Heat Exchanger Servicing

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Moonstruck

Moonstruck

Guru
Joined
Nov 27, 2008
Messages
8,276
Location
USA
Vessel Name
Moonstruck
Vessel Make
Sabre 42 Hardtop Express
It is time for one of the most important items on a diesel engine to be serviced. The last thing you want is saltwater getting into your engine. With 2 each of engine, oil, transmission, and after cooler heat exchangers it is an expensive but necessary item. Oh yeah, don't forget the generator. New gaskets and seals as well as replacement for any corroded parts.

I thought while out of the water for hull sides and bottom painting it would be a good time to get it taken care of. With that done the only major thing left on my list is to spruce up the finish on the exterior teak. Then it's cruising time.
 
Oh crap! I thought I was doing good servicing the engine and tranny coolers this winter. I didnt even think about the genset. Thanks Don. More stuff to figure out here.
 
Thanks for the reminder, Don. A couple of years ago I cleaned and refurbished the stbd H/E during a manifold replacement but left the port go. Yesterday I changed the zincs in the H/Es and oil cooler.

Maybe it's time to remove the port H/E for a cleaning and refurbishment. Same for the oil coolers. How often do you guys remove and clean these units?
 
Here is a question - should transmission HXs be considered a threw away item after say 10 years. Unlike a plugged or failed engine HX, a failed tranny HX can be catastrophic, at least for the tranny anyway.
 
sunchaser said:
Here is a question - should transmission HXs be considered a threw away item after say 10 years. Unlike a plugged or failed engine HX, a failed tranny HX can be catastrophic, at least for the tranny anyway.
Click to expand...

That is probably a good idea.:thumb:
 
Just pulled my engine/transmission oil cooler off yesterday, after ten years she will get a new one installed next week........:thumb:
 
I discovered this last year when I went to pop the drain plug off the gear cooler - it was rotted through. It was original from 1998, so I think I got my $$ worth.

A new cooler was put in and is now on a 5-year replacement cycle


Cummins 5.9 with Hurth gear
 
Regarding tranmission coolers, if they don't have a pencil zinc, then they have a shorter life than you might think. The cooler deteriorates in the same way as the engine's heat exchanger would if you don't change that zinc. When the transmission cooler went on my charter boat several years ago, after examining the failure and lack of a zinc, I rectified the problem on the new cooler. The end cap on these coolers has a spot that could be drilled and tapped for a drain plug. So I drilled and tapped it 1/8" fpt. There is now a pencil zinc in my cooler that lasts about 2 charter seasons.

Ted
 
it was rotted through. It was original from 1998, so I think I got my $$ worth.

For a few more bucks you can find servicible units , that just take a gasket set when ever you go inside.

Sendure among others,
 
FlyWright said:
Maybe it's time to remove the port H/E for a cleaning and refurbishment. Same for the oil coolers. How often do you guys remove and clean these units?
Click to expand...

I remove my main heat exchanger every 2 years and flush it out at home, then paint it.
Oil and tranny coolers get pulled and replaced at 5 years.
Engine is a Ford-Lehman 120, oil and tranny coolers are identical.
 
I'm not aware of conditions where you are but calcium scale is the only real concern in my waters, we don't experience biological growth. Every thousand hours on the boats I service I remove the water injection hose, extend it onto a bilge pump in a bucket, disconnect the raw water pump outlet hose & extend this to the bucket, fill bucket with descaling acid, start pump and go and have a leisurely cup of coffee. Stop pump after 15 minutes, reconnect hoses, start engine and good to go. Now I have fittings available for all the boats I work on the whole process take less than 1/2 hour per engine for ALL the coolers on that engine.
Biological growth, unless it is actual shells stuck in tubes, can usually be taken care of by a soak and vigorous back flush with water as hot as possible. If your friend has a steam cleaner, these are ideal. Every time a cooler is removed & dismantled the potential for damage is substanitally increased.
BTW, in a properly set up and maintained cooling arrangement, seawater won't contaminate other fluids. The pressure of the fluids being cooled will alwys be higher than the raw water pressure so will leak out into the raw water discharge.
 
Nightcap said:
I'm not aware of conditions where you are but calcium scale is the only real concern in my waters, we don't experience biological growth. Every thousand hours on the boats I service I remove the water injection hose, extend it onto a bilge pump in a bucket, disconnect the raw water pump outlet hose & extend this to the bucket, fill bucket with descaling acid, start pump and go and have a leisurely cup of coffee. Stop pump after 15 minutes, reconnect hoses, start engine and good to go. Now I have fittings available for all the boats I work on the whole process take less than 1/2 hour per engine for ALL the coolers on that engine.
Biological growth, unless it is actual shells stuck in tubes, can usually be taken care of by a soak and vigorous back flush with water as hot as possible. If your friend has a steam cleaner, these are ideal. Every time a cooler is removed & dismantled the potential for damage is substanitally increased.
BTW, in a properly set up and maintained cooling arrangement, seawater won't contaminate other fluids. The pressure of the fluids being cooled will alwys be higher than the raw water pressure so will leak out into the raw water discharge.
Click to expand...

Just to clarify: The water injection hose-Is this the hose that connects to the exhaust elbow? Also are you using muratic acid as a descaler?
 
Yes, the hose to the exhaust elbow. You basically want to make a loop of the entire engine cooling system and circulate through it. If god was good I would be able to use muriatic but Vanuatu is a bit short on this sort of thing & I don't have an import licence for dangerous goods. I use 12.5% hydrochloric and pray to the descaling gods throughout the process. Touch wood I haven't damaged a cooler yet but Cummins 6BTA air coolers make me nervous.
 
I just replaced the transmission oil coolers on my boat and the new ones, besides having zinc's, also have a terminal to ground the cooler to the engine. My old ones did not nor do my engine HX. The engine HX do have a pretty good mechanical connection to the engine where as the transmission cooler not so much. Any thoughts?
 
jstauffer said:
I just replaced the transmission oil coolers on my boat and the new ones, besides having zinc's, also have a terminal to ground the cooler to the engine. My old ones did not nor do my engine HX. The engine HX do have a pretty good mechanical connection to the engine where as the transmission cooler not so much. Any thoughts?
Click to expand...

Bonding when working properly is great...

Bonding when you have stray current corrosion is a nightmare....

If all of the coolers/HXers are metal strapped to the engine and have zero resistance or continuity between them then the terminal is unnecessary (but ultimately an easier bond to keep corrosion free).

Roll the dice...
 
Just take the coolers apart and go to a work shop with an ultrasonic cleanig machine 30-60 min then its like new again!
 
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