FC thermoswitch for FD
02-19-05, 10:31 PM
#1
RX-7 Bad Ass
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It's official - do NOT buy a Miata thermoswitch until you read this!
OK, I guinea pigged this one, and all worked out for the best 
.
As you may recall, I posted a while back that I saw in a copy of RX-7 Magazine from Japan that they were using the '89-91 FC thermoswitch as an upgrade. This jogged my thinking...well, fast forward to today. I got the thermoswitch last week and installed it today.
Here's the deal -
- SAME operating specs as the Miata switch
- BUT, uses the stock FD plug - NO CUTTING OR HACKING. Unscrew old switch, screw this one in, plug it in, you're done.
It was about $50 from Ray Crowe at Malloy Mazda (1-888-544-3400). He didn't have it in stock, so it took a day or two for him to get it and ship it my way. But, I explained the deal with the switch to him, and he was VERY interested - I think if he gets an order or two, this will be a stocked item soon. Part number is PN41-18-840. It's for the '89-91 RX-7, non-turbo or turbo.
Dunno if you can see on the pics, but the FD switch has "108" on it, and the FC switch has "95" stamped on it. That's the switch-on temps - 95 deg. C and 108 deg. C. Fans come on sooner, car stays cooler, engine stays happier.
It was a little bit of work to install. I removed the crossover pipe and alternator, then had access. Unplugged the old switch (you have to hunt for the "button" to unlatch the connector - it was on the under side of mine), used a 17mm closed-end wrench to break it loose, then unscrewed it. Some water was lost, but it was just water in the top of the thermostat housing. Put a little oil on the O-ring on the new switch (came with the switch, and it was already on there) and screwed it in. Plugged everything back together, put the car back together, good to go. Pulling the alternator was the most time consuming part - it's a little tricky to get out of there.
Anyhow, this is a done deal - the Miata thermoswitch is now a "dead mod". Unless it's WAY the hell cheaper or something. I'd much rather have one that plugs right in just like stock!
Dale
.As you may recall, I posted a while back that I saw in a copy of RX-7 Magazine from Japan that they were using the '89-91 FC thermoswitch as an upgrade. This jogged my thinking...well, fast forward to today. I got the thermoswitch last week and installed it today.
Here's the deal -
- SAME operating specs as the Miata switch
- BUT, uses the stock FD plug - NO CUTTING OR HACKING. Unscrew old switch, screw this one in, plug it in, you're done.
It was about $50 from Ray Crowe at Malloy Mazda (1-888-544-3400). He didn't have it in stock, so it took a day or two for him to get it and ship it my way. But, I explained the deal with the switch to him, and he was VERY interested - I think if he gets an order or two, this will be a stocked item soon. Part number is PN41-18-840. It's for the '89-91 RX-7, non-turbo or turbo.
Dunno if you can see on the pics, but the FD switch has "108" on it, and the FC switch has "95" stamped on it. That's the switch-on temps - 95 deg. C and 108 deg. C. Fans come on sooner, car stays cooler, engine stays happier.
It was a little bit of work to install. I removed the crossover pipe and alternator, then had access. Unplugged the old switch (you have to hunt for the "button" to unlatch the connector - it was on the under side of mine), used a 17mm closed-end wrench to break it loose, then unscrewed it. Some water was lost, but it was just water in the top of the thermostat housing. Put a little oil on the O-ring on the new switch (came with the switch, and it was already on there) and screwed it in. Plugged everything back together, put the car back together, good to go. Pulling the alternator was the most time consuming part - it's a little tricky to get out of there.
Anyhow, this is a done deal - the Miata thermoswitch is now a "dead mod"
. Unless it's WAY the hell cheaper or something. I'd much rather have one that plugs right in just like stock!Dale
02-19-05, 11:38 PM
#5
RX-7 Bad Ass
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Yep, comes on at the right temp and everything - has the same operating properties as the Miata switch.
Dale
Dale
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02-20-05, 12:10 AM
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Originally Posted by skunks
what again does the thermoswitch do again?
Originally Posted by DaleClark
Dunno if you can see on the pics, but the FD switch has "108" on it, and the FC switch has "95" stamped on it. That's the switch-on temps - 95 deg. C and 108 deg. C. Fans come on sooner, car stays cooler, engine stays happier.
Originally Posted by adam c
Did you check it to make sure the fans came on at 210?
-Alex
02-20-05, 02:33 AM
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Originally Posted by superior force
question is who cares?
the car runs fine with the stock switch
the car runs fine with the stock switch
If you havn't noticed our cars run pretty damn hot. The FC thermoswitch allows the fans to turn on sooner to help insure the car doesnt over heat. Especially people with front mounts, and heavily modded cars.
-Alex
02-20-05, 02:38 AM
#14
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Originally Posted by superior force
question is who cares?
Reliability is everything on an FD. Having the thermoswitch make the fans come on at 95ºC especially for people that live in hot sunny *** areas all the time. Or people that encounter heavy traffic going to or from work. Thats like saying, "Why get a bigger radiator? The stock one is fine." Again, maybe YOU haven't encountered close-overheating problems, temp. rising in heavy traffic on a hot day, etc. But MANY MANY MANY other people have noticed cooling differences and appreciate people like Dale in discovering more and more upcoming ideas, write-ups and information to help out the rest of the Rx7 community. Go do a search about the miata thermo-switch and see how many people love the earlier temp that the fans go on. You'll also find that many people question how to wire the miata thermo-switch due to the switch having two wires and not one. This FC thermo-switch makes things alot easier as to not stir up confusion during the swapping process and to also serve the same purpose as the miata thermoswitch. So before you go doing the whole "who cares?" thing, have some support for your statement so people don't just straight flame you for something like what you just did.
Mad props Dale. I was looking into the miata thermoswitch mod and now seeing this makes things alot easier with the wiring
. Annnd maybe the price?
Jeremy
02-20-05, 02:39 AM
#15
No it's not Turbo'd
Yes, Anyone with a Programmable Engine Management system, EMS...
Power FC, Haltech, Microtech, AEM, Etc... can change some settings in the programming of the EMS, to have the fans come on whenever you want.... so this is a Reliability mod for people with the Stock Computer (EMS).....
-DC
Power FC, Haltech, Microtech, AEM, Etc... can change some settings in the programming of the EMS, to have the fans come on whenever you want.... so this is a Reliability mod for people with the Stock Computer (EMS).....
-DC
02-20-05, 10:09 AM
#19
RX-7 Bad Ass
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You could get a switch out of an FC, but it might be a good idea to find a new O-ring for the switch to ensure a good seal. Dunno if Mazda sells that part, but I imagine if you go to an auto parts store with a selection of O-rings you could find one that would work.
That's interesting that you would have a 115 deg. C switch - I'll have to look into that one.
I'm still not 100% certain why Mazda tried to make the FD run SO hot. It may have been for fuel economy or something - a hotter engine gets better fuel economy. But, it really beats the hell out of all the other parts of the motor.
IMHO, if you can keep the temps reasonable, I believe that will promote longer engine life. Running over 100 deg. C may not be *bad*, but I think long-term it's not the healthiest for the engine.
I have other ideas on the fans as well - stay tuned. I've hopefully got some more good stuff on this one.
Thanks for all the positive feedback!
Dale
That's interesting that you would have a 115 deg. C switch - I'll have to look into that one.
I'm still not 100% certain why Mazda tried to make the FD run SO hot. It may have been for fuel economy or something - a hotter engine gets better fuel economy. But, it really beats the hell out of all the other parts of the motor.
IMHO, if you can keep the temps reasonable, I believe that will promote longer engine life. Running over 100 deg. C may not be *bad*, but I think long-term it's not the healthiest for the engine.
I have other ideas on the fans as well - stay tuned. I've hopefully got some more good stuff on this one
.Thanks for all the positive feedback!
Dale
02-20-05, 10:24 AM
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Thanks Dale, for fixing another Mazda engineering flake...
I don't care how well everything works in stock form, the engineer's best route is to "Over-engineer" products. Make things MORE than capable of how they are when things are "Right". Twin towers that can hopefully withstand a hit by a 747 for example....
Plastic endtanks on something (Radiator) that holds coolant, plastic AST tanks, a HIGHER degree thermoswitch,...ugh. Gee, this new Rx7 will have more power, 2 turbo's, and probably make more heat...lets make things plastic and let the fans wait even LONGER to come on than the FC! BRILLIANT!
Hope the one guy who had these awesome idea's was fired. I know they wanted weight savings as a mindset, but come on...
Nonetheless, thanks for an awesome find. BTW- 95c is 205f for those of you (LIKE ME!) that have Water Temp gauges that read in Fahrenheit.
I don't care how well everything works in stock form, the engineer's best route is to "Over-engineer" products. Make things MORE than capable of how they are when things are "Right". Twin towers that can hopefully withstand a hit by a 747 for example....
Plastic endtanks on something (Radiator) that holds coolant, plastic AST tanks, a HIGHER degree thermoswitch,...ugh. Gee, this new Rx7 will have more power, 2 turbo's, and probably make more heat...lets make things plastic and let the fans wait even LONGER to come on than the FC! BRILLIANT!
Hope the one guy who had these awesome idea's was fired. I know they wanted weight savings as a mindset, but come on...
Nonetheless, thanks for an awesome find. BTW- 95c is 205f for those of you (LIKE ME!) that have Water Temp gauges that read in Fahrenheit.
02-20-05, 10:32 AM
#23
RX-7 Bad Ass
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The plastic AST was a bad idea. Plastic/aluminum radiators are actually prety nice - very efficient, less prone to corrosion, and light weight. The sad thing is plastic end tanks CAN be replaced, but there aren't many places in the US that can do that kind of work.
Also, the FC had a clutch-driven fan as its main cooling method. The electric fan was a VERY small fan (about 8-10") in front of the radiator and condenser that only ran if the car got hot enough (kicked on by the thermoswitch) or if the AC was on to increase air flow through the AC condenser.
Considering the FC ran relatively cool, it's still odd that the FD ran so hot. They may have needed to run the car hotter to get fuel economy to where they wanted so it wouldn't have been hit with the gas guzzler tax. It may be another thing, like the precat, that Mazda *had* to do to be able to sell the FD in the US.
But, the good thing is we can find solutions around the things Mazda had to do. That's the goal with my car - to make it into the car that Mazda wanted to build.
Dale
Also, the FC had a clutch-driven fan as its main cooling method. The electric fan was a VERY small fan (about 8-10") in front of the radiator and condenser that only ran if the car got hot enough (kicked on by the thermoswitch) or if the AC was on to increase air flow through the AC condenser.
Considering the FC ran relatively cool, it's still odd that the FD ran so hot. They may have needed to run the car hotter to get fuel economy to where they wanted so it wouldn't have been hit with the gas guzzler tax. It may be another thing, like the precat, that Mazda *had* to do to be able to sell the FD in the US.
But, the good thing is we can find solutions around the things Mazda had to do. That's the goal with my car - to make it into the car that Mazda wanted to build.
Dale
02-20-05, 10:54 AM
#24
Rotary Enthusiast
"However, I am perplexed as to why I have a 115 degree switch? Maybe because of the automatic tranny?"
This is a separate trans switch for autos, located where one of the plugs normally resides in the fill neck hsg. If coolant hits 240F, atx logic engages torque converter lock-up more often, to reduce heat from torque converter.
You still have 108C fan switch, behind t-stat. Replacing with FC-or-miata switch means, with ac off, fans come on 1st at 207F at med speed, vs 221F (ecu controlled) at slow speed then 226F at med speed. Note this may only change med speed trip to 221F for some.
Alternative is to run with parking lights on, or cabin fan at 3 or more, in hot traffic. This trips fans on slow at about 200-210F.
This is a separate trans switch for autos, located where one of the plugs normally resides in the fill neck hsg. If coolant hits 240F, atx logic engages torque converter lock-up more often, to reduce heat from torque converter.
You still have 108C fan switch, behind t-stat. Replacing with FC-or-miata switch means, with ac off, fans come on 1st at 207F at med speed, vs 221F (ecu controlled) at slow speed then 226F at med speed. Note this may only change med speed trip to 221F for some.
Alternative is to run with parking lights on, or cabin fan at 3 or more, in hot traffic. This trips fans on slow at about 200-210F.
02-20-05, 11:32 AM
#25
Constant threat
Originally Posted by KevinK2
"However, I am perplexed as to why I have a 115 degree switch? Maybe because of the automatic tranny?"
This is a separate trans switch for autos, located where one of the plugs normally resides in the fill neck hsg. If coolant hits 240F, atx logic engages torque converter lock-up more often, to reduce heat from torque converter.
You still have 108C fan switch, behind t-stat.
This is a separate trans switch for autos, located where one of the plugs normally resides in the fill neck hsg. If coolant hits 240F, atx logic engages torque converter lock-up more often, to reduce heat from torque converter.
You still have 108C fan switch, behind t-stat.
Thanks for the info!
(Though I feel a little stupid.....)
