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Engine Coolant Flush

Discussion in 'Post Yacht' started by Davidoc, Jun 5, 2016.

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  1. Davidoc

    Davidoc Senior Member

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    What do you think is the best solution and procedure for flushing out and cleaning the cooling systems on my 6v92's? My engine temps are creeping up a little more than normal on a run at 1850-1900 RPM and while pulling the heat exchangers again, I was thinking of cooking the engine cooling system with something this time. What do you think is the best practice? Thanks as always.
    David
  2. Capt Ralph

    Capt Ralph Senior Member

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    while pulling the heat exchangers again


    When was the last time the green water side of the thru hulls, cocks and hoses was inspected or serviced?
    I have found more stuff growing in the hoses before the engine than Carter has pills on several supposed clean systems.

    I remember where one old hose de-laminated and was drawing air at speed.
  3. ranger58sb

    ranger58sb Senior member

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    Our engine maker recommends periodic draining/flushing/refilling the closed cooling system. The "flush" product they recommend is called Restore.

    I've used Rydlyme in the raw water side, from sea strainer through the water pump (impeller removed), fuel cooler, aftercooler, gear cooler, heat exchanger...

    I fashioned a recirculation system on one engine, and that seemed to work well enough... but instead of that I did the fill/sit/flush routine on the other engine, and that seemed to work equally well. My intent was really focused on the preventive; it seemed to clean the system out, but I didn't happen to see any drop in temps... and I'm putting that down to the system being in relatively good shape in the first place.

    -Chris
  4. Davidoc

    Davidoc Senior Member

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    We clean the external strainers monthly and we had the thru hulls cleaned about a year ago when on the hard. All new inside hoses within last two years. Fresh impellers. The big Groco glass strainer is great in terms of quick checking the flow and water quality coming in. I was thinking of trying some type of flush for both sides in addition to the normal stuff we do to keep them cool.
  5. Davidoc

    Davidoc Senior Member

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    Thanks a lot Chris. This is what I am looking for. I will look at the Restore product for the inside. Do you have Detroit's in your boat?

    I have thought a lot about a raw water re-circulation system but haven't figured out where to catch the output water. I do have some Rydlyme and Barnicale Buster I use for AC unit flushing. Where did you tap into the output water?
  6. mwwhit1

    mwwhit1 Senior Member

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    Several years ago I did this. Detroit sells a solution. I think it was two part. First the cleaner, then a neutralizer. Took several water changes to get it clear before adding the final distilled\antifreeze mix.
  7. ranger58sb

    ranger58sb Senior member

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    Ours are Cummins, hence the Restore (Fleetguard, I think) product.

    I removed the hose that runs from the heat exchanger to the exhaust elbow -- at the exhaust elbow end -- and captured the Rydlyme mixture there by dropping it with a short hose back into a bucket (actually a Rubbermaid-like file box container thing). I put a hose bib on that container in a lower corner, and then used a 115V transfer pump to recirculate from container back into just under the sea strainer (via Groco SSC flush valves). I could have tapped it right at the output from the heat exchanger, but it was slightly easier to just use a PVC fitting that would slip inside the hose at the other end, and then I stepped that PVC fitting down to garden hose connectors.

    You might not have the issue, but I also had to solve a loss problem through the cooling hoses that run from water pumps to our dripless shaft seals. Wasn't difficult, just puzzling at first.

    I made up the container/hoses/fittings/pump thing so I could flush mains, genset, and ACs relatively easily; just cobble the various connectors together, dump in the stuff, turn it on and go have a beverage.

    As an experiment.... Turns out on the main engine it also worked fairly well to just backfeed the whole raw water system using that same exhaust hose connection. Just pumped the stuff the other direction. Opened the top of the aftercooler (removed a high zinc) to allow air to escape, stopped pumping when I got water out that "vent".

    On our system, it happens that when liquid comes out the top of the aftercooler like that when the "vent" is open... it means the whole system is pretty much full; everything else (fuel cooler, gear cooler, etc.) is lower than that "vent." It also meant I didn't have to remove the water pump impeller. OTOH, it also also also !!! meant the solution wasn't cleaning the sea strainer so I had to do that separately.

    I'm told recirculation is probably better, but I couldn't tell much difference. OTOH, I was also starting with a relatively clean system.

    Be aware, Rydlyme says it eats zincs. So I took mine out of the system before doing the flush. Another approach might just be to do a flush when you know you'll want to replace zincs anyway... and then do that afterwards.


    -Chris
  8. Davidoc

    Davidoc Senior Member

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    Thanks for the information. I will see what I can fashion for the flushing system. I did build one for my AC systems and can probably modify it for the mains. I searched for the Detroit flush product but only found the power-cool coolant (I have used it since I bought the boat in '05). I'm thinking the salt water side needs the attention.
  9. Capt J

    Capt J Senior Member

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    The best solution is pulling all of the heat exchangers and coolers and having them professionally cleaned on land by a shop that does that. Most of the time, the debris stuck in the tubes does not come out when circulating the various cleaning products through the raw water system.
  10. ranger58sb

    ranger58sb Senior member

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    I tend to agree. The on-engine flush for us is more like a prophylactic or preventive treatment, in between real cleanings.

    -Chris
  11. Davidoc

    Davidoc Senior Member

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    Thanks guy's I have been using Broward Radiator in the past with very good results and fair prices.
  12. Capt J

    Capt J Senior Member

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    They are very good and also who a lot of engine dealers use to clean their customers heat exchangers and coolers.
  13. Davidoc

    Davidoc Senior Member

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    Thanks Capt J. I took you advice and finally started pulling the exchangers. The port engine coolant is very black in color. The exchanger looks pretty clean, excetp fot the black sooty looking stuff on the fresh water side, but I am taking them down to Broward. I don't think I have oil in the coolant, it looks like it could be soot or a rotting hose somewhere. The are a few very old hoses left around the water pump and the thermostat housing. The black seems to settle like a fine mud in the bottom of the bucket. '89-90 6v92's. I'm going to drain some coolant (I only use powercool no antifreeze way up here in Delray) and pull the starboard exchanger. I changed all filters and fluids last week. Ran the boat offshore. Both engines warm towards 190 plus at 1850 rpm. Themostats are 180's. I had the sync on and I could not get much more than 1950. The bottom was clean and my speed was good for the rpm I did get. Pretty normal soot for me. I used a fleet guard test strip before draining the coolant and it really didnt read any protection. I also wonder if the coolant turns black after several years of use. I dont think that is the case because I am always checking it over time.
    Any advice you could give me would be much appreciated.
    David
  14. Capt J

    Capt J Senior Member

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    If you have any coolant left, pull samples and send it out to a lab. The CAT dealer sells the sample and comes with a bottle, pre-paid postage etc. If you have exhaust gasses in the coolant you're in trouble because it means your cylinder head o-rings are failing and inevitably if you don't replace them, you'll be doing a rebuild. It could be old coolant and hose material too, but for less than $60 I'd confirm that.

    If the bottom was clean I'd also highly recommend figuring out where your lost RPM's went. I'd start out with clean fuel filters (primary and secondary), clean air filters, and boost gauges (fuel pressure gauges would help too) and another seatrial to see where everything is at for sure. If the results are the same and boost is where it should be, I'd dive under the boat myself to confirm the diver is doing what they're supposed to be doing, and then start cutting props. 350 rpms is quite a bit to be missing.
  15. Davidoc

    Davidoc Senior Member

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    Thanks Capt J. I would like to have the water analyzed this Monday. Do you have a local lab recommendation? All the guy's I have used in the past are out of town and require some time to ship and analyze.
    The starboard coolant still measures good but looks a little dirty to me. The exchanger in the starboard is dirty. I am taking them both down Monday to Broward. I peeked into all four coolers pulling them too. I do have aftercoolers under the blowers. I need to get this all flushed out of everything
    I will check the impellers again and clean the strainers. Air seps are on the list too. I do have 180 degree sensors in my stainless exhaust elbows that are tied into my high temp alarm.
    Running gear is Prop Speed. I check the bottom when I get thru all this stuff and find out how much I have to do on the port engine.
    I don't have boost or pressure gauges but my buddy Morgan (whom you may know) is coming down this week to give me a hand if the analysis shows combustion in the coolant, and he has the tools.

    Thanks again for helping to steer me in the right direction.

    David
  16. Capt J

    Capt J Senior Member

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    Yes, go to a Caterpillar dealer and buy the sample kits, they're around $30-35 each. The kit has the bottle to put the sample in, a larger bottle for mailing it, and a pre-paid postage label. You basically put the sample in it, sticker on the outside with your return info, and drop it in the mail and within a few days get the results back via email.
  17. Capt Ralph

    Capt Ralph Senior Member

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    If you get the Cat SOS kit, pay for the LEVEL II coolant testing.
    It takes a lil longer for the results but tells you everything about your coolant.