Cat3126 heat exchanger end cap

kvduff

kvduff

Well-Known Member
Jun 22, 2011
715
Long Island N.Y.
Boat Info
1998 450 Sundancer
Engines
Caterpillar 3126 -420hp
139E1DE6-57C0-4765-BFFF-7290EAE1FBA7.jpeg
Prior to purchase of my new to me boat , engine surveyor recommended changing the end cap on the heat exchanger, the brass insert that the anode is secured through was spinning while he attempted to remove the anode to inspect the heat exchanger with a scope.
I have the new end cap on hand along with a new anode and two new seals for the end cap. I realize I will have to drain some of the coolant. Can I drain the coolant through this drain in the bottom of the elbow in the picture below. Also, I have three gallons of cat elc on hand, I think I read the system holds 7 gallons, how much do you figure will drain out of the heat exchanger itself? I want to make sure I have enough coolant so I don’t have to make another run to the cat dealer. Thanks In Advance
 
I'm not sure I understand...It's my understanding that the end cap encloses the raw water side. Further, your picture shows a belt cover and what I think is a raw water line...Not 100% sure...Can you show a picture of the area and items you are removing circled? BTW - Zincs are on the raw water side, not coolant side, so no coolant should come out.
 
It very well be me who does not understand.
Your point about the zinc being on the water side makes sense. So I guess there is no concern in losing coolant when I remove end the end cap.
 
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I thought I had taken a photo when I was on the boat but I don’t have it. The end cap I am asking about is in this diagram labeled letter A, enlarged picture on bottom right
 
On the 450DA heat exchangers, the anodes go in the end caps....no where else. However, one end cap (the stbd end cap) has 3 anodes in it; the other end has only one. The end with 3 anodes can be removed and replaced without losing any coolant.

Also, if your coolant is Cat ELC (pink) it has a 6 year life and if you don't know when it was last changed, you need to change it now both so you have a baseline on the coolant service and so you know the engines are protected. Diesel coolant does more than protect against freezing........it also has anti-foaming/cavitation additives, anticorrosion additives and the SCA's (supplemental cooling additives) diesels require. The photo you posted (drain plug in the bottom of the "U" on the white pipe) is the correct drain point for the engine coolant.

Edit: you posted the heat exchanger breakdown while I was typing.........end cap A should be on the stbd side of both engines and is the one with 3 anodes in it. It can be changed in the boat without losing any coolant. The only gotcha is the o-ring seals....be careful and don't score or tear them. Also, with the end cap removed you should be able to visually check the condition of the tube bundle inside the heat exchanger. and this is t he time to remove and clean the tubes if you need to.
 
Frank - I believe one of the ports on the hose connection side is to be plugged (only 2 anodes required) at least on the 3116TA.
I have removed the other end cap (on my 400DA with 3116's) without having to drain the coolant. The key here is to remove the coolant reservoir cap so no pressure is on the system and carefully remove the end cap without pulling the heat exchanger bundle loose. Both end caps FYI are raw water and the heat exchanger bundle has it's own seal to the housing but is retained with the end cap bolts. Use caution to not overtighten the bolts as the caps are composite.
 
Frank, I will take a photo of the end cap if I get out to the boat today, the end cap I am referring to is on starboard engine, inboard side. On my 45 this end-cap only has 1 anode spot.
 
Hey guys, the end cap I am referring to is the starboard engine inboard cap. Frank I verified the cap on the outboard does indeed have 3 ports for zincs while the one I have to replace is the cap with just zinc.
Is the correct procedure to drain the exchanger of coolant remove end cap, replace gasket/o-rings and cap.
Frank mentioned draining and replacing all of the coolant bc it has a six year lifespan and I am not sure of its age. That seems like an easy task to undertake by removing the drain plug in the picture I posted above. Any thing else I should look out for?
 

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You don't need to drain the coolant to replace one end cap.........just don't unbolt both end caps at the same time.

I hop I didn't mislead you on changing the coolant. You don't need to drain the coolant to replace the heat exchanger end cap, but this would be a good time to replace the coolant if you don't have the service history telling you how old it is or if it has been extended with Cat's ELC SCA extender. Unlike gals engines, diesel coolant serves multiple purposes and all are important. Cats (pink) predicated ELC is a great product that has a 5-6 year life and changing it is as easy as just removing one plug so a 5 year replacement regimen if kind of a slam dunk for me.
 
fwebster said:
You don't need to drain the coolant to replace one end cap.........just don't unbolt both end caps at the same time.

I hop I didn't mislead you on changing the coolant. You don't need to drain the coolant to replace the heat exchanger end cap, but this would be a good time to replace the coolant if you don't have the service history telling you how old it is or if it has been extended with Cat's ELC SCA extender. Unlike gals engines, diesel coolant serves multiple purposes and all are important. Cats (pink) predicated ELC is a great product that has a 5-6 year life and changing it is as easy as just removing one plug so a 5 year replacement regimen if kind of a slam dunk for me.
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Thanks for getting back Frank. I have a clearer understanding of what to do now.
I am going to drain/replace the coolant because I don’t really know when it was last done. Have a great day!
 
I just changed my coolant. You need a minimum of 15 gals, but buy 3 cases (3x6 bottles) to have some extra on hand. Also, there is a small o-ring that seals the plug at the bottom of the u pipe. Buy 2 new o-rings. If you have a small leak at that o-ring, you have to dump the whole system. Cat o-rings are cheap.
 
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