These type of leaks are common in older cars with plastic reservoirs. I imagine you could get a used one in good shape for cheap. Note that you can buy these online from USA dealers, e.g. here. here. You can get them way cheaper from a Japanese source. I would recommend Amayama here. About 230 usd vs 90 usd! And funny enough shipping is about the same eiether way! I've ordered dozens of parts for my MR2 from Amayama and have nothing but positive experiences. Suppliers like Jason Streeter are great for aftermarket parts in Japan, but in my experience they don't like messing with OEM parts. Another great thing about Amayama is you can get a lot of oem parts unavailable in the USA. I just ordered most the hardtop seals/plastics from Amayama and most of these are unavailable in the States.

 

Amayama is solid for sure. I'd check some of the online dealers in the states too and just source a new one for as little $$ as possible.

 

Couple quick thoughts.

These can be had on eBay from time to time for around $90 shipped.

Or, there appear to be quite a few stainless universal units with similar dimensions and a pressure cap with the same rating and function. Why put crap plastic back in when stainless is cheaper?

 

Depends on if you are going for the OEM look. And the plastic one makes it easy to see the level.

 

I have the stainless one from Gokey. It looks fantastic and build quality is top notch. But it is certainly way more expensive than oem. And yeah, there is a site glass to check level, but it's not nearly as useful as the oem. In the end, the Japan sourced one from Amayama is by far the best bang for buck. Why buy a used one for the same/slightly less and risk having the same thing happen? Plus, used ones almost always look like poo.

 

Wow you aren’t kidding! Half price when shipped directly from Japan!

 

Is the tank cracked, or did you just release some coolant from the pressure cap? If the tank is cracked you need to replace it right away because the system needs to hold pressure in order to avoid pump cavitation and boil-over
IF you over fill the tank, it will spit some coolant out near the filler neck when it gets hot; that is normal

 

It’s hard to tell. I will take some pictures tonight. When it happened the top area of the reservoir was still dry and dust, and only the area around the seam was wet.

 

The reservoirs have a small hole underneath the cap that will leak out coolant if it gets to that point. But then you would have to ask the question why.

Radium makes a coolant tank that aluminum. Looks nice. Not sure if I have pic for it.

 

The passage under the cap only lets coolant or steam out if the pressure cap pressure level is exceeded. The tank is pressurized. The function of the tank is expansion and also to de-aerate the coolant. Coolant (along with steam or air bubbles) continually flow into the tank through the small top hose, and only pure liquid is returned to the engine via the lower hose. The tank has baffles to help separate the bubbles from the liquid, so it you want to replace it with a simple metal tank, it should be higher capacity (greater than 1 quart) and must have pressure cap and the proper in and out hose fittings.

 

I bought a couple off Ebay ... they still come from Japan so it takes a little while to get them .

Pardon Our Interruption...

 

If you order from Amayama you will get the part very fast. I've ordered dozens of parts from them and usually I have the part within a week, two max. They ship very quickly and always have tracking.

 

One thing I forgot to mention before is that a couple of weeks ago I hydroplaned the front end into a curb. The bumper rode up onto the curb pretty much straight on and it messed up the underbody plastics somewhat. It doesn’t look like there is any other damage, but could that somehow have potentiated the issue?

I don’t have a way of getting the front end up in the air right now as I don’t have a low profile jack and the ramps I have are too steep for the front. I know there a some work-arounds but I also keep running out of daylight for car work.

 

Shouldn’t have anything to do with the rear of the car leaking coolant.