Series of events....

1. Car was idling for about 15 minutes.
2. Heard/felt small pop (not a backfire).
3. Turned car off immediately.
4. Noticing coolant just below the pullies on the right side of the engine bay (just behind battery box).
5. I have an Aluminum AST, aluminum radiator, and an aftermarket stock mount intercooler.

So I'm noticing a small puddle of coolant forming on the underbody panel just behind the back of the battery tray. It's way far down in there but I can distinctly see the green puddle so I KNOW it's coolant. I don't know how long it took to form as I was sitting in the car for a while. I believe the hose coming out of the bottom of the filler neck also is leaking a bit. Not sure where that one terminates but considered coolant could be running down that one to form this puddle.

I have yet to tear the car apart but I'm going to get started tomorrow or Saturday. I can already see I'm going to have to pull out quite a few things to even get down there. Intercooler, battery, etc...

Questions...

1. Is there a hose or something in that area that commonly fails?
2. Do I need anything special to replace it?
3. If the hose has just popped off due to pressure....what does that mean?
4. In order to better see everything I need to take out my stock mount intercooler. Can I idle the car (for diagnosis purposes) without the intercooler attached? I would like to actively see where the coolant is coming from.

Here's a picture of where the coolant puddle is forming. It's hard to see but it's below the pulley.

 

^Bottom of that picture is the back of the battery.

 

The lower rad hose runs relatively close to there. Not that common of a failure point but at least it's a start. What you need to do is wait until you have some sunlight, hook up a pressure tester and pressurize the cooling system (there's a tool that hooks up like a rad cap). Or if you're comfortable with it, too up the coolant and go for a quick drive until it's warm and has some pressure on the system. Then just give a visual inspection all around the area. Sounds like all you have is a leak so once you find it, just replace whichever hose is causing the problem. Not hard to do but you may need to refer to the factory service manual to remove some components in order to actually get to the hose.

 

If it was a *pop* you heard it could be a hose ripped open. You said you turned the car off immediately so It wouldn't have kept feeding coolant through the hose. It could also be something bigger like a part of the iron housing giving out or cracking, though I doubt it very much. As far as running the car on idle without the SMIC hooked up you're fine. the MAP sensor is just looking for vacuum at idle and this wont affect it if you need to warm up the engine. let us know what you find when you get it taken apart! No one likes an incomplete thread

 

Pops, in my limited experience, are usually hoses...

Was idling an FD up on a car hoist a few years back. Car had no front bumper and was raised up about chest height to me. Walked round to the front of the car. Large POP and I got my head and chest covered in coolant. Forgot to tighten the radiator hose clamp.... :p

Let us know how you go

 

That would **** me off so frigging much... coolant is my arch nemesis of automotive stuff... its the one thing that whenever I do it, I find myself at the very least swearing profusely in my head, then verbally shortly there after...


J.

 

I'll let you guys know what I find! I'm hoping to get her up in the air tomorrow during the day and poke around at the very least.

This may sound stupid but I'll ask anyway. if I need a new hose because I've ruptured the old one, can I use generic tubing cut to length from a place like AutoZone or is there something special I need? I ask because I've seen some of these hoses appear to have bends/turns in them that look like they were formed that way.

 

For the most part, as long as the hose has that fiber reinforcement within the walls, it is OK to use for coolant. You may find the tighter bends causing kinks in thicker hose, avoid that.

Looking at your picture, it could be the hose from underneath the throttle-body popping off and draining its coolant out (enough to cause a puddle). I can tell you that that is a 90deg bend hose, only replaceable by removing the TB (because they bake on pretty well), and a bitch to get store-bought hose to fit without a kink. For that, I went OEM.

 

There are several hoses that have specific bends/elbows in them that, unless you have the room to allow for a large radius, you hadn't ought to try to replace with straight hose. Seems like there are a couple that run in that area that go to the AST, for example.

One of the reasons I replaced every single hose with OEM version when I did my rebuild was to not have to worry about things like you are experiencing. Generally speaking, leaking hoses are the "most difficult easy repair" you'll ever do, meaning the fix is easy, but getting to it is a PITA.

 

^I agree 100% with your last statement. Easy to replace the actual hoses but had to take half the car apart to get down to where I could even see them.

Long story short, I pulled most of the stuff out and found this nice puddle of coolant.



After looking around and tracing drip paths it seems like the culprit was actually a loose low coolant sensor. The coolant would run down that main hose and then collect in the underbody tray. Very easy fix but I wanted to check all the hoses and they all look good.


I was hessitant to really toque down the sensor because I know the threads are plastic. It's much tighter now and I think it's good to go. I ran the car up on jack stands with the battery and intercooler out of the car. I let it sit for a good 20 min idling (garage was open then) and didn't notice any more leaks.

Thanks for the help guys.

 

Thanks for posting your solution. There's too many ghost threads where people get close to finding a solution to their problem and then disappear. This might help someone else with a random coolant leak the can't find!

 

I started up my rx7 after a month of being safely parked inside my garage from cold harsh winter temperatures lol. Today it was about 0 C or 32 F, so I decided to start her up and let her warm up a bit. I noticed some white smoke but I thought it was normal since it was fairly cold and she hasn't been started up for a while. After a couple of minutes the add coolant light started beeping and I noticed a small puddle of coolant under the car, about the size of a tennis ball, and after about 30 seconds after the revs dropped the add coolant light shut off. Once the car started warming up there was no white smoke from the exhaust, so I'm just wondering if I'm dealing with a crappy hose issue or something that might be bigger as in engine problem?? I hope its not the latter. I'm guessing the cold temperatures make the hoses tend to fail?

edit: the leak wasn't consistent, after the initial puddle it stopped and it didn't leak after the engine was shut off

 

I would find the leak and fix it. Don't just trust that it won't come back. Obviously there's a leak somewhere in the system that needs attention. Check for marks around hoses for where coolant has been running down them. It should be fairly clear where it's been coming from. I'll be honest though, a lot of the cooling system is deep in there.