^takes a big man to admit when he's wrong!

youre all good … keep doing the good work!

 

Maybe a closed system under pressure is the key, not enough pressure under atmosphere

 

Just in case anyone is still curious about this, a guy called Charles replied to a thread I started on facebook about this and they took some photos that show exactly how this is connected. The holes are quite high up in the sides of this area we've been talking about and coolant actually flows DOWN into that area, which is not something I'd ever considered at all, and explains everything.






After seeing this, looking back at my original photos and videos it seems really obvious now lol but yeah, end result is that all of the VQ35 engines are open in this area and the pathfinder mod does work as intended on all engines, not just US ones.

I've got to say though, it does make me question how useful the mod is... because the logic I've always seen people say is that the coolant goes to the rear cylinders and then has no easy escape route, so this mod adds that. As shown in the diagrams below:





On the blog post where those images were taken from, they say: "the coolant flows from the front of the engine to the rear cylinders and has nowhere else to go". Then regarding the pathfinder setup they say "If you follow the same flow, from the water pump and into the engine block, you’ll find that the coolant now has a “back door” out of the block". But I think the diagrams are very misleading and I can now see that the coolant flows up out of those rear cylinders and into the heads (just like all the other cylinders), and on its way some of it drops into this area that feeds the pathfinder mod thermostat etc.

So if this mod isn't actually adding a back door allowing coolant to escape that couldn't escape before, what is it doing? Also someone just pointed out to me that the HR and VHR don't even have this option (i.e. there's no blanking cap for you to remove and replace with anything else), so Nissan can't have thought it was that useful

 

Maybe it clogged.

 

Chris - I agree with most of what youre saying and I think this mod is helpful. Necessary? no, but helpful.

I think the diagrams are misleading too and I do think you're giving the coolant a 'back-door' or just a 3rd door to cycle through. Not that the OEM pump provides so much flow that the two coolant passages in the heads are insufficient but allowing coolant to find it's way out of the lower portions of cylinder jackets is a step in the right direction.

Ive learned not to attempt to think like an OEM ... I 'speculate' that nissan did not put this modification on the 350z/g35/maxima/altimas/murano/FX/M/etc because it was unnecessary and the cost of doing this to many many many vehicles outweighed the benefits. If it saved $100 per vehicle in materials/labor/warranty risk and was deleted from the 10s of millions of engines used between ~2003 and ~2008 that is a significant cost savings. We all know that cost was a serious factor when nissan decided to bring the Z back from the dead.

So to eliminate as many of these unnecessary mechanisms was a step in the right direction.

 

Hello to OP and all contributing to this thread. I'm a new 03' 350z owner and have been lurking/reading as many relevant posts as I can over the past 3-4 weeks to learn about issues and improvements for our cars. Wanted to say this is one of the best threads from any car forum I've read... and I've read a ton... current and previous owner of OBS F350, C4 Corvette, SN95 Mustang Cobra as well as all the normal boring stuff I've own(ed)
This thread should be used as an example to which all threads should be structured; Great pictures, staying on topic, intelligent discussion and research; that's all any thread should contain. Thumbs up. I'll be checking back to see how this all concludes. I'm curious now that its established the coolant passage way and direction if the Pathfinder Mod actually aids in cooling the cylinders or heads to a useful degree? I suspect under normal driving conditions the P.Mod has no affect. What about in severe situations?

 

Yeah I've been surprised how many people are willing to take the time to go take pictures and videos to help get a good understanding of this, so big thank you to everyone that's done that.

As for checking back to see how it concludes though, I'd say it is pretty much concluded now. We know this passage is definitely connected on all of the VQ35DE and REVUP engines, and the only thing left is speculation as to how useful this mod is really. I can't compare overall coolant temp before and after doing this mod because I'm doing it at the same time as going twin turbo and changing loads of things so it would not be a fair comparison at all. I do remember seeing a shop post something about this mod lowering their coolant temps by about 15 degrees F if I remember rightly, but I'm pretty sure they were selling a kit to do the mod so you never know how trustworthy that is or how fair their comparisons before/after were.

 

Thanks ChrisDE Yep, my guess is no benefit or need in normal driving even spirted driving to a mildly modified VQ. For your situation and the situation I'll be using my Z for would be nice to know if coolant temps are reduced during a 20-30 minute neck ringing track session.
Best of luck with your TT build.

 

Do people typically buy the whole kit from z1. I was thinking about pick a parting it off a pathfinder.

 

I welded fittings on the cover plate and a bung on the coolant hard pipe, no thermostat.

 

I have one i'm not using i would sell you for way cheaper than Z1.

 

Hi guys,

Drilled this evening holes for the pathfinder mod. I had no holes. Talking about a v4y711 build in Renault which are basicly vq35de Altima engines. I drilled the holes in a bricked block so I could practice where to place em. The reason my study object was bricked were cooling issues in the rear end of the block.
Make sure aluminium drilling chips are cleaned. I used a vacuum cleaner. The holes need some adjustments with a grinder. But I know where to drill. One could easily mistake the bottom protrusion for the place to drill. If you do that you drill straight in the oil line.....

 

BTW, for everyone doing this... Just keep in mind, if you use the pathfinder pipe, you won't be able to remove the cam position sensor without draining the coolant and unbolting the pipe.The Z pipe has a bend in it to allow removal of the sensor. The Pathfinder pipe doesn't.

 

I guess you didnt actually read this thread then lol the conclusion we all came to was that there are already holes there and you do not need to drill anything. The existing holes are in the side and you can't see them from the top but look at the photos in post 23 and you'll get the idea

 

I know ChrisDe, but I also read there was someone pooring fluid in which did not flow away. In my engine it's obvious there was no connection. The first post in this thread stated no holes in the engine even though they are easily seen on the pic. Therefore I posted mine my block had no holes and no blank plate on top. Now it has.
I stumbled upon this thread after I drilled the holes. Since it bothered me no one was talking about drilling when dicussing the pathfinder mod. I figured it out myself. But thanx to the 350Z guys bringing this up! I suffered from severe cooling issues and besides this mod I am gonna run with waterless coolant. I also changed the ceramic catalitic (close couple) converters for metal based.