Alex's R32 GTST oil cooler

Its quite common to see aftermarket oil coolers fitted to skylines as oil temperatures seem to be a problem on all models when pushed hard. Never one to blindly follow the crowd, I decided to fit an oil temp gauge and see for myself the oil temperatures reached on my RB20DET on the track. At Snetterton this Feburary, on what was a pretty cold day, I was seeing temps well over 110 degC after 5-10 mins of track action. Outcome; "the crowd" are quite right to fit oil coolers, so lets join them!

After some umming and ahhing I wandered down to ThinkAuto of Mocal fame. True to form they gave me some good advice and a good price on the kit of parts needed to do the job. Here's what I got; 4x 90deg swept steel fittings -10 jic with tails for 5/8ths hose. 4x ferules for 5/8ths hose 1x Thermostatic sandwhich plate 1x 3/4UNF sandwhich plate adapter 3m Mocal 100R6 Steel over-braided hose 1x 19row 230mm oil cooler 2x 1/2BSP to -10JIC Male to Male adapters 2x 13/16 ID Bonded seal washers These fittings need swaging, basically you slide the ferule onto the tail of the fitting and slide the hose into the ferule and then crush it so as to hold the hose tight on the tail.  Normally you'd get this done when you order the bits but since I wasn't sure how long the hoses needed to be I went home and test fitted the kit and then returned the fittings all marked up so they could be swaged on at the correct angles back at Mocal. Its probably easier to fit Aeroquip style fittings which dont need swaging and can be assembled with hand tools, but its also much more expensive! 5/8th hose (-10JIC) is pretty big bore stuff and 1/2BSP (-8JIC) may well do the job on an RB20DET and would have been a bit cheaper but for the sake a of a few pounds I went for the -10JIC as used by Abbey on their Mocal based kits for the RB26DETT. I went for a thermostatic sandwhich plate which means the oil will flow through the cooler when it reaches 80degC, a small amount of oil always flows through the cooler as the valve never fully closes, this helps the car warm up more quickly and prevents any problems with over-cooling the oil in winter. You'll see alot of debate as to the best place to fit an oil cooler, especially in conjunction with a FMIC. You've 4 options really, 1. Mounted upright bewtween the FMIC and the Radiator. 2)Lying flat behind the front cross member, level with the sump, sort of under the fan. 3)Behind the bumper in the passenger side wheel arch. 4)Behind the bumper in the drivers side wheel arch. Weighing up air flow, risk of stone damage, length of pipe runs and the problems of transmissing heat to the intercooler pipes, I decided to go with 4. I fabricated a couple of brackets from bits and bobs that I had lying around the garage and found that the cooler fitted quite nicely tilted back slightly under the FMIC return pipe.

I had already had to make a hole in the engine bay, under the battery tray for the FMIC return pipe, so I enlarged this slightly and ran my oil cooler hoses through next to the IC pipe. The swept fittings are pretty large and the -10 hose is fairly inflexible, which means its a struggle to get everything fitted up in the tight space under the intake manifold. Below is a picture taken from under the car looking up, you can see the stock oil pressure sender, above and to the left of the oil cooler take off, the stuff close to the camera in the bottom left of frame is the steering linkage. From above you can see how close the hoses run to the main power lead for the starter motor.

An oil cooler is no good without air flowing through it. So you need an easy entry and exit for the air. The entry is OK thanks to the position of the vents in the factory bumper. But for the exit you'll need some largish holes cut in the arch liner, I was a bit worried about stones getting kicked up and into the back of the oil cooler so I meshed over the hole ( holding the mesh in place with some panel clips and self tapping screws). To guide even more of the air through the cooler I fitted a duct to the front and ran some convoluted ducting to the vent in the bumper. You can see that I've allowed alot of extra hose so as not to created any tight radius bands that may kink the hose. To try to minimise the chance of the hoses bouncing around and losening the hose fittings or mounting brackets I cable tied the hoses to each other and to the bumper support With all the hoses in place and the cooler firmly bolted into position its time to fill the engine with oil and crank the the car without starting it until the oil cooler, hoses and filter have filled with oil. You can do this by unpluging the CAS which is mounted on the front of the cam belt cover. It takes a fair amount of cranking before you will see any oil pressure and you will need to top up the oil with at least 500ml. During this process I noticed oil way leaking heavily from the fittings at the sandwhich plate end. I gave Mocal a call to make sure I'd put it all together correctly and they suggested lubricating the threads and flares of the fittings with grease before assembly to ensure the threads werent binding and preventing a good seal at the "flare". Hey presto fixo After some cleaning up and a thorough test drive I noticed how hot the oil cooler hoses were getting in the engine bay, knowing the problems skylines suffer from with engine bay heat as it is I decided to make a heat wrap for the length of the in the engine bay. I bought some aluminised fibre glass mat from Mocal £10 for 1m sq and made a long tube to fit over the hoses. I used more of the same material to seperate the FMIC return pipe and the hoses where they run closest together. The cover for the hoses should also protect nearby rubber fuel hoses and wiring from chaffing on the stainless over-braid In use, the oil pressure gauge shows better oil pressure when the car is upto temperature and even after a 20 min session on track, I'd guess this is a sign that the oil is running cooler. The real test will be when I've figured outa way to refit my oil temp gauge, unfortunately the sandwhich plate for the oil cooler didnt leave enough room to retain the takeoff plate I was using for the temp gauge sender. I'm considering a T off the oil pressure sender, or fitting a sump plug adapter ...