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Old 01-09-2017, 03:17 PM   #21
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"smitty:
Your pics show a wider gasket sealing surface than are found on o-ring sealed after coolers, but it is still a bronze to aluminum joint that can corrode and fail."


You are looking at cast bronze and cupronickel parts there is no aluminum within this assembly. The open parts show the raw water sections and pathway only - at the base of the air side path there are no "O" rings at all. But there is a 'space' in height where the water and blowby can collect (if any) this area has a drain and inspection plate that can be utilized if/as necessary.
These intercoolers are installed on boats that have seen more than 30 years of use and I have never heard of a failure or problem with service with any of them.
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Old 01-09-2017, 04:15 PM   #22
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I didn't realize that the after cooler body in your pic is bronze. What engine is that on. It must weigh a lot!!!

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Old 01-09-2017, 04:40 PM   #23
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Originally Posted by djmarchand View Post

sunchaser:

1. All engines with after coolers are installed after the turbo. There would be almost no point in running 90 degree intake air through an after cooler with 70 degree raw water to cool it maybe 10 degrees and then run it through the turbo. As Ski noted, after coolers cool the air hundreds of degrees because compression heats the air. So the AFTER cooler is after the turbo.


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You are correcting the wrong guy. I pointed out to a Cummins and Yanmar dealer and supposed expert that he did not know which end of the after cooler goes where.
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Old 01-09-2017, 07:43 PM   #24
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"I didn't realize that the after cooler body in your pic is bronze. What engine is that on. It must weigh a lot!!!"


Hello David - Although I have had more than a few out to clean them I never weighed one. Perhaps 20-25 pounds when empty I guess. The entire engine weighs in at 1,250 dry - Hino WO6 series.
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Old 01-09-2017, 08:23 PM   #25
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Perkins multicoolers

I went through both my Perkins multicoolers last Winter. I had corrosion issues in the aluminum in the area of the o-ring seal not only in the after cooler sections but also the oil cooler sections of the multicooler. I believe that the o-rings over time take a set and allow the salt water to touch the aluminum. As soon as this happens the condition progressively gets worse due to corrosion until you have a failure. I think that setting the o-rings in place with a high quality waterproof grease and a maintenance plan to disassemble, re-grease and replace the o-rings on some schedule is the way to go.

I do not believe that flushing with fresh water will help much as the problem starts in very tight edges/corners of the o-ring joint and any salts in these areas are not likely to be washed away. they are in a sense trapped under the o-ring.
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Old 01-09-2017, 08:26 PM   #26
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Flushing the salt is good, but a few comments..

The flush connection must be bullet proof, as far as breakage or it could cause much larger issues.

An operator who flushes, and forgets to secure the system could cause damage.


You can't do this on engines under warranty because it will probably void it if big brother finds out.

What about rydlime or barnacle buster or similar decalcificaion solutions? I.E., many people do this annually at the dock, in a controlled environment, and appear to get very good results, hence the flush after very use can be avoided.
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Old 01-09-2017, 08:50 PM   #27
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What about rydlime or barnacle buster or similar decalcificaion solutions? I.E., many people do this annually at the dock, in a controlled environment, and appear to get very good results, hence the flush after very use can be avoided.
This is mostly conjecture, but it is backed up with some theory and a little bit of experience:

Calcification only occurs during running. Why? Because it is heat that precipitates the calcium/magnesium compounds present in sea water out on the heat exchanger surfaces. Calcification will not occur in engines just sitting at the dock. Critters may grow (see below) but calcium compounds will not precipitate on cold metal. Take a look at your bronze rudder. It has barnacles on it, but no calcium deposits.

Fresh water flushing is almost entirely for corrosion mitigation, and is not expected to help with calcification. Fresh water flushing does do some good for marine critters. Marine critters were bred to thrive in a salt water environment. When a few critters are left in an engine after use but their environment is changed to fresh water, they die.

So bottom line, I consider fresh water flushing and periodic acid flushing with Rydlyme, etc. complimentary, but one will not suffice for the other.

And BTW I would acid flush only every 5 years or if I see temps rising at wot, not every year. Too much corrosion for yearly use.

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Old 01-09-2017, 09:03 PM   #28
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Configuring a fresh water flush is something that I have wanted to do since I bought the boat. I have a Cummins 5.9 QSB. It has the vertically oriented aftercooler. I had it removed and serviced shortly after I bought the boat since it had never been done in its 6 years and 773 hours of life.

I was hoping that doing a fresh water flush would help extend its lifespan, and like David, thought that it could extend the times between servicing of the aftercooler. Given the information that the corrosion may come from the air side and not the raw water side, makes me less inclined to do it.

After looking at lots of options for a fresh water flush, I had decided that for my boat a system such as this would work the best for me. I didn't want to have to swap out the top of my sea strainer each time and the location in the ER means I can't leave any fittings in place on top of the strainer. My plan was to use the above fitting and run a hose to the stern with a hose fitting. Then flushing would be as simple as connecting the fresh water hose from the dock and then opening the valve while the engine is idling.

It would be a bit of grunt work to setup however, and if it won't really affect the ultimate problem , then I likely will give up on the idea and simply look at doing a yearly flush with some kind of descaler.
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Old 01-10-2017, 07:35 AM   #29
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I have commercial lobstermen using the same Cummins, Cat etc. engines (though mostly no turbo's) and I have numerous engines in excess of 15 years old and 8000 - 18,000 hours that have never ever been fresh water flushed. I can't recall the last time I replaced a core pack or HX due to corrosion. For these guys the engines will rust through from the outside before they corrode from inside. I have some that are so rusty it is hard to even tell brand color but the salt water cooling circuit still works......

Never flushed, no corrosion in the raw water circuit requiring HX replacement.. IIRC this engine is a 1986 vintage..




Be aware that on certain installations incorrect flushing (pressure feeding the RW inlet) can lead to hydrolocking the engine and potentially destroying the engine.

I know of two boaters who bought the Forespar flushing valve and direct connected a garden hose to it thus hydrolocking their engines. One engine was ruined the other badly flooded.....
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Old 01-10-2017, 10:01 PM   #30
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Quote:
Originally Posted by djmarchand View Post
So bottom line, I consider fresh water flushing and periodic acid flushing with Rydlyme, etc. complimentary, but one will not suffice for the other.

And BTW I would acid flush only every 5 years or if I see temps rising at wot, not every year. Too much corrosion for yearly use.David
It appears you have done your homework on the subject, but I still question this and would think a descaler can take care of all of the build up inside the raw system. The fact that it runs through the entire system and wil clean the rubber hoses as well is a plus.

It is not common in my area, but apparently quite a few people on the east coast use it.

Agree, yearly is probably overkill, but how do you know it will cause corrosion? I have not used it, but from what I have read it is a fairly mild solution and no one has reported corrosion issues. We pulled apart the coolers on our 2.5 year engines and it is starting. I am therefore leaning to every few years, but still trying to figure out how to get it through the drives..long story.
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Old 01-10-2017, 10:05 PM   #31
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Be aware that on certain installations incorrect flushing (pressure feeding the RW inlet) can lead to hydrolocking the engine and potentially destroying the engine.

I know of two boaters who bought the Forespar flushing valve and direct connected a garden hose to it thus hydrolocking their engines. One engine was ruined the other badly flooded.....

Yup, I can attest to that. Luckily I was able to remove the injectors and crank the water out of the cylinders. 3 oil changes later it ran again.

I didnt break a rod or a piston but I could still kick the idiot that suggested doing it on here.
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Old 01-10-2017, 10:09 PM   #32
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Quote:
Originally Posted by CMS View Post
I have commercial lobstermen using the same Cummins, Cat etc. engines (though mostly no turbo's) and I have numerous engines in excess of 15 years old and 8000 - 18,000 hours that have never ever been fresh water flushed. I can't recall the last time I replaced a core pack or HX due to corrosion. For these guys the engines will rust through from the outside before they corrode from inside. I have some that are so rusty it is hard to even tell brand color but the salt water cooling circuit still works......

Never flushed, no corrosion in the raw water circuit requiring HX replacement.. IIRC this engine is a 1986 vintage..




Be aware that on certain installations incorrect flushing (pressure feeding the RW inlet) can lead to hydrolocking the engine and potentially destroying the engine.

I know of two boaters who bought the Forespar flushing valve and direct connected a garden hose to it thus hydrolocking their engines. One engine was ruined the other badly flooded.....
... If I ever heard that fresh water flushing was that great...the tens of thousands of commercial operators that frequent mags, forums, coffee shops, etc...etc...would be screaming the benefits...not a peep.

The industry has worked hard on designing materials to NOT require flushing.....

Sure it might help... a bit...maybe....possibly....

Never have seen much in the way of published proof that it does.
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Old 01-10-2017, 10:19 PM   #33
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It appears you have done your homework on the subject, but I still question this and would think a descaler can take care of all of the build up inside the raw system. The fact that it runs through the entire system and wil clean the rubber hoses as well is a plus.

It is not common in my area, but apparently quite a few people on the east coast use it.

Agree, yearly is probably overkill, but how do you know it will cause corrosion? I have not used it, but from what I have read it is a fairly mild solution and no one has reported corrosion issues. We pulled apart the coolers on our 2.5 year engines and it is starting. I am therefore leaning to every few years, but still trying to figure out how to get it through the drives..long story.

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Old 01-10-2017, 10:48 PM   #34
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Quote:
Originally Posted by CMS View Post
I have commercial lobstermen using the same Cummins, Cat etc. engines (though mostly no turbo's) and I have numerous engines in excess of 15 years old and 8000 - 18,000 hours that have never ever been fresh water flushed. I can't recall the last time I replaced a core pack or HX due to corrosion. For these guys the engines will rust through from the outside before they corrode from inside. I have some that are so rusty it is hard to even tell brand color but the salt water cooling circuit still works......

Never flushed, no corrosion in the raw water circuit requiring HX replacement.. IIRC this engine is a 1986 vintage..




Be aware that on certain installations incorrect flushing (pressure feeding the RW inlet) can lead to hydrolocking the engine and potentially destroying the engine.

I know of two boaters who bought the Forespar flushing valve and direct connected a garden hose to it thus hydrolocking their engines. One engine was ruined the other badly flooded.....
I will need my entire life to put this number of hours on my engine
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Old 01-11-2017, 12:27 AM   #35
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Quote:
Originally Posted by djmarchand View Post

Fresh water flushing is almost entirely for corrosion mitigation, and is not expected to help with calcification. Fresh water flushing does do some good for marine critters. Marine critters were bred to thrive in a salt water environment. When a few critters are left in an engine after use but their environment is changed to fresh water, they die.

My thought is that since those marine critters are Brad to live in a salt water environment that is oxygenated, that they would die quickly in an engine cooling system without any any air exchange. Think of how raw water flush systems smell during the first flush after the system has been sitting. All the critters die as the water loses its O2.
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Old 01-11-2017, 07:47 AM   #36
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I have boated on the east coast in salt water for over 25 years now and have not had the need to use 'acids' tp clean the raw water systems on any engines. When winterizing we do fresh water flush before draining the system but do not fresh water flush as a rule. When disassembling any parts of the raw water systems there is little or no evidence of any 'crud' buildup within the system.
IMHO - if you insist on adding an acid to the raw water system try and keep the time limited and then follow up with a soda ash neutralization.
While it is true that these cleaning acids will not 'attack' metals such as stainless, CuNi and the like quickly they will certainly go after Al, soldered joints and brazing quite quickly.
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Old 01-11-2017, 08:53 AM   #37
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The corrosion problem seen with the aluminum aftercooler housings is on the air side of the system. Fresh water flushing will not flush the air side. The salt comes in with the incoming combustion air. Salt cristal built up on the walls o the after cooler. The salt laden air condenses on the tubes and on shut down will drain to the bottom. The Cummins QSB aftercoolers now have a condensate drain in the bottom air. There was a service bulletin in 2008 to correct this in earlier engines. Tony Athens has great information on this subject on his web site . http://www.sbmar.com/articles/afterc...-some-queries/ and here is his aftercooler service guide . Cummins Marine Aftercooler Maintenance - Seaboard Marine
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Old 01-11-2017, 08:54 AM   #38
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I miscopied the link to the cooler service. here it is. Cummins Marine Aftercooler Maintenance - Seaboard Marine
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Old 01-11-2017, 09:17 AM   #39
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The corrosion problem seen with the aluminum aftercooler housings is on the air side of the system. Fresh water flushing will not flush the air side. The salt comes in with the incoming combustion air. Salt cristal built up on the walls o the after cooler.
Would air intakes that are mounted on the outside of the hull exacerbate this situation? Especially with go fasts where spray is flying everywhere. Many slow speed vessels with inboard mounted air intakes seem to show little if any salt buildup in ER around air intakes, further noted by nil ER room corrosion.
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Old 01-11-2017, 09:59 AM   #40
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The placement of the air intakes will affect it somewhat. Placing the vents higher shold reduce the salt ingestion. But as you know, anytime you are running in saltwater you tend to get spray and salt on most surfaces. We run 7 KT, but have been known to have salt on top of the Bimini. I do not recall ever seeing any engine rooms with significant salt accumulations, but I do see evidence of salt crystals in the aftercoolers. It does not take much salt to create a crystal which will bridge the aluminum to bronze gap in the aftercooler. .
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