CAT 3126 HEX

dtfeld

dtfeld

Water Contrails
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Jun 5, 2016
5,566
Milton, GA
Boat Info
410 Sundancer
2001
12" Axiom and 9" Axiom+ MFD
Engines
Cat 3126 V-Drives
As I get deeper into the cooling system cleaning and refurbishment, I've found my starboard Heat Exchanger is weeping a very small amount of antifreeze. Its corroded right underneath the aluminum I beam were salt water is know to drip onto the genny and other parts back there. There has always been a little rust and I originally thought this was external (still might be). This is the shell leaking, not the bundle (#1 in the picture).

Regardless this thing must come out and be taken care of. If the starboard side is bad, the port probably isnt far behind.

Question is can they be repaired or am I going to have to buy a new shell?

Anybody been down this road?

Capture.PNG
 
Last edited:
Fire sale at CAT...$923 each...ouch
 
David, My stbd one was corroded on the flange end from sea water dripping through the hatch seal. the PO had the hatch seal re-done to run at an angle on the corner - that stopped the leaks. Back to the HE. The flange bolts go all the way through - when removing spray both sides with PB Blaster. I then cleaned up the threads with a thread chaser (1/2", I recall a 1/4 NPT tap is needed). Bought a new O ring from CAT (not expensive) and cleaned it up and repainted. Also, you can find all the impeller pieces in there!

Don't ask me why a 1/2' thread takes a !/4 NPT tap...
 
carterchapman said:
David, My stbd one was corroded on the flange end from sea water dripping through the hatch seal. the PO had the hatch seal re-done to run at an angle on the corner - that stopped the leaks. Back to the HE. The flange bolts go all the way through - when removing spray both sides with PB Blaster. I then cleaned up the threads with a thread chaser (1/2", I recall a 1/4 NPT tap is needed). Bought a new O ring from CAT (not expensive) and cleaned it up and repainted. Also, you can find all the impeller pieces in there!

Don't ask me why a 1/2' thread takes a !/4 NPT tap...
Click to expand...

Carter

I have the exact same thing, same place. I'm going to pull the HEX off the boat and evaluate the whole shooting match.

Did you replace the shell or was your servicable?? I've called a couple guys that think they can repair it, but I'm tempted as expensive as the part is to just replace it. That lets go while running and ill cook the engine before i know whats going on.
 
carterchapman said:
I cleaned mine up. Does your hatch have the angled seal mod?
Click to expand...

I doubt it. My aluminum beam has no edges, so whatever ran down there, ended up on the generator and the HEX, I guess standard issue for the 410's.

You wouldnt have some old pics or a link to something on the site?

Back to the HEX. Like I said, I think I need to get the whole shooting match off the boat, get her stripped to bare metal and see what needs to be done.

Mine is dripping just a very few drops of antifreeze. I dont have high hopes, but we shall see. I'd rather find it now than July 3rd.
 
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I thought OSD9's pictures of the fix were in the 400 page document that I sent you - but I jsut looked - no joy. I couldn't find it here either. It basically involved changing the stbd aft corner gasket from a 90° angle to about a 4" piece cutting a 45° angle across the corner.
 
dtfeld said:
As I get deeper into the cooling system cleaning and refurbishment, I've found my starboard Heat Exchanger is weeping a very small amount of antifreeze. Its corroded right underneath the aluminum I beam were salt water is know to drip onto the genny and other parts back there. There has always been a little rust and I originally thought this was external (still might be). This is the shell leaking, not the bundle (#1 in the picture).

Regardless this thing must come out and be taken care of. If the starboard side is bad, the port probably isnt far behind.

Question is can they be repaired or am I going to have to buy a new shell?

Anybody been down this road?

View attachment 64799
Click to expand...
$992 is not bad - I have my HE's off being cleaned by MAN and he told me a new shell is $8500 and a tube bundle is about the same...pay me now or pay me later!!
 
carterchapman said:
I thought OSD9's pictures of the fix were in the 400 page document that I sent you - but I jsut looked - no joy. I couldn't find it here either. It basically involved changing the stbd aft corner gasket from a 90° angle to about a 4" piece cutting a 45° angle across the corner.
Click to expand...

I'll have to look next time out. Thanks Carter!
carterchapman said:
$992 is not bad - I have my HE's off being cleaned by MAN and he told me a new shell is $8500 and a tube bundle is about the same...pay me now or pay me later!!
Click to expand...

Holy Snipes!!!
 
I hope they offer mortgages on those
 
carterchapman said:
Just part of the "good negative cash flow" of our wonderful hobby and enjoyment...
Click to expand...

Do I need a full coolant change or can a get away with a partial draining when removing the HEX? It’s up pretty high...

It was just changed, but what’s another few $$$ while I’m at it?
 
carterchapman said:
$992 is not bad - I have my HE's off being cleaned by MAN and he told me a new shell is $8500 and a tube bundle is about the same...pay me now or pay me later!!
Click to expand...
Carter, not that I need them, but MAN in Pompano Beach gave me a quote of $14,000 for a complete heat exchanger that has the updated design. And yes, times 2.... plus removal and installation.
 
carterchapman said:
I thought OSD9's pictures of the fix were in the 400 page document that I sent you - but I jsut looked - no joy. I couldn't find it here either. It basically involved changing the stbd aft corner gasket from a 90° angle to about a 4" piece cutting a 45° angle across the corner.
Click to expand...


Carter,

I was involved with this on the Sea Ray end. The problem is that the guys at Merritt Island who initially installed the drain gasket stretched it as it was installed. After several years the pressure sensitive gasket shrunk back to its original shape. Dominic sourced the pressure sensitive material on his own rather than waiting on Sea Ray to send a replacement, and when he "fixed" OSD he covered the corner of the hatch with a 45˚ cut rather then butting 2 90˚ cuts together.

Also, some of the owners (Dom!) maintained that a rapid deceleration would cause the stern wave to enter the deck drain thru hull and that in turn would overflow the scupper into the engine room. We had 3 410's at the marina at the time and the service manager and I ran all 3 in every imaginable way (chopping the throttle from right at planing speed to cruise speed then immediately turning to port) and we never could force the stern wave to back up into the drain.

Frank
 
Frank and Carter

Thanks for the info. I was under the impression, that water was dripping down between the decks that meet at the aluminum beam. The boat has been uncovered in Tampa most of its life, so I expect some salt water made its way down there. The HEX and the generator took the worst of it

I haven’t seen any drippage since I’ve taken ownership, but I’ve sealed/repaired the camper top and I’m now in fresh water under a covered slip, so hopefully the wear and tear has slowed down.

I’ve never noticed any water coming up the scupper, but I’m pretty easy coming off plane, no idea if that was an issue for previous owner.

Regardless, I’m going to get her back to as close to pristine as I can. It’s slow but making progress.
 
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