Aftercooler maintenance

[Comodave]

We bought out current boat 2 years ago. I have been going through the boat and catching up on possible deferred maintenance. Last summer I was going to service the aftercoolers since it is pretty important. I removed the easy to get to cooler and tried to remove the core. No matter what I tried I couldn’t get the core out. So I pressure tested the cooler and reinstalled it. This spring I decided to buy one new aftercooler and put it on the port engine, the hard to access one. Cummins saiid if I did an emergency order it may come in within 100 days. They quoted $3,700 plus $153 for overnight shipping. I called each month to get status of the order. Finally on 22 May they said it was delivered to Saginaw Cummins on 11 May. I went to pick it up and they said it would be $5,200+. I was astounded. They said the cooler was $4,990 plus $370 for overnight shipping. I told them that the overnight shipping was bogus since they never called me to tell me it was there for 11 days. And that when I ordered it they quoted $3,700. After about 30 minutes they said they would delete the shipping and sell the cooler for $3,700. Ok. Good even if I had to make them see reason.

So I got home and disassembled the new cooler and lubricated it per Tony Athens recommendations. Cummins doesn’t lube the new cooler, why? Who knows but my new cooler was bone dry. I tried for about a week to get the core out of the old aluminum housing. 3 metals in very close proximity, what could go wrong? So today I took the cooler to a machine shop and had them press the core out. It was amazing how much pressure it took to get the core out. 13 tons, 26,000 pounds of pressure when it finally started to move. The old core didn't look great, a lot of corrosion on the bottom end which sits in water when not running. So I have a new cooler on the port engine and I am going to buy a new core for the housing. Then I will put the rebuilt cooler on my starboard engine.

Just a heads up if you have aftercoolers on your engine you may want to service it frequently. The first two photos are of one side, the heavy corrosion was from the lower end. The next two photos are from the other side. The fifth photo is the bottom end of the housing and the last photo is the top of the housing.

 

[DDW]

That corrosion is on the air side, no? What model Cummins?

My QSB has a drain valve at the bottom, with a check ball in it, which drains any condensation. Don't know how common that is. Cummins does use a soup of galvanically dissimilar metals in these, for sure: mine have a copper or copper/nickel exchanger, a cast aluminum housing, and bronze end caps, all immersed in salt water. What could go wrong with that?

 

[Comodave]

That corrosion is on the air side, no? What model Cummins?

My QSB has a drain valve at the bottom, with a check ball in it, which drains any condensation. Don't know how common that is. Cummins does use a soup of galvanically dissimilar metals in these, for sure: mine have a copper or copper/nickel exchanger, a cast aluminum housing, and bronze end caps, all immersed in salt water. What could go wrong with that?

Yes, it is on the air side. Mine are 6CTAs, 450hp. Yes, it has copper/nickel, aluminum and bronze all in close proximity. One issue is that Cummins will not lubricate them when they are manufactured. Another is that the original coolers did not have drains. The new one that I just bought has been somewhat redesigned and has drains. But the drains are not self draining you have to unscrew them with a large metric allen wrench.

 

[Simi 60]

Wow, that seems shockingly expensive and crazy difficult compared to our nta855

Seems our outer separates into two halves with bolts and gasket
And easy out innards.

Buy the whole setup new for about a grand.

 

[Comodave]

Don’t I wish…

 

[sunchaser]

Wow, that seems shockingly expensive and crazy difficult compared to our nta855

Seems our outer separates into two halves with bolts and gasket
And easy out innards.

Buy the whole setup new for about a grand.

Simi
Is your exhaust manifold wet or dry?

 

[BruceK]

It may be worth knowing, though it`s no help to Dave, that Cummins 210s don`t have aftercoolers. Everything putting out more power does.

 

[Comodave]

It may be worth knowing, though it`s no help to Dave, that Cummins 210s don`t have aftercoolers. Everything putting out more power does.

Right. The 5.9B are natural, the 5.9BT is turbocharged and the 5.9 BTA are turbocharged and aftercooled. The aftercooler on the BTA needs regular maintenance too. I suspect that the aftercoolers on my engines have never been serviced in the 25 years since they were manufactured. So given that they aren’t in horrible condition but the boat has always been in freshwater never saltwater. In saltwater they would have failed years ago.

 

[DDW]

The new one that I just bought has been somewhat redesigned and has drains. But the drains are not self draining you have to unscrew them with a large metric allen wrench.

You may be able to fit a self draining one? On mine, it has a ball check valve that is very lightly held open with a spring. As soon as there is any pressure it closes. At idle it flutters open, you can barely feel a little puffing out of it, but when the engine is off, it is open. I don't see this part in the Cummins parts view, it is just shown as a plug. So may have been added, and maybe you can add it too.

I had a fair difficult time getting it apart when I bought the boat, fresh water boat, it had been apart several years prior and reassembled without greased. It's about time to do it again, will find out if the grease made the difference.

 

[Comodave]

I will check with sbmar and see if there is an automatic drain plug that will fit the new cooler. But I suspect that if there was they would have offered it when I ordered the plugs for $10 each. Cummins can’t be put out to include even the drain plugs in a $4-5K cooler…

 

[fgarriso]

Hay Dave
Now I know where I lost my blue handle channel locks at

 

[Comodave]

Hay Dave
Now I know where I lost my blue handle channel locks at

Yes, I found a pair the other day…

 

[Gdavid]

At the risk of stating the obvious, it is really easy for shoppers of used boats to underestimate the effort required to service and expense related to higher output diesels. As ugly as this core looks, I'm confident there are many others in worse condition in boats out on the water with owners unaware of the performance degradation and risk of engines ingesting seawater if the core fails completely.

Intercoolers mounted on one side of the engine, like pretty much every modern design uses, makes access and service pretty difficult on twin engine applications. If something isn't easy to service, it probably doesn't get serviced.

I'm a huge fan of the 6CTA diamond series, very reliable and almost as efficient as the engines of the common rail generation. This one of their few vulnerabilities.

My silly, relatively low output perkins had an intercooler which wasn't serviced even in its past even though it was easy to access and easy to assemble/disassemble. I had to replace it last season.

 

[Hippocampus]

Thing people forget is service of the main heat exchanger , intercooler, and the oil/fuel cooler has nothing to do with engine hours on Cummins. Rather anytime the boat sits in salt water all heat exchangers regardless of what they are cooling are batteries and their internals will corrode. You need to replace anodes regularly on the basis of time not engine hours. You need to flush out all salt water from all heat exchangers before winterizing.

At present my QSC 540hp is in pieces. All coolers off. Hydraulic press to remove cores as any other way to remove them will likely destroy them. After inspection, service and pressure testing only then placed back on. Of course replacement as necessary. We do zincs every 3 months along with the SeaKeeper one (same thing a battery even when not used). And put in fresh anodes if inspection justifies before any layup. Was told it’s not uncommon for people to pay attention to the main heat exchanger anodes but not the other four anodes required.

Been told they will deteriorate with moist salty air and no drain is 100% effective. Replacing the anodes is painless on my single engine boat. Anodes easy to get. 15 minute job for all six. Will forgo drains but have given more thought to fresh water flushing. We use the boat frequently and flushing just to go asleep seems silly but seems like a good idea if it going to sit for awhile.

 

[lwarden]

I faced a similar issue with my AC's last year. One needed a new core, the other core looked to be a newer version and was replaced 7 years before. A drain would be a good idea on these, even if it were a manual version you could crack every once in a while, or when the boat is going to sit. There is a lot of condensation that gets created inside there, especially with colder water temps.

This is another reason fresh water flushing is a good idea and worth the effort, especially with the cost of these parts (and availability).

 

[BDofMSP]

Comodave, thanks for this post. We have the same engines, and we serviced ours when we bought the boat. They were in pretty good shape (didn't need a press to get the cores out) and were lubed and reassembled. I ASSUMED that they were in good shape because they spent most of their life in fresh water. Seeing your post is a good reminder that even though we're in Lake Superior, I need to keep an eye on these things.

Right now I have them on a 3 year maintenance schedule, which means I'll be doing them over the winter. I'll be very interested to see if there is much change.

 

[jleonard]

Right. The 5.9B are natural, the 5.9BT is turbocharged and the 5.9 BTA are turbocharged and aftercooled. The aftercooler on the BTA needs regular maintenance too. I suspect that the aftercoolers on my engines have never been serviced in the 25 years since they were manufactured. So given that they aren’t in horrible condition but the boat has always been in freshwater never saltwater. In saltwater they would have failed years ago.

I had a 5.9. 6 BTA that was rated at 270 hp and was antifreeze cooled. I purposely bought that model because it didn’t have the raw water corrosion issue.

 

[sunchaser]

Our Perkins Sabre (Cat 3056) 225TI after coolers are easily removed for servicing. Right from the factory they came apart easily. When boat shopping the question on past raw water after cooler servicing is a must during a survey.

If they've not been removed and cleaned within the past 3 years it is wise to have the current owner get it done properly before closing. If not the potential new owner faces a litany of future issues at an unknown cost.

This area is part of boat maintenance 101 and deserves the same attention as the oil change threads that proliferate on TF. Read Tony Athen's for a few decades or be friends with a top marine engine guy and you'll become a believer.

 

[Fletcher500]

Smart to be proactive. As you noted, if they were in salt for 25 years it likely would have looked differently.

The 6.7 also has a check valve at the bottom of the after cooler that will weep a little on low loads. Took me awhile to figure out where the discharge was coming from, and that it was normal.

 

[Simi 60]

Simi
Is your exhaust manifold wet or dry?

Wet

 

[DDW]

I will check with sbmar and see if there is an automatic drain plug that will fit the new cooler. But I suspect that if there was they would have offered it when I ordered the plugs for $10 each. Cummins can’t be put out to include even the drain plugs in a $4-5K cooler…

Well of course if the drains say "Cummins" on them they will not be $10. They are in fact $85 from SBMar. Described as fitting your engine, new and old intercooler.

 

[Simi 60]

I'm getting bloody confused reading this thread

OP puts up this pic

Which to me looks like multiple cooling fins like on a radiator that I assumed was for turbo air cooling as described here

The aftercooler is an element that has tubes running through the inside of the unit. These tubes have engine coolant flowing through them as part of the coolant system. The function of the aftercooler element is to cool the intake air that has been heated by the turbocharger during pressurization

https://akmicorp.com/after-cooler-e...ent,by the turbocharger during pressurization.

But sbmar pages shows an aftercooler as this

https://www.sbmar.com/articles/cummins-marine-aftercooler-maintenance/

Which to me I've always called the tube bundle from a heat exchanger (raw water/coolant)
On ours, looks like this and is mounted in a bronze housing.

What am I missing here?

 

[DDW]

You have it right. They are similar tube bundles, but the water-air exchanger has the tubes buried in fins to better transfer heat from the air. The reason it corrodes is when the air is cooled, it gives up a lot of moisture as condensation. While the engine is running this condensation is ingested by the engine but when stopped, the condensation can continue (at a lower rate) filling the housing with water over time.

 

[luna]

It looks like you chose to attach picture #20 of Sbmar's aftercooler assembly information.

Have a look at picture #19 and things should be clear.

 

[Simi 60]

It looks like you chose to attach picture #20 of Sbmar's aftercooler assembly information.

Have a look at picture #19 and things should be clear.

Ok, got it
So very different to our setup
Thanks

 

[firehoser75]

All raw water cooling components require regular (every 3-5 years depending on a number of factors) servicing "off engine" where they are disassembled, properly cleaned, "seals" replaced, and pressure tested before being re-installed, especially the aftercooler. Tony Athens on sbmar.com has complete instructions for servicing an aftercooler (Cummins for sure, but can be adapted for other makes). It is not hard, as long as it is not left too long!!!! The key aspect when reassembling the unit is to use LOTS OF GREASE to act as a barrier between the various metals. If the aftercooler was put back together with lots of grease, and you service it again in 3 years if not FW flushing, then it should come apart easily (hand pressure), and the service should be "routine". Otherwise you run the risk of needing to press out the core, replace the core, or even the entire unit. Not only are these parts expensive, but they are in short supply.

Regular freshwater flushing will keep all of the raw water cooling components in better condition between services, and will allow for a longer time period between "costly" regular off engine maintenance (unless you do it yourself). Flushing with a corrosive (like Barnacle Buster) will not protect these components (especially an aftercooler) from the battery like corrosion that does occur when you leave saltwater resting in your system in contact with dissimilar metals!! If you operate only in freshwater, your time between services can be extended, but not ignored (as per Dave's aftercooler on his new to him boat). Also, often an oily sludge can coat the fins on the aftercooler core over time, drastically impairing the ability to cool the hot intake air, and restricting the airflow itself. Another reason for the regular cleaning (off engine).
On my Cummins aftercooler (6BTA) all that kept the saltwater out of the air intake (and killing the engine) was the "O" ring seal and the smooth mating surfaces. Pitting, corrosion, or relying on old failing "O" rings could lead to the need for a new engine, so regular servicing is essential IMHO.

 

[Simi 60]

All raw water cooling components require regular (every 3-5 years depending on a number of factors) servicing "off engine" where they are disassembled, properly cleaned, "seals" replaced, and pressure tested before being re-installed, especially the aftercooler. .

It's odd
Every time one of these threads and the Tony Athens pics come up I go into mild panic mode, pull out the workshop and operations and maintenance manual for ours which covers quite a lot plus the daily, monthly, yearly checks and servicing to be performed.

No where in there is aftercooler mentioned
And an exhaustive interwebs search finds nothing regarding aftercooler servicing for the NTA 855 M
It is coolant cooled and there are no dissimilar metals used so is that it?

 

[tpbrady]

Service mine on a 6CTA every 2 years. One thing to watch is pitting on the aftercooler housing where the heat exchanger fits in. The seal between salt water and air is dependent on a tight fit with a proper grease for isolation of the dissimilar metals, otherwise there is the possibility of salt water ingress into the intake. If my housing ever gets pitted beyond safe use, the aftercooler gets bypassed.

Tom

 

[DDW]

At least on my QSB, the o-ring sealing surface could be refinished once or maybe even twice before the housing would need to be replaced. You'd need to have a knowledgable machinist (or be one) but it looked possible to me. If they really are $5K a pop, then it would be worth a try.

 

[Comodave]

They certainly aren’t cheap. I really haven’t looked at the housing yet since Friday was my wife’s birthday so I have been busy with that. Hopefully I will be able to reuse the housing and just buy a new core.