CAT 3126 Heat Exchanger End Cap Removal

[david_h]

I need to remove a couple of very stuck sac anodes from the end caps of one of my heat exchangers. I have one stuck anode in each end cap of the heat exchanger.

Will I need to drain the anti-freeze prior to removing the end caps? I actually already started to remove the end cap closest to the after cooler side, and saw some pink drip out which was a big surprise to me, as I would have thought that there should only be sea water in there. I bolted it back up so that I could research it a bit more before proceeding. While I also use a pink winterizing fluid, I would have thought that the pink winterizing fluid would be all flushed thru by now after running the engines for a bit.

If I need to drain the anti-freeze, is that done by removing the plug at the bottom of the goose-neck pipe located under the alternator?

Many thanks,

Dave

 

[dtfeld]

Hey Dave

Here's my adventures with the CAT HEX's. http://clubsearay.com/index.php?threads/cat-3126-hex.91223/

If you pull them out you will need to drain the coolant. Bottom of the J pipe is the drain, 7.5 gallons as I recall. You'll need several 5 gallon pails and a good pump to keep up.

The HEX caps are composit. The biggest issue I've had were the sacrificial anodes in the transmission coolers. I had to pull one and drill out the brass cap that I stripped. That's a whole other adventure.

Edit. HEX caps have metal instert as pointed out by Tom.

 

[david_h]

David C., thanks so much for getting back to me!

When refilling the anti-freeze, would you pour about 1/2 of the drained contents back through into the rad cap perhaps 1/2 full, then start the engine, and then pour the 2nd half back in? As you can tell, a relative newbie. I am basically asking for your advice for the refill procedure.

FYI, I boat in fresh water. The aluminum (not zinc) sac anodes have a tendency to aquire a bit of growth so that they get stuck, and in my case, actually snapped the threaded portion off into the plug . So now I have to pop the caps off to get at them, (have purchased the gasket assemblies already).

Thanks again,

Dave

 

[ttmott]

I need to remove a couple of very stuck sac anodes from the end caps of one of my heat exchangers. I have one stuck anode in each end cap of the heat exchanger.

Will I need to drain the anti-freeze prior to removing the end caps? I actually already started to remove the end cap closest to the after cooler side, and saw some pink drip out which was a big surprise to me, as I would have thought that there should only be sea water in there. I bolted it back up so that I could research it a bit more before proceeding. While I also use a pink winterizing fluid, I would have thought that the pink winterizing fluid would be all flushed thru by now after running the engines for a bit.

If I need to drain the anti-freeze, is that done by removing the plug at the bottom of the goose-neck pipe located under the alternator?

Many thanks,

Dave

The end cap opposite the raw water pump hose interfaces (where one anode is installed) can be removed without impacting the engine's coolant. The cap on the other side can be removed carefully but ensure the coolant cap on the expansion tank is removed and there is zero pressure on the coolant side. As soon as that Hx end cap is off get some bolts back in to hold the tube bundle in place and against it's gasket. You may get a little bit of a leak when the cap is removed but that will stop when the bolts are back in to hold the bundle (it takes a lot to pull the tube bundle away from the housing). But, there is always a bit of a risk so if you are uncomfortable with this procedure drain the antifreeze down below the Hx.
As dtfield says the end caps are plastic composite however, where the anodes are installed in the caps are metal threads with a metallic bond to the heat exchanger housing (the anodes are electrically bonded to the heat exchanger and engine). So, use caution and don't get all radical forcing things as you will end up buying new end caps.
From the school of hard knocks....

 

[david_h]

THanks for the additional info. Will give it a go, in a couple of days.

tks

Dave

 

[dtfeld]

David C., thanks so much for getting back to me!

When refilling the anti-freeze, would you pour about 1/2 of the drained contents back through into the rad cap perhaps 1/2 full, then start the engine, and then pour the 2nd half back in? As you can tell, a relative newbie. I am basically asking for your advice for the refill procedure.

FYI, I boat in fresh water. The aluminum (not zinc) sac anodes have a tendency to aquire a bit of growth so that they get stuck, and in my case, actually snapped the threaded portion off into the plug . So now I have to pop the caps off to get at them, (have purchased the gasket assemblies already).

Thanks again,

Dave

I'm pretty sure that the system filled almost completely on the first try. I monitored the over flow reservoir and added ELC as needed. It was a couple ounces here or there. By the Way Tom is correct in that the caps have a metal insert, and they could be corroded...I'll correct my earlier post.

Just to clarify. Do you have stuck anodes ( striped or rounded off head), or did you get the head loose and loose the anode in the HEX? From a practical standpoint, if you lost an anode or two inside the HEX, I would simply replace the anode and get back to boating. The CAT cooling system is pretty robust and can handle several anodes and impeller fins. Is there something else going on with the cooling system?

 

[david_h]

The anodes broke off at the threaded portion, (they were stuck to the anode cavity, and I tried the 1/8-turn over-tighten but it didn't work). I guess I could just 'punch' them in, and put a new anode in the cap and re-insert. But it is probably time to have a peek at the water pump side of the HEX, and clear out any busted fins.

Can you confirm that the core is not bonded mechanically in any way to either end cap? And if so, do they come off easily, or do you need to use a rubber mallet, or twist, or ?? Mine seem pretty stuck, and with the talk of plastic caps, not sure how much force I should be using.

Thanks, for the help thus far. I figure (hoping) I am half way there...... for first time HEX work.

tks

Dave

 

[ttmott]

The anodes broke off at the threaded portion, (they were stuck to the anode cavity, and I tried the 1/8-turn over-tighten but it didn't work). I guess I could just 'punch' them in, and put a new anode in the cap and re-insert. But it is probably time to have a peek at the water pump side of the HEX, and clear out any busted fins.

Can you confirm that the core is not bonded mechanically in any way to either end cap? And if so, do they come off easily, or do you need to use a rubber mallet, or twist, or ?? Mine seem pretty stuck, and with the talk of plastic caps, not sure how much force I should be using.

Thanks, for the help thus far. I figure (hoping) I am half way there...... for first time HEX work.

tks

Dave

Take the hoses off and bolts out and they will just about "fall" off. Get replacement end cap gaskets. I don't know why but I seem to remember the part number is 4P3872; no guarantees.

 

[dtfeld]

If I recall, I used a putty knife to get the cap moving by gently tapping it in (be careful not to gouge anything). I thought they popped of after that...been a while. There is an o-ring in there that seals everything up. I would have a set of those on hand.

Here is the exploded view and if you put your zip code in, you'll find your local dealer. I would expect these to be in stock.

https://parts.cat.com/AjaxCATPartLo...zj01455&langId=-1&requestType=3&storeId=21801

 

[david_h]

Thanks guys! Water pump side just popped off, and I think I can see the end of the tunnel!

tks

Dave

 

[david_h]

Opps, had a bit of a setback.

With the water pump side end-cap off, I started to try to free up the after-cooler side, end-cap (6 bolts removed). It won't budge. And, I find that the core bundle spins freely in the housing, seemlingly 'glued' to the after-cooler end-cap.

Just checking back in with you to be sure that I haven't missing anything.

Comments?

Dave

 

[david_h]

Update:

I finally got the stuck after-cooler side end cap off! I talked to a 'visiting' CAT mechanic on a neighbor's boat, and he suggested that I rotate the cap just a few degrees, and use 2 bolts inserted the wrong way (from the tube side), to in effect push the end cap off. It finally popped off, after exposing about 1" of the core. Amazing, I found a totally free anode inside the end cap, and it was positioned so that it would prevent the end cap from coming off easily. So a bit of a struggle, but eventually, got it done.

This also reinforced the need to have a set of taps on board. The water-pump side end cap needed a few of the bolt holes to be cleared out of rust and debris before the bolts would go back in properly!

Thanks for everyone's suggestions.

Dave
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[carterchapman]

Update:

This also reinforced the need to have a set of taps on board. The water-pump side end cap needed a few of the bolt holes to be cleared out of rust and debris before the bolts would go back in properly!

Thanks for everyone's suggestions.

Dave
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+1 on the taps. I had to chase the threads on my 3126's HE cap as well...I also replaced the bolts with SS ones...