I thought this might be useful....
This is a description of how I fitted a GReddy 10 row oil cooler to my R34 GTR. It is not a ‘How To’ guide as I am no mechanic, so if you decide to copy any of the things I did, then it is your decision and I cannot accept any responsibility for any damage or injuries to persons or property howsoever caused.
So, this is the GReddy kit as it comes out of the box and it includes everything needed to fit and mount the cooler.
The GReddy coolers come in two sizes: 10 and 13 rows. I chose the smaller 10 row unit as this will be ample for the occasional track day that I do and my 420 bhp. There is also a choice of mounting positions: in front of the radiator or in the nearside bumper, and this determines the brackets and length of pipes that are included in the kit. I chose bumper mounting, as I didn’t want the oil cooler to restrict airflow to the radiator, and because I have a Nismo front bumper which has the air holes specifically to flow air to the cooler location.
I was well impressed with the quality of the kit and it looks great in with the anodised blue finish. Unfortunately, the instructions were in Japanese and an extensive search of the web was not fruitful in finding an English version. Luckily there were pictures…
So first, I assembled the brackets onto the cooler following the instructions.
Although the side pieces look similar, they are subtly different, so I had to take care to get the set up exactly as the diagram. All the bolts are 10 mm, so I used a ratchet wrench and a spanner to do them up.
Next I assembled the sandwich plate, taking care to make sure that the sealing ‘O’ rings on the fittings were seated correctly. I did these up using a 22mm (I think that was the size) hex spanner, and fixed them tight, but not overly tight, to avoid splitting the alloy nuts. The ‘O’ ring should make a good seal without tightening the life out of them.
Now to the car. The bumper needs to come off to get access to the space where the cooler is to go, and that’s just held on by six 10mm bolts. However, it’s not that simple. To get access to those bolts a load of other stuff has to come off.
First I jacked up the car at the front and stuck axle stands underneath to hold her up. A bit of space to get underneath and see what you are doing is pretty handy. Then I removed the engine under-tray. There were 12 bolts holding this tray on (some marked in the picture).
Some of these bolts are difficult to see, but I worked my way round and undid bits that were still hanging on. I have seen a two-piece version of the under-tray too on other cars, which would be removed slightly differently, but the principal is the same.
Next, I undid the six bolts each side holding on the brake ducts in front of the wheels. A squirt of WD40 might have been helpful here as these bolts were well rusted in. Nissan seem to make them disposable, because 5 out of the six snapped. It’s not the end of the world if this happens though as you can just replace the spring clips which have the threaded section in and add new bolts (available from Nissan at £2 each or 20p from a local motorfactors!)
Once these were off I removed the wheeh arch covers. I undid the three clips at the front and side of the cover (in the wheel arch), by inserting a medium head flat-blade screwdriver under the centre cap and slowly twisting until they pop open, then easing the whole clip out of the hole.
Then, back under the front splitter, I removed the three 10 mm bolts at the side of the bumper (easiest with no extension on my wrench I found). The arch covers took a bit of manoeuvring to get them out, but they did come out.
This all gave me access to the two 10mm bolts at the top side of the bumper.
I undid these on each side, then supported the bumper on some bricks on each corner before I undid the last two bolts in the centre section.
The bumper then came away by lifting over the two plastic lugs in the centre section and disconnecting the wires from the indicators by undoing the clips before moving the bumper too far away.
Whilst I had the spanner in hand, I also removed one of my air filters to give access to the bolt hole for mounting the cooler.
With all that done, I could test fit the cooler. In the case of the GReddy unit, it uses holes that are already in the bodywork, two on the bumper frame and one under the air filters.
I left the fittings a bit loose so that I could adjust it, but even so, I had to gently apply some force to slightly bend the brackets to get the unit to sit nicely without rubbing against the bumper frame.
I then removed the cooler and loosely connected the oil pipes in accordance with the instructions diagram. I used a small amount of plumbers PFTE tape on the threads to ensure a good seal, but this was really just an extra precaution against leaks. I then refitted the cooler and tightened up all the bracket nuts and bolts (but not the oil pipes at this stage).
I threaded the pipes under the car and up towards where the oil filter is located, making sure that they did not foul the accessory belt or fan, and taking what looked like the most logical route.
Then I conlected the pipes to the sandwich plate, again using PFTE tape. I connected the pipes to the inlet and outlet in accordance to what my interpretation of the instructions said, so that the oil flows down through the cooler and back up to the plate from the bottom. Once the fittings are tight, they do not swivel, so I took into account the final angle that the sandwich plate would be before tightening, to avoid having any undue twists in the pipes. I used two 22mm spanners to tighten the fittings, one on the plate adaptor (amber) and one on the fitting (blue) to avoid over tightening the adaptors. Again, a firm pressure on tightening, but not to death.
Next, I refitted the air filter and then warmed up the oil by running the engine for four or five minutes. I then drained the oil by undoing the sump nut (14mm) and having a cup of tea while it drained into my suitable receptacle that would allow me to take it to my local recycling facilities. When it had stopped flowing, I undid the oil filter by hand, attempting to minimise the amount of oil that spilt out once it is undone. My filter was only replaced about a thousand miles ago, so I kept it for reuse on this occasion.
Now came the fiddly bit that severely tested my patience. I wiped a bit of clean oil around the seal on the sandwich plate, and attempted to mate it to the oil filter plate on the engine block, and screw in the fixing adaptor nut. This took a bit of work and much cursing. I found that I had to move the wiring harness by undoing the cable tie, to allow the pipes to sit properly. I also found that removing the dipstick was pretty helpful.
Getting the adaptor nut to tighten was the tricky part. The sandwich plate had to be sitting flush with the engine block to stand any chance of getting the nut to thread and I was very careful not to cross thread it. With a bit of patience and by adjusting the angle of the pipes, the nut went on and threaded up easily. Oil filters are normally only done up hand tight, so I tightened the nut by hand and then just nipped it up with a 22mm socket to make sure.
I then smeared clean oil on the seal of the oil filter and screwed this onto the sandwich plate, doing it up hand tight.
Back down at the cooler, I tightened up the fittings and routed the pipes safely under the engine.
With everything in place, I stuck a new washer on the sump nut and retightend it, then added in 4 litres of 15w50 Mobil 1, which took the oil level on the dipstick to full. A final check that everything was connected and tightened, then I started the engine and ran it for about a minute, before turning off and topping up the oil to the full mark again.
I checked all the fittings for leaks and when I was satisfied that everything was sound, ran the car for another four or five minutes to circulate the oil further. The GReddy cooler is thermostatically controlled, so only a small amount of oil flows to it until a certain temperature is reached, and the valve opens fully. This meant that it took a little while for the cooler to start to get warm and indicate that the oil was flowing through it correctly. Now that the cooler was full, the oil needed topping up again, making it exactly 5 litres in total (of course including whatever was left in the system already).
I checked for leaks all over again and once satisfied, cable tied the oil pipes into position, covering them with the supplied plastic protector where there was a chance of any rubbage.
Next, I cut a small section of the near-side arch-liner to accommodate the pipes before refitting the trim and bumper in the exact reverse order of removal. (note the new spring-clips marked in red arrows and hole I cut in a green circle)
Here is the finished unit sitting nicely behind the side vents.
Finally, I went out for a test drive to get the car up to full temperature, taking things steady until I was sure that oil pressure was being maintained and there were no further leaks. It certainly makes a difference to the temps. The thermostat means that the oil gets up to 70 degrees in exactly the same time as previously, but she runs about 10-15 degrees cooler on the motorway than before.