Another RB overheating thread

[godzilla_753]

So Ive read the sticky on the overheating issues that RB's have. Ive bled the system multiple times with the heat on and it jacked up. Ive got it mostly under control the only problem is my temps go up as soon I get on it at all, even normal acceleration I see the temps immedietly responding to the increased load on the engine. At idle the car sits about 80*c with the fans cycling on and off, but under load the temp rises, it got to 100C and i shut the car off
The car currently has:

Koyo radiator
2 12" pusher fans on the condensor in front of the condensor (I planned on running a/c until this overheating s*** started)
1 12" puller fan with shroud (when the fans kick on together they are pushing ALOT of air)
Honda coolant (per that overheating thread)
Brand new water pump
Compression is even and good across all cylinders
Coolant flush (alot of gunk came out, car had been sitting with nothing but water inside for awhile)

Overall the car itself runs pretty good, Idles at 850 ish, I recently did the timing belt with the water pump, and pretty much eyeballed the timing, according to the FSM a consult cable is needed to set timing properly, I bought a consult cable and im in the process of rechecking the timing to rule that out, but other than that Im really stumped. My next action would be to add an undertray and some ducting.

What could be causing this stupid overheating while driving? If i leave the fans on, theyll keep the engine at 70C all day long.

oh and btw this is all on a RB25det NEO - I adapted the 26 throttles and intake manifold but I dont think this has anything to do with the overheating. If anyones interested ill post some pics.

[SlowKoop]

From what I remember some people have problems with they koyo radiator, because the fins are really close together.

[Yellow4g63]

Get one of those swirl pots, it will really bleed the system right with no guess work.

[godzilla_753]

Really thinking about going back to the stock radiator, saw some threads where people managed to fit the stock clutch fan and shroud with a little trimming.

[Darius]

Is the thermostat stuck closed?

[godzilla_753]

Forgot to mention that Ive got a brand new Nismo thermostat, dont think its stuck, Ive got my temp probe after the thermo so my gauge only reads temp once the Thermo opens (its kinda cool because I can see exactly when it opens when Im warming up the car). Im not sure whats going on with it now, drove it today to the muffler shop to pick up some pipes and the car ran like a champ never went above 80C (I had the fans hooked up constant to the battery, Im in the process of rewiring the fans with a better thermo switch).

I think Ill drive it some more, ill set my thermo to 85C and see what it does, hopefully the fans cycle on and off like they should, I know the fans shouldnt be running all the time.

[LSDrift]

Considering you have pullers and pushers on a koyo I'm assuming you have an S14? I have two 12" FAL pullers on a S14DE radiator in my S13 and I don't ever have any overheating trouble until I stay on the highway for extended periods of time in 85+ degree weather. Due to this fact though, I'm going to probably go back to the clutch fan because it seems to be the end all in the threads I've read for fixing overheating.

Sometimes I wonder though, with pusher fans, could it be impeding airflow to the radiator while driving? How's your ducting up to the radiator itself? FMIC in the way? I'm also assuming you don't have an A/C condenser in the way because of your pushers...I still need to remove mine.

[godzilla_753]

Lol I actually have a hatch, AND have the condensor as well. Thats a good point, I can see how the pushers would be impeding flow. The damn clutch fan does seem to be the end all, that thing pushes massive amounts of air. As far as I can tell my setup should be good now, dont know what happened but its running great now. Im gonna hook my A/C and see what that does to the system.

Ill post up pic of my fan setup if you want, Ive got 2 12's on the front with no shroud, and then a single 10" on the other side pulling air out.

[LSDrift]

Yeah put some pictures up. I'm amazed you got pushers in there with the A/C condenser too! Good to hear it is working good now though, maybe you had a build up or mild blockage in your system from old dried out coolant build up...I know my system is still somewhat orangeish after dropping the coolant 3 times. I really need to flush it.

[godzilla_753]

lol know exactly how you feel, I flushed mine at least 3-4 times before the coolant stopped looking like crap, Ill take some pics for sure, gotta borrow a camera. Im so excited, the car runs beautifully now, AAC valve opens and closes like it should (had to remote mount it because of the GTR plenum).

[240z4u]

I am guessing you didn't reinstall any way to bleed the cooling system when you swapped intake setups. The factory setup has a bolt you undo to let the air out at the highest point in the system. Do you still have this? It was located on the forward part of the intake manifold and had a little gold sticker next to it.

[godzilla_753]

nope thought of that, the r34 AAC valve has the bleeder screw built in, I hung it up higher than the engine and opened up the bleeder valve to bleed the system, bunch of bubbles came out. Think Im going to invest in a swirl pot though, should make any further bubbles easily bleedable

[Yellow4g63]

If you look on ebay they call them radiator breathers. Well worth it.

[godzilla_753]

Ive heard, Ill be ordering one from Powered by Max theyve got some cool looking ones. Thanks for the help though guys, and LSDrift ill be posting up pics soon, been so busy with work and school havent had a chance

[LSDrift]

Oh I hear ya, I just got a chance last night to flush my coolant again and I'm still getting brown crap. Put some more cleaner in there though so hopefully that takes care of it. I'll be installing a defi temp gauge here soon too so that'll be neat. I'm definitely going to get one of those swirl pots as well...not sure which brand though. I'm kind of a Greddy whore but am a little low on cash lately.

Btw those powered by max ones are crazy lol.

[godzilla_753]

ok man i finally got some good pictures of the setup. I got the PBM overflow installed. STILL overheated, I finally caved in and took all my front end apart to fit the clutch fan back in. Honestly if you have the tools, this is the easiest way to go. Im not sitting at 65/70 C, Im thinking my setup is TOO good now, ive got honda coolant, with the PBM coolant tank, plus the clutch fan and nismo thermo. Even with hard driving it barely got to 70. Im gonna recheck a few things, but I might be taking the nismo thermo out, and putting a regular z32 one in, when it gets cold over here, this thing will never warm up...

ok here are some pics!

[gawdzilla]

Even with hard driving it barely got to 70. Im gonna recheck a few things, but I might be taking the nismo thermo out, and putting a regular z32 one in, when it gets cold over here, this thing will never warm up...

good to hear. i'm also somewhat in the same situation now. clutch fan in and the temps on a cool, 55 degree day i can't even get the motor to a healthy 180F. also thinking about going to an oem thermostat as well. looking back, the low temp thermostat might've been a ricer mod

i've also got a hood vent going in. eager to see how well everything does on the track in 95+ degree heat.

[LSDrift]

That's awesome to hear that you guys are having such good luck with the clutch fan. I've still been just running the 2 12" FAL pullers with the S14 AT Radiator. Works decent in town but the motor puts out way too much heat on the highway for the system to keep up. I'm not going to worry about it till winter is over here in Montana though cause I'm already having a hard time getting it up to 170-180 range before I get to school. And that's with a 10 minute warm up lol.

My question is, how are people trimming the clutch fan to fit without causing it to wobble due to balance issues? I see that you guys both have S14s so maybe you aren't trimming the fans whereas I have to trim it in the S13.

I've got a 2" Koyo radiator sitting in my garage at the moment but I don't even think that trimming and flipping the fan would allow it to fit in. I already went through one run of the trimmed fan with my S14 radiator but I apparently didn't cut each blade close enough to the same and it ended up wobbling enough to worry about.

I've been thinking about one of those new Chase Bays ones that are designed to fit under the upper radiator support...$400 bucks though...can't quite make that up with selling the Koyo even though it's unused hah

[USMCgetsome]

ok to begin with tell me what alternator your running. next tell us what relays your using to run the fans. You need some serious amps to run those 12in fans they usually pull 20-30 AMPS a piece. So next time your under the hood feel how hot the power and ground wires feel. You'll need to get a better amp rated relay to take the heat off the motor of the fan. Also, are the fans a two step fan that run at a low and high speed or just one high speed? Are your fans running in FWD OR REVERSE AND CHECK THE DIRECTIONS OF THE FAN BLADE THEMSELVES! Are they running the whole time or do you have a fan contoller?

After all the the next step is lookin into a blown headgasket.

[godzilla_753]

to Gawdzilla:
I agree, only reason I put the nismo thermo in was because I couldnt get the darn thing to stop overheating, now that Ive got an adequate cooling system Im thinking its gonna have to go. Have you had any problems with your engine running cool? Im not gonna lie, mine runs great but it seems to still be lacking according to my butt dyno haha. Im thinking about hooking up consult to see if I have any codes.

To LSdrift:
Ive actually got an S13 just like you man. Heres what I did:
Ive got a big a** Koyo radiator, at least 3 inch thick so im guessing its its the double/triple core one. Buying a new one was out of the question as I decided im not going to spend anymore money until the car became drivable.
I started by cutting the top radiator support and taking out my condensor, In my pictures if you look closely youll see Ive actually fit my whole koyo underneath. When I dropped it in it was obviously too tall, I had to modify the lower radiator support as well, I ended up cutting it and moving it forward and rewelding it all together. On the bottom theres your 2 brackets for the suspension (the long triangle things that tie your suspension to the lower core support with 2 bolts on each side, look at the nismo power brace) I had to extend this brace so that it could be bolted back up.

Once I did that (about a days worth of work), I dropped in my unmodified RB clutch fan, Ive got TONS of clearance now, easily will be able to fit a fan shroud in there. This also allowed me to keep my condensor as theres stilll some room under the core support with the koyo. Im going to be getting my lines made soon for it so I can run A/C. I kept my two pushers on the condensor, these will only come on now with A/C.

Im telling you man, the only way us S13 folks can get any cooling love is to run that clutch fan, the amount of air it pushes it stupid, I bet you half the reason why it work so well is because Its throwing so much air onto the engine itself and circulating that air out. If you dont want to have to get rid of the koyo and dont mind a little fab, you can easily get it under the core support and run your clutch fan. Take a closer look at my pics, Id be happy to answer any questions

[gawdzilla]

to Gawdzilla:
I agree, only reason I put the nismo thermo in was because I couldnt get the darn thing to stop overheating, now that Ive got an adequate cooling system Im thinking its gonna have to go. Have you had any problems with your engine running cool?

I don't street my car that much, maybe once every few weeks on average. mostly track where i make sure oil temps are up to 160s before starting to get on it. So no, but I don't get a good "feeling" when i'm cruising on the highway with the coolant temp in the sub 160 degree range. plus in the winter time the heater sucks when the coolant temps are that low

[LSDrift]

Well good work on making everything fit! I feel like for not recognizing that you have a S13 haha
I'm still running my crash bar so I don't know if I'd have enough room to still have the A/C condenser. I definitely have the goal of eventually running my A/C again someday...but that's not a worry where I'm at in MT until next July pretty much But that was clever cutting the supports to fit such a big radiator. I know it's been done before but good job anyways. I think I might just get the Chase Bays radiator when it comes time for it though...I just seem to be paranoid of doing much cutting even though re-supporting areas with welds etc. can more or less make up for it.

[godzilla_753]

I gotcha man, I wasnt too afraid since this is the only option I had without having to dump more money into it. Sweet thing is I can still hook up the factory ri-bar up. Although I did have to cut some chunks out of it to fit the intercooler. Im gonna be looking at making my own bash bar soon, Im thinking of investing in a pipebender, make a badass bashbar up front like the pro-drift cars out there. Either way, good luck on your cooling woes, hope you get it worked out. Im gonna be cleaning up my engine bay real soon here, and then post it in the "clean RB thread"

[Shocker]

Clutch fan and swirl pot are my best mods to date imo. I can trash my car on a warm day without my temp gauge really moving. I've logged WOT 0 to 150 pulls during 90 degree day and my temps only rise about 4 degrees f. After about 10 seconds its back down to 180. now that the weather is so cool it dues take about 8 to 10 minutes of driving to get to operating temp.

As for getting the fan to fit in a s13 I flipped my fan 180 degrees around on the clutch and added washers as shims to keep the fan off the clutch. That made the fan package at least an inch thinner. I mounted it with the rad in and slightly trimmed and sanded to fit. I run a fluidyne and non cut rad support too.

[higgzy]

to Gawdzilla:
I agree, only reason I put the nismo thermo in was because I couldnt get the darn thing to stop overheating, now that Ive got an adequate cooling system Im thinking its gonna have to go. Have you had any problems with your engine running cool? Im not gonna lie, mine runs great but it seems to still be lacking according to my butt dyno haha. Im thinking about hooking up consult to see if I have any codes.

To LSdrift:
Ive actually got an S13 just like you man. Heres what I did:
Ive got a big a** Koyo radiator, at least 3 inch thick so im guessing its its the double/triple core one. Buying a new one was out of the question as I decided im not going to spend anymore money until the car became drivable.
I started by cutting the top radiator support and taking out my condensor, In my pictures if you look closely youll see Ive actually fit my whole koyo underneath. When I dropped it in it was obviously too tall, I had to modify the lower radiator support as well, I ended up cutting it and moving it forward and rewelding it all together. On the bottom theres your 2 brackets for the suspension (the long triangle things that tie your suspension to the lower core support with 2 bolts on each side, look at the nismo power brace) I had to extend this brace so that it could be bolted back up.

Once I did that (about a days worth of work), I dropped in my unmodified RB clutch fan, Ive got TONS of clearance now, easily will be able to fit a fan shroud in there. This also allowed me to keep my condensor as theres stilll some room under the core support with the koyo. Im going to be getting my lines made soon for it so I can run A/C. I kept my two pushers on the condensor, these will only come on now with A/C.

Im telling you man, the only way us S13 folks can get any cooling love is to run that clutch fan, the amount of air it pushes it stupid, I bet you half the reason why it work so well is because Its throwing so much air onto the engine itself and circulating that air out. If you dont want to have to get rid of the koyo and dont mind a little fab, you can easily get it under the core support and run your clutch fan. Take a closer look at my pics, Id be happy to answer any questions

How did you move the front support forward and extend the brace? Do you have any photos of the progress? I'm toying with the idea now as I have the engine out and need a solution to its overheating. Also does a clutch fan work when the engine is at idle?

[godzilla_753]

I really didnt take too many pictures of the progress, all I have is my crappy cell phone camera. I can definitely walk you through the process. Ill take some pictures of the lower brace, thats where all the magic happens, the top is easy, all you gotta do is chop it up to accomodate your upper rad hose, and cap.

On my bottom brace, it was already pretty loose, my brother accidentally jacked up the care from the middle of the bottom support and ended up popping the spot welds loose. In your case Id drill them out so that you can move the support forward. and reweld. Ill take some good pictures tomorrow and post it up. The clutch fan does indeed run at idle, Ive read numerous threads debating on the whether or not it robs power...thats up to you to decide but in our case the fans needed to provide adequate cooling. The clutch only engages at lower speeds, so idle itll be on all the time, at highway speeds not so much.

One issue I forgot to mention, which might not affect you is that you lose room for the pop up headlight motors if you decide to run the condensor as well, it hits by about 2-3 inches and wont let the motor sit flat against the supports like originally, if this is an issue, im sure you can work around it somehow... Ill take a pic of this as well for future reference if people wanna attempt it. I myself went the supermade bucket style headlight.

[robbie2883]

i didn't take time to read every single post but wanted to tell you i have pretty much the same setup as you mentioned in your first post. Fal pushers (pullers wired backwards) on the front of the condenser both of which sit in front of the radiator. i have no real cooling issues at all. on the hottest days here in FL i'll sometimes creep up to 90-92c in traffic, but it doesn't go higher than that and only gets there maybe once a year. rest of the time i'm in the low-mid 80's during the summer and low to mid 70's in the cooler months. nismo tstat, oem water pump ect....the ONLY difference is i have a swirlpot constantly pulling air out of the system.

[LSDrift]

Shocker - I was hoping you might chime in on this thread. I saw your RB30 thread and was ecstatic to see the clutch fan like you've got it. Like I mentioned above though, how did you trim the blades evenly enough to avoid any balance problems? Shimming it with washers was quite an engineering idea though haha props.

[julio]

Shocker - I was hoping you might chime in on this thread. I saw your RB30 thread and was ecstatic to see the clutch fan like you've got it. Like I mentioned above though, how did you trim the blades evenly enough to avoid any balance problems? Shimming it with washers was quite an engineering idea though haha props.

I used a ruler, a sharpie, and tin snips to trim mine. No huge imbalance issues to speak of and I wouldn't be too worried about it either. How many times have you seen a fan missing part of or even an entire blade and continue to run without issue?

[LSDrift]

Eh, I'm just worried about long term damage to the water pump/pump bearings. I trimmed mine via sharpie and some snips as well and it wasn't a "terrible" imbalance, but it was somewhat wobbly at idle. I'd just like to see how everyone's doing it and their success(or not) with balancing the fan. I had to trim quite a bit off due to my upper radiator hose...ended up going back to the efans for now.