Lehman 120 diesels

[Brusky1000]

I have a Bluewater 40' Pilothouse Trawler, circa 1978 in good condition, but have a couple of issues with the twin diesels. First, I am loosing coolant in the starboard engine, but no water is entering the bilge. I suspect I need to replace the heat exchanger. Any other possibilities?

Next on the port engine, I am getting air in the fuel system. I have checked ever connection, etc. The only thing I can think of is that maybe the fuel pump bellows has a hole and is the reason. Any thoughts?

 

[RT Firefly]

Greetings,
Welcome aboard.

 

[jjorgenson3]

Seems like you could be on the right track. Check your primary fuel filter and see if the cap is a little loose or if you see a little puddle of diesel on top. How much coolant are you loosing? A Call to Brian at American Diesel is probably best.

 

[Lepke]

Water loss can be a head gasket, crack in the head, block, exhaust manifold (if it's fw cooled) besides the exchanger. If it's a small leak occurring when the engine is at operating temp the leak could be evaporating. Any good radiator shop can clean and repair your exchanger. If the leak is there it's usually a tube needs resoldiering.
Air leaks can come from anywhere in the fuel plumbing. Old seals and gaskets in the filter housing is common. Most have rebuild kits available. Adding a 12v fuel pump after the primary filter will make bleeding and filter changes easier and will pressurize the lines and secondary filter making leaks in that part easier to find when not running. Also look for places where fuel lines are subject to rubbing from vibration. I had a tiny wear hole in a long run between the primary and secondary that took pressure to find. It didn't leak fuel, but would suck air.
A vacuum gauge at or after the primary shows if your filter is getting dirty. A new filter shows a slight vacuum that gradually climbs with filter age. Any sudden drop in the reading would indicate a air leak.

 

[Cigatoo]

Start with a pressure test of the cooling system. If you don’t have a pressure tester Advanced Auto Parts will loan it out to you. A couple of pounds above the rating on the radiator cap is enough to expose a leak. Once pressurized it should hold pressure for hours. Look for leaks while pressurized. Also listen. Sometimes you can hear the leak. Don’t rule out the cap itself.

 

[Tator]

Coolant leaks from a defective gasket between the exhaust manifold and the exhaust elbow are fairly common. The coolant goes out the exhaust so no sign of leakage. In most cases, an easy repair. I believe your Bluewater 40 is the first East Coaster I've seen.

Tator

 

[slowjoe]

Start the engine and see if prestone is coming out the exhaust when it starts ...if that is happening it’s the exhaust elbow on the motor ..

 

[Brusky1000]

Lehman Diesels cooling and fuel problems

Thanks for all the good ideas. Will be at boat for a couple of weeks beginning May 2 and will see if can solve problems. Love my boat!

 

[TJM]

Last fall I upgraded and added a new fuel line to my generator from my main engines primer fuel pump. This allowed me to bleed the fuel systems very easy. My Lehmans already had the system and plumbing. Silly me used brass hose barbs to connect the diesel hose to the fittings. I struggled all late fall with air intrusion into the genny and main engine that I tapped into.
I am in the process of replacing all of my fuel hose barbs with new Parker Hannifin hose and crimped fittings.

 

[Brusky1000]

Lehman Diesels cooling and fuel problems

Somehow I am getting air into the port engne on onboard fuel filter. Opening the bolt holding the filter releases a few bubbles of air. Don't thing gen is involved and all lines from engine back to main fuel filters are tight. My initial reaction is that somehow the fuel pump on the engine has a leak. Any thoughts. Thanks for your input!

 

[Cigatoo]

Somehow I am getting air into the port engne on onboard fuel filter. Opening the bolt holding the filter releases a few bubbles of air. Don't thing gen is involved and all lines from engine back to main fuel filters are tight. My initial reaction is that somehow the fuel pump on the engine has a leak. Any thoughts. Thanks for your input!

Could be a fuel pump, but start simple. Splicing in a piece of clear line down hill from a suspected leaking location will let you see any air. I would do this after triple checking all fuel lines and connections. Maybe loosen and retighten each connection.