Coolant Leak

6 posts in this topic


My 1st post.

I've checked this thread via Google for my specific problem, have not found my specific problem, so if it's been brought up before, please point me in the right direction, here, or elsewhere. Thanks.

I have a 1996 Mazda 626 2L I4 MTX, so I think I'm in the right place to ask the following question.

I have a coolant leak.

It's on the driver side somewhere's very close to the coolant drain valve located on the radiator.

It's been leaking for a while, it was a very slow leak, until I flushed and replaced the coolant on Tuesday.

Now it's a fairly steady drip, every second or so.

The leak appears to occur only after running the car for a while, by that I mean the steady drip.

I have a flashlight and a stick mirror, but so far have not located the actual leak.

I have the appropriate Mazda shop manuals for this particular model year, and will revisit for troubleshooting guidance.

Any help or recommendations or suggestions would be greatly appreciated.

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How many miles are on the car? It would not surprise me if your radiator end cap was causing the trouble. Rather hard to locate, especially if working in the dark with a flashlight.

In my experience, these radiators with plastic end caps are bound to fail eventually.

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The upper radiator hose is right above that. I'd inspect that. The drain plug has an o-ring but if that were leaking it would be obvious. Set up some rags or some way to inspect for leaks and track down where the leak is coming from. You can't fix it until you find it. ;)

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The car has 96K (I got it when it had 88K about 2.5 years ago), I know the previous owner, a friend of mine, he's a "neatnik" (well ordered life, everything in its proper place, so to speak) so he had kept up with the scheduled maintenance. However, I'm a "slob" meaning I have not bothered to check anything since I bought it from him, until now (moving and plan on putting on much milage in a short period of time). So far I've replaced the oil sensing switch (it was leaking oil), oil change, and replaced the fuel filter myself.

So the car is only driven locally and has very low annual mileage (considering its age).

But that will change shortly, as I'm moving out to Colorado from Mississippi, and will be doing a lot of camping along my twisted path, meaning I could add 10K miles over the next few months.

I do think it's the plastic-to-metal interface, and it is not immediately obvious (to me, at least), if anything along that interface can be tightened down in some fashion.


Yes, I checked the upper radiator hose, not leaking from there, completely dry. The drain plug is closed, as closed as I can get it, with the stick mirror and things dried out beforehand, it does not appear to be leaking from there.

Over the next few days I'll continue checking with the flashlight and stick mirror, drying things out beforehand, to see if I can isolate where the leak is occuring.

I've looked into replacing the radiator, people here recommend an all metal radiator (can't find online), the current one looks just like a metal/plastic Spectra (white plastic drain valve), I can get one locally for about $100, and replace myself, or get it done at a shop for probably $140-$150 (assuming 1 hour of labor).

Anyways, I'd like to thank you both for the help, and I'll keep looking here for any other additional suggestions and what not (and if I do the repair myself, I will inform you all on my experiences/results).

Also, this website is FANtastic!

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If you get an all metal radiator you must always ensure you have a proper coolant/anti-freeze mix. Using water only will cause rust in a very very short amount of time. The radiator can crack as applesauce said. It could be leaking from one of the sides and traveling down but again you have to find the leak to fix it. Replacing the radiator without confirming the location of the leak is a gamble but if you are confident it's the radiator leaking then you should be good to go. I don't have any opinions on plastic vs metal. I've never replaced mine. GL and keep us updated.

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I thought I'd update you all on the coolant leak.

With the help of a good friend, we were able to isolate the leak as coming from the radiator, driver's side, engine side, about half way up along the joint between the plastic end piece and the aluminum radiator.

Yesterday we replaced the radiator. No more leaky radiator. But the upper radiator hose had a very slight slow leak where it meets the radiator. But after some reseating of the hose and hose clamp the leak there also appears to have stopped.

Having the shop manual was a big help, and the replacement was a fairly easy task.

We then took apart the old radiator to see what all was going on at both ends (but particularly the end that was leaking). As I had guessed, there was a rubber gasket between the aluminum and plastic pieces. It was also rather obvious that there was a fair amount of metal corrosion where the rubber gasket meets the aluminum face.

Finally, I took the old aluminum radiator to the scrap yard and got $2.10 for the ~6 lbs of aluminum.

I do have some two other issues with my car, but I'll start a new thread to discuss those issues at a later date.

Again, thanks for all the advice (mainly making sure where the leak was coming from (djdevon3)).

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