran the motor today but because I'm currently in a busy anchorage I wasn't able to put a load on the motor to get her warmed up completely. But the white smoke is way less. Still a little but nothing like it was before I did the valves. I have to go to the pump out dock in the next couple days :ermm: which will get her a chance to warm up.
There were bubbles in the coolant reservoir but at this point I'm open to the fact that the two issues may or may not be related.
Is there a way to test/check the injectors without pulling them?
 
Oh and I did have to burp the coolant and I did it cold with ear plugs, goggles and without anything dangling.:) Thanks!
 
Johan:

First off, your coolant situation may be the normal expansion that takes place when the engine heats up. If you fill your coolant to the absolute top, the first time you run the engine hard, it will spit out the volume that corresponds to the thermal expansion out of the overflow tube under the radiator cap. This is normal. When the engine cools down, the level will be low by that amount. This is also normal. After that you shouldn't get any more overflow. Many engines use a plastic catch tank to hold the expansion volume and then allow it to get sucked back into the system when the engine cools off. Your old Ford may not have this, and it's no big deal one way or the other.

All that matters is that there should not be any persistent overflowing without you adding antifreeze. If there is, then you have some fluid, undoubtedly lube oil, entering the system. This most likely is from a leaking oil cooler. The oil pressure is much higher than the cooling system pressure so any leak will show up as oil in the antifreeze.

If you have a leak, you won't have any problem determining it - oil in the antifreeze stands out like a sore thumb. If you have to ask yourself "Do I have oil in the antifreeze?" - the answer is No.

I think XSBank is right on with the advice to run 'er hard to check out the cooling system. It's common for the heat exchanger to accumulate fouling and you don't want to find out it's overheating when you're trying to outrun weather.

Those old Fords tended to use lube oil - a Lehman 6 (120 hp, if memory serves...) used a quart in a 24 hour day. I re-ringed 'er and it still used a quart a day. It also leaked a lot. Just made 'er hard to love.

Testing injectors is best done at a fuel injection shop. You may be amazed at the improvement in performance - easier starting and less smoke. Just drop 'em off and "test and service as necessary" then smile at the thought of thousands of hours of steaming in your future. Trouble is, those shops are going out of business - the availability of inexpensive replacements over the internet is killing them.

I say: "Keep calm and cruise on".

Good Luck!

JS
 
Driftless said:
Those old Fords tended to use lube oil - a Lehman 6 (120 hp, if memory serves...) used a quart in a 24 hour day. I re-ringed 'er and it still used a quart a day. It also leaked a lot.
Click to expand...

This can certainly be true of an individual engine but it is by no means a blanket attribute. The two FL120s in our boat were marinized new in 1973 when our boat was manufactured. Sixteen years ago when we bought the boat, each engine burned less than a quart every 100-150 hours. Today, some 3,000 hours later, each engine burns less than a quart every 100-150 hours.

They put out some blue smoke at cold startup but within a couple of minutes the exhaust is just a faint haze and that's only visible if the sun is shining through it. This has not changed in the 16 years we've had the boat.

While they have a few oil "weeps" here and there, none of these develops into an actual drip into the drip pan under the engine.

The only time we've had an actual oil leak into the pan is when the fuel lift pump gasket on the starboard engine started to leak, a common situation wth these engines. The resulting leak, while not much in terms of the actual amount of oil, looked like the engine was hemorraging oil by the appearance of the absorbant cloths in the pan. After putting up with it for a bunch of years we had the gasket changed (and took the opportunity to install a new pump at the same time) and no more leak.

Because we have two of them, I've done a lot of research on this particular engine, which Ford of England named the Dorset diesel after the factory the engine was manufactured in. This includes talking to people in the UK whose careers included operrating, maintaining, repairing, and overhauling the Dorset diesel in everythng from trucks, in which it was a miserable failure, to combines and industrial equipment like cranes and generators, in which it was very successful.

What I learned is that the health, longevity, and condition of these engines are very dependent upon how they're operated, moreso than with newer generation diesels.

Operated within the correct power range, they will run reliably and trouble free (the core engine, not necessarily its anciliary equipment like pumps and whatnot) for many thousands of hours. Operated outside this range, and the same kind of trouble-free performance will most likely not be obtained, which is why it was such a dud as a truck engine.

We were fortunate in that the three or four previous owners of our boat operated the engines in the manner that suits them best. We inherited their excellent condition and have tried hard to continue it. This has included learning everything we can about them and then operating them in the manner strongly suggested by people who know these particular engines intimately.

Ironically I'm not a fan of the FL120 but this is for reasons that have nothing to do with their reliability and longevity.
 
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oil use can be increased by running angle. My dipsticks were mismarked with the full maker spec oil level they used oil until they got to the level they liked due to the install angle they oil use went way down.


I suggest letting it go down and see if it still continues to use oil.
 
Xbank wrote;
"Now I would tie her tight to the dock and run it under load to warm it up, then run it at wot in gear for 5 minutes while I monitor with my infra-red heat gun."

WOT tied to the "dock" is very overloaded IMO. I can't get anywhere near rated rpm tied to the float. And I'm not over propped. If a boat was overpropped it would be even worse. To run 5 min at WOT one needs to be at rated rpm. I think your'e advice is very good except that it should be done at rated rpm.
 
Running the boat at WOT , loaded in gear, tied to the dock is BAD advice.
.There will be a huge strain on the cleats, the lines, and the dock tie point.
If anything gives way the boat will surge ahead smashing into something, another boat or the dock. There will almost guaranteed be damage.

WOT in gear under load should be done out in the harbour. That may mean you need a helper to run the boat while you do your tests.

Running at the dock , tied, under low load just above idle is another matter. Even then you may be surprised how hard the boat pulls on those lines so do not leave and be ready to kill it.
 
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Driftless said-
Trouble is, those shops are going out of business - the availability of inexpensive replacements over the internet is killing them.

That's a great point. There is a shop in Baton Rouge I have used since last century ?, Kents Diesel. Ronald Kent had worked for the bigger shops back when they were open, but has been solo now for about 10 years and in business about 20. He is a great choice for most any old school diesel fuel systems. I can provide contact info if anyone is interested.


1983 Present 42 Sundeck
Twin Lehman 135's
✌️
 
This engine produces about 80 HP. Not a Diamond Series Cummins. Do you really think it will rip the marina apart? Has your marina ever weathered a storm? Tie some knots? Put some extra ropes on it? Put the bow against something?

WOT should equal rated rpm. If it doesn't, go to rated rpm. I've never had a boat that wouldn't get rated RPM at wot, but YMMV. Anyway, you don't think that I am suggesting that you just jam the power lever wide open and stand back, do you?

You can't go charging around at full throttle with someone in the engine room. Just tie it to the dock. Or a piling, or an immovable object, like Obama.

The idea is to push the engine to its rated rpm and horsepower to see if it is in good enough condition to achieve its ratings. If it has been damaged by overheating or poor cooling or whatever,the weakness will show and then you fix it. None of us run our engines flat out because we are too fussed with hurting them or burning too much fuel or making too much noise or smoke, but they were designed, in this case, to make 80 hp, at about 2400 rpm? (That's a guess for you with manuals). I'll bet that this engine hasn't had to make 80 horsepower for, well, ever. They are designed for wot, not some theoretical percentage of it.

The alternative is to do nothing, it will fail if it is planning to, probably at an inopportune time, like crossing a bar. Or rip it apart and rebuild it. Throw money at it before you know what it needs.
 
Good point about the oil, all marinized Lehmans came with the original dipstick. Then they were tilted at that angle they all sit at to drive the boat. That resulted in chronic overfilling of the oil, which the engine doesn't like. Burying a journal in oil results in thrashing the oil until it blows out of the breather or if you are unlucky, a seal. This continues until the level of oil in the engine reaches the correct level and the consumption stops. The solution to all Lehman dipstick issues is to do an oil change and measure the proper amount of oil that the manual demands, then wait a little while and re-mark the dipstick with a file or similar. You will now reduce your oil consumption, unless your engine really is worn out, which is very unlikely.

One other bit of Lehman trivia, that oil leak that appears to be coming from the head or the pan or the rear seal? Dollars to doughnuts it's actually coming out of the lift pump gasket. Really. If you doubt me, go and look closely at yours, or just change it anyway as it's probably due, then be amazed at the clean oil diapers. The oil migrates all over the block and congregates in seams and such, then it drips off, looking for all the world like a leak from wherever it gathers. The pump/block mounting point is very flimsy. You'll see it when you take your pump off. You do have a spare pump, right? They are cheap at about $80 but can ruin your fun.
 
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If you have Lehmans which continually send coolant out the overflow (and/or the cap itself) after you have the level right, try changing the caps. I suspected mine were original and spring weak, 30years+, bought new ones from AD (ridiculously low psi, 4 from memory), problem solved. We check but rarely need to add coolant.
 
Too right, the caps are probably ancient. A really good mod is the American Diesel coolant overflow kit. It comes with a new neck and a bottle and hose so you can do away with the coolant that usually ends up in the bilge, it all goes back into the engine. Cheap, if I remember correctly.
 
Driftless said:
Johan:

...
Those old Fords tended to use lube oil - a Lehman 6 (120 hp, if memory serves...) used a quart in a 24 hour day. I re-ringed 'er and it still used a quart a day. It also leaked a lot. Just made 'er hard to love.

Testing injectors is best done at a fuel injection shop. You may be amazed at the improvement in performance - easier starting and less smoke. Just drop 'em off and "test and service as necessary" then smile at the thought of thousands of hours of steaming in your future. Trouble is, those shops are going out of business - the availability of inexpensive replacements over the internet is killing them.

I say: "Keep calm and cruise on".

Good Luck!

JS
Click to expand...
:thumb::thumb:

Great Advice John,

Thank you.
 
Greetings,
An inexpensive alternative to the AD overflow kit is a remote translucent vessel connected to the overflow. One can easily see anything that is spewed out the expansion tank and the spewage is contained in the bottle to be put back in the expansion tank as necessary.
 
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