Minor smoke in exhaust of 1998 450DA Cat 3126's

Caterpillar engines are high torque motors. The additional torque also means large diameter props with a lot of pitch to hold the torque. When you put them in gear, you need to know where you are going because you are going to get there in a hurry. After 10 years with a gas 390EC, the Cat powered 450DA is a pleasure to operate since it is infinitely more controllable around a dock or in crowded conditions. I have developed the habit of checking everyone to be sure they are either holding a grab rail or seated before I put the boat in gear.
 
Here's a photo of the smoke at 2,200 RPMs
 

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Our 1998 450 Da with 3116 cats has 900 hrs. Turning 22 x 22 4 blade props. Never seen any smoke like that from going from a idle all the way to 2800 or just cruising at lower rpms. I don't post much, But read quite a few. All Franks advice and knowledge of Cats is spot on. Ido run the Cat oil. Best of luck on you problem.
 
My port engine used to push a lot of blue smoke at start up. Turned out to be a bad cylinder and that resulted in having to replace the block. But black smoke while underway, isn't that a sign of running too rich?

Probably been done already but has cleaning the air filters been done?
 
Yeah, cleaned the air filters with no improvement. Reading thru the manual, it says that black smoke and power loss can result from a dirty turbo-charger. I've never cleaned one before though.
 
There are a lot of potential causes for what I see in that photo. Some of them can cause serious damage to the engine if not repaired and almost none of them can be handled by someone other than a qualified diesel mechanic. If you have cleaned the intake air filters, then you have done about all an owner can handle on his own. My advice here is to call your local Caterpillar dealer and get a technician on the boat to properly diagnose the cause.

Good luck with it.............
 
Called our local Cat tech and he spent a few hours on her. Could be one of many issues. Sticky check valve, dirty air intake (not the filter) or a bad turbo. I have a feeling this won't be a cheap one. SMH
 
One thing you cannot trust on a sea ray is the tachometers. When I bought my 400DA one tach was 200 rpm different than the other when the sync was on. I quickly upgraded to Aetna Digital Tachs and still love them today. You can't set your idle or really know your WOT rpm by reading the OEM Tachs. You have to use a hand held tach on the damper or go digital.

Pete
 
Update. Man, did lady luck come through on this one!

Cat tech spent an hour in the bilge and found that the boot on the turbo had come off. Fingers crossed!!!
 
fwebster said:
Grey-white smoke is usually steam in the exhaust . That is caused by the hot exhaust cooling water mixing with cool seawater. Are your impellers fresh? What about the engine temps? Does the engine temp rise to 195˚ and stay there or does it continue past there until you pull back the throttle. Cat engines have a lot of cooling capacity but when the cooling sustem needs attention, they will run up past 195. Another less likely cause is a blown head gasket. A blown head gasket brings on other symptoms like disappearing antifreeze and a sweet odor to the exhaust.

Sooting on the transom comes from overloading the engine or from restricted intake air....check the breather element and replace or wash it depending on the type. A fouled aftercooler will also cause sooting.


Disclaimer: Y'all realize that I am 2500+ miles away from either of you and have not been on either boat, so the above is a generic educated guess based on what usually happens with 3100 series Cat engines.
Click to expand...

Plus 1 on impellers.
 
I have an update to post on this. I noticed that the temp on the port engine was starting to climb during longer cruises (30+ minutes) - it would start out normal and then climb to about 195 until I throttled back. I knew that it was time to investigate further. I removed the heat exchanger caps on both sides. The starboard engine had one fairly good sized chunk of impeller, plus some kind of rubber band looking item. The port side though, my gosh I was surprised at how much stuff was in it. Impeller blades, shells, old anode rods, etc. I removed all of it, and then did the Barnacle Buster flush over the weekend. I haven't been able to test drive it yet, I ran out of time. I know just removing that junk will help with the temps being steady, I'm looking forward to seeing that it removed the white steam plume as well.

Here's a pic of what was removed. Left side is from the port motor, right from starboard.
 

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To add to Mr. Webster's comment - your fuel may need treatment / shock treatment. The modern ultra-low sulfur diesel is hard on the injectors and injection units and can just as easily create soot in the exhaust. You may want to get an analysis on the engine oil done so an assessment can be done as to the level of fuel in the oil. The last thing I'd offer is there are several little check valves in the injection unit that control the return fuel and over time they tend to gum up which will affect the fuel pressure to the injectors and consequently can cause a rich condition.
Frank did a great write up on fuel treatment and it's posted on this site; take a look at it.
Tom
 
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