Adjusting my valves on my Ford Lehman 120's

I want to adjust my valves and flush out the freshwater coolant out of both my engines. I have twin Ford Lehman 120's. I've drained the coolant out and want to flush it out. The manufacture recommends running the engine with the flush out and water for 20-30 minutes, then drain and put in the coolant. Is this OK on these?
I also want to adjust my valves after that is done and I have the covers off. I replaced some of the injector seals and O rings where they were leaking a little. So can I run the engines with the valve covers off or should I just screw them back on? Also, any tricks I need to know while adjusting my valves for the first time?

Thanks, Gary

Greetings,
Welcome aboard. Wherever you are..

Put the covers back, the engines will splash oil around and oil mist that would normally be controlled with the breather.

Welcome.

My understanding is the valves can be set cold. You could do them now and button it up before you run it again.

From my Lehman manual...adjust valves when engine at normal operating temp.

"Adjusted valves today. [FWIW—I emailed Bob Smith and he confirmed that the head bolts are NOT to be retorqued, but he did say that the bolts securing the rocker arm shaft should be retorqued prior to adjusting the valves and that the valve clearance is .015 COLD. So I didn't warm up the engine first.]"

Go crazy.

good info ...thanks!

but I'm starting to hear so much conflicting info from American Diesel...both against the manual and from posters....

Makes me wonder....

Greetings,
Mr. psneeld. I hear ya. I asked Bob Smith on one occasion about the requirement of changing the injector pump oil on the 120 Lehman every 50 hours while engine oil replacement was every 100 hours. He stated that the 50 hours was a misprint in the manual and I could change both every 100 hours. Go figure....

RT Firefly said:

Greetings,
Mr. psneeld. I hear ya. I asked Bob Smith on one occasion about the requirement of changing the injector pump oil on the 120 Lehman every 50 hours while engine oil replacement was every 100 hours. He stated that the 50 hours was a misprint in the manual and I could change both every 100 hours. Go figure....

Click to expand...

And other's are adamant that AD says 50 hrs....hmmmmm

While I love having a serious resource for our ancient engines, and that no one or one org is perfect or consistent...wonder the possibility/reasonableness that someone would create a "new" manual as some of us have low time rebuilts that could last another couple decades.

A user built and screened on line manual like Wikipedia only for Lehmans?

That's a good idea about the manual. The old clam crushers are so simple and so reliable that as long as they have fuel and air, they will beaver away until something critical breaks. Most of your maintenance can be done with Crescent wrenches and a hammer. Maintenance is dead easy and if you change out the drain plug on the Simms with a tap (and use zip-lock bags) all that's left is to suck out the oil occasionally, check the belts and plug any leaks. Filters, buy a new trans cooler and keep your old for a spare, buy a new lift pump ditto (single largest cause of oil leaks). Anyway, I'm repeating myself.

Penray has an excellent 2 part cleaner to flush an engine.

The easiest method for adjusting the valves is 2 feeler gauges.

Its called GO -- NO GO and does away with the >feel< requirement to get the adjustment correct.

IF 15 thou is required 14 should pass thru with minimum drag and 16 should be really hard to shove in.

The trick is to hold the adjusting screw in position and seat the lock nut at the same time.

Go for it , its easy,

12.003 – Penray Off-Line Cleaner Twin Pack

penray.com/wp-content/uploads/2012/12/TechnicalBulletin12003.pdf‎
Removes harmful scale and sludge deposits from the entire cooling system. - Removes ... Flushes the cooling system of loosened debris. USAGE NOTES:.

PS ,,for folks purchasing a dock queen that may never have had a proper oil change Penray also has oil flushing products.

Thanks everyone for all the great input!

I didn't change my injector pump oil for several years. Now I do it every year. No difference. It never even thanked me.

Make sure you use coolant made for diesel engines.

alormaria said:

It never even thanked me.

Click to expand...

"Thank you!!"
There, I heard it.

dannc said:

Make sure you use coolant made for diesel engines.

Click to expand...

American Diesel if you take their recommendation says plain old Green Prestone is fine...the engine was designed long before the coming of the long life diesel coolant.

Anyone hear different from them or Bomac? Anyone know if the issues requiring higher performance coolant are ever present in a Lehman?

AD's response to me was that the cavitation and corrosion issues just aren't there on a low performing Lehman.

Green AF is fine in a Ford/Lehman. No steel liners to get cavitation/corrosion damage. There is some aluminum in the system- header tank on front of head, maybe some elsewhere. Anytime you have al in the system, it becomes important that the corrosion inhibitors not be depleted. So change coolant every few years or so.

The 225/275 have lots more al, especially that sandwich at back of manifold. Those really need the corrosion protection. I think most here are talking about the NA 120's etc.

dannc said:

Make sure you use coolant made for diesel engines.

Click to expand...

Oh great. I just switched to this too. Even bought the indicator stuff.

Again. Nuttin.

Greetings,
I just buy the 50/50 pre-mixed purple diesel stuff. Pour it in and VIOLA. Don't have to mess with mixing buckets or transfer from jug to jug. Not the cheapest but a no-brainer as regards simplicity.
Mr. Al. Last change I did, port side "pee'd" warm fluid on my leg. Can I interpret THAT as some sort of thanks?

Is your "purple haze" from before or after the coolant leak?

The diesels in my Ford truck and JD tractor both require diesel rated coolant. The tractor engine, a Yanmar by the way and an excellent engine has a liner but the Ford does not. Both engines are using the same coolant type and I use JD coolant in both engines.

I can't see how a marine diesel operates in such a manner where cavitation is not possible or a concern. It certainly is a big topic/concern for tractors and trucks. The JD coolant I am using is good for 3-5 years but there is coolant out there that lasts for even longer.

I do buy the premixed coolant since it is fool proof.

Later,
Dan

Pretty sure it's because of construction and compression...the Ford Lehman is 16.1 to 1 compression...almost the bottom of the scale for diesel compression ratios. Don't misinterpret that ALL marine diesels can get by with low tech coolant...I was just talking Lehmans which is what the OP was discussing.

Cavitation Article

Cavitation is a direct result of an engine having an extreme compression ratio. Standard diesel engines compression ratios usually range from 16:1 to 22:1. A standard gas engine has a ratio of about 7:1 or 8:1, therefore they do not suffer from cavitation. Some high performance gas engines range up to about 14:1, and seeing this is a relatively high ratio they do suffer from cavitation like diesels.

psneeld said:

A user built and screened on line manual like Wikipedia only for Lehmans?

Click to expand...

Umm, my wife suggested the same thing, only that it shells be fur the entire boat and that I should do it.

I can't even post pictures.

Good idea though for someone.

"Shells be fur..." Good thing I use an iPad too so I know what the stupid thing does to writing.

Umm, now I just read that whole article. Two thirds down they mention the real issue, if your engine was not designed to be a real diesel or your cylinder walls are too thin, then you will have these issues and need to mitigate then by buying special stuff.

Which reminded me that a jeep engineer ten years ago told me that the reason I had to get the special friction modifier for my transfer case, was because that's how they dealt with design/manufacturing problems.

I did like the above article did explain why diesels are built sui robustly.

Many true high performance diesels will have a lower compression ratio BUT require SCA .
Tiubos putting out 30-40 PSI of boost underway create enough combustion pressure to really ring the cylinder walls.

Its the in operation loads that count , not the paper compression ratio.

Wxx3 said:

Umm, now I just read that whole article. Two thirds down they mention the real issue, if your engine was not designed to be a real diesel or your cylinder walls are too thin, then you will have these issues and need to mitigate then by buying special stuff.

Click to expand...

I'm pretty sure the 8.3L cummins in my rv was designed to be a "real" diesel. It requires sca's to prevent cavitation.