Cummins QSC500 Turbo Color

Chief Ed

Chief Ed

Active Member
Jul 19, 2020
168
So Cal
Boat Info
2006 44 Sundancer
Engines
Cummins QSC500
Hi all,

Sea-trialing a 2006 44 Sundancer with QSC500s tomorrow. Engines have 440 hours. This is the only pic I have thus far. Does the color of the turbos look “normal”? Wouldn’t quite call it “vanilla” nor would I call it “chocolate”. Somewhere in the middle?

Obviously, I’ll get RPM and Fuel burn data tomorrow. Just trying to get an opinion beforehand…

Thanks as always for the help…
 

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Good to hear! Thanks for that...

Hoping like h**l this one works out. Had a 460 fall out on survey a couple of weeks ago. Probably a blessing in disguise as this 44 is beautiful and looks to be much better taken care of. Same color as yours, Blueone. You’ve got good taste!
 
Good luck..... if you can ..get a Cummins tech to survey the engines
 
Roger that. Had a Cummins tech on the last one. Cost $1700 to tell me what I could already see myself.

Doing this one with a mechanic friend who is in the industry. I know it’s unorthodox, but I’m pretty sure we can analyze things about as well, if not AS well. If it goes good, I’ll buy him dinner/drinks and come out $1500 ahead! If goes bad, it’s only $30K or so right?!?

PO has really good records. Entire cooling system was done in 2019 to the tune of $13K. Boat was hauled in April (bottom job, cutlass bearings, Tides shaft seals, etc).

We’ll see.... Not busting the champagne bottle over the bow sprit quite yet...
 
I am not sure about the blankets... I am mechanical so quite a bit different then you and chief Ed has QSC500’s.. don’t know why you would want to keep heat in
Here is an old pic of mine
CDF920D4-1F82-4264-A828-81C5260BE9DE.jpeg
 
The inlet to and the aftercooler itself being discolored are a much better indication of high EGT’s. Most of not all of these boats are over propped from the factory. Regardless of what c series Cummins you have make sure it will reach 50-100 rpms past the wot spec posted by Cummins during a fully loaded seatrial. If you do this the temps will stay in range for the long haul.

edit: I despise the word “normal.” As used above. Mainly because The discoloring is normal but not correct. If the boats were not over propped and were cooling properly then it wouldn’t be “normal.”
 
Any idea what the purpose of the insulating blanket on that portion of the turbo is?
 
Chief Ed said:
Hi all,

Sea-trialing a 2006 44 Sundancer with QSC500s tomorrow. Engines have 440 hours. This is the only pic I have thus far. Does the color of the turbos look “normal”? Wouldn’t quite call it “vanilla” nor would I call it “chocolate”. Somewhere in the middle?

Obviously, I’ll get RPM and Fuel burn data tomorrow. Just trying to get an opinion beforehand…

Thanks as always for the help…
Click to expand...
I've got the same number of hours on my 2006 44DB and the compressor section and associated pipes are just turning off white. I mostly cruise at 30 percent power/load due to the distance and conditions we travel though. About every third trip I run at 65 percent. I can easily turn 2650-2670 at WOT fully loaded.
Glad to hear the PO has kept up with the prescribed service, I would be inclined to think you should be ok. The one thing that the Cummins guy will have in his favor over your buddy will be the ability to read the engine data for signs of abuse with his wisbang proprietary software. I get wanting to save the $1500 but spending that money is no guaranty of future seaworthiness anyway. I hope you close on this one and enjoy her for years to come! Welcome to CSR and the Blue Hull Club!
Carpe Diem
 
I don't have turbo blankets either. I would describe the color of my turbo's as vanilla to toffee... without whip cream :p
 
Normal color. Compressing air heats it. Usually half the aftercooler is chocolate milk color as well...when it finally cools the charge enough, the aftercooler is white. My "MAN man" paints mine (turbos and charge air coolers) with black Imron paint. Solves the chocolate milk look!
 
The turbine section is water cooled as is the exhaust riser so there should be no thermal blankets. Unless someone changed to a dry turbocharger (AKA QSM11) you should remove the blanket as that is a source of moisture collection and corrosion. The compressor can get as hot as 400 degrees due to the heat of compression and inevitability will turn the paint to a yellow/tan color. Those engines visually look great; make sure you have a full oil and coolant analysis done as part of the survey.
 
I have had 3 boats with QSC's. All had the blankets and the turbos looked like the above picture. Keep the blankets they were installed for a reason.

You are very lucky to find a boat with the cooling system having just been done. If you are in salt water install a fresh water flushing system and they will last longer before needing to be done again.

I hope everything works out for you on this purchase. We had an 06 44 we bought in 08 and they are terrific boats!
 
Thanks for all of the help, Gents. Really appreciate it. I hear ya in the Cummins tech diagnostic software, but I agree about the uncertainty even with that. The boat lives in salt water and I was just researching the fresh water flush system on SBMAR this evening. Absolutely going to do that. Going to build a manifold in the transom storage area so I can flush them when we get back to the dock without even lifting the engine hatch.

She’s about 100 miles from my home marina. Hope to have some pics of the maiden voyage on here in the next week or so!

Look what I just did. I’m already making plans before the sea-trial. I, if anyone, should know better than that by now...

Thanks again!
 
Check the fuel flow at multiple RPM settings against the published Cummins fuel/power curve. As long as the fuel flow remains below or equal to the Cummins data, your prop is fine. If the fuel flow goes above the Cummins Data at a given RPM, that would indicate you are overpropped.
 
Thanks, Blueyonder. Got the chart in my phone. Will definitely do that...
 
Shaps said:
Any idea what the purpose of the insulating blanket on that portion of the turbo is?
Click to expand...

Dual purpose. Keep heat in the turbine housing to keep gas velocity up through the turbine and also to stop heating up everything else around it.

On a QSC 540 probably good idea to remove during inspection to see if the waste gate shaft seal is leaking as evidenced by black soot around the shaft. Not a cheap repair.

I ceramic coated the turbine housing and used a turbo blanket on my 400 rwhp 2 litre 4 cylinder. Stops the paint on the hood blistering too, but still didn't save the nearby ABS system.

On a turbo race car, the turbine housing can glow cherry red.
 
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