So my radiator header tank CAC8614 is in pretty grubby shape. I cleaned up the outside but the inside is pretty crusty and since I'm replacing the entire cooling system - I need to address it.

In my parts search, CAC8614 is a Special Order item. That means I'm going to have to wait a long time for it.

CCC6725 looks like a suitable replacement, but most of the vendors are selling the Uro version and the reviews on that are terrible. Plus most of them are sold out.

But what if there was a way to do the same thing using aftermarket parts - but better/cheaper? On my header tank, the top hose near the filler neck (#1) goes to the atmospheric catch tank behind the LF tire. The bottom hose (#3) goes to the coolant crossover rail, right on top of the feed to the water pump. The middle hose (#2) goes to the venting arrangement on top of the radiator. The theory being that the water pump draws low pressure on #3 and any air in the system gets purged from the top of the radiator and ends up in the header tank via the higher pressure in #2.


Instead of using the factory header tank, what if I used something like Moroso 63766? It has a bottom fitting that I could put in a adapter and use it as #3. I could put a fitting in the middle port and it could function the same as #2 on the factory tank. There's still a radiator cap and overflow on the top to act the same as #1 on the factory tank.

It's about $120 so it's slightly cheaper than the Uro tank. It's aluminum so it won't rust like the factory tank. The only downsides I see are that the ports are on the wrong side (which is easy enough to fix) , it looks to have less capacity than the factory tank, and there's no provision for the coolant temp probe (but I could weld in a bung for that).

What am I missing? Does the factory header tank do (or not do?) something I'm unaware of? Why is this a bad idea?

 

Vinegar.

Plug the holes, fill it with Vinegar, drink beer, about 6 maybe. Aussie for 6 hours or so, drain, and flush, repeat of needed.
The once has always worked on mine, but if its 45C outside a 2nd is needed, just so I can legally keep my fluids UP.

NO idea what Vinegar, I dont read labels, just raid the pantry, and then plead ignorant, not hard, when asked :"what happened to that new bottle of Vinegar".

There are many mods, and alternative that can be done, but try that first, you may be satisfied, like I was.

 

Instructions unclear - am I supposed to drink the vinegar and flush the tank with beer?

Just kidding. Here's a before shot of the inside of the neck of the tank:


And here it is after I plugged the hose fittings and let it sit with vinegar for about 7 hours:


I flushed it about 25 times this morning until all the debris stopped coming out. It looks like most of it was paint but there was some rust scale that came out as well. I'm going to do another vinegar soak today and see if I can get it any cleaner.

 

HAHAHAHA, dont waste the beer, or I will stop posting on your threads.

JUST KIDDING.

Looks good from down here.

Beauty of the HE tank is that the in and out flow of fluid is via that spout on the side, waaaaay up from the bottom, so sediment in the bottom basically stays there out of harms way.

Not so the PreHE, as their spot is out the bottom, direct to the radiator bottom hose spout, oops.

 

What about filling it with some kind of rust converter, like Ospho 605?

 

That's a good idea, I have used a similar product in the past but have never tried Ospho. If it was a rusty bumper bracket or something like that I would be all over it, but I worry about how well it would hold up to the repeated heat cycling of the inside of the cooling system. Between hot coolant and steam - it's a tough environment. And will it start to flake off and cause more problems than I already have?

That's why I'm leaning towards cleaning it as well as I can, with Plan B being the aluminum tank.

 

Thomas, sadly you have the ABS unit in the way, if not, and just as you may be interested, the cooling system can be substantially simplified and improved as explained here:

 

Thanks Greg - it's something to think about.

 

After a total of 24 hours of soaking in vinegar, this is what it looks like now:


There is still rust, but less than there was before. The concerning part was that I could never flush all the debris, which mostly consisted of paint, out of the inside of the tank. There were some rather large pieces that would have caused issues.
So I went another direction. Moss Europe sells CCC6725 which is an aluminum version of the coolant tank. It wasn't cheap, but I felt like it was probably the best option for the situation. Do it once, do it right, do it all. Thanks to all for the suggestions/ideas.

Next up is the coolant cross-over pipe. I'm thinking of fabbing one out of 316 stainless tubing.

 

Great find. After years of being NLA, it seems that at last these tanks are around. Even Jaguar have them in stock!