Is this a problem / overheating?

Anyone tell me exactly what the obvious burning on the exhaust elbow signifies?
I would guess an over-heating incident, perhaps interupted water flow.
Other possibilities?
What else might have been damaged?
What should I be worried about?
What should I be checking?
(Westerbeke W100)

Greetings,
Mr. SG. My "guess" is simply paint burnt off and not necessarily due to an overheat. That section of exhaust elbow is the only part of the system that is NOT cooled by water. You will notice that area downstream of your injection nozzle still has paint. Could easily be that you can't get a high enough heat resistant paint to stick there but a good idea to repaint in any case.
For example: http://www.rustoleum.com/product-catalog/consumer-brands/auto/specialty-paints/high-heat/

Thanks M. RT!
You are absolutely correct - in my haste to post I did not even notice the obvious fact that the burning is upstream from the water injection point.
However, it still begs the question, why did the exhaust gasses get so hot at that point to burn off the paint? That can't be normal?
(BTW - this is on a boat I am considering for purchase)

ps. RT - why did I not warrant one of your famous little video clips, such as the one Donna got of the young lady "swimming" in the mud?

Greetings,
One thousand pardons sir...

Why, thank you Sir!
I now feel like a bona fida member of the Trawlers Forum!

I agree that this simply overheated paint and no cause for concern. You could always wrap it with fiberglass tape. I never did understand why Westerbeke sprays the total engine red after assembly, including all hoses and connectors. I guess it is the cheapest way to go but not necessarily the best approach for rubber hoses etc.

For whatever it is worth, on my 4 cylinder genset no sign of paint burning on exhaust elbow. Ditto larger gensets I've seen after 10'000 hours. My suspicions would be an overheat, especially when boat shopping. Or maybe a failing Al elbow?

But some owners or Ski may have plenty of burned elbow experiences with this engine.

My Lehmans get over 600 degrees before the cooling water is injected. I wrapped the exhaust with high temp header wrap.

Thanks for all the suggestions so far!
My main concern is that a previous engine over-heat incident has done permanent damage elsewhere?
Is this a legitimate concern, and what evidence of further damage should I be looking for?

SlowGypsy said:

Thanks for all the suggestions so far!
My main concern is that a previous engine over-heat incident has done permanent damage elsewhere?
Is this a legitimate concern, and what evidence of further damage should I be looking for?

Click to expand...

lift the hood up on your car and you will see the same thing on your exaust

I'm agree with RT on this one. The exhaust gas temperature is probably a thousand degrees or more before the water is injected into it. I wouldn't be surprised if that section didn't glow red in the dark with the engine running. It would be interesting to aim an IR thermometer at that spot.

SlowGypsy said:

Thanks for all the suggestions so far!
My main concern is that a previous engine over-heat incident has done permanent damage elsewhere?
Is this a legitimate concern, and what evidence of further damage should I be looking for?

Click to expand...

Does anybody on TF have a Westerbeke showing same scorch pattern? Maybe this is an incorrectly designed aftermarket elbow. You as a potential buyer are correct to raise the question, which may well prove to be unfounded. What HP and size vessel?

And Capt Jerry, I'm anxious to see your Westerbeke powered vehicle with a raw water cooled exhaust elbow.

capt jerry said:

lift the hood up on your car and you will see the same thing on your exaust

Click to expand...

Good point - it is just that I have never seen this on any of my old boat engines (mostly Volvos)
Quite willing to accept that it is normal.
Now I can worry about something else! ?

HopCar said:

I'm agree with RT on this one. The exhaust gas temperature is probably a thousand degrees or more before the water is injected into it. I wouldn't be surprised if that section didn't glow red in the dark with the engine running. It would be interesting to aim an IR thermometer at that spot.

Click to expand...

Now that I have an infra-red thermal "gun", I will be checking a lot of temperatures I was only guessing at before. Plan to keep a temp. log so I have a record of what is normal, so I can see when it gets out of line.

sunchaser said:

Does anybody on TF have a Westerbeke showing same scorch pattern? Maybe this is an incorrectly designed aftermarket elbow. You as a potential buyer are correct to raise the question, which may well prove to be unfounded. What HP and size vessel?

Click to expand...

Thanks Sunchaser - 100 hp Westerbeke / 40' trawler 25,000 lbs.

SlowGypsy said:

Now that I have an infra-red thermal "gun", I will be checking a lot of temperatures I was only guessing at before. Plan to keep a temp. log so I have a record of what is normal, so I can see when it gets out of line.

Click to expand...

You're on the right track now! You'll also find that the IR Temp gun is very useful at helping you pick the very coldest beer from the fridge! That in itself makes it a worthy investment!

FlyWright said:

...You'll also find that the IR Temp gun is very useful at helping you pick the very coldest beer from the fridge! That in itself makes it a worthy investment!

Click to expand...

Ah, Obi Wan FlyWright. Master of truly useful advice.

Looks like original mfr's paint, judging by clean hoses and fuel lines. Odd, to me, is the way that ell burned the paint off starting right at the flange that's bolted to the heat exchanger. Surprised that the mfr's paint choice would burn. I suppose that the PO pushed the boat for some hours, but since there's paint everywhere else, I doubt an overheat episode. It's not as though a diesel can run rich and hot.

Dad's '51 Studebaker had a glowing red exhaust manifold after crossing a desert (in '52).
My '83 Volvo Turbo used to have a glowing red exhaust manifold after highway travel. Still got 170k miles before that turbo's oil bearings caked and I had to rebuild it.