leonrx7

Might be a bit of a silly question, but at what temp does the standard thermostat open on a fd? and what oppearting temp is normal? and what is too high? ive recently installed an aftermarket temp gauge because the stock one seems useless! I just want to know what temp to turn the car off if it did get high.. ive heard a lot of bad stories about overheating rotaries.. lol

Signal 2

IIRC the factory thermostat fully opens at 95 C. What is 'normal' temp for your car depends alot on ambient temp. Obviously if it's really hot outside, the car will tend to run hotter. The factory thermoswitch which activates the fans is set at 105 C. But many of us install the 89-91 FC thermoswitch which is a direct plug-in but activates the fans earlier, at 95 C.

Your smart to install the aftermarket gauge. Any responsible owner of an FD should do the same. The factory temp gauge isn't linear and really is worse than no gauge at all since it gives a false sense of security.

As for temps getting too high, most of what I read suggests that coolant seals can begin to degrade at about 115 C.

Other inexpensive things to do for cooling....keep as much distilled water to FRESH coolant as you can safely where you live. Use upholstery foam to plug any little gaps around the radiator. Replace the factory caps if they're old.

leonrx7

Thanks for the fast reply, well i left it on idle for about ten mins and the temp stayed constant at around 85c i wont be driving it for a while got plenty more ideas for the car before its ready.. and plenty more to do lol. Yeah, the factory gauge just sat half way all of the time which was annoying and i didnt trust it. thanks, i have changed factory caps and will try the upholstery foam tip!. Im still quite new to FD's but i have been reading alot its become a sort of obsession the past couple of years, also.. the car seems to get very hot compared to that of other jap cars ive had, but i just put that down to the heat the engine generates compared to a piston engine? ill look into putting the 89-91 thermoswitch in, is it easy enough to do? i also know the 'AC' button will activate fans alone with air con, thanks again, Leon

Signal 2

Replacing the fan thermoswitch isn't exactly a walk-in-the-park, but it's not THAT difficult either. It sits behind the waterpump housing and you'll have to remove the crossover, alternator and a few other things to reach it. Search for a Factory Service Manual (FSM) for more info and a better idea of what's involved. It's not an uncommon mod so a previous owner may have already changed it. With that new temp gauge installed you might want to watch carefully from a cold start and see when the fans come on.



Other basic (but not necessarily cheap) reliability mods for cooling include replacing OEM radiator with an all-metal version. The factory radiator had plastic end-tanks which can fail with heat and age. Usually guys go for something with a little larger capacity. Two common brands are Fluidyne (150% larger) and Koyo (200% larger) but the larger you go, typically the more issues you'll have with fitment. The Air Separation Tank (AST) should be swapped for an all-metal version for the same reasons. But again, these might have already been done by a previous owner...just thought I'd mention them.

Lastly, if your car wasn't equipped with dual oil coolers you can add the second one using new or used parts. It's definitely more involved but worthwhile.

thatpoorguy

I have a koyo rad and a Fmic and fitment is fine but you have to make your own mounting brackets. I you go the same route keep a decent gap between the intercooler and the rad. I hit a raccoon at 70mph and it made the Fmic punch a hole in my old fluidyne radiator. My thermostat must've been changed at some point because according to my commander my temps rarely go above 85 C even during the hottest parts of summer

leonrx7

Thanks, thats really helpful i will have a look at the radiators asap, ill get that done next, i know its a standard rad in the car, i have fitted a stainless AST which i can see the build quality is much better! i presume the rads are also better, thats a simple idea i hadnt thought of, 'turning the car on and see what temp the fans come on' ill defo do that before anything, cheers! im really unsure of any mods on the car other than what ive been doing gradually, because i got the car at a real bargain price i havent heard from the owner since.. i think he regrets selling it, he didnt want to at the time lol! its done around 29 thousand miles (42 thousand km). engine seems to run quite well so far, just been worried about it getting to hot..



I have had trouble getting a coolant temp sensor, ive managed to get one from a local car spares shop but instead of having one 'prong' for the single wire to connect, this one had two? would you know why this is?



thanks Leon

Signal 2

There is a coolant temp sensor that signals the ECU with the current engine temperature...can't recall how many wire lead it has.

There's also coolant thermosensor which signals the fans to turn on. You may have gotten the wrong one.