Hey everyone, long time lerker but a first time poster.

So I've bought an 03 MCS this past December with 87k on the clock. Sure there were a few blemishes but that's all expected out of a used car. One nagging and royally annoying issue I've been facing is the stupid CET splitting at the seams and pissing coolant all over the engine bay. CET #1 went within a few weeks of owning the car. CET #2 within 2k or so miles after that. I was stupid and should have gotten the aluminum can at that point but cheaped out and went for plastic CET #3... And surely enough, after my commute home from work last night I started to smell the now very familiar odor of coolant evaporating off the hot bits and noticed the coolant spilling from the seam right around the MIN/MAX mark.

Now, before I go ahead and order the aluminum can, I decided to make my last stand and try out a much cheaper "fix".

The idea is simple, take the CET out, dry it off and clean it from whatever remaining coolant might be in the seams and epoxy the crap out of it.

On the surface, this seems like a good idea but 2 part epoxies generally don't like, and I'm quoting, "Polyethylene, polypropylene, Nylon™, Teflon™ or flexible materials". I don't know the exact composition of the CET but I wouldn't be at all surprised if it falls under the first two as they are the most commercially applied polymers including the automotive industry. If this works, good; if not, I'll be no more than a few bucks short and on my way to getting an aluminum can.

To have the best chance of success, I scuffed the extruded surface of the seams all around and used an engraving bit with a dremel to get into the tighter space before applying a liberal layer of epoxy. Here are some pictures of the finished product and I'll check in once in a while to post updates whether this fix is something to go for or not:

 

Make sure that you have bleed the cooling system properly. This might be contributing to the failure of the already failure prone tank.

my 2 cents.

 

One tip....
If you overfill the tank, it will leak MUCH FASTER...i am still on my second tank on my 2005.....

 

Bleed? You mean burp? If that's the case, I've had the thing idle with the CET open and waited until it stopped releasing pockets of air before and intend to do the same. Then again, I've had a mid 90s Accord and a Cherokee before I got my hands on the Cooper so I'm basing the techniques from maintenance and repairs on those. If there's something I'm missing, do let me know.

 

My tank hasn't started leaking yet.
Yet.
Probalby because the cap leaks enough to relieve any excess pressure. Nevertheless I was thinking of being proactive and supplementing the existing material.
Permatex makes a that has worked for me in the past. It comes with strips of fiberglass for reinforcement. My idea was to lay the fiberglass over the seam and epoxy it all up.
In the meantime I can put away my pennies for an aluminum tank.

 

I, too, always thought the tank was at fault but ZippyNH has the right idea. When cool, the coolant should only have about 1" in the bottom of the tank. If anyone needs another tank and cap, I have two spares at extremely lucrative prices.

 

Tried that awhile back & it eventually came back. Just go w/ the Canton or RMW. They use real man's caps.:D

 

Seems unusual to go through that many tanks. Are you sure there is not something creating too much pressure and/or heat in the cooling system?

 

First tank I assume had it coming being so old and whatnot, the second tank went because the power steering fan seized, blew the fuse in the circuit that the radiator fan was also on and ended up overheating the car. Last one is just bad luck.

As a side note, the epoxy fix seems to be holding together even though I let it cure for only 4 or so hours and took it on a 50 mile commute.

 

Just spring for a Forge aluminum or the other aluminum one that I cant think of the name right now but its not as pricey as the Forge.

 

Canton....I think...but needs an elbow fitting to fit right...
Or RMW...MORE $$, but fits better from what I have heard...no mods needed...

 

Replace it with the polished aluminium tank, it is also available in black finish. I've seen people try to epoxy them before and it never lasts.

 

I switched to the Canton racing with the Slant 30# cap? I did not have to make any modifications.

 

It think that may be worth exploring. My 2003 had one tank replaced at 40,000 miles and it now has 140,000 on the upgraded OEM tank.

How does the car run otherwise? If there is a slight head gasket leak, you could be creating a lot of pressure in the cooling system. 2000 miles for a new tank is VERY unusual. I would have a leak down test done for starters.

///Rich

 

I don't think there's a leak. At least not enough to show signs in the coolant or the oil if that's at all possible.

 

http://www.pelicanparts.com/techarti...ant_Change.htm

Good article. Look at the pic 14 etc...

This should help.

 

Yup...remember...
There are 2 bleed valves....
The obvious one on the top rad hose....
And a second, kinda hidden by the thermostat... Near the airbox...
Not bleeding usually results in overheating...and split expansion tanks and or liquid spewing out the top.......

 

Ok, so here's an update.

For those interested in using general 2 part epoxies to fix the seam; don't do it as a permanent solution. Checked mine over the weekend and there was a pinhole leak around the MIN/MAX line and this morning that grew to a 5mm or so split. Those epoxies do not like the material our tanks are made of even with the scuffed surfaces.

Having said that, this does work for a quick fix or to at least minimize leaking until a new tank comes in. Anybody have suggestions for an aluminum tank? I've seen people above list a few but wondering what the general take is for a relatively inexpensive upgrade?

 

Go Canton, you won't regret it. RMW is similar, fits a bit better, just a bit pricier. These 2 are a 1 time investment.
Forge uses the low pressure stock plastic cap & would still be prone to cap leak should pressure exceed 16psi.

 

Is anyone opposed or heard bad things about the M7 expansion tank?

 

I have yet to hear bad things about aftermarket tanks. The oem ones on the other hand...

 

I'd say we replace a leaky coolant tank every 2 weeks in the shop. Most the time we just install our polished aluminum tank as it bolts in and is sealed like the stock one


We alos offer the pressure relief cap style for racing. If you use this on a street car we recommend checking your coolant level more often as this will allow it to escape when the cap vents.


Either way I never recommend going back with the stock plastic tanks as the new ones seem to have about a 90 life cycle before they leak again.

 

I keep seeing people post about RMW CET, yet I can't find it on the site? The "RMW" people are referring to is Revolution Mini Works correct? And if so, can someone point me in the direction of a link or is it something you need to call to order?