M35 Performance Radiator - Does anyone make one?

[azeiler]

I have a built M35, which all of a sudden started overheating. I do see some coolant on the plastic piece underneath, so it's def leaking from somewhere, although I'm not 100% sure from where. I'm having to add a little coolant every couple of days, so it's a small leak. I'm going to replace the radiator and the t-stat, the two places I think I see signs of leakage. I can find performance t-stats (i.e. lower temp), but can't seem to find any performance radiators. Koyo has one, but it's only for the G with a manual transmission. They do make an OE rad for the M, but I'm trying to get performance. Mishimoto makes one for the G (which i assume will fit the M), for either transmission, but it's freaking expensive (more than 2 times a regular rad). I think I've read every thread here on overheating and I haven't seen anyone talk about who makes a good radiator, preferably a performance one. Any suggestions????

[CPJ LB]

try and check the upper plastic portion of the radiator...the Infiniti radiators are known to leak from the top...I guess the gaskets go bad or even the plastic gets worn over time.

I replaced the OEM radiator with the Koyo radiator -- the OE replacement...works fine.

as far as a lower temp T-stat, I'm not sure how reliable those are....I think someone posted a thread or link about how detrimental a lower temp T-stat can be...

I noticed you got a built motor....was curious if you upgraded your fuel pump and/or injectors too?

[azeiler]

I've heard good things about Koyo, but I was hoping for a 2-row rad. I'm still waiting to hear back from a company in Japan. Mishimoto and Koyo both make a 2-row for the G, but these won't fit the M without some fabrication.

Some guy in one of the threads talks about why using a low temp t-stat is bad. It almost makes sense, except that I once ran a car (not my M) without a t-stat and it ran noticeably cooler. If it doesn't work well, I'll post about it, but the guy that finished my build also uses low temp t-stats on all his builds.

I have not upgraded the fuel pump or injectors yet. I will most likely do this when I get either Nitrous or a turbo - down the road a little. I did however, have my transmission rebuilt with heavy duty clutches and a shift kit - very nice and worthwhile upgrade.

Thanks for the info on the rads, I didn't realize there was an issue. Another reason I want a performance rad - they're all aluminum, no plastic.

[CPJ LB]

nice stuff!! Ya, I was going to install the TransGo shift kit...just never got around to it... it might be my winter project.

you might want to check and see if Koyo makes the performance radiator for the G Sedan....might be a close fit with the M.

let us know what you go with.... keep mod'n!!!!

[DeanM45]

Unless you are forced induction or have a major detonation problem there is no benefit to running a lower temp stat. When you lower the stat (or run without one) of course your car's coolant will be cooler. Assuming the first two things are not present then you will decrease the efficiency of the engine (hurt gas mileage) and INCREASE wear. I've been working with cars for a very long time and every motor that I have tested or seen tested produces more power with normal (~195) coolant and ~180 oil temp. You don't gain power by lowering the coolant temp, you gain power by lowering the intake charge temp.

[azeiler]

I keep my engine in the "race" tune all the time. And for good reason, I love driving hard. As a result, my engine temps are high. Hence the low temp t-stat. In my case particularly, I think the t-stat will be fully open most of the time. Another guy mentioned that when the t-stat opens earlier, the coolant in the radiator doesn't have sufficient time to cool and as a result, the engine doesn't actually run cooler. I don't quite believe this entirely, but this is why I wanted a 2-row rad. Besides, I want to start prepping for forced induction.

Koyo's performance radiator for the G35 is for manual transmission only. The Mishimoto G rad is for both transmission's. However, the G rad is about 2 inches shorter than the M rad and has the fill spout in a different location. All other dimensions seem to be the same (except 2-row rads are thicker). Because the G rad is smaller, the M fan shroud most likely won't fit. I'm also not sure how the condenser would mount to the G rad, not to mention modifying the rad mounting points. I'm not ready for that much work yet. I've checked with Nengun in Japan, but they're not as helpful as their website would lead one to believe.

I just ordered the Koyo OE replacement rad and Mishimoto low temp t-stat.

The whole overheating thing is just wierd how it all of a sudden happened and how it actually overheats. It runs at normal temps for about 10-15 mins, but then slowly creeps up (I'm running a/c). It doesn't fluctuate between moving or being at a red light; it just keeps creeping up. Only when I turn on the heat does it come back down to near normal, and stay there. The temp needle also bounces a little up and down (about one notch at a time). I've been told this is one the signs that air is in the system. And as far as I know, the only way for air to get in, is for coolant to get out (i.e. a leak).

[CPJ LB]

well, it'll be safe to get the Koyo OE replacement for now...better to get a new radiator than drive around with what you have. also, there is a bleeder valve for the coolant/air to be released. It's located near the back of the engine (passenger side firewall)...phillips head screwdriver will open up the relief valve....that should get the air out

The Koyo OE replacement is a good product...all stock shrouds mount up perfectly...I don't have a rebuilt engine like you but run a fair amount of mods and the temp is at normal....

take care of that heating issue -- quickly -- so you can enjoy your ride

[azeiler]

I got one of those no-spill funnels to help get the air out, in addition to using the bleeder. I'll also put the front end up on ramps to help the air out (and also easier for me to work since I'm over 6'). Can't wait to get things back to normal.

[antzrus]

[azeiler]

Antzrus - Where'd you get the steel skid plate? Or did you have someone fabricate it using the plastic one as a template? How much did it cost? My plastic one has a hole in it and with all the construction going on down here, I'm constantly hearing things hit the underside of the car.

I think with the right mounts, I could probably fit that Goodman in the engine compartment - it might be a little tight though.

[azeiler]

Nevermind on the skid plate question - i just found a bunch of threads on it.

[antzrus]

Nevermind on the skid plate question - i just found a bunch of threads on it.

[azeiler]

Koyo radiator in along with Mishimoto t-stat. Runs normal temp except at red lights. Fans not coming on. Put direct power to fans and they work. put direct power to the fan control unit mounted on fan shroud - fans come on. i'm guessing it's the relay so I order a new one. in the mean time, I try to bypass the relay so I have fans on while the car's running, but something sparked and clicked. now my speedo, tach, fuel gauge, temp gauge & a/c don't work. I also cannot get the car out of park. checked fuses in all three boxes - everything looks good. Any ideas what the hell I broke now?

[mexillis]

only thing i could thing of is see what wires go where on the wiring diagram with what you touched to create the spark...maybe there's a fuse or relay open now.

[azeiler]

My multi-meter wasn't working right. A fresh set of batteries in my meter and I found a bad fuse - #14 Meter. Everything came on except the radiator fans. Tapped on the fan relay with the back end of a screwdriver and the fans kicked on. Unbelievable. Getting a new relay anyway. I'm just happy it's all working again.

BTW, also replaced the temp sensor - thought I blew that out too. Besides, with new rad and t-stat, just thought it was a good idea.

Anyway, just drove around for a while with the a/c on and the temp remained normal. Flushing system this week to get everything cleaned out.

[azeiler]

System completely flushed and running steady at normal temps, no matter how hard I drive or how hot it is outside. The Koyo radiator is doing a very nice job. When I bleed the air out of the system, I squeeze both the incoming and outgoing rad tubes. The outgoing is considerably cooler now than it was with the old rad.

[azeiler]

Forgot to mention that new relay has fans working properly now too.

[fat3oy]

You can get custom radiators made for relatively cheap. I'll find the company later...

I am currently f/I
And under constant boost. I see no real need for a cooler stat... even the nismo stat doesnt run that much cooler oropen sooner than our stock ones... it does but not that much of a difference...

The car actually runs better, on the dyno even when closer to its stock operating temperature rather than cooler.... at least that is what I have found.

[ojkush]

does anyone know a part # for the m35 coolant air relief plug??? dealership cant find part i need..