Hello,

I have a 2009 Pathfinder (VQ40DE) that I am shortly to do a coolant flush on. While I'm pretty familiar with the procedure in general I hear anecdotally the VQ40 engine can be a little tricky to remove airlocks/pockets from when undertaking a flush. Two points of interests if any of you would be so kind as to provide some input on:

Air Relief Valve (Bleed Screw): I keep finding nominal and poorly framed references to the aforementioned in the context of refilling coolant and/or ensuring air is purged from the system. These are pretty common on a number of vehicles across manufacturers and models however I'm struggling to locate this valve/screw on the Pathfinder and similarly I'm struggling to locate explicit details about its location. References vary from somewhere on the fire wall to the top of the engine block near the intake manifold. Has anyone located this bolt and perhaps have a photo or technical diagram to locate it. I know there are a couple of drain screws on the left and right side of the engine block to assist in draining the cooling jacket, these are pretty low on the engine behind the alternator and the other on the part of the block bear the steering linkage and accordingly would not be suitable for bleeding.

Part two related to clamping off the top heater hose when bleeding the cooling system - this appears to be in the procedure for purging air, I'm just curious what this is achieving? One is simply stopping coolant reaching the heater core (?).

Many thanks and all the best.

Steve.

There is no bleed screw on the 09 Pathfinder. On earlier models, there was a nipple with a rubber cap on it on the plastic heater piping near the firewall, but this was deleted on 2008 and later models. Clamping the heater hose would stop the flow through the heater core, but there is no reason to do this on your model. Just do this:

Remove the radiator and reservoir caps and fill the radiator with coolant. Install the radiator cap. As needed, add coolant to the reservoir until it reaches the "MAX" line and install the reservoir cap. Jack the front of the vehicle up as much as safely possible; if you can't do this, park on a hill with the nose facing upward. Start the engine and turn the heater on maximum heat setting (do this to the rear heater, as well, if equipped). Run the engine at approximately 2500-3000 RPM for about 15 minutes or until the air coming out of the vents blows hot. Shut of the engine and lower the front end, if jacked up. Let cool down and top off coolant in reservoir as needed.

Thanks for clearing that issue up. Yes I will be sure to jack the front end up high when refilling, this works really well with a no-spill funnel.

Many thanks once again. I may try and do a post with photos if that would be of use to anyone.

Cheers.