DIY: Budget Oil Cooler Setup Using An FC3S Cooler

[Rustys14]

I just got done installing this setup on my car and took some pictures along the way so I figured I would do a quick writeup on how to adapt the FC3S oil cooler to work on our cars (or any car for that matter). I put this on my 89 coupe with a ka24e but this setup is pretty universal and should work on just about any car/engine setup.

First up, this is a pretty simple install and I realize that most people probably don't need a full writeup but I figured its worth throwing out there to give people some fresh ideas.

Secondly, if your considering your options for a cooler almost all the information you could ever need regarding oil cooler setups can be found here http://zilvia.net/f/showthread.php?t=225223

Now that that's out of the way lets get into it!

Difficulty: 3 out of 10
Time required: 1-3 hours depending on how creative you get when your routing your oil lines (drilling holes, etc)
Tools: Basic hand tools and a 23mm socket or wrench for removing the factory FC banjo bolts (an adjustable wrench will work too if you don't have one).

Why an FC3S cooler?
1. Its cheap! I got my cooler from the local pick a part for a whopping $9.52.
2. It has a built in 160 degree thermostat which eliminates the need for an expensive thermostat sandwich adapter combo.
3. Its as big as a small core intercooler so you don't ever have to worry about it being up to the task. If anyone has ever owned a rotary you know what kind of heat they generate so this thing was made to be overkill from the factory.
4. Its easy to source. All FC Rx7's came with this cooler and there are usually one or two at every junkyard.
5. Its a OEM part so you know your getting OEM quality and not some hit or miss eBay cooler.

Why do you need it?
I was noticing that I was getting pressure drop after long stints on track which is a sign that my oil was getting too hot. This cooler is a cheap way to keep that from happening.

Now on to the install:

This is the FC3S cooler as it comes off of the donor car:
http://i1304.photobucket.com/albums/s532/jfox31/IMG_0733_zpsa5f7e0ab.jpg (http://s1304.photobucket.com/user/jfox31/media/IMG_0733_zpsa5f7e0ab.jpg.html)

The mounting brackets face forward on the FC but you can also run the cooler the other way around like I did:
http://i1304.photobucket.com/albums/s532/jfox31/IMG_0739_zps827807e5.jpg (http://s1304.photobucket.com/user/jfox31/media/IMG_0739_zps827807e5.jpg.html)

Now you have two options for mounting it on your car:
1. Go to your local hydraulic supply store and have custom lines made that utalize the factory banjo bolts
2. Adapt the cooler to use AN fittings so you can use sexy stainless steel braided lines or push on line fittings to use standard cheap oil lines. This is the part most people get stuck on because they can't find the correct adapter fitting. Fortunately, I have you covered.

If you go with option 2 you will need to order these http://www.summitracing.com/parts/FRA-461018/ These -10 AN to 18mm x 1.5 adapter fittings are all you need to turn the factory FC cooler into a universal oil cooler.

Picture of the part #:
http://i1304.photobucket.com/albums/s532/jfox31/IMG_0740_zps2f72878a.jpg (http://s1304.photobucket.com/user/jfox31/media/IMG_0740_zps2f72878a.jpg.html)

And what they look like for those that have never seen a AN fitting before lol:
http://i1304.photobucket.com/albums/s532/jfox31/IMG_0742_zps8915d2ae.jpg (http://s1304.photobucket.com/user/jfox31/media/IMG_0742_zps8915d2ae.jpg.html)

Remember to use thread tape on the standard thread portion of the fitting, DO NOT use thread tape on the AN portion (As G5SR20240 pointed out below, crush washers should be used here instead of tape since teflon tape is not as effective on metric threaded bolts):
http://i1304.photobucket.com/albums/s532/jfox31/IMG_0750_zpsed384a25.jpg (http://s1304.photobucket.com/user/jfox31/media/IMG_0750_zpsed384a25.jpg.html)

Once installed you end up with this:
http://i1304.photobucket.com/albums/s532/jfox31/IMG_0753_zpse0631056.jpg (http://s1304.photobucket.com/user/jfox31/media/IMG_0753_zpse0631056.jpg.html)

Now you have to make it so your car can send oil to the cooler by installing a sandwich adapter. Since the Rx7 cooler has a built in thermostat I just ordered a $23 -10 AN sandwich adapter from eBay. When you get these cheap adapters be sure to go over it and clean out any metal burrs around the fittings so they don't break off and get into your engine.

The adapter in question, as you can see it comes with the fittings to adapt it to almost any car make on the market:
http://i1304.photobucket.com/albums/s532/jfox31/IMG_0754_zps66a32ebe.jpg (http://s1304.photobucket.com/user/jfox31/media/IMG_0754_zps66a32ebe.jpg.html)

The adapter flows directionally but for this application it doesn't really matter:
http://i1304.photobucket.com/albums/s532/jfox31/IMG_0755_zps8f58c5cc.jpg (http://s1304.photobucket.com/user/jfox31/media/IMG_0755_zps8f58c5cc.jpg.html)
http://i1304.photobucket.com/albums/s532/jfox31/IMG_0756_zpscfac32af.jpg (http://s1304.photobucket.com/user/jfox31/media/IMG_0756_zpscfac32af.jpg.html)

Now all you have left to do is install the lines and the setup is complete! I used 2 48 inch -10 Stainless braided lines that I had laying around from another project but the material is up to you. Length will vary depending on your project and mounting location as well. When its all done though it should look something like this:
http://i1304.photobucket.com/albums/s532/jfox31/IMG_0769_zps0a8e5eb4.jpg (http://s1304.photobucket.com/user/jfox31/media/IMG_0769_zps0a8e5eb4.jpg.html)

Where to mount it is up to you. A lot of boso cars run these coolers externally mounted but that's not really my style. I have no desire/plans to turbo this chassis so I decided to mount it up front since it would get the most airflow there and I don't have a intercooler for it to interfere with. The stock FC brackets also line up perfectly with the 240sx headlight brackets so it was just a matter of drilling holes in the brackets and bolting it on.

All mounted up:
http://i1304.photobucket.com/albums/s532/jfox31/IMG_0771_zpsf80acc20.jpg (http://s1304.photobucket.com/user/jfox31/media/IMG_0771_zpsf80acc20.jpg.html)

And with the bumper on (no trimming required):
http://i1304.photobucket.com/albums/s532/jfox31/IMG_0775_zps7d934c0b.jpg (http://s1304.photobucket.com/user/jfox31/media/IMG_0775_zps7d934c0b.jpg.html)

Also since I'm running a single cam (which uses a L series oil pump) I went ahead and installed a Nissan Motorsports oil pump (same part # as the automatic 280z turbo) since it is made to be run with a cooler and pushes more oil. It looks like a standard oil pump but makes a huge difference lol:
http://i1304.photobucket.com/albums/s532/jfox31/IMG_0761_zps7681c3b7.jpg (http://s1304.photobucket.com/user/jfox31/media/IMG_0761_zps7681c3b7.jpg.html)

Make sure to line up the punch mark on the gear with the pump when installing:
http://i1304.photobucket.com/albums/s532/jfox31/IMG_0762_zpsf37087e7.jpg (http://s1304.photobucket.com/user/jfox31/media/IMG_0762_zpsf37087e7.jpg.html)

That's about all, your oil system should hold a quart to a quart and a half extra oil now depending on how long your lines are and most importantly your oil temps will stay where they need to be on track or during spirited driving. If I include the cost of the stanless line and fittings this whole setup cost me right around a hundred bucks.

[waxball88]

someone finally gave up one of the best kept secrets.
:-/

[zooopreme]

someone finally gave up one of the best kept secrets.
:-/

It's not necessarily a new thing or a new-found method though. 86 guys have been using this method (maybe not with AN fittings) and MotorMavens put out an article with a TE72 wagon with it mounted in the exterior of the car.

Plenty of people have been doing it is what I'm trying to say lol

[racepar1]

Yeah, I'm doing this. Great info!

[bejota180sx]

i find these coolers all the time in local FB groups, how efficient are they really? and is the thermostat opening temp adequate for say our SRs? i know i've read a few thread about this with mixed reviews but no clear numbers or anything. Anybody care to share experiences?

[waxball88]

Being that it is an OEM cooler and having known several people that have used them. A lot if people like them, are you really that concerned about the t-stat, especially considering so many bosos run no t stat with super cool moroso coolers for more than quadruple the price?
It's cheap
Has t stat
Oem quality
Pretty good size/thickness (just accept the girth)

[racepar1]

i find these coolers all the time in local FB groups, how efficient are they really? and is the thermostat opening temp adequate for say our SRs? i know i've read a few thread about this with mixed reviews but no clear numbers or anything. Anybody care to share experiences?

All the thermostat does is allow oil to bypass the cooler internally untill the oil gets warm. This allows the engine to get up to temp faster, which is a good thing, ESPECIALLY on a street car. Your question as to whether or not the thermostat opening temp is adequate makes no sense. It seems that you're thinking of it as operating in the same manner as a coolant thermostat, when it's actually exactly opposite. As for efficiency, it's an OEM cooler. I'm POSITIVE it does it's job just fine.

[bejota180sx]

All the thermostat does is allow oil to bypass the cooler internally untill the oil gets warm. This allows the engine to get up to temp faster, which is a good thing, ESPECIALLY on a street car. Your question as to whether or not the thermostat opening temp is adequate makes no sense. It seems that you're thinking of it as operating in the same manner as a coolant thermostat, when it's actually exactly opposite. As for efficiency, it's an OEM cooler. I'm POSITIVE it does it's job just fine.

yeah, i didn't state my question correctly. But still you answered what i was trying to ask. Thanks.

[inuyasha3466]

Nice! What are dimensions of the oil cooler?

[racepar1]

yeah, i didn't state my question correctly. But still you answered what i was trying to ask. Thanks.

Also, I was searching around to see if the thermostat was replaceable and I ended up on the Mazdatrix website. According to them the factory oil cooler is one of the most efficient they have found. I'm sure a bigger cooler could remove more heat, but I don't think a bigger cooler would be necessary on a little 4-cylinder engine. So, yes it is efficient...

[Rustys14]

All the thermostat does is allow oil to bypass the cooler internally untill the oil gets warm. This allows the engine to get up to temp faster, which is a good thing, ESPECIALLY on a street car. Your question as to whether or not the thermostat opening temp is adequate makes no sense. It seems that you're thinking of it as operating in the same manner as a coolant thermostat, when it's actually exactly opposite. As for efficiency, it's an OEM cooler. I'm POSITIVE it does it's job just fine.

Couldn't have explained it better myself. Also did you find a replacement thermostat? I know that it is replaceable but I can't seem to find the part number for it anywhere. I assume it is a dealer only item but I have also heard rumors that Stant makes a replacement that is available at autozone. Either way I have used several of these coolers over the years on various projects and have never had a thermostat go bad.

Nice! What are dimensions of the oil cooler?

Ask and you shall receive!

FC Rx7 Oil Cooler Dimensions:
Length (including endtanks) 22.5"
Length (core only) 19.75"
Height 4.5"
Width 2"

And the proof to back it up (only measured the core size):
http://i1304.photobucket.com/albums/s532/jfox31/IMG_0745_zps078f4f3c.jpg (http://s1304.photobucket.com/user/jfox31/media/IMG_0745_zps078f4f3c.jpg.html)
http://i1304.photobucket.com/albums/s532/jfox31/IMG_0744_zps582a237f.jpg (http://s1304.photobucket.com/user/jfox31/media/IMG_0744_zps582a237f.jpg.html)
http://i1304.photobucket.com/albums/s532/jfox31/IMG_0747_zps9272ba5c.jpg (http://s1304.photobucket.com/user/jfox31/media/IMG_0747_zps9272ba5c.jpg.html)

Also when your out looking for one here are some things to look out for:

1. Remember that these are older then a lot of the people on this forum so the fins can be very brittle. Don't stick anything sharp in them and you should be good to go.
2. These have a problem with oil seeping through the welds on the endtanks when they are on their way out. If you notice this at the junkyard move on to the next one.
3. The bolt holes have a problem with cracking and leaking when overtightened. Make sure to inspect it thoroughly when you get it off since who knows how many "mechanics" have messed with it over the years. Also be careful not to overtighten and crack it yourself when installing it.

[G5SR20240]

Nice setup and affordable! But you should really run an aluminum crush washer with those adapter fittings. They are machined flat to accept one, the thread tape will eventually lose its effectiveness since the fittings are not npt and you will lose oil. But nice setup either way

[racepar1]

Nice setup and affordable! But you should really run an aluminum crush washer with those adapter fittings. They are machined flat to accept one, the thread tape will eventually lose its effectiveness since the fittings are not npt and you will lose oil. But nice setup either way

Yep, I was going to mention that myself. You should DEFINITELY run crush washers between the adapter fittings and the cooler...


As for the thermostat being replaceable, I only searched for like 5 seconds so I didn't really pursue it fully. I did see some pictures of brand new thermostat assemblies for it though, so I KNOW that you can get them, I just didn't bother pursuing it to an actual source.

[inuyasha3466]

Thank you for the measurements! :bigok:

[Rustys14]

Nice setup and affordable! But you should really run an aluminum crush washer with those adapter fittings. They are machined flat to accept one, the thread tape will eventually lose its effectiveness since the fittings are not npt and you will lose oil. But nice setup either way

That is a really good point, I never really thought about that until you brought it up. I'll probably go back and add crush washers next time I have the bumper off. I've never had issues with just the tape on similar setups in the past but your right and its better to be safe.

[Rustys14]

Figured I would do a quick update on this:

I just got back from a all day event. There were almost no lines so I pretty much hot lapped the car from 10am to 4pm with only a few short breaks to change tires. Oil pressure stayed much more consistent then it has in the past, in fact I didn't seen any pressure drop at all which is a first for this car. I haven't made it to enough events this year to do a full report but I'm pretty happy with the fc cooler so far.

[cured13]

How is that sandwich adapter holding up, any leaks or do you have any problems with it when changing filter. Many people with Sr20 prefer Tomei type plate but since I don't plan on doing filter relocation the sandwich type make it much simpler setup.

Does anybody use Volvo sandwich adapter with thermostat built in and regular oil cooler?

[Rustys14]

How is that sandwich adapter holding up, any leaks or do you have any problems with it when changing filter. Many people with Sr20 prefer Tomei type plate but since I don't plan on doing filter relocation the sandwich type make it much simpler setup.

Does anybody use Volvo sandwich adapter with thermostat built in and regular oil cooler?

The sandwich adaptor is holding up fine. I've used several in the past and have never had any issues. Just make sure it is the proper diameter for your engine and don't forget to put some oil on the O ring to help it seal like you would with a oil filter. The oil filter goes on and off just like it did before, without any issues. The average person doing a oil change probably wouldn't even notice that there is a adaptor installed.

I can't really comment on the Volvo adaptor since I've never personally used one but I have heard that they work fine. I don't see why you would have any issues with one as long as you can find fittings that will work with it.

[Dolph_KYAS13]

I love threads like this, Thanks for contributing to the forum. I wish there was a spot for this mod on my R32

[idae209]

where did you order your steel braided lines from?

[Rustys14]

where did you order your steel braided lines from?

I had them laying around from another project but I believe those lines came from eBay since that is usually where I buy my line from. Most speed shops keep line and fittings in stock as well if you want to stay local.

Edit: Yup, these are the exact lines that I used http://www.ebay.com/itm/AN10-STAINLESS-STEEL-BRAIDED-OIL-FUEL-LINE-HOSE-FITTING-HOSE-END-ADAPTER-KIT-/351018204275?pt=Motors_Car_Truck_Parts_Accessories&hash=item51ba50bc73&vxp=mtr. The 48 inch hose will work for most applications but remember, length is dependent on mounting location so you may need piece together longer/shorter lines if you plan to mount your cooler in a different spot. Just type in 10 an stainless line on eBay and you will get a whole bunch of options.

[bejota180sx]

i've been searching around for one of these, and the prices i get now are stupid compared to a few years ago, hell even a few months ago online. Almost close to new oil cooler prices, or at least close enough to just say to myself to keep saving a little bit more. Every price i get is close to $100 and to be honest, no being able to check it in person doesnt make me want to buy it after reading all the things i should check that could leak.

I want this cooler cause it would fit exactly where you positioned it, and with my mid mount setup it would fit perfect. And that would let me use my brakeducts (like the ones racepar1 did a how to) only for brake cooling. I've seen some ebay knockoffs with this same size and brackets, does anybody have experience with those? can i use the oem thermostat with them?
practically one of the one im talking about
http://www.ebay.com/itm/high-performance-aluminum-oil-cooler-Mazda-RX-7-RX7-FC3S-S4-S5-13B-1986-1992-/121218954204

[ixfxi]

There's nothing wrong with doing things on the cheap, but the thing you guys need to think about is that these are USED oil coolers... with USED oil inside of them (and maybe debri). I wouldnt run that mother fucker without a thorough flush. And still you're left with a used cooler, with all types of shit in the fins, that may or may not leak. This all makes sense on a junkyard build car with a KA24E... doesnt make sense if you are building something you care about.

Now if these were available new, that would be awesome. Especially since they have integrated thermostats. But even then.........

You can buy a name-brand MOCAL oil sandwich adapter that not only has an integrated thermostat, but also has serviceable parts like the O-ring seal. That with a nice NEW Setrab or Mocal cooler and you're good to go. Nothing to flush, nothing to leak. Nothing used.

And yes, you should have run copper washers on the straight thread portion of the AN fittings. Teflon....... come on man, we're not working on home plumbing.

[ixfxi]

Oh, and if you really wanted to keep things on the cheap you'd ditch the pricey stainless steel AN lines and simply use hose w/ clamps + banjo fittings with barbs.

http://specialtauto.com/delorean-parts/images/fuel-fittings-1.jpg

[Rustys14]

I've seen some ebay knockoffs with this same size and brackets, does anybody have experience with those? can i use the oem thermostat with them?
practically one of the one im talking about
http://www.ebay.com/itm/high-performance-aluminum-oil-cooler-Mazda-RX-7-RX7-FC3S-S4-S5-13B-1986-1992-/121218954204

I don't have any experience with the new ones on eBay, but the listing does list it as a OE replacement unit and it looks to have the opening for the thermostat. I would message the seller and ask if the OEM thermostat can be used. Report back with what he says since this may be a option for some people and would address some of ixfxi's concerns.

I would NOT buy one of these coolers without personally being able to inspect it because of the above issues. These are incredibly cheap if you go to the junkyard and pull them yourself (not sure if that is a option in PR). I would never pay anywhere near $100 for one of these coolers.

There's nothing wrong with doing things on the cheap, but the thing you guys need to think about is that these are USED oil coolers... with USED oil inside of them (and maybe debri). I wouldnt run that mother fucker without a thorough flush. And still you're left with a used cooler, with all types of shit in the fins, that may or may not leak. This all makes sense on a junkyard build car with a KA24E... doesnt make sense if you are building something you care about.

You can buy a name-brand MOCAL oil sandwich adapter that not only has an integrated thermostat, but also has serviceable parts like the O-ring seal. That with a nice NEW Setrab or Mocal cooler and you're good to go. Nothing to flush, nothing to leak. Nothing used.

And yes, you should have run copper washers on the straight thread portion of the AN fittings. Teflon....... come on man, we're not working on home plumbing.

The first part goes without saying. I always flush these before installing, I didn't think to mention doing a flush because its common sense (lacking in this community, I know). Theoretically speaking the oil filter SHOULD catch any debris from the cooler if you didn't do a flush, but it is something that should be done prior to installing.

The MOCAL adapter is another great (and reasonably priced) option as well for those who want a thermostat. I just wanted to put this option out there since I get a ton of questions about my cooler and most people don't know what it is.

As you said, this car is just a cheap practice car for me and my friends to use at local events while my other one is under the knife. It didn't really make much sense to go with a more expensive setup on this particular chassis. That said, I wouldn't necessarily call it a junkyard built car either, the car is built to be as reliable as possible on track so there are lots of high end parts on it. I realize that the core support makes it look half assed though...


Oh, and if you really wanted to keep things on the cheap you'd ditch the pricey stainless steel AN lines and simply use hose w/ clamps + banjo fittings with barbs.


This is another good option. I still prefer the AN fittings since there is less of a chance for leaks but that would probably be the absolute cheapest way to do it.

[ixfxi]

I agree, its budget at its best. Thing I like about the FC cooler is that it has a built in thermostat. Kinda cool, all things considering.

Thing I dont like however, is the sandwich adapter. I would rather spend a couple bucks more and buy a Mocal, at least its a solid piece & is serviceable. As we all know, failure with any section of the oil system is (usually) catastrophic.

Thing about AN plumbing is that it still has its flaws. Fucking aluminum fittings are over priced and pain in the ass. They gall up and even the slightest dent causes them to leak. The steel AN fittings however, are solid. This is why I suggested the banjo barbs -- they are steel and cost a fraction of the price. They do the fucking job.

How are you flushing the cooler?

[Rustys14]

My friend's dad is a diesel mechanic and has a parts washer/pump setup at his house so I usually remove the thermostat and pump clean oil through the cooler for a few minutes. Kind of ghetto, but its better then nothing and should flush most of the old oil (provided there isn't a bunch of sludge) out of the cooler. Honestly the old oil shouldn't make too much of a difference as long as there aren't any metal shavings in it, but I always feel better running some clean oil through since you usually have no idea why the donor car is in the junkyard.

The guy who taught me about these coolers used to flush them with water followed buy a whole bunch of compressed air but I REALLY don't like that method because I worry that the water would get trapped in the endtank and cause damage to the engine. That said he has used several of these coolers in the past and hasn't ever had any issues so maybe I'm the idiot who likes to do things the hard way...

I agree that the AN fittings are a bit pricy and have their flaws but I still prefer them over the barb setup. To each their own though, either will work fine and your option is cheaper.

[Def]

Never use PTFE tape on metric straight threads - always use a crush washer.

ONLY USE PTFE TAPE ON PIPE THREADS!!!


I think 95% of the posters on Zilvia improperly use teflon tape and wonder why their shit is leaking all over the place.

[Rustys14]

Never use PTFE tape on metric straight threads - always use a crush washer.

ONLY USE PTFE TAPE ON PIPE THREADS!!!


I think 95% of the posters on Zilvia improperly use teflon tape and wonder why their shit is leaking all over the place.

That topic was already addressed, but I should probably add it to the original post. Crush washers are DEFINITELY the way to go. I honestly didn't know that the teflon tape didn't work on metric threaded bolts until I made this thread, so its good that people caught it.

Edit: Edited original post to reflect the tape issue

[ixfxi]

You should keep teflon out of anything that has to do with the oiling system. On small piece of teflon could clog something vital and leave you fucked. Remember, straight threads are not designed to seal - thats what the machined surface is for, hence the reason for the crush washer. Either that or o-ring boss. The Setrab fittings on my oil cooler are ORB.

If I were to flush that cooler, I would use mineral spirits or some type of inexpensive solvent. Anyone have any other suggestions?

[Rustys14]

If I were to flush that cooler, I would use mineral spirits or some type of inexpensive solvent. Anyone have any other suggestions?

I'm sure mineral spirits will work as well and would probably do a better job of breaking up any sludge that may be trapped in the cooler. My main concern with using chemicals (especially ones designed to break down oil) is that some of the solution may get stuck in the cooler and cause issues when it mixes with oil in the engine. Maybe it would be best to do a chemical flush followed by a flush with clean oil? I might just be paranoid though, since there probably wouldn't be enough trapped in the cooler to cause any real damage...

[FaLKoN240]

Is there anyway to pressurize the process? That would probably help too.

Maybe put an inline restrictor on the in or out?

[ixfxi]

I dont think the cooler would hold onto enough solvent to make a shits worth of a difference. You only have the end tanks and the tubes. I would just empty it well and then blow some compressed air through it for about 5-10 minutes. I would install it a few days later.

Remember that solvent evaporates.