QSC 8.3 No Raw Water Circulation

[Bobby Harvey]

I had the boat out 0f the water for maintenance for about 2 months. Installed new raw water pumps, hoses, seacocks, strainers. (New bilge). When I tried to start one of the engines, I couldn’t get water to circulate (out of the exhaust). Water is getting to the pump and to the fuel oil cooler ok but no water beyond that. It was working fine before this. I tried priming the system with water first from the heat exchanger to mitigate possible vapor lock situation. ??? No dice. Maybe a plugged or failed oil cooler? I’m out of ideas about what to do. Any ideas? The other engine started up fine.  Thanks guys.

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John

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[Bobby Harvey]

I am in the process of replacing both Aftercoolers. The old ones have never been serviced. Crushed them both trying to press them out of the housing. Able to save one housing. The port Gear Oil/Fuel cooler was plugged up. Hopefully that was the water circulation problem. I’ll find out when I get it back together. Both Gear Oil Fuel Coolers tested good. 100%. So, I can re-use them. I’m waiting on Seaboard to ship me the new Aftercoolers. Painfully slow. Daily burn rate waiting is painful.

One of the hoses on the fuel side, braided and underneath going from the cooler to the block, Cummins doesn’t make anymore, and it is very special of course. Impossible to find and Hard to duplicate. I was wondering if it is really necessary to cool the fuel like this. Could this possibly be illuminated? Is the fuel so hot that it needs to be cooled? Probably a dumb question but I am curious. 

Yes, the heat exchangers are next. 

 

[Rob Schepis]

“After this it will be a new boat.”

Well all that will get you is a new list of problems!  Keep us posted as you move fwd with this.

[Bobby Harvey]

Rob, I just put the fresh water flush caps on. I don’t think that’s the problem. Sadly, the previous owners never serviced anything on this boat. Seriously. I mean nothing! I have both Aftercoolers and Fuel Oil Coolers off right now having them serviced. I’m pretty sure at this point it’s a plugged F/O Cooler causing the p[roblem. Heat Exchangers will be next. After this it will be a new boat. I will post the outcome when I solve it.

Thank you for your help. I appreciate all you guys on this forum. 

[Rob Schepis]

When was the freshwater flush setup installed?

What is the history of the servicing of the seawater circuit coolers?

[Bobby Harvey]

Thanks Clark. All your suggestions are a possibility at this point. Strainer is primed and so is the intake hose and pump. I was able to detect a small amount of air through the fresh water flushing cap valve when I opened it while I had it running for a few seconds. 

The o/f cooler is plugged, or at least restricting the water flow probably enough to cause this problem, and the O ring seat for the Stainless Tube to the o/f cooler is badly corroded and pitted and leaking water (possibly sucking air). I will give everything a good servicing and try it again. So, I am pulling the Aftercooler and the oil fuel cooler. After I reinstall them, I will double check all the hoses and clamps again.

I will post the outcome. 

 

[Clark Leighs]

Any chance of an air leak before the pump? 

Air will negate the pump priming.

Loose hose or poor clamping,? 

Any leaks before the pump will stop it cold as air is far easier to pull through the system than water?  

Has the sea strainer primed?

Can you use  a vacuum guage before the pump  and/or a pressure guage after the pump?    Very low vac. would indicate an air leak.   High pressure would indicate a clog or blockage.

[Bobby Harvey]

John. This is brand new water pump. I replaced the impeller after trying to get the water circulating, because it go too hot trying to get it working, and while I had it open, I gave the spline a look and it seemed solid. But I might put the old one back on just to and see if it solves the problem.

This is the port side and a new water hose. It’s a bitch to get on. GAWD! Ugh! But “a man’s gotta do what a man’s gotta do!” (John Wayne!)

Brian could be right about the fuel/oil cooler being plugged. That was my first suspicion after checking the pump spline and water supply. It’s a boat, right? That’s what everyone keeps saying to me. 

Thanks for your help guys!

[Bobby Harvey]

This is what I am suspecting and acting on at this time. But I think I need to pull the pump and check that also. 

[Brian Will]

Is it possible your fuel/oil cooler is completely plugged? 

[John]

Impellers ok?

Spun hub on one of them badly maybe?

[Author]

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