How much do your Cummins VT-903’s smoke when cold?

[sgharford]

How much do your Cummins VT-903’s smoke when cold?

For all you Hat owners lucky enough to have Cummins VT-903’s installed , how long do yours smoke when cold? Mine smoke like banshees (white smoke, no oil burning) until temp gauges start budging off pins if idling (about 100 degrees), and are reduced by at least ½ when I put them in gear when cold. On calm days I can see sheen of unburnt diesel on water at exhaust. When engines warm there is no smoke at idle or higher rpms. Understand it’s somewhat ‘normal’ for turbo engines to smoke at cold idle due to lower natural compression ratio, cold block, and turbo’s not making much if any compression at low rpm.

I bought the tools to do injector and valve clearances on ebay over winter. Was thinking of saving that project for end of season but if above isn’t normal by VT-903 standards maybe I’ll tackle it sooner.

 

[kwerges]

Re: How much do your Cummins VT-903’s smoke when cold?

For all you Hat owners lucky enough to have Cummins VT-903’s installed , how long do yours smoke when cold? Mine smoke like banshees (white smoke, no oil burning) until temp gauges start budging off pins if idling (about 100 degrees), and are reduced by at least ½ when I put them in gear when cold. On calm days I can see sheen of unburnt diesel on water at exhaust. When engines warm there is no smoke at idle or higher rpms. Understand it’s somewhat ‘normal’ for turbo engines to smoke at cold idle due to lower natural compression ratio, cold block, and turbo’s not making much if any compression at low rpm.

I bought the tools to do injector and valve clearances on ebay over winter. Was thinking of saving that project for end of season but if above isn’t normal by VT-903 standards maybe I’ll tackle it sooner.

Mine smoke slightly (white smoke, no oil burning) at start, but continue until warmed up or under load. Even warmed up they still smoke ever so slightly. Need to have injectors and valve clearances as well, as they haven't been done for as long as I've owned the boat (4 years). Please let me know what you find out...

 

[Boatsb]

Re: How much do your Cummins VT-903’s smoke when cold?

I just sold a boat with VT555's the little brothers to them and the fuel condition was the reason for the smoke. Fresh fuel with cetane boost does the trick.

 

[sgharford]

Re: How much do your Cummins VT-903’s smoke when cold?

Fresh fuel with cetane boost does the trick.

Very Interesting (and sounds cheap!). I used AJX last year and did notice less smoke. Not sure if that it has cetane booster too, will check it out tomorrow as still have some left I need to put into current tanks. Been meaning to try Diesel Kleen as I believe it's alot cheaper. I'll be sure to write back when done testing now that I'm specifically looking for results.

 

[Boatsb]

Re: How much do your Cummins VT-903’s smoke when cold?

I have been using diesel Kleen on my detroits and am switching to AJX.

 

[sgharford]

Re: How much do your Cummins VT-903’s smoke when cold?

I have been using diesel Kleen on my detroits and am switching to AJX.

And that begs the question "Why"? Have you had better experience with AJX? I have never used Diesel Kleen but read others seem to like it.

 

[Boatsb]

Re: How much do your Cummins VT-903’s smoke when cold?

About Diesel kleen

It's cheap. It's sold at walfart. It's the most basic that fits the additive needs but it does nothing for tank maintenance. If price is the deciding factor thats the way to go.

I am changing over to the AJX TMS as it will keep everything better than the diesel kleen.

 

[sgharford]

Re: How much do your Cummins VT-903’s smoke when cold?

I got the same general response about tank maintenance when I asked the question 2 years ago and picked up a couple of quarts of AJX. Curious about AJX boosting Cetane rating, guess it does. I know I still had enough smoke to make my neighbors run below every time I cranked em over when I was using it (sail boaters mind you). Unless it's your gas making the stank, it's hard to enjoy it

 

[Boatsb]

Re: How much do your Cummins VT-903’s smoke when cold?

TMS boosts cetane while TCS cleans better. I know with clean fuel the 43DC with 903's that I sold a while back did not smoke like that. Check with another member (Mel Tucker) to see if he has the same amount of smoke. It may be tune up time too.

 

[REBrueckner]

Re: How much do your Cummins VT-903’s smoke when cold?

What do you mean by "cold"? At 30 degrees you'll be lucky to get your engines started...at 80 degrees ambient likely they'll start promptly and smoke a LOT less. Is this some sort of change from earlier "cold" starts??

If you are getting no smoke at normal cruise RPM, and your exhausts are clear after a few minutes at rated WOT RPM, I'd not worry. That means compression and combustion is sufficient to produce proper WOT RPM's.

I had a smidgen of smoke several years ago, so I thought, at start up, with my 8V71TI's, and the same guy who did my overhaul "tuned" them up....the only guy I let touch my engines on two boats over 25 years....both smoked just a tad MORE after the "tune up"...I was really disappointed.....Asked the mechanic "Are you getting too old for this work" and he replied "It feels like it." Had the mechanic come back and double check his work...all was well, he used the same valce clearances as six years prior....I wasted time and money over nothing.

Even if you are burning a tad more fuel, meaning that maybe in a perfect world a tune up might yield a slight improvement, so what? Unless you are running say a thousand annual hours you'll spend far,far,far more on the cost of a tune up than any fuel savings. "Don't "fix" what ain't broke."

Why not install block heaters, or engine oil pan heaters..to warm your engines before start...that will eliminate the vast majority of cold start smoke at any ambient temperatures...

 

[sgharford]

Re: How much do your Cummins VT-903’s smoke when cold?

I think the engines smoke less then when I bought her 3 years ago. Previous owner only put 60 hours on engines in 5 years (By chance my engine surveyor did the survey for prev owner when he bought boat). I actually did install block heaters this year - no easy task on a 903. I have to finish up my thread on that later this month. Have yet to really kick tires on block heaters.

I'm not overly worried about the smoke, outside of pissing other people on dock off, which I don't lose any sleep over. Was excited to finally find proper tools to do injector and valve timing this winter after 3 years on the hunt. I hate doing projects during the boating season, that's what winter is for, so I will wait for end of season on this one (want her in water so I can test when I'm done).

Point of this thread was to establish base line of what is normal for old 903 in terms of smok'n. Got a good PM on subject along with your guys feedback all seems normal as I described. Thanks all.

 

[34Hatt]

Re: How much do your Cummins VT-903’s smoke when cold?

I got the same general response about tank maintenance when I asked the question 2 years ago and picked up a couple of quarts of AJX. Curious about AJX boosting Cetane rating, guess it does. I know I still had enough smoke to make my neighbors run below every time I cranked em over when I was using it (sail boaters mind you). Unless it's your gas making the stank, it's hard to enjoy it

Yes it does raise your cetane

 

[jim rosenthal]

Re: How much do your Cummins VT-903’s smoke when cold?

See what they do once you get the block heaters up and running. Most engines smoke far less at startup when they are preheated with pan or block heaters. The problem may go away by itself. I think white smoke is unburnt fuel, isn't it? My guess is that once the heads are warmed up the fuel burn pattern is much more even and more effective.

 

[REBrueckner]

Re: How much do your Cummins VT-903’s smoke when cold?

"...I think the engines smoke less then when I bought her 3 years ago. Previous owner only put 60 hours on engines in 5 years..."

No surprise. With block heaters, I'd not even give it a second thought...

"I hate doing projects during the boating season, that's what winter is for.."

Amen.....


Other discussions here on Sam's properly note than an engine with hardly any running time builds up some corrosion in the cylinder walls as a result of the moist marine environment...and so when the engines are finally run with some regularity, the pistons (hopefully) scrape the cylinder walls clean and combustion/compression actually improves t....Hence if an oil analysis is done on an engine that has been sitting around iron content, for example, may show a lot higher than after a season of regular use...