The sweet smell of leaking coolant

[thaxman]

My 06 only has 79K on it, so even though its been around for 10 years, its been driven less than most.

I discovered the smell of coolant tonight after coming back from the store. It was dark out, but my nose told me it was coming from right around the radiator cap, so I was wondering if anyone had any coolant loss experience to point me in the direction to look specifically for Mazda5s and maybe Mazda3s.
No spray BTW and I couldn't be certain but it looked like the reservoir was empty.

 

[FiftySix]

How old are the radiator hoses and heater hoses?

On my cars of any make I replace them at 5 years or 100,000 miles, whichever comes first. If possible of course.

Anyway, on one vehicle the upper radiator hose developed a pin hole leak right where it attached to the radiator. On another vehicle, an oil leak from a cam cover gasket softened a heater hose until it sprayed out a leak of coolant. Then on another car that had a 12 year old radiator (guesstimate on age), the upper plastic radiator "end cap" developed small fractures from stress and chemicals and started leaking out of one of those fractures.

 

[Davicho]

Check for leaks thoroughly when you get a chance, but if after looking all looks as it should and coolant level is where it should be then it's probably the infamous sweet coolant smell that our Mazda5s are known for. I've owned three MZ5s and they all have had that smell and none have been leaking it. It's weird.

 

[Silentnoise713]

coolant dye + UV light.

First place to check is almost always the radiator hose.

 

[thaxman]

It was running a bit warm, and my wife was complaining for a few days that the AC was working even worse than usual (although temps are down a bit) which I surmise is due to the ECU killing the compressor the same way it kills it under hard acceleration.
So I know the coolant level is off. I hope to have enough light when I get home to search for dried coolant sprays or drips in the engine bay. Just wanted a heads-up before I searched so I could focus on specific regions first.

 

[thaxman]

OK, got looking around. Put a good 3 qt in the cooling system. Cannot locate any coolant spray or leak residue anywhere. Did some driving, and still no evidence, except for a slight hissing from the radiator cap, and possibly a bit of fluid below the crank pulley that may or may not be coolant.

So, anyone here have a premature water pump failure?

 

[Swenny]

it's probably the infamous sweet coolant smell that our Mazda5s are known for. I've owned three MZ5s and they all have had that smell and none have been leaking it. It's weird.

Just like the groaning when backing out. Must be a "feature"

 

[Davicho]

OK, got looking around. Put a good 3 qt in the cooling system. Cannot locate any coolant spray or leak residue anywhere. Did some driving, and still no evidence, except for a slight hissing from the radiator cap, and possibly a bit of fluid below the crank pulley that may or may not be coolant.

So, anyone here have a premature water pump failure?

Perhaps the water pump but I'd be more inclined towards the thermostat unit (15-172 in the picture)

 

[thaxman]

Already took care of the thermostat. It appeared to be doing better today, but then I also kinda forgot to obsess over the temp gauge.

 

[Dave88LX]

Any news?

 

[thaxman]

I am thinking it could be the cap. It would explain loss of coolant w/no visible leaking, b/c its just steaming off. Rock Auto wants ~$10+ shipping, locally, aftermarket it ~$15, but Tasca wants ~$15 OE + shipping, so that may be the way I go.

 

[thaxman]

Bought an OE cap for $18 (local Vatozone etc was $15 and it was $10+ship from RockAuto, so I figured OE was worth the extra coins)
The new cap seemed to be a bit more resistant than the old cap, so I believe that the problem was loss of coolant through slow steaming. We'll see when I check levels in a few days.

 

[Vasy]

From my last two experience with different cars, when I was able to smell the sweet smell of coolant inside the car and observe a small loss without any visual loss externally, it has always turned out to be heater core.
It was not a catastrophic type of failure the often floods cars but my cores developed pin hole leaks that were small enough to let water get out and evaporate on the heater core creating smell and loss of coolant. The heat of the core took care of 90% of the leak evaporating it and small amounts of water that went by got caught in the carpet with out much external trace until i tore the dashboard apart and located the leaks.

 

[ratr0]

i get a slight whiff of coolant every once in a while when stepping out of the van. cant spot any leaks anywhere and coolant level is good so I am not worrying about it too much. Temp gauge is reading fine.

If that thermostat housing mentioned above is plastic, i know thats a common failure point on some ford focuses that also have plastic housings. replaced one of those before....

 

[Davicho]

i get a slight whiff of coolant every once in a while when stepping out of the van. cant spot any leaks anywhere and coolant level is good so I am not worrying about it too much. Temp gauge is reading fine.

If that thermostat housing mentioned above is plastic, i know thats a common failure point on some ford focuses that also have plastic housings. replaced one of those before....

Our engines are shared with the Ford Focuses, Fusions and Escapes. So yes the plastic t-stat is a weak point on these engines.

 

[thaxman]

No, the smell was only outside when walking in front of the car to get to the house. And after a 30+ some mile wild goose chase today, I think that was the solution. Got 10 years out of the last one, so lets hope the new OEM is good for at least another 10.