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Tech Tip: Fix your leaking radiator with sockets and a flashlight
Tech Tip: Fix your leaking radiator with sockets and a flashlight
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Tech Tip: Fix your leaking radiator with sockets and a flashlight
Fixing a leaky radiator inlet is one of the last jobs on my current project bike, and while it's an easy fix, I've never seen a good write-up on this repair.
Motorcycle liquid cooling systems are quite robust. Consider the torture that modern dirt bikes endure! However, refrigerant will always escape if it finds its way out of the system, and unless you check your refrigerant levels frequently, a leak can turn into a big problem. Old hoses and failed water pump seals are the usual suspects. Another failure mode I've seen over the years, and the topic of today's how-to article, is a bent radiator inlet. Track your coolant leak, and if the problem is an inlet, you'll see a leak where a hose connects to the radiator.
Radiator inlets can be damaged if you are not careful when removing old hoses. Hose clamps that are too tight can also cause problems. (I suspect this is how this Kawasaki ZRX1100 was damaged by the previous owner, who had a real overtorque problem.) The inlet walls are thin, so it doesn't take much to warp one in a crash, shipping, or even bump into warehouse. The good news? A propane torch and a handful of outlets should solve your problem for free. Try this method before you shell out for a new radiator.
Drain the coolant and remove the radiator
If your bent rad is already off the bike, move on to the next step. For everyone else, take a clean container and empty the cooling system. Removal and cleaning will be much easier this way. Find and disconnect any associated wiring. You will likely have a fan and temperature sensor that need to be disconnected. Unscrew the radiator from the motorcycle and move it to a clean workspace.
Identify the source, gather the tools
With the radiator on the bench, it should be easy to identify the leaking area. One of the entrances is obviously mutilated. The other is passable, although not perfect. Let's solve it.
You will need a variety of sockets and an elongated extension, approximately 8-10 inches long. Try to avoid short grips and shaky extensions if possible. If the damage is severe, pliers and duct locks may be helpful.
Restore shape
Find the largest socket that fits the dented inlet and connect it to the extension. Light the torch and begin heating the aluminum with the tip of the flame. We aim for persuasive, non-destructive heat. (Not sure how hot is too hot? Mark some bare aluminum on the heated area with a marker. If the mark disappears, you're overheating.
It's helpful to have a friend move the torch around to evenly heat the area during the next step, but you can also do it yourself if you're working quickly.
Attach the socket to the extension for an improvised shaping tool. Using the extension as a handle, roll and push the dent with the grip. Focus on making room to fit the next socket, avoiding the temptation to do all the work with one size. Move to larger holds as soon as possible for best results. Add a little heat, pull a little more, and continue working back and forth until the entrance is round again. I had to use a small pair of channel locks to refine the edge of the burr before I could fit my final grip.
Reinstall and inspect
Check for burrs and sharp edges before reassembling. Reinstall the radiator, fill the system with coolant, and check for leaks every few miles, just in case.
Coolant leaks are a problem and radiators are expensive. Rather than spend €727,85 on a ZRX1100 radiator from Kawasaki, or roll the dice with a €100 unit from eBay, the above method got me back on the road, drip-free, in less than an hour. I've used this technique for dirt bikes, street bikes, and even some non-motorcycle projects. When it comes to odd jobs like this, sometimes you already have the tools you need. You just have to see them in a new way.
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