I believe, but am not sure, that I may have a cooling problem. I have a seperate pod temperatutre gauge, (detecting temperature at the front-most end of the radiator), in addition to the stock gauge. The pod gauge shows about 108 degrees C before the fans come on. It then cools down quickly, but the fans typically stop at about 102 to 103 degrees, so the operating temp is typically over 100 degrees C on a hot day, (I can reduce this by running the A/C on high and thus having "permanent fan-on). The stock gauge, as usual, is no help at all and says "all's well."

The fans themselves appear to be running correctly, but are mabe being "mis-directed" by the computer.

All may be well but the horror stories of rotary overheating makes me worry!

Looking in the manual I suspect, but am not sure, that the fan switch-on/off is controllled, (via the computer), by the "Water Thermoswitch." This is the sensor that is 0.5 ohms at 101 degrees C and 1 mega-ohm at 108 degrees C. It would seem that the computer checks this and makes a call based on its resistance. In my case it seems to favor the high end of the range to make the calls on the fan.

Can someone verify my above assumptions please?

As everything else seems OK, I want to check out and, if required, replace, the Water Thermoswitch. On the car, this sensor appears to have a sort of green collar at the end of it and it is located on the back of the water pump assembly. Assuming this is correct, I can see it, but I'm not quite sure how to get to it.The manual is not much help and suggests you have to remove a whole bunch of stuff to get to it, (section E-16). I'm sure there is an easier way, so help from anyone who has replaced it would be much appreciated.

Finally I believe ther are 2 additional water temperature sensors, (electrical, that is), on the car. Could somebody tell me what these are and what they do? I assume one is for the stock gauge. Also, I know there is a water level sensor. However, I heard somewhere there is yet another temperature sensor. May be I'm wrong. Would appreciate any input

Thanks

Dave




Thanks

Dave

 

Well the thermoswitch and thermosensor are two different sensors.

I JUST replaced my thermosensor. It is the green 2 prong sensor on the back of the waterpump housing. My car is non-seq so i don't know how well this will work for you, but these are the steps i took.

1. Remove intake pipe
2. Remove upper intercooler pipe
3. Remove Alternator Belt.
4. Remove Alternator
5. Remove some coolant from the filler neck using a turkey baster.. a lot less fluid will come out if you do this.
6. Using a 19mm deep socket and a 3/8" ratchet, remove the old water thermosensor and then replace immediately, that way not a lot of coolant is removed.

Install reverse of removal. Replace lost coolant.

 

There are a ton of write ups on this subject.

Be aware that an auto has an extra temp sensor for the tranny. The filler housing configs are different.

Recommendation - Get an FC thermoswitch.

 

Also. There are 3 total on the water pump housing.

The water level sensor is the one in the front of the housing.. its single blade. IIRC
The water thermosensor is the 2 prong green sensor
The water thermoswitch (controls fans) is the black single blade sensor on the back IIRC
The water temp guage is located on the side of the engine next to the oil pressure switch by the spark plugs. It is single blade as well.

 

Twinturborx7pete -

Thanks for the input. The question then is, "is this the sensor with the described 101/108 degree C operation. From your description, the color is right and the location is right. It seems that we may be talking about the same thing using 2 different names. Did you have similar symptoms to me?

As a final check that we are talking about the same thing, looking in my shop manual, I see no reference to a Thermosensor in the water pump/cooling section, E-16. I only see a "Water Thermoswitch," which seems to be in the same place as you describe. (Sorry, I appreciate your help and I'm not trying to be pedantic here, I'm just trying to be sure we are or are not talking about the same thing).

Thanks

Dave

tsmysak 1 -

Thanks. Car is manual. Is your understanding that the Thermoswitch is located as described in this thread?

I've been though the threads, but still came out confused with the different names, locations, and how to get to it in the easiest way. Hence the post.

Thanks

Dave

 

Twinturborx7pete-

Thanks for the info. It's getting clearer.

Forgive my ignorance - what does "IIRC" stand for?

Dave

 

Twinturborx7pete-

Note, to clarify, my first post to you was sent to you before I saw your second post, above (to when I just replied asking for IIRC clarification).

 

thermosensor trips low speed at 221F
thermoswitch trips med speed at 226F
(FC thermoswitch trips med speed at 207F)

bump both up a speed if ac is on.

 

Pete there's four sensor's/switch's/probes....whatever you want to call them on the thermostat and water pump housing for the auto. Two on the back of the water pump housing, two on the thermostat housing. I always get confused as to which is which on the back of the water pump housing. Tom Johnson was the guy to go to with these questions as he had an absoulte knowledge of how the fans system worked. I would thing the FC replacement would help his problem as well as the fan mod.

 

KevinK2/CantGo Straight -

Thanks for info. Do you have a link/username for Tom Johnson? Anyone know what the IIRC stands for, (ref earlier post above)?

Thanks

 

I wish I knew. I haven't heard from Tom in at least a year and a half (maybe longer) I'm glad you asked about the "IIRC" as I've seen this too and couldn't figure it out.
try this link/thread
https://www.rx7club.com/showthread.p...03#post4607203

 

IIRC = "If I recall correctly"

 

Dave that was worth the price of admission. I've seen it....not that often but enough to wonder WTF !!!! Thanks abunch, Jack