Tethlah

Attached picture pretty much says it all. While driving, usually for longer stints where I have very little variance in RPMs, the Coolant Level Light will come on. After looking under the hood there is coolant splattered all over under the bonnet. If you look at the pictures it's pretty self explanatory.

The res keeps going down to about half way. A buddy says he thinks it's the cap, I'm thinking maybe there is something wrong with the thermostat causing the pressure to rise and spraying the coolant out the overflow. But how could it be getting all over like that? Maybe it's hitting the fan?

Anyway, Coolant Level Light and lots of overflow. Anyone encountered this before?

j9fd3s

yes, you have a leak somewhere, kind of looks like its coming from under the coolant tank, so it might be the radiator, one of the hoses, or the tank.

you need to pop the covers and trays and stuff off, but it should be pretty easy to find

jasonrxeight

looks like the little plastic neck on top of the radiator is cracked and spewing coolant.

tomtomgt356

iTrader: (1)

I had the same issue with mine. There was a crack right below the cap on the coolant reservoir. Since the reservoir is part of the coolant pressure system, the system is loosing pressure and boiling the coolant. If you have to replace the reservoir, there is a small coolant hose going from the bottom of the reservoir into the radiator. Be careful when taking it out because the radiator connection is plastic and will break easily requiring a new radiator (ask me how I know this....).

Also keep a close eye on your coolant gauge until you get this fixed. The coolant gauge is a dummy gauge and wont move off normal till 230 which is already getting into the danger zone for a rotary.

JamesD31

That is what I was thinking.

The shitty dealership I bought from replaced the coolant reservoir, but I guess broke the top off the radiator and ghetto rigged it; only to find this out MONTHS later after I got my engine replaced since most Mazda dealerships seem to not want to mention everything at once...

Tethlah

I'm wondering the same thing. The coolant reservoir is REALLY loose. I had to tighten it down because it was so loose. Now I'm wondering if this same thing could have happened with my car. How much did it cost to replace it?

JamesD31

I complained about the engine lights and stuff on the car when I bought it, so they replaced the coolant for free.

Later down the road when they found the part that is probably broken (like the pressure thing at the top of the radiator) there is no way to fix it so you will have to get a new radiator (~$400).

AthensSilver8

iTrader: (1)

I had this same problem.
In my situation the radiator needed to be replaced. The coolant reservoir was overflowing onto the fan underneath and was shooting the coolant all over the engine bay.
Yours looks like a similar situation because there is coolant over on your fuse box.
Try turning your car on with the reservoir cap off and see if you have any bubbles.
You might need a new radiator.

Tethlah

I think I found the leak, I could see some coolant coming from the top passenger side corner of the radiator. So I'm going to buy a Mishimoto radiator next week and I've thought about if I want to go ahead and replace the expansion tank while I'm at it.

Just not sure if it's a necessary step.

AthensSilver8

iTrader: (1)

It probably wouldn't hurt. It does look like from the pictures that you have,
coolant is coming from the reservoir cap also. That cap is easy to mess up the seal or break the plastic. Good luck man

j9fd3s

since the coolant level sensor fails, you should replace the tank too. reason number 2 for replacing the tank is that its really easy to break the radiator changing the tank, so if you just do both, then you don't need to worry about either one again.

Tethlah

I've been looking at replacements to go with rather than the OEM, I noticed that the tank has 3 hoses hooked up to it. One that goes straight into the top of the rad (I'm assuming that's return, and 2 on the left, I figured one of them is inlet on the bottom, but what is the top one for?

Also, does it matter if I get a replacement without a sensor and just have the side gauge instead? Or will the light always be on if no sensor is connected?

37hayden

My car is currently doing the exact same thing and the coolant light is on in the car.
It doesn't look near as bad as his and only has a bit of splatter on top nothing around the sides.

Should this be a top prority for me or can i go without replacing it for a bit without damaging
my car?

9krpmrx8

iTrader: (46)

Anything coolant related in a rotary is top priority. If coolant is exiting your system then that means it is boiling over and that is deadly for your engine.

tomtomgt356

iTrader: (1)

I'm with 9k. It should be a top priority. If you can't fix it right a way, keep a close eye on your temperature gauge and if it starts to move even a little bit, pull over and let it cool off. Its a dummy gauge and doesn't start to move till 230 which is above what most people recommend as the max for this car. When my coolant tank ruptured, I didn't know how bad the gauge is and I let it get almost all the way to hot before stopping. My engine didn't die right away, but I'm pretty sure that is why it eventually did die.

Tethlah

I filled my car with distilled water every day while I waited for the rad to get here, but I would most certainly suggest that you replace it asap.

37hayden

So I guess this is a pretty urgent matter.. Is there any recommendations for what radiator to buy or does anyone have a link to a specific one to buy.

tomtomgt356

iTrader: (1)

I got the Mishimoto radiator from Assaultech (link) because it was all aluminum, reasonably priced and they had it in stock.

bigireland

Bumping this thread because to a lesser degree, this is exactly what's going on with my car. Currently checking reservoir tank before I start every day and topping off when needed. I've got my temps under control for now but I'm watching it like a hawk with Dash Command. Saving up for a CSF radiator, silicone upper and lower hoses and a thermostat. I can replace the reservoir tank easily but I'll let the shop install the radiator.

NotAPreppie

Coolant overflow diagnostic steps (this assumes that you've been monitoring your coolant temps and they don't go above 230F).

Step 1: When cold, remove your air separator tank cap. Take a clean cloth and wipe clean the rubber seal on the cap and the matching mating surface in the AST.

Step 2: If that doesn't fix it, go to autozone or advance auto parts and rent a coolant system tester. It will require a ~$300 deposit which will be refunded. It will have a hand pump and a ton of different adapters. Pick the correct adapter and connect it in place of your AST cap and pump it up to 13+ PSI. If it doesn't hold pressure, find your leak. Most likely in the AST but could be hoses or the radiator itself.

Step 3: If it does hold pressure, your cooling system doesn't have a significant leak. Use the "radiator cap" attachment to test your radiator cap. If it holds pressure then your cap is good.

Step 4: Buy a new cap anyway because they are cheap and you might end up as somebody's hero at a rotary meet when their cap goes bad and you can give them your spare.

Step 5: If your coolant system appears good but you are still having overflow issues, have your coolant tested for exhaust gasses (google this, it's not hard to do). Also, send a sample of your oil to be tested for traces of coolant.

Step 6: If you haven't found exhaust in your coolant or coolant in your oil then I'm out of ideas.

bigireland

For clarity, my engine bay looks almost exactly like OP's but I only have coolant spatter to the left of the AST and over by the fuse box. The AST itself only has it by the relief hose. Also, there's dried as well as fresh looking spatter on the under tray. I took it to a radiator shop and they did a pressure test but it held pressure. I'll look into getting the oil and coolant samples tested. I'm glad I found this thread(was googling aluminum AST's and saw the picture that aside from coolant on and above the AST looked exactly like my engine bay coolant spatter pattern). The highest temps I've seen were low 220's but that was once and it scared the bejesus out of me and that's how this all started. Since I've been closely monitoring and keeping the coolant topped off to offset the leak, my temps are good. Stays in the low 180s on the freeway. Can get up to low 200's in traffic and at stop lights but once I get going goes back down to low 180s. Thanks for the feedback.

Steve Dallas

Save your money and buy Gates or other quality rubber radiator hoses. Silicone hoses offer exactly zero benefit in this car (and most other cars).