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Honda CRV Radiator Leak

1999 Honda CRV. Just took a 3-hour highway trip. Before trip I topped up coolant reservoir which was a little low, but radiator was full. I did notice some dried white spots on the front of valve cover and spark wires. Wasn’t sure what it was, but now realize it was coolant residue. Probably only 1-2 cups were missing from the reservoir, so the leak had just started.

After 3 hour trip, checked engine compartment again. This time the reservoir was totally empty (radiator still full) and the engine was well sprayed with greenish coolant residue. The radiator was cool by the time I checked it, so the leak source wasn’t obvious, but it looks to be coming from the seam where the plastic top meets the aluminum.

I will replace the radiator when I get home, but first have to drive the 3-hour return trip. Will it be OK as long as I start full of coolant and keep an eye on the temp gauge?

I would put some JB-weld or other epoxy over it.
It’s a short term improvement.
Will hold for the trip.

I agree with @circuitsmith And yes, check the level and temp gauge regularly on the drive back.

This type of leak doesn’t usually blow out suddenly, but it can get a little worse so I would plan on stopping every hour of the return trip and top off the reservoir. You can use a gallon of distilled water for this purpose or you can buy a gallon of premix 50/50. I don’t think the JB Weld will help, but it wouldn’t hurt either.

What might help would be to take a big pair of channel lock pliers and squeeze the crimps around the edge of the tank/core interface.

When the engine is cold, remove the radiator cap and add about a tablespoon of black pepper to the coolant and reinstall the radiator cap.

The black pepper will stop the leak long enough for you to drive back home.


Mythbusters had a car myth episode where in one part they proved putting an egg in the radiator would stop a small radiator leak.

If I had that same problem, and found myself 3 hours away from home with a leaky radiator, I’d have the radiator replaced before driving home. A leaky radiator won’t hold the required pressure, and that could cause overheating and damage something expensive. Radiator replacements on econoboxes like that isn’t overly expensive. I replaced the radiator on my Corolla a few years ago, cost me $90 for the part, and 1.5 hours to do the job in my driveway.

Edit: BTW, my Corolla’s radiator sprung a leak b/c the radiator fan stopped working, so suggest to check that as part of the radiator replacement.

I think you’ll be ok if you keep an eye on it and have extra coolant along. I was 150 miles out at night once and developed a pin hole leak in a hose. I did stop at a Walmart that was open and got some repair tape but it still leaked and it was ok getting home.

Thanks guys. Well, this is embarrassing, but in a good way. Turns out a new radiator cap stopped the leak. What fooled me was (1) not seeing the leak in action, only its results, and (2) seeing the coolant pooled along the top seam, a known failure point. Fortunately I decided to buy a $10 radiator cap before going whole hog on a new radiator, and after an hour of highway driving there’s no more leakage. Finally, I catch a break!

Good for you for getting to the bottom of it. Glad you are back on the road, and for short money. Sweet.

Keep an eye on your reservoir level. There may still be a problem.