Hello ,

I am thinking of upgrading my coolant overflow tank on my 2004 r53 as it seems that it is perhaps stil original and has perhaps seen better days .

After my last episode of it overflowing with milkshake it seems there may be some hairline cracks on it .

I am thinking of going with the canton coolant tank . Ecs tuning sells one with a 30psi cap which does not make sense to me . I have found some past posts about the cap psi also but was wondering what psi the majority are running and if you had any issues because of the higher psi rated caps sold for aluminum.tanks . With our cars being older parts and many dont have the functional lower fan speed doesn't put much more strain on other parts.

Am I safer to just get a stant cap perhaps at 18 psi to help with the boiling point a little or just stick with the 30 psi one it comes with from canton ?

 

I run the canton with a 30psi cap on my track car and have no issues.

 

I've also run a 30psi cap on the track car for over 10 years now.

 

So…. I’ve thought about this. I’ve just replaced the tank with a plastic one. My logic is to leave that as the weak point. A Canton tank will never blow. What will? I don’t want to know. Oe tanks are easy to keep a spare, and easy to replace. Just my 2 cents.

 

that makes sense to me noodlesandsam. i do the same

 

Thanks for the replies . Although you guys run 30 psi caps on track I wonder if it would.just be too much for a daily driver with being stuck in traffic and only high speed fan .

Also I do agree that the stock plastic tank is probably a best bet in case it needs to let go , but is the overflow tank cap not supposed to act as the pressure release in case things go bad ?

 

It does work. Mine did release / 2.0 bar - 31 psi - it let loose in traffic. The tank held, the cap did its job. This was in San Diego traffic before the Automatic / non cvt was rebuilt - now it does not have the beer can heat exchanger - just an external cooler loop.

 

You can get a lower PSI cap to replace it at about any auto parts store, if it is something that you are concerned about....

 

So, here is what I know with having had an r53 since March 2005 - 181k miles, and almost all my own work for many of those years. The OE cap is a 2.0 bar cap. Basically 30 psi. The OE plastic tank is a 2 part design, welded plastic - that is what generally leaks as it gets old. I replaced mine 3 times. I put a new water pump in at 150k. New radiator and all hoses in at 170k. Mine is the 6 speed AUTO. At 177k, we rebuilt the transmission - fully, new everything including torque converter - switched to an external cooler - ending that beer can heat exchanger that added load to the Rad.

The cap is not the problem if the system is working.

 

My early 2002 R53 build must've received a defective coolant reservoir. It is still under the bonnet after 23-plus years, and looks basically brand new, with no evidence of any leaking at the seam. Now that I've just jinxed it, I'll probably replace it with a Canton, but use a lower release cap as the car sees the track several times/year. My track buddy and ex-engineer @Eddie07S recommended that I at least replace the bottom rubber tubing, but it too, looks pristine.

 

Yes i agree , and that is probably the way I will be going for peace of mind . Depending on the info I put toguether .I would like to keep the cap same company ad tank ( Canton) as they do build a quality product, but the 30lb cap is throwing me off as from what I am reading online the mini is a 1.1 bar system

 

from the info i am gathering online i was ynder the impression that mini r53 cap isaround 1.1 bar or 16 psi . Even accoring to mini mania website . This is why I am not understanding why canton is recommending a 30 lb cap with our system . I can see raising the bar pressure a bit but all the way to 30?
l

 

Wow u got lucky ! I am on my second one and the last one let go when the oil cooler went bad . The cap released the pressure thanks god ,but am now seeing hairline cracks on tank again , so this time would also like to go aluminum . I have never felt good about that plastic sitting right above my header especially with the heat it produces . It can't be good for plastic...

 

Agreed, it doesn't seem like smart design, but plastic is a lot cheaper than aluminum. The MINI beancounters figured the cars would be out of warranty by the time the seam failed.

 

+1 for this idea. With the OEM cap

Remember that the R53 has basically an old design engine which had a lot of history when it went inti the MINI. The design needs were well understood. That would include what pressure the coolant needs to run at. The cap, at a minimum, needs to be the same pressure as the OEM cap in order to preclude boiling around the cylinder walls and head which can lead to damage. Those areas will run hotter than measured temperature so the measured temperature isn’t a good indicator of what is being protected against. Going to a lower cap pressure really doesn’t buy one anything, either. So, if the OEM cap pressure is unknown, I would suggest sticking with OEM parts.

As for track use, a high cap pressure would be better to preclude boiling, than a lower pressure cap. Going to a pressure higher than OEM does bring into question if the rest of the parts can handle the pressure. That said, if the OEM design cap is working on the track, why change it to a different pressure? Also, a street car that is run on the track is different than a full fledged race car where things have been upgraded or at least the limits of parts are known.

My totally uninformed guess is that the metal replacement with the 30psi cap was/is intended for track use as well as for the street. When new, I would guess everything else in the system could take the pressure. In an older car, will it be ok? Don’t know.

My 2 cents.

 

I understand the logic to some degree, but going from OEM level to 30 is a huge difference!

 

Do you know what the stock pressure is? I have seen several different ideas stated here. I may have misread something, not sure. My caution is to not go below the stock pressure.

 

So, I don’t have the r53 in front of me - it’s on the other side of the country. I thought the pressure was 2.0 bar, maybe not ( I do have an e38, an e39, and an e46, so my brain is used to 3.0 bar.

this is a good write up from folks that know Minis.

https://www.gtt.uk.com/gtts-cool-gui...ooling-system/

 

Ok, after all of this I did a search on R53 MINI Cooper coolant system pressure. The Google AI result said 1.1 bar or 16 psi.

MINI Mania says 1.1 bar (link). This link is also pretty good for other coolant system info.

This would be typical of engines of this vintage.

So, the lower cap pressure should be ok. Now why didn’t the just make the tank to take the MINI cap…

 

Yes from what i gathered t's 1.1 bar system on r53 , and cap is around 16 lbs I believe . I totally agree they should have mande the proper cap psi for stock system available for the kit especially when the tank is mini specific .

Reached out to canton and they responded with the folowing reason for the 30 lb cap recommended with their tank ..... " However we recommend the 30 psi cap so the radiator cap overflows first instead of the tank. Unless you have a sealed core radiator, then go ahead with the 16psi. " .

Also I guess some guys are running more diluted coolant ratios or straight up water which i guess would require the higher cap for higher boiling points at the track .

Anyhow have bought the tank but am going to try the 18 lb stant / gates cap and a 16 lb on the side in case i see issues with the 18 . Definetely need to get my lower speed fan fixed up in the near future .

 

Wait. So they designed a tank for a car that doesn’t have a separate radiator cap, but then they sell it with a higher pressure cap assuming that the car does have another cap on the radiator? Are the track guys running radiators with caps? It wouldn’t be the highest point of the system, so it seems like it would be a strange choice.

I mean, the R50 does actually have a cap on the thermostat, but the tank on that car is unpressurized and generally not at high risk of failure.

 

yes i find it weird also . That is why i was so confused with this whole scenario of an aluminum tank with a 30 lb cap .

I guess vendors such as ecs , etc. Should of paired it with a 16 lb cap from the getgo . Well maybe something I'm not understanding, all i know is I'm not gonna risk it with a cooling system this old . I am going perhaps an 18lb just to raise the boiling a little and see if that helps. I know some.guys run it without issues , but I dont feel confortable taking that chance

 

Just for clarification this is the reply part from canton....

"However we recommend the 30 psi cap so the radiator cap overflows first instead of the tank. Unless you have a sealed core radiator, then go ahead with the 16psi. " .

the rest of the post was just my 2cents

 

There is (or was) a popular aftermarket radiator for these MINIs that is much larger than the stock on. That is likely what they are referring to.

 

FWIW, I run a CANTON tank and the 18-22 lb. STANT cap. The CANTON has an overflow tube in the filler neck so I routed clear tubing from it to the spout of a clear ketchup/mustard bottle that fits in the void next to the brake fluid reservoir. If the system "burps" anything, I can see it and see how much. Under the hottest track days on a 25 minute session, I've never collected little more than a teaspoon in the bottle.