gavinpitchford

Hoping someone might help me with the logic on this one...

My 2004 (standard, 88,000 km / 55,000 mi) has recently begun leaking coolant from the left side, only when running and - I believe, only after the temp gauge starts to move / reaches the half way mark (but it may be before then, but it's just not hitting anything hot enough to generate the smell).

It stops leaking almost instantly after the engine is shut off. The amount smells like a lot when driving - but when topping up the coolant to first drive it home - and then to the dealer (both trips about 5 miles) the amount of coolant required to do so - and get it right to the top of the reservoir - was minimal.

No heat warning lights. No history of overheating except once (6 months ago, mid summer) when running at higher RPMs (6,0000-8000? / 80-85 MPH or so, often 4th gear) for 10 plus minutes (light came on, shifted to 5th gear, slowed to 70, and light went out a few seconds later)

The dealer (Scarboro Mazda in Toronto) is telling me that the rad is leaking, and the whole radiator assembly needs to be replaced - at a cost of $1500 CAD including rad, labour, hoses, clamps and coolant. Ouch!!

It doesn't seem logical to me that a radiator full of coolant would only leak under pressure - and stop more or less immediately upon shut off (the residual leaks I think are likely just drips that have already escaped the system). But it does seem logical that a hose or a connection might leak under those conditions.

I can't see the leak - and have nowhere I can go to be able to look properly myself. So reliant upon a mechanic.

Am I getting hosed? (pun intended)

Any advice would be welcome.

dannobre

iTrader: (3)

When the water pump is turning there is flow and pressure in the system and when it warms up it pressurizes....it will leak when this occurs. When the system pressure drops it won't leak if the hole is in a hose especially......

Look for a leak in a hose....or the nipple on the top of the radiator.

You should be able to get a radiator and Hoses for a lot less than that....

gavinpitchford

Does the fact the leak is on the left (driver) side provide any clues?

NotAPreppie

Go to Advance Auto Parts (Autozone may also have it) and rent their coolant testing tool. They'll charge you ~$300 for it and then refund it when you return it.

Use it to pressure test your cooling system. If there's a leak, it won't hold pressure. You can also use it to test the cap.

Just guessing but I wonder if it's your heater core. If the smell is very strong but the quantity minimal, that might make sense.

dannobre

iTrader: (3)

Where does it seem to be coming from? Most of the Hoses are on the passenger side....except the heater hose that is on the drivers side under where the oil filter is.

Further forward and it's likely the radiator itself....or maybe even the drain is leaking?

gavinpitchford

I cannot see where the leak originates (and haven't spoken to the mechanic - only the service advisor) but the drips when it is running appear from under the front fender, and about 16-18 inches to the drivers side of center.

dannobre

iTrader: (3)

Sounds like the radiator...likely the plastic tank is leaking close to the top....otherwise it would likely leak when the engine isn't running

gavinpitchford

I'm far from knowledgeable on this engine - but it seems like the reservoir is higher than the rad, and it is completely full when I set out, so would the rad not also be completely full as well? and if not, if there was a hole, would that not let any air out and the coolant from the reservoir in to replace it, until the coolant leaked out the hole?

Or is the rad only leaking under pressure (testable by NotaPreppie's suggestion)?
Does that happen?

And if it is indeed the rad,
a) do i want an aluminum OEM i.e. Koyo - or a Mazda plastic replacement?
b) presumably makes sense to replace hoses and clamps at the same time as the car is 13 years old, even if only 88K?

Really appreciate the advice - thanks!

dannobre

iTrader: (3)

I would pressurize it and see what happens. I would bet that you will see it easily enough

Then you can decide what you want to do. For a totally stock car that isn't going to be used for anything out of the ordinary, an OEM compatible replacement is adequate. You could likely get an aluminum aftermarket one for about the same price..... I would replace the hoses and clamps as well....if you can do the work yourself it isn't so much of an issue...but there is no sense paying someone to do it later when it is all part of the rad replacement

gavinpitchford

Thanks!

Steve Dallas

Based on what I have read so far in this thread, I suspect the upper radiator tank, pinhole leak in the upper or lower radiator hose, and the water pump.

I know things are a little different in Canada, but a name brand (TYC, etc.) OEM style radiator in the US costs $60. A Denso (OEM in my car) costs $90. The upper and lower hoses are $9 each. Mazda FL-22 coolant costs $50 for 2 gallons (and you should use it). Labor should be about 3 hours for a mechanic who knows what he is doing. To have this done in the US should therefore cost as little as $430 plus tax and/or shipping, assuming it is not the water pump.

gavinpitchford

Thanks Steve!