QSC 550hp 35 Cabo Flybridge

[Mike E]

I purchased the last 35′ flybridge ever made. I was told by the previous owner that he regularly ran at 2450rpm at 27knots port motor 171 degrees and the starboard running 172 degrees. I have been running them at 2430 around the same speed but the port is at 172-174 degrees and starboard 174-176. I am curious if this is well within the operating range or if I have to pull the heat exchangers and coolers and get them cleaned and pressure tested. New impellers are in and no change. There are no sea strainers but I have checked and there are no restrictions to the raw water pumps.
Load is around 70% based on the smart craft gauges.

Thank you for any info.

mike

Topic

[Tony Athens]

Mike,

Make your aftercoolers a serious maintenance priority……….They suffer quickly from “Marine Age” as they were assembled dry at the factory.. Since you have 540’s, that means not less than 7 yrs of “Marine Age”?

Not good and there is a good chance they will not be serviceable regardless of all the tricks we have learned over the last 25++ years doing this..

Tony

[Mike E]

Agreed and thank you Philip. As for the the impeller I was just stating they were in good condition so it wan’t the problem, however I do feel they should be running a bit cooler from others experiences (however they were in different lower weight boats). I’ll definitely service them this winter and get it all cleaned up and tested. Upside is they were flushed every Fall and spring when they were laid up and not much growth where they were in in the N. East. However, yes way overdue on pulling them, pressure testing and cleaning etc. Seaboard has a great reputation and is not far for me for work I can drive up there so that is the plan.

Much appreciated – Mike

[Philip]

Good news that the boat came from your father and that you can verify everything that’s been done. Having said that having never pulled the cooling system components you are way overdue. It’s not hard work, and will take a good day to pull all the coolers (aftercooler, fuel/gear oil, and heat exchanger). The only way to service that stuff is to pull them off and service them in the shop in the bench.

If your not comfortable servicing them yourself I wouldn’t hesitate to drive them up to Ventura and let Seaboard and Brandon service them. You will learn a ton just from talking with them and feel much better about operating your engines.

It will take another day to get things back together. Again not hard, just time. A few new intake hoses, clamps, etc along the way. Consider a fresh water flush of some sort, it’s worth its weight in gold extending service life considerably. And you will know your boat and engines that much better.

Might I also suggest removing th fan belt and spinning everything on the front of the engine, anything that makes noise or feels odd replace. Nothing is that expensive.

Not having a crack in the impellor means little as to total cooling system health.

[Mike E]

They will hit max RPM at 3000 to 3050. Starboard will climb to 181 degrees and then back down to around 178 and hold, port to 178 and hold back down to 176. I usually don’t put it on the pins for more than a minute.

I purchased the boat from my father who regularly serviced the boat but he has never pulled the inserts or the coolers. The boat is a 2009 with the 550 cummins. It only had 340 hours in the Northeast and is now with me in Southern CA. The boat was in the water from late May to early October each year since new. Pulled flushed and winterized, then put in indoor storage. When I changed the impellers a month ago the old ones didn’t even have a crack in them. Not what I’m used to after running Volvo’s and Cat’s before. I love these engines but I am far more anal than my old man and do most maintenance myself. However I won’t be pulling the coolers myself.

Mike

[Philip]

I too have a 35 Express with QSC540’s. What’s you max rpm?

When was the last time the aftercoolers were disassembled, cleaned, pressure tested, and reassembled?

My experience was the previous owner had a mechanic service the entire cooling system Pre sale and even though I personally spoke with the mechanic who assured me with words it was done right, a year later I ended up removing everything and having them reserviced for my own personal comfort and to establish my own baseline. Ended up with two new aftercoolers as the originals were not serviceable – I can only imagine what would have happened if I hadn’t done the service when I did.

As for temps, those are normal range. Do the temps Ho,d at max RPM? And again what is you max RPM?

[Author]

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