M35 Stagea Cooling System Overhaul

[bigkevracer]

Let me know if I've missed anything/got anything wrong

Part 1: http://performancewagons.com/blogs/ryan/nm35-cooling-system-overhaul-part-1

Temperatures in the Stagea were a bit high for my liking, and it looked like it was only a matter of time before the paper thin standard Nissan radiator failed in the tougher conditions of a harsh Australian summer.

So the decision was made to start accumulating the parts I needed to do it this summer.

The first step was to install Scotty's cooling mod. Then, replace the radiator, thermostat, hoses and fluids. Finally, I intended to remove the clutch fan and replace it with twin thermo fans, but that will have to wait for Part 2.

One thing to note with these instructions is that I don't have the stock airbox installed in my car - I have a R2C pod with AM Performance intake pipe. If you still have the airbox installed you may need to remove it during the Preparation stage.

What I used

Nismo VQ35 Thermostat

The Nismo thermostat is designed to open at 68 degrees rathern than the 76 degrees of the OEM unit, which gets the coolant circulating earlier and keeps temperatures lower.

I ordered my Nismo thermostat through Jesse Streeter.

Mishimoto G35 Aluminium Radiator

The Mishimoto aluminium radiator is dual pass and approximately twice the thickness of the OEM radiator. It has the added benefit of being completely aluminium, as opposed to the plastic end tanks of the OEM. However on my unit it has male screw on fittings for the automatic transmission cooler rather than the hose barbs found on the stock radiator. These fittings seem to be a random size, neither BSP or NPT and apparently not dash. I'm hoping Mishimoto will be able to clear this up.

Mishimoto 350Z Silicon Radiator Hose Kit

The Mishimoto silicon radiator hoses apparently offer better heat reduction and pressure tolerance, but I just wanted to replace the stock hoses and change up to blue hoses. The 350Z radiator hoses appear to be a direct fit to most VQ engines, including the VQ25DET and VQ35DE.

Drift 32mm Temperature Sender Adaptor

The thermo fan controller that I'll introduce in part two used a temperature sensor which needed to be tapped into the top radiator hose, so the sender adaptor was needed. It's a metal part that you can splice into the top radiator hose, and includes a threaded hole in the top that you can insert the temperator sensor into. The included hose clamps are almost useless, so best to replace with something better quality.

Nulon Long Life Concentrated Coolant

This 'green' coolant is designed for a long service life (up to 4 years/250,000 km), and Nulon long life concentrated coolant was what Autobarn had on sale - nothing more complicated than that. It's necessary to use Coolant in your cooling system rather than plain water as it includes anti-boil/anti-freeze chemicals and is designed to prevent corrosion.

Distilled Water

Concentrated coolant needs to be mixed with water for best results. Distilled water has most impurities removed, such as minerals and ions which can cause corrosion of the cooling system and can react with coolant to reduce its effectiveness.

MoCool

I decided to try Motul's radiator additive, MoCool, as I had never used it before and it claimed to reduce temperatures by 15 degrees. Given the whole point of the overhaul was to improve temperatures I thought it was worth a try. It is mixed up at very small volumes in the radiator with the coolant and distilled water.

B&M Automatic Transmission SuperCooler

I took the opportunity to also finally install an external automatic transmission cooler. I went with something reputable which would fit in the cramped front end of an NM35 Stagea. In the end the B&M SuperCooler I went with was the second biggest they made, and included transmission hose, hose clamps and a variety of fittings which came in handy.

Valvoline MaxLife Automatic Transmission Fluid

Since my dad stocks Valvoline fluids at his workshop, when I first bought the Stagea I contacted Valvoline to see what fluids they had to suit. I ordered a 20L drum ofValvoline MaxLife Automatic Transmission Fluid, as it's a fluid that can be used in quite a lot of places. It's a Matic J compatible transmission fluid, which is vital for the auto trans in the NM35 Stageas.

Miscellaneous

Hose Clamps - The silicon hoses are slightly larger diameter than the stock hoses, so the original hose clamps had to be replaced with something larger.

Emery Paper - I had some corrosion under the top hose on the engine side, so took the opportunity to clean the corrosion off with emery paper.

Thread Sealant - A quality thread sealant was used on the water temperature sender.

What I did (and what I should have done)

Preparation

• Before you get started, you'll need to get the front end of the car up and off the ground to give yourself easy access to everything. I jacked each side up one by one from near the front of the chassis rails and used two jack stands, one per side. Always make sure you use jack stands - never get under a car that is being supported by a jack alone no mattery how good it is.
  
• Remove the undertray.
  
• Put a drain pan under the drain plug on the radiator and remove the plug. I wanted to ensure all old fluid was out, so I left it for a while.
  
• Remove the air intake snorkel that sits above the radiator. It has two plastic body clips holding it in place. Just pop them out and remove them. You may also want to take this opportunity to remove your airbox or parts of your air intake.
  
• Move the drain pan to under the bottom radiator hose, and remove the hose clamp. After leaving it to drain for a while, jack the rear of the car up higher than the front to ensure any coolant in the back of the block drains too. I did this and noticed a fair bit more coolant drain out.
  
• You can then remove the top hose clamp from the bottom radiator hose and remove the hose. The top of this hose is connected to the thermostat - remember this, you'll need to know this later!
  
• The top radiator hose should now be ready to be removed. You should be able to remove the hose clamps and remove the hose without much/any coolant leaking out. You may need a flat head screwdriver to give the hose some persuasion.
  
• At this point you can remove the fan shroud. Undo the top two bolts which hold the fan shroud against the radiator.
  
• Underneath, you will find in the centre of the fan shroud there is a removable panel which gives you clearance against the clutch fan. Undo the 4-6 plastic clips on the left and right side of this panel and you should be able to lift the panel off.
  
• You should now be able to lift the fan shroud straight up and out. Don't force it. I found it easier to remove the clutch fan...
  
• ...Which you can remove by removing the 4 nuts on the clutch fan. You will need a 10mm spanner (preferably a ratchet spanner). Hold the pulley the clutch fan is bolted to and carefully undo each of the 4 nuts. The clutch fan should then be easy to remove straight off the end.
  
• Next is the transmission cooler lines. The top line is the hot line, and will leak fluid when you disconnect it. The solution I found to this was supplied in the B&M SuperCooler kit. There were male and female 5/16" BSP fittings with hose barbs in the kit that I connected together to loop off the standard radiator, minimising the amount of transmission fluid that leaked out.
  
• Undo the top radiator locks and remove them. They're really easy, just twist and lift out.
  
• The last thing to do before removing the radiator is to disconnect the air conditioning condenser. This can be a really tricky job, so just take your time to avoid damage.
  
• Find and remove the two bolts which hold the condenser against the radiator. These are found behind two holes in the front radiator support - simply look through the holes on the left and right hand side of the radiator until you see them.
  
• Lift the radiator up slightly (about an inch or so) to free the mounting pins at the bottom from their mounts. You can then push the radiator back against the engine and get a better look at the condenser. Make sure you retain the two rubber bushes that were/are around the bottom mounting pins.
  
• The condenser is now held in by two locating tabs in slots on the bottom of the front of the radiator. These are frustrating as there are a couple of 'hooks' on them, so take your time and angle the condenser to clear it. You can then lift it slightly and should be able to see it clear the radiator slots. Push it back against the front of the car to give yourself room to remove the radiator.
  
• If you're replacing the hoses, like I was, remove the top radiator hose which links the left and right sides of the engine together. Remove the two hose clamps at each end and use a flat head screwdriver to unclip the plastic clips in the middle of the engine.
  

Have a beer, and celebrate finishing the prep! Take this opportunity to check the metal where the hoses connected for corrosion, particularly the top hoses where I found rust. Just use a bit of emery tape to clean off the rust before you put it back together.

Replacing the thermostat

This is one of the easier jobs, and with the radiator out you have plenty of room to get to it.

• Locate the thermostat. It is on the passenger side, where the top end of the bottom radiator hose connects, and the passenger side of the top hose connects. You should have already removed the two hoses.
  
• The thermostat is connected to the engine with three bolts. Remove all three and lift the thermostat out.
  
• Double check the gasket has been removed.
  
• Pull the new thermostat and gasket out of their box. At this point you can make this job a bit easier by using some form of gasket sealant to retain the gasket on the thermostat while you're bolting it back on. Mine kept moving and it was a complete pain.
  
• Put the new thermostat in place and secure it with the three bolts.
  

Have a beer to celebrate completing the easiest part of the job. Because now you have to do the worst part...

Replacing the radiator

This is a really crap job. Really, truly awful. Make sure you have something you can cut the front radiator support with - I used an Ozito Dremel knockoff with Dremel cutting disks.

One thing to note is this does vary depending on whether or not you have already replaced your intercooler. I had already fitted a HDI GT2 Intercooler which involves sitting a slimline electric fan in place of the standard fan. If you did a good job of this, you'll be fine. If you didn't, you'll have a world of pain with your electric fan and you'll probably end up replacing the mounts for the electric fan. I mounted mine against the air conditioner condenser using the plastic mounts that came with it.

• Remove your radiator from its box. If you got the Mishimoto, admire yourself in its shiny, polished alloy shiny. Enjoy how pretty it is before it gives you a painful hour or two.
  
• If you're retaining the clutch fan, you will need to trim the original fan shroud to make it fit the new radiator. Line the fan shroud up against the new radiator. You should be able to work out quite easily what you need to trim - I just needed to trim one side in the end, after which the other side stuck over the edge.
  
• Grab your trusty Dremel/cutting implement and start in the top left and top right corners of where your radiator was. You can see some plastic which cuts the corner off, just carefully trim it out.
  
• At this point you may find it easier to drop your new radiator into the car so you can start to see where it fouls. I found I needed to trim 5-10mm off the top of the bottom radiator support (there is a lip above the diagonal bracing that can be removed), as well as the area on the support where the bottom front slots are.
  
• Repeat step 4 until the radiator fits. Feel free to punctuate this process with loud expletives that wake neighbours.
  
• Once you've got it close to fitting, consider your top and bottom mounts. We trimmed the bottom rubber mount on the passenger side to lower that side - the radiator just seemed to sit up too high on the passenger side. We also had to trim the bottom of the top locking mounts to make them fit, and elongate the hole the passenger side locking mount went into.
  
• Hopefully your radiator now fits, and you haven't gone hoarse from shouting expletives or cut any limbs off by mistake.
  
• Slide the radiator in and sit it on the lower mounts leaning the top against the engine.
  
• Pick up the air conditioning condenser and slide it into the bottom slots on the front of the radiator. You can then secure it into place by putting the bolts back in at the top. We took the opportunity to put shorter bolts in.
  
• Put the bottom mounting bushes in the bottom mounting holes.
  
• Slide the radiator bottom mounting pins into the bottom bushes.
  
• Pull the radiator towards the front of the car and under the front support.
  
• Put the locking mounts back in and lock them.
  
• Hold the clutch fan against the fan shroud and drop it into the engine bay. Place the clutch fan over the four bolts you removed it from and re-tighten the nuts.
  
• Reinstall the two bolts which held the clutch fan in place.
  
• Have a look underneath the car. Reinstall the clip in centre section of the fan shroud.
  
• Check that the bottom of the fan shroud sits secure and tight. I ran a cable tie from the bottom of the radiator support to a hook on the fan shroud to keep it in place.
  

Have a beer or ten and celebrate that ordeal being over. It's all rainbows, butterflies and cherries from here on out.

Fitting the transmission cooler

Check whether your radiator has a stock transmission cooler in the bottom of it. If it has hose barbs, consider yourself lucky, disconnect the hoses you previously looped and connect them to the hose barbs on the new radiator. Laugh at how easy that was and move along.

If your radiator doesn't have a stock transmission cooler, or it has random fittings like my Mishimoto, read on...

• Decide where you want to fit your transmission cooler. There are many diferent options here. At dad's insistance, we chose in front of the radiator.
  
• You may find it easier to remove the front bar for this. Undo the four plastic clips which hold the grill in place, and lift the grill up and out. Remove the two plastic clips at the top which hold the front bar in place. Remove the screws which hold the front bar in place - there is one either side up in the left and right hand side up near the end of the front bar, just pull back the inner guard lining. Remove the remaining bolts - two per side underneath the car.
  
• Now the next steps are specific to how I did my install, so just customise them for your install...
  
• Remove the reo behind the front bar. Four bolts per side.
  
• Remove the top and bottom bolts which hold your intercooler in - the HDI has two which hold supports at the bottom, and the two at the top.
  
• Remove the hose clamps which hold the intercooler in place, and pull the hoses off. You should now be able to pull the intercooler out.
  
• You will need some form of spacer to separate the intercooler from the transmission cooler. In my case dad made up some 10mm thick eurothane spacers.
  
  
• I then trimmed the eurothane with a hacksaw so that it would sit hard up against the passenger side of the intercooler.
  
• You're now ready to mount the transmission cooler to the intercooler. Place the transmission cooler where you want it, and move the eurothane blocks under the right holes on the cooler.
  
• Carefully thread the nylon ties through the cooler, the eurothane and the intercooler. Place the locks on each of the nylon ties, slide the up tight and cut the excess off.
  
• Refit the radiator, bolts and hose clamps.
  
  
• Connect the new transmission hose to the top barb on the transmission cooler and secure it in place with a hose clamp. Preferably, recycle the old constant tension hose clamps. Thread the other end of the hose through the same path as the intercooler piping. Trim it as appropriate, and clamp into place on the top metal transmission outlet.
  
• Connect the rest of the new hose to the bottom barb on the cooler, thread through the same path as the other hose, and connect to the bottom metal outlet with the same constant tension hose clamp.
  
• Look at how your hoses are positioned. You may need some cable ties.
  
• Bolt the reo back down, and refit the front bar and grill.
  

Transmission cooler complete! Drink beer and celebrate!

Refitting hoses

The home stretch. For all of these steps, you will likely need to replace the hose clamps as the silicon hoses are thicker.

• Install the bottom radiator hose. One end connects to the radiator, one to the thermostat. Double check you have it the right way around - one way it will be fine, the other it will foul against a pulley.
  
• Install the radiator hose that links the left and right banks of the engine.
  
• Install the top radiator hose. If you're installing a water temp sender, cut the hose to fit the sender adaptor and secure with decent hose clamps - make sure you check what you're using isn't a complete train wreck that will come loose. Put some thread sealant on your sender and secure the sender to the adaptor.
  
• Install the new hose for the overflow bottle, and bolt it back down to the radiator support. Connect the other end to the neck of the new radiator.
  

Refilling the radiator and finishing off

This gets its own section to get the mix right. The cooling system holds about 7L.

• Remove the radiator cap and poke a funnel in.
  
• Fill the radiator with a mix of 5% MoCool, 47.5% coolant and 47.5% distilled water. I did this by using 2L bottles, and filling 2L of distilled water, 100mL MoCool, 2L coolant, 100mL MoCool, etc.
  
• When full, top up the radiator overflow bottle to the max line with the same mix.
  
• Start the car. Turn the heater up to 32 degrees with the AC on.
  
• Wait for the thermostat to open. You should see the water temp gauge move, or look at your Informeter until it shows over 68 degrees.
  
• Open the bleed tap on Scotty's bleed tap if you've done this mod. If you haven't, GTFO and do it!
  
• Put a funnel in the tap, and fill the cooling system from the tap. Do this slowly and carefully. After a little while you should start to see the radiator neck overflow.
  
• Reinstall the radiator cap.
  
• Continue filling the tap slowly. Make sure you're holding the tap straight up. After each small fill, check to see if bubbles are still coming out of the top of the tap. Continue to fill until no more bubbles come out, then close the tap.
  
• With the car still idling and now warm, check the transmission fluid level. Top up as necessary. Once you top up, leave the car to idle for a while for all the fluid to settle down and recheck. Repeat until level is fine.
  

You're finished! You may need to check/rebleed again in a couple of days.

And that's it! Celebrate it being over, and drink many more beers!

[PN-Mad]

Wow. Detailed write up mate.

I'd love to know those stupid mishimoto fittings too.

[bigkevracer]

Wow. Detailed write up mate.

I'd love to know those stupid mishimoto fittings too.

Cheers mate. Hopefully it helps someone.

I've emailed mishimoto about the fittings but they're shut until the new year. Could be dash fittings but I don't think so. A tiny fraction smaller than 5/16 x 1/4.

[impul535w]

Couldn't you just take the radiator into Pirtek or something like that? They would have test fittings and be able to find something that fits surely.

[bigkevracer]

Still an option, but not sure I need to with the external cooler.

Before I fitted it I took the radiator to Autobarn and they supplied 5/16x1/4 BSP which was fractionally too big. It's a metric 12mm fitting but I don't know the thread pitch.

[PN-Mad]

I did that, and got some barb fittings. However after a day on the dyno they started to leak. I tried some tape on them and subsequently did the thread some damage when trying to tighten. So at the moment I'm just running the external which I haven't had any issues with. I would like to sort it though incase stuck in really shitty traffic.

Might have to try the barbs again, and seal it up with some gasket stuff. I dunno. It's pretty high pressure when your up it.

[bigkevracer]

I did that, and got some barb fittings. However after a day on the dyno they started to leak. I tried some tape on them and subsequently did the thread some damage when trying to tighten. So at the moment I'm just running the external which I haven't had any issues with. I would like to sort it though incase stuck in really shitty traffic.

Might have to try the barbs again, and seal it up with some gasket stuff. I dunno. It's pretty high pressure when your up it.

I'll let you know what Mishimoto say about it, hopefully they can point us in the right direction.

[WAGON_BOY]

Wow. Detailed write up mate.

I'd love to know those stupid mishimoto fittings too.

they are dash 5

edit.......... (https://www.facebook.com/index.php?lh=25ebf854d7c3da066a4ca8b3e4e8fdaa#!/LAMBCHOPZ/photos_stream)

Edited December 27, 2012 by WAGON_BOY

[PN-Mad]

Sure they are -5AN and not -6AN?

Just looked for barb fittings and its impossibru to find. 4 yes 6 yes 8 yes 10 yes.... 5 NO!

We might have to go to a weld on for a solution. Its 3/8 hose yeah?

[scotty nm35]

They are auto trans specific, I got a transmission cooler kit recently that had the correct flare fitting included in the packet.

If they are a standard BSP thread a liquid teflon sealant should work.

http://www.transmissioncoolers.us/category/cooler-fittings.html

[WAGON_BOY]

my thermostat came with 2 o-ring's i couldn't see where they are required or used....... ???