Jimmy cold start analysis

[Mako]

Appreciate your thoughts when analyzing this dead-cold start:

• DD 4-71 naturals
• 1976 (48 years old)
• 4500 hours each
• Never rebuilt, nor major service (engine head replace, etc.)
• Haven't been run in over a month

Thanks SteveK for the hint on posting videos!

 

[DavidM]

I don’t see a problem. A little puff of grey smoke that lasts for maybe a second when the right engine starts. No smoke on the left engine.

Looks good for many more hours.

David

 

[mbevins]

Depending on ambient temperature there's absolutely nothing wrong with those engines.

 

[lwarden]

Looks amazingly good for 48 year old engines. My Cummins 6BTA's smoke that much when cold, and they aren't 2-strokes!

 

[PierreR]

Does not look like and issue to me. Do you have any diesel floating on top of the water coming out of the exhaust?

 

[Cigatoo]

With my buddies DD 471 it’s a good day if you can still see the boat when he starts it. Must be something wrong with yours.

 

[Ken E.]

2-cycle Detroits love block heaters. I had the immersion type, Kim Hot Starts, and my 871's would start on the first rotation with no smoke.

Further to the OP's question, I would just start them as is, which will entail some cranking and smoke.

 

[Mako]

@Cigatoo,

Funny. Reminds me of my old 2-stroke Merc on my fishing boat. I would smoke-out all the other boats at the ramp when launching. Got a lot of dirty looks!

Very embarrassing.

 

[Mako]

Seriously, the first couple of seconds of smoke are meaningless, right?

 

[jleonard]

Yes. Youll get fuel injected into the cylinders while it it turning over. That overfueling condition results in stat up smoke.

 

[tiltrider1]

Seriously, the first couple of seconds of smoke are meaningless, right?

Those engines basically started up smoke free. My 4 cycle Cat’s smoke more then that on start up. I suspect those edges had block heaters. Still nothing wrong with that.

You can do an oil analysis but I doubt you will learn anything from a one off oil analysis on those engines.

Did you sea trial? Did they over heat at full throttle?

 

[Blissboat]

Agree with everyone above. If those Detroits have any issues, you sure can't tell it from the startup exhaust. Looks and sounds great to me!

 

[Mako]

Thanks everyone. I was told years ago that you can tell a lot about the condition of Jimmies (even more so than 4-strokes) by the cold start. Was just looking for some outside feedback

 

[rslifkin]

A small puff of grey on startup is normal for just about any diesel when cold, especially older designs. Some (such as Cat 3208s) will often throw a little bit of grey haze for the first few minutes until they start to warm up.

 

[High Wire]

They look great!

 

[Brisyboy]

I agree they look strong.

One thing I did notice was when the stbd enging first fired there was a small brown "sludge?" thrown into the water. I have a similar "issuing" on my two Lehmans - I always assumed it was a bit of rust in the muffler (they are home made steel by the PO) but it is more pronounced. Should I be worried - is my assumption re the rusting mufflers correct - or could it be coming from upstream?

Sorry Mako - not trying to hijack your thread and I don`t think its an issue for your beauties - just curious...............

 

[Mambo42]

They look absolutely fine to me. You should see my engines when I start them up (ford Lehmans) and they are basically brand new (250 hours roughly), still running in. We actually have to apologize to our neighbors in the marina when we start up
So would not worry about your engines at all.

 

[Lepke]

The engines start and sound like they have a decade or two left. When they begin to give trouble cold starting, put in block heaters. Plug them in a couple hours before starting and the engines are probably good for a couple more decades. As they age they'll use a little more oil and smoke a little. But that won't change the reliability.

 

[Mako]

One thing I did notice was when the stbd enging first fired there was a small brown "sludge?" thrown into the water. I have a similar "issuing" on my two Lehmans - I always assumed it was a bit of rust in the muffler (they are home made steel by the PO) but it is more pronounced. Should I be worried - is my assumption re the rusting mufflers correct - or could it be coming from upstream?

In my example it is just the brown, muddy lake water that's been sitting in the pipes for more than a month. Sediment. The pipes are fiberglass.

In your case it could be rust, but that would be extreme. Why don't you rent or buy a borescope and see if you can get inside a bit on both ends?

Also, I've always like thread drifts. Discussions lead to people thinking about similarly-related topics. Maybe the Moderators don't, but I'm good with it

 

[rslifkin]

I've seen brown sludge like that as rust from exhaust risers / injection elbows if they're cast iron and don't have a good protective coating on the inside. I've also seen it as mud / silt buildup when a boat is docked in a muddy river and a little bit of mud settles in the raw water side of the cooling system, the mufflers, and the exhaust tubes after shutdown (especially if some water splashes into the exhaust tubes at the dock to accumulate more mud).

 

[hollywood8118]

Good grief, My Volvo smokes more than that when its not running!
Those motors started fantastically!
HW

 

[Capn Bob]

I’m very familiar with the 71 series Detroits, having run them in several vintage boats. Actually, your engine started up clean as the driven snow compared to the ones on my old boats, all of which were WW2 surplus boats which had been driven hard and put up wet. And they STILL ran beautifully!

Those Jimmies are good for another 20,000 hours, easily!