i just noticed today that the oil cooler on my '84 SE has a leak. a couple drips every couple hours, it appears.

i was wondering what the best way to tackle it would be. next time i get a chance, i will be putting the car up on jacks and trying to locate the exact location of the leak.

are there any problem spots on these things? is it most likely just the lines (the oil is coming from the left side).

if i do end up having to change the cooler or the lines, i need to drain the oil from the car, correct?

 

i have a leak in my cooler on the left side where the line screws in the cooler has cracked i removed it to day and sent it off the get it welded up because it is alloy but when u remove it you will lose minamal oil because the oil line is about 100mm higher than your sump so not much oil is lost and it cost me $10 to get it welded

 

Actually, its probably not the lines.

Its the aluminium flanges that are part of the cooler, that normally stress fracture over the years. So even a tiny crack will leak a lot of oil at high pressure.

Sometimes people will crank the adapter fitting for the lines too tight against the flange and crack it (that is what I did )

 

So is welding the cooler a good fix for that stress fracture? I have a small leak as well.

 

tig welding is the only fix. take it to a professional, unless you or someone you know has a tig welder or can tig weld. eViLRotor is right, the leak probably is at the fittings where the lines meet the cooler. they are VERY sensitive to cracking and to poor crush washers. to know for sure, you will have to pull the oil cooler out and clean it and inspect it thoroughly. even the smallest crack can mean an oil spot in the driveway or your engine in the long run. please let us know what you find.

 

Very common problem with the SE coolers. I think we all have this whether we realize it or not. My SE leaks about 2-3 drips per minute under idle conditions, and probably much more under heavy throttle and high oil pressure.

As the others have mentioned, the cooler lines aren't the problem (unless yours are very old and brittle), and the problem is actually the 'bungs' that are welded to the cooler, itself. When you install the lines (or adapters if you're using SS lines), the crush washers must be NEW, if you try to reuse the copper crush washers, you will certainly break the 'bung', causing a hairline fracture that runs lengthwise across the threads - this will later leak oil no matter what you do. Further tightening in trying to stop the leak will MAKE IT WORSE.

I found that actually LOOSENING the leaking line connector and/or adapter can actually decrease the leaking, YMMV.

The only long-term fix is 1) a new cooler at $400 from Mazdatrix or RB, or 2) tig welding through a reputable shop that may even be able to reinforce the welds on the bung to make it more resilient to torque.

Since the cooler is made from aluminum for maximum heat dispersion, they tend to be brittle and unforgiving for torquing down those fittings. Even if you use 2 wrenches, chances are your cooler has cracks. What it really needs is a steel collar press-fit around the aluminum bungs to keep the metal intact, but who asked me???