Lehman 120 oil leaks

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Dave_E

Dave_E

Senior Member
Joined
Sep 2, 2014
Messages
276
Location
USA
Vessel Name
Agnus Dei
Vessel Make
36' Shin Shing
Hi All,


I know I've asked you before about oil leaks. I put a new oil pad in the drip tray below the engine and in several places I have oil spots (2-3" in diameter), about 3 of them AND I have oil accumulated on the starboard rear engine mount leg of the motor (where the data plate is). Shine a flashlight at the bottom of the head and I see shiny. Touch it with a clean paper towel... it's oil. I'm not loosing any antifreeze, exhaust color is like it always is. I also have streaks from the head to the oil pan say 7 or 8 of them in various places on the block. Idles and runs like a champ (never above 1800 RPM).



Anyone else ever had this on their Lehman? Input?



Dave
 
Last edited:
Greetings,
Mr. DE. Easiest thing to try is snug down your valve cover. NOT tight, snug. You may have to replace the gasket. If so, make sure the cover is not deformed where the screw holes are. Perhaps a previous owner was a bit too exuberant in fastening down the cover.
 
Last edited:
I had the same problem. It is most likely coming from the valve cover. Try tightening the large screws holding the valve cover down. Mine work loose every so often.
 
While the valve cover is off take a straight edge and make sure it is flat so it will seal with the new gasket. If it has been over tightened in the past it may have deformed.
 
200w.webp
 
I have the same thing on starboard aft motor mount. Changed valve cover gasket with same result. I tried to straighten it but it’s a big beast and PO must have cranked them down a bit.
 
Agree about valve cover gasket and possibly a seal where one or more injector lines go into the head.


My other dips were/are from sender's on the port side or accumulated oil in the air filter.


None are really anything to worry about. Even the rear main has to leak a lot before many mechs will say change it.
 
Dave_E said:
Hi All,


I know I've asked you before about oil leaks. I put a new oil pad in the drip tray below the engine and in several places I have oil spots (2-3" in diameter), about 3 of them AND I have oil accumulated on the starboard rear engine mount leg of the motor (where the data plate is). Shine a flashlight at the bottom of the head and I see shiny. Touch it with a clean paper towel... it's oil. I'm not loosing any antifreeze, exhaust color is like it always is. I also have streaks from the head to the oil pan say 7 or 8 of them in various places on the block. Idles and runs like a champ (never above 1800 RPM).



Anyone else ever had this on their Lehman? Input?



Dave
Click to expand...


Without using gasket sealant which I don't really recommend, I think *everyone* has this on their Lehmans in varying degrees. Its almost surely from the valve cover gasket. Its old school - old style which is very hard to get completely leak free even with a new gasket. If they haven't been replaced lately I would start with a new gasket. First check the valve cover for "dents" around the screws from previous overtightening. If there are dents, these need to be carefully "massaged" out, then install a new gasket and carefully tighten the valve covers - not too tight.


Ken
 
There are long steel valve cover hold downs available at the auto parts store - see picture.
They are available in several shapes.

I use those on my Lehman valve covers to spread the pressure to a larger area. Some grinding of the holdown may be required to get the holdowns to fit around the shape of the valve cover.

Use a new gasket with these and tighten evenly and no more leaking valve cover. I do use a gasket sealant to glue the gasket to the valve cover only to keep the gasket from moving around during tightning.

Lehmans are leaky engines.
 

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kchace said:
Without using gasket sealant which I don't really recommend, I think *everyone* has this on their Lehmans in varying degrees. Its almost surely from the valve cover gasket. Its old school - old style which is very hard to get completely leak free even with a new gasket. If they haven't been replaced lately I would start with a new gasket. First check the valve cover for "dents" around the screws from previous overtightening. If there are dents, these need to be carefully "massaged" out, then install a new gasket and carefully tighten the valve covers - not too tight.
Ken
Click to expand...

I know I can tighten mine annually, and by tighten I mean with a small screwdriver trying not to dent the holes.
I use the round part of a ball peen hammer to "un-dent" the holes.
The spreader "washer" is a good idea, I may but some.
 
Also, take a close look at the mounting for your fuel lift pump. It mounts with 2 bolts that are not very well placed. Oil coming out of there usually goes up and looks like a leaky valve cover. Really. A new gasket or sealer works well. Also those 6 seals that press against the block where the injectors enter are also an issue.
 
syjos said:
There are long steel valve cover hold downs available at the auto parts store - see picture.
They are available in several shapes.

I use those on my Lehman valve covers to spread the pressure to a larger area. Some grinding of the holdown may be required to get the holdowns to fit around the shape of the valve cover.

Use a new gasket with these and tighten evenly and no more leaking valve cover. I do use a gasket sealant to glue the gasket to the valve cover only to keep the gasket from moving around during tightning.

Lehmans are leaky engines.
Click to expand...


Those are a great idea. I think I'll look into them.


Ken
 
People who own old British cars have been experiencing oil leaks for about 100 years.
So why’s it so objectionable on a boat.

Now that I’ve had my snarky say I had an oil leak on my new (basically) engine and finally figured out where it was coming from. Hasn’t leaked since I took out the offending hardware. But it’s not an old British engine.
 
OK, too many answers all saying the same thing. I'm going to take the cover off this weekend, check for flat surfaces, install a new gasket. Let you know what I find.
 
A note regarding oil leaking at the bottom of the bell housing. Brian said it is rarely the rear seal but rather a leak around the freeze plug at the end of the cam shaft.
 
While I respect Brian, there are more than a few owners and confirmed by mechanics that have had rear seal leaks. I currently have one.


They are aggrivated by overfilling with oil which is part of the hub bub over proper oil level.


How does a freeze plug that only seals for coolant produce an oil leak?
 
FL's can leak oil if blowby is high and the little rocker cover vent gets overwhelmed by high flow, pressurizing crankcase. Nobody wants a lot of blowby, that means there is leakage past rings, but that is a tough nut of an engine and even with blowby it can serve well. On a couple I have welded in a larger fitting on rocker cover for blowby and the leaks basically went away. Rear seal, even if old, does ok as long as crankcase is not pressurized.

Even with low blowby, some leak a bit. Easy fix: Wipe it up.
 
Dave_E said:
OK, too many answers all saying the same thing. I'm going to take the cover off this weekend, check for flat surfaces, install a new gasket. Let you know what I find.
Click to expand...
Make sure you use a fresh gasket. I recently replaced a leaking gasket with one that was aboard the boat when I bought it five years ago. And who knows how long it was on board before that. Anyway, it leaked like a sieve. That old orkk was too hard to compress enough to provide a good seal. A fresh gasket from American Diesel solved the leaking. To use a sealant is a decades old debate among mechanics, both on boats and vehicles. I used a modest amount of sealant. No leaks. I have no idea of whether I would have gotten a good seal without a sealant. And, I don't care. I only care that my valve cover no longer leaks. By the way, my leak was bad enough that, somehow, some way, the oil found its way along the underside of the bell housing and transmission to the shaft flange. Yup, that rotating assembly would sling that oil and make a mess. Engines are FL 120s.
 
The freeze plug is actually a plug on the back of the cam shaft. That’s where the oil comes from. Maybe “freeze” is not the correct terminology in this case.
 
Dave_E said:
Hi All,


I know I've asked you before about oil leaks. I put a new oil pad in the drip tray below the engine and in several places I have oil spots (2-3" in diameter), about 3 of them AND I have oil accumulated on the starboard rear engine mount leg of the motor (where the data plate is). Shine a flashlight at the bottom of the head and I see shiny. Touch it with a clean paper towel... it's oil. I'm not loosing any antifreeze, exhaust color is like it always is. I also have streaks from the head to the oil pan say 7 or 8 of them in various places on the block. Idles and runs like a champ (never above 1800 RPM).



Anyone else ever had this on their Lehman? Input?



Dave
Click to expand...
First, lightly snugging up the bolts around the valve cover but don't get carried away, if they are loose snug them slightly, but do not over tighten. Also Lucas has a oil stop leak stuff that I have used that actually works like magic and I have used for years. It makes the seals swell a little, however I never use it as directed, I cut the amount in half and give it a few weeks to do its work then change the oil... Discovered it many years ago and have never had anything with oil leaks after using it.
 
Dave_E said:
OK, too many answers all saying the same thing. I'm going to take the cover off this weekend, check for flat surfaces, install a new gasket. Let you know what I find.
Click to expand...

It only goes down with 22-inch pounds. That is a very like touch, and assumes a flat surface on the cover! It bends so easily.
 
RT Firefly said:
Greetings,
Mr. DE. Easiest thing to try is snug down your valve cover. NOT tight, snug. You may have to replace the gasket. If so, make sure the cover is not deformed where the screw holes are. Perhaps a previous owner was a bit too exuberant in fastening down the cover.
Click to expand...
I agree, replace valve cover gasket.
 
Hi All,


Well we made it back from our 10 day cruise in the San Juan's.:) I say that because on our first 4 hour leg I went below for a first hand observation and this is what I found: At 1800 RPM the head gasket was seeping oil and water making these burning streaks down the side of the block... burning off the red paint. Could smell the burning oil.


At the end of that 4 hour run, the diaper in the catch pan below the engine was brown with oil/anti freeze. The anti freeze collected at the lower end of the pan. Oil had once again collected on the starboard aft engine mount leg. Oil level on the stick looked like it didn't move, but the anti-freeze was down to the bottom in the tank.


So... on the next leg, I ran the engine at 1500 RPM (thinking I could make it through the trip). That leg and all others (8 more hours) there was no anti-freeze loss that I could measure. There was no oil accumulated on the engine mount leg.



I have done no testing of any sort to this point. First thing I'll do is a cooling system pressure test. I re-torqued the head prior to this trip. This winter I'm going to go for a head gasket change. Any discussion is always appreciated as we learn together. :thumb:


Dave
 
I had a strange coolant leak. At the end of last season my starboard engine started leaking coolant. I filled it up several times and then put some dye in the coolant. Unfortunately with my wife having her 5th shoulder surgery I didn’t have time to follow up on it until this spring. After launching and running 1/2 mile to our dock, I had 3 gallons of antifreeze in the drip pan. I used the black light to see where it was coming from. It appeared to come from the thermostat housing. Filled it up and pressure tested it, no leaks. And so far we have had no more coolant loss. I am not sure on my next move.
 
Dave_E said:
Hi All,


Well we made it back from our 10 day cruise in the San Juan's.:) I say that because on our first 4 hour leg I went below for a first hand observation and this is what I found: At 1800 RPM the head gasket was seeping oil and water making these burning streaks down the side of the block... burning off the red paint. Could smell the burning oil.


At the end of that 4 hour run, the diaper in the catch pan below the engine was brown with oil/anti freeze. The anti freeze collected at the lower end of the pan. Oil had once again collected on the starboard aft engine mount leg. Oil level on the stick looked like it didn't move, but the anti-freeze was down to the bottom in the tank.


So... on the next leg, I ran the engine at 1500 RPM (thinking I could make it through the trip). That leg and all others (8 more hours) there was no anti-freeze loss that I could measure. There was no oil accumulated on the engine mount leg.



I have done no testing of any sort to this point. First thing I'll do is a cooling system pressure test. I re-torqued the head prior to this trip. This winter I'm going to go for a head gasket change. Any discussion is always appreciated as we learn together. :thumb:


Dave
Click to expand...

While you have the head off, you should have it checked for cracks and have all the valves serviced.
 
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