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Dave_E 10-14-2013 09:34 AM

Diesel Smell
 
Hi All,

As I've mentioned before, diesel ownership on a sailboat is new to me. I've smelled/inhaled plenty of diesel exhaust in my day, (used to work at heavy duty truck dealerships and truck stops as a lad).

My 34 year old Universal 5424 with 3317.3 hours, starts up from cold... (30 seconds on the glow plugs) - no sweat. Warm engine... starts right up. Hits 2800 top RPM good and idles at 550-600 smoothly. No black smoke, exhaust is thin and fairly colorless with good water flow (fresh water cooled).

Here's the deal. At RPM's less than around 2100... smells like diesel to me, but get on it hard and you get that "somethings cooking" smell. It so alarmed me last week that I throttled back to look for problems. No change in exhaust color or density, oil pressure OK (no light), temp hovering around 150. It does this every time. Something I should be concerned about? Any thoughts or suggestions? Thanks as always.

Dave

Faster 10-14-2013 09:47 AM

Re: Diesel Smell
 
We had a pervasive exhaust odour below a while back, despite numerous 'visual' inspections was unable to determine the source.

In the end I decided to remove and inspect the exhaust elbow. While scraping a 'little' surface rust the tool went right through it! While it appeared 'whole' turns out it had corroded to the point that it was porous. Built a new one out of SS and no issues since.

Given the mixing of salt water, elevated temperature, thermal shock etc involved here it's not surprising that this is where the worst corrosion will occur, not to mention simple carbon buildup.

T37Chef 10-14-2013 09:47 AM

Re: Diesel Smell
 
Sounds like a leak, maybe an injector or injector pump. Might be time to rebuild that pump?

Hard to say. Dry rag and rub it around the engine and see if you smell diesel.

Dave_E 10-14-2013 10:09 AM

Re: Diesel Smell
 
The smell is from the exhaust. No leakage anywhere around the motor, oil, water or fuel. Doesn't smell like burning rubber, but will take a look at the exhaust path (amazingly long).

Dave

arf145 10-14-2013 11:30 AM

Re: Diesel Smell
 
With my last boat I'm pretty sure I had the situation Faster describes, except that I was a little too clueless to look closely at the exhaust coupling when I kept smelling diesel. The elbow looked perfect. When the coupling broke one day (lots of drama), I was able to see that the coupling had many small perforations that were no doubt leaking before the dramatic end. Worth a check!

seaner97 10-14-2013 10:59 PM

Diesel Smell
 
Just replaced my exhaust elbow- same issue. Damn thing split in two when I went to inspect it.

Faster 10-15-2013 12:26 AM

Re: Diesel Smell
 
Quote:

Originally Posted by Dave_E (Post 1104304)
The smell is from the exhaust. No leakage anywhere around the motor, oil, water or fuel. Doesn't smell like burning rubber, but will take a look at the exhaust path (amazingly long).

Dave



Dave E... to be clear, we're talking about the last fitting before it goes to hose, just where the cooling water mixes with the exhaust stream. Of course it's also possible you have a leaky connection at the muffler or elsewhere, but a water leak will usually accompany a problem there since the exhaust is wet by that time.

The elbow is usually right off the exhaust manifold, with a smaller water line connected to the side that takes your RW cooling water and injects it back into the exhaust to cool and quiet it.

Minnewaska 10-15-2013 08:15 AM

Re: Diesel Smell
 
Do you have an engine compartment blower that exits near the exhaust?

Dave_E 10-15-2013 10:11 AM

Re: Diesel Smell
 
Thanks Faster, I'll look there first. Going to the boat tonight.

I have a blower... pick up is near the bottom of the engine bildge, don't use it much, it's never on after the engine is running.

Osprey 26 10-19-2013 10:50 PM

Re: Diesel Smell
 
Here's the deal. At RPM's less than around 2100... smells like diesel to me, but get on it hard and you get that "somethings cooking" smell. It so alarmed me last week that I throttled back to look for problems. No change in exhaust color or density, oil pressure OK (no light), temp hovering around 150. It does this every time. Something I should be concerned about? Any thoughts or suggestions? Thanks as always.

As you described 150 is not warm enough for Diesel Engine. Should be around 180, and it takes time to get there. Any oil on the block from last oil change, and possible couple drops spilled on top of it?


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