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Heater Core Flush?

14400 Views 14 Replies 5 Participants Last post by  Clint
Hey everyone. This is my first real post and pretty much why I joined. I'm hoping for some good advice as I keep my '07 Frontier for at least a few more years (cross fingers). Anyway, here is my issue.

Recently I started noticing the scent of anti-freeze. After checking things out, I discovered a leak around one of the heater core hoses (see pics). I don't have anything leaking in the interior of the truck. It appears to just be from that hose. So, a couple of questions:

1) Is it possible just flushing the heater core could fix my problem?

2) What exactly is that plastic connector that the rubber line is going into and the metal pipe going off to the right?

3) if that plastic part is some sort of valve, could it be blocked or malfunctioning and need to be replaced (instead of an issue with the heater core)?



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They simply refer to it as a heater hose assy. It's a fairly common failure. The good thing about plastic coolant fittings is that they don't corrode like aluminum fittings; the bad thing is that over time, they get brittle and break. The only reason I could see that they use the plastic fitting is that it is a really tight bend from the heater core fitting at the firewall to the pipe on the firewall, so it would be easier to make by using a plastic fitting. At least they are not too expensive on the Frontier; the ones on the Pathfinders w/ rear heat are around $175. As far as flushing the coolant system, there is very little need to do so. Today's coolants are long-life, so usually a drain and fill at the intervals recommended by Nissan serve well enough. If you have a 2007, you're still using Nissan green coolant, so the first interval would be at 90,000 miles and every 60,000 miles, afterwards, if I'm not mistaken (you can check your owner's manual to be sure). If you use concentrated anti-freeze, mix 50/50 with distilled water (not tap water). As mentioned, if you still have the original radiator and have an automatic transmission, it would be a good time to replace the radiator due to the trans cooler issues with them.


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Check the top radiator tank for a Calsonic sticker. If it has any of these P/N's, the radiator is original and you should bypass the cooler or replace the radiator (if there is no sticker, it is likely aftermarket): 21460-EA200, -EA215 or -EA265.
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