Smoke from the engine

[c130king]

I seem to have light black smoke coming from the "breathing tube" that comes out of the top of my motor. The tube/hose is connected to the cover on top of the engine very near the oil fill opening. The tube/hose routes over the top of the motor and exhausts near the engine air filter.

Not sure what this tube/hose is for.

The smoke is a little "sooty" and is turning the engine compartment black and turning my air filter cover very black.

M25XPB with 2500 hours.

Thoughts????

Thanks,
Jim

 

[Don S/V ILLusion]

Not sure if that engine has a breather tube as you describe but if so, the symptom you describe indicates a restriction on the engine exhaust such that back pressure is created causing the breather tube to serve as another exit.

 

[c130king]

Is it like a positive crankcase ventilation valve...may be failed?

Looks like a valve in that rectangular housing on top of the crankcase cover.

How does one remove that valve?

Presume I have to remove crankcase cover. Probably has a gasket that would need replaced? Source for gasket?

Pictures attached of hose, valve and black soot all over white wall on back of engine compartment.

Cheers
Jim

 

[JK_Boston_Catalina310]

Is it like a positive crankcase ventilation valve...may be failed?

Looks like a valve in that rectangular housing on top of the crankcase cover.

How does one remove that valve?

Presume I have to remove crankcase cover. Probably has a gasket that would need replaced? Source for gasket?

Pictures attached of hose, valve and black soot all over white wall on back of engine compartment.

Cheers
Jim

Jim,

I don't think there is much to the crankcase vent that can fail on our boats. See the page from the technical manual. They don't cover replacing a valve and I have never seen a part number for one listed. I think it just lets air escape the crankcase by the structure.

I think you have two possibilities. First the clogged or restricted exhaust. Check the elbow. Do you see water coming out at the stern?

Second, something looks off on your belt. Are you sure what you are seeing is soot and not belt wear. My belt was rubbing on the water pump fitting and I got a similar soot look to the engine compartment.

 

[SimiSAilor]

I think if you had a breather tube issue you would be seeing oil dripping from the air cleaner. My WAG is you have an exhaust leak. I would take a look at the clamps and check for good flow out the back of the boat. A restriction will cause increased pressure leading to a leak. Might want to pull the riser and take a look if you suspect it is not flowing well, reinstall with new clamps. Keep us updated.
Jeff

 

[c130king]

I have learned that crankcase is not the correct word...I am not a mechanic by any stretch off the imagination. It is the cover over the valve housing (???). Right where the oil goes in.

What is the purpose of that hose that comes out of that valve housing cover?

I now have sooty smoke coming out of it. Very easy to see when the engine is running.

Jim

 

[c130king]

The belt is good...looks a little off kilter from the angle of the picture. I have seen belt wear "dust". This is very evident smoke coming from that hose/tube.

I suspect clogged exhaust or some sort of "leak" around the exhaust valves. I do have the normal water flow out the exhaust on the lower rear starboard side. Maybe some sort of carbon build up on my valves preventing them from sealing closed properly?

Have my mechanically much savvier buddy coming over tomorrow and we will check it out.

Engine seems to run fine with the normal speed/power I would expect. Temps are fine. But sooty smoke comes out of that hose/tube.

Cheers,
Jim

 

[Don S/V ILLusion]

The belt is good...looks a little off kilter from the angle of the picture. I have seen belt wear "dust". This is very evident smoke coming from that hose/tube.

I suspect clogged exhaust or some sort of "leak" around the exhaust valves. I do have the normal water flow out the exhaust on the lower rear starboard side. Maybe some sort of carbon build up on my valves preventing them from sealing closed properly?

Have my mechanically much savvier buddy coming over tomorrow and we will check it out.

Engine seems to run fine with the normal speed/power I would expect. Temps are fine. But sooty smoke comes out of that hose/tube.

Cheers,
Jim

It's hard to diagnose via the Internet but the normal water flow you observe has nothing to do with the path exhaust gases take up to the point they mix with the water. Stated differently, you can't eliminate an exhaust clog simply by seeing a good water flow rate at the stern.

Your mixing elbow, which does what it's name implies,I.e., mix water and exhaust, if clogged,could cause this problem.

If it hasn't beencleaned or replaced in 2500 hours, it's looooooooooong overdue.

Also, this problem isn't limited just to Catalinas. Limiting your post to theC forum severely limits those who read your post to onlyC forum readers ( and people who might read all forums. Best to place such posts in "ask all sailors"forum.

 

[Meriachee]

When I acquired my 270, there was a small leak that was traced back to the elbow going into the Vestus muffler. Upon extracting the muffler, I found enough sand and small gravel in there to start my own beach. Blockage isn't just limited to the elbow. If there's trouble, the exhaust is going to come out someplace.

 

[c130king]

Going to check the exhaust riser today. It is new...built & installed last Summer after the old one cracked apart at the nipple where the water from heat exchanger is injected into the exhaust.

The old one was a continuous curve. The new one is made from stainless pipe but with 2 90 degree turns instead of continuous curve. So it might have deposits building up.

Cheers,
Jim

 

[c130king]

Exhaust riser is in good shape. No blockage of any sort is evident in the exhaust riser. However, did have too much oil. Pumped out some oil. Will do engine oil change in the next couple of days and use a higher weight oil (40 weight).

Also recommended an air filter for the breather tube to catch the excess smoke/soot so at least it doesn't coat everything in the engine compartment.

No smoke today but it didn't really get very hot. Going to watch it closely the next few days and see if the smoke situation improves.

Cheers,
Jim

 

[JK_Boston_Catalina310]

I redirected mine into one of these: http://www.jegs.com/i/JEGS+Performance+Products/555/52205/10002/-1

What weight oil did you use?

 

[c130king]

Don't remember which oil...think it was 10/30. My friend recommended I try 40 weight and hopefully that will slow/stop the seeping around the rings...if that was the problem.

I will look for one of those filter elements as well.

Ran engine on my sailing trip today...no smoke...but I also didn't run the engine very long.

Cheers,
Jim

 

[rpwillia]

Two thoughts

JK, Your post on the oil separator was pretty good. I made a thing similar to the oil separator but generally following the PaulJ mod. We both modified our respective crankcase vent hoses connecting them up directly to our air filters.

PaulJ's magic commentary on his use of the K&N air filter (which I did as well) is in this thread. http://forums.catalina.sailboatowners.com/showthread.php?t=157234

I can post pictures of what I did when I can find the pictures, but I essentially used a 1.5" pvc end cap with clear plastic tubing that fit inside with 90 degree connectors to route the host in from the crankcase and then feed it to the air filter so any oil gets a chance to collect in the end cap.

From my 310 Manual:
Some UNIVERSAL engines use a replaceable air filter element wrapped around a metal canister. This element can be removed and brushed off or cleaned with an air hose. When it becomes contaminated it can be replaced. The canister’s interior element should also be removed and cleaned periodically. Simply wash the assembled unit in a non-flammable cleaning solvent. Use this cleaning procedure for other UNIVERSAL air cleaners that use a similar type canister. Note: To operate efficiently a diesel engine muss intake a continuous volume of clear air. Hard starting, erratic idling, and black exhaust smoke are symptoms of restricted air intake.

Exhaust smoking problems
1. Blue smoke
2. White smoke
3. Black or gray smoke

1. Incorrect grade of engine oil
1a. Crankcase is overfilled with engine oil (oil is blowing out through the exhaust)
2. Engine is running cold
2a. Faulty injector or incorrect injector timing
3. Improper grade of fuel
3a. Fuel burn incomplete due to high back pressure in exhaust or insufficient air for proper combustion (Check for restrictions in exhaust system; check air intake)
3b. Improperly timed fuel system, misadjusted valves or poor compression
3c. Lack of air – check air intake and air filter. Check for proper ventilation
3d. Overload
3e. Propeller

 

[JK_Boston_Catalina310]

JK, Your post on the oil separator was pretty good. I made a thing similar to the oil separator but generally following the PaulJ mod. We both modified our respective crankcase vent hoses connecting them up directly to our air filters.

I also followed PaulJ on the K&N air filter.

At first I had the breather valve tied into the K&N like PaulJ and Maine Sail did. I was noticing the oil level increasing in the crank case. It was very slight but it was happening. I talked to some diesel mechanics I knew and they said you could pull some diesel past the cylinders with that setup. I removed the air filter connection, changed the oil and monitored it again. It didn't increase without the connection.

Just my observation. I don't know what the true cause was but it doesn't seem to be an issue now.

Jesse

 

[rpwillia]

Interesting

I also followed PaulJ on the K&N air filter.

At first I had the breather valve tied into the K&N like PaulJ and Maine Sail did. I was noticing the oil level increasing in the crank case. It was very slight but it was happening. I talked to some diesel mechanics I knew and they said you could pull some diesel past the cylinders with that setup. I removed the air filter connection, changed the oil and monitored it again. It didn't increase without the connection.

Just my observation. I don't know what the true cause was but it doesn't seem to be an issue now.

Jesse

That was one concern for why I put the air break. If I get fumes they will get sucked into the cylinder and burned. I promise pictures this weekend.