im sure its been covered before, but I cant find where. where is the best place to tap in to the water system for the best temp readings? is that spot right above the t-stat good? or somewhere else? where is the stock water temp sensor? or is the thermosensor the stock one.... if the thermosensor has nothing to do with that... then what DOES the water thermosensor do? and where is the stock location of the water temp sending unit. thanks

 

Above the T-stat - NO

The rest is up to you most tuners and mechanics will tell you pump housing right below the T-stat. I chose the coolant return line below the water thermo sensor. Other people suggest the lower RAD hose but this will yield you tuning to lower numbers. Some gauges have a small enough probe to put them in the stock block setting.

 

what do you use to drill the hole I believe the bung ive got to screw in is 5/8. I dont think ive got a bit that big, so id have to use a spade wood working bit....

and like I asked before... what exactly DOES the thermosensor do? my check engine light is telling me mine is broken, but I dont know what its affecting

 

You use smaller bits and work your way up to a 5/8s bit as I did then you tap it with a 5/8s x 18 thread tap. You need to go buy some bits or take it to a machine shop.

IIRC the WTS tells the ECU the water temps so that it can add more or take away fuel and advance or retard timing. Just another link in the chain.

 

I see from the fsm that the stock location for the temp gauge is on the rear of the engine block. Is this a good location? if my gauge kit came with the correct adapter to screw in... would it be a good place for my gauge sensor?

does anyone know what size the hole is that holds the sensor in?

 

ilike2eatricers is using that location with his blitz gauge. Unfortunately I do not know of any sites or have data logged on what is normal operating temps in that location. IMHO that location is subdued to temp spikes and the pump housing is a more solid reading as will tell you right when your T-stat should be opening.

 

There is a threaded plug on the drivers side of the front plate. One of the fitting adpaters from my autometer guage fits there perfectly

 

Mine is there.... So what? (Yes, I know that NZconvertible is going to have a field day with this..) Just because I have to wait a few mins longer, the readings are still the same (as verified on my laptop). Actually, an even better place would be to remove the stock sensor for water temp (gauge) which is located in the oil filter area, and put your sensor there.

Thats basically what it does, although I dont think it affects timing so much. It compensates for whats known as BSFC. I am going to let you figure that one for yourself, but what it boils down to, is that a car needs more fuel when its cold, and less fuel when its warm. This is why alot of cars are running hotter these days, it assists in fuel economy.

Yep, I have seen this also. Kind of a bitch to get to though when your PS is installed.

 

what is the front plate?


my only problem was that I dont have a 5/8 bit, guess its time to go shopping.

 

IIRC it has an allen plug in it. I posted some pictures of it a few years back.

 

eh sorry a term I use, it is in the front side housing

Even without the PS or AC equipment there, the plug was still a pain to get out. The hex wrench was a perfect fit, but still ended up rounding the socket for it.
I ended up using a Bolt Out tool to get the sucker off. #8 Craftsman

 

Thx for the add-ons J-Rat. I have to argue the before T stat so please debate back helps us all learn.

How can it possibly be the same temp?? The water ahs already gone through all its cooling stages and is waiting to take place of the hotter water in the motor and pump housing? If I spike temps from a long pull I will see my temp gauge just under T stat spike up and quickly drop when the T-stat pops full lift then closes. This has to indicate that the water outside of it is cooler then the water inside.

 

so there is a spot in the fronmt rotor housing for one of the adapters? thats awesome..

 

I think one of us has our coolant flow backwards, and I can pretty much guess who it is.

Unless I am completely off base, water flows from the bottom of radiator, through the block, then up through the water neck, through the thermostat. That means the difference in temperature of the water being sampled over the thermostat as opposed to under it (assuming the thermostat is now open), is EXACTLY THE SAME. Unless the extra 2 inches of travel is that critical.

The only downfall to the way I do it (and I freely accept it as being a downfall), is that if your thermostat happens to start malfunctioning (as in sticking closed) you will get a slower reading, if at all. Unless you dont scan your gauges, you will discover the anomoly before any damage occurs.

 

I searched for "where install water temp".

2nd hit: https://www.rx7club.com/forum/showthread.php?t=459639
About 1/4 down the page: https://www.rx7club.com/forum/showthread.php?t=433079
About 1/2 down way down the page: https://www.rx7club.com/forum/showthread.php?t=314526
1/2 down the page: https://www.rx7club.com/forum/showthread.php?t=402793
https://www.rx7club.com/forum/showthread.php?t=203915
3/4 down the page: https://www.rx7club.com/forum/showthread.php?t=361879

So I'm not sure what you searched for, but I had no trouble at all finding it with 10 seconds of searching.

 

Bad J-Rat assuming I have my flows backwards ;-) Of course the water leaves the motor into the lower RAD and comes back into the motor through the top. This means the top is the colder water getting ready to go into the motor. Now I completely agree that the lower hose is a safe place to use your temp sensor but the degF/C that you judge good bad temps buy are lower then in the housing or block.

So with a T-stat blocking the flow of the hot water going backwards and the RAD has cooled the other side of it how on earth are these temps the same between pump side of T-stat and RAD side of T-stat?

 

Let me clarify, one of the adapters that came with my guage happened to fit in the threaded plug. I bought the Z series from Autometer with an electric sender. I really have no idea what the purpose of the threaded plug really is.

 

You have your flow wrong. You REALLY, REALLY need to get a fsm and look at the COOLING SYSTEM. There is a picture of the water flow there.

Flow is from the bottom hose of the radiator........to the inlet of the water pump.......to passages in the left top half of the housings (front, rotor, intermediate, rotor, rear housings) then back to the water pump thru the reverse process using other passages in the housings, then from the water pump past the thermostat to the top hose of the radiator. Pictures and flow diagram shown in the COOLING SYSTEM chapter.

 

In case anybody is wondering I dont get temp spikes in the stock sensor location.

Hmmm sounds like what I did!! Stock temp gauge for s5's= useless. S4's are a little better but not by much IMO. I dont see a reason for the stock temp gauge if you know your aftermarket one is reliable and accurate.

 

And recently (this last weekend) I took some advive off this forum and installed a Autometer water temp sensor in the drain hole in the intermediate housing. OOOOps. Not a good place. The first thing I noitced was how the water temp rose waaay slower than the oil temps and quite a bit slower than what I saw with the sensor in the outlet hose of the water pump.

The reason is easy to see if you go look at a intermediate housing. That *DRAIN* hole goes to a passage that is about eight inches long and interfaces with the water passages in the middle of the housing. What it is, is there is no FLOW there. It's a dead ended passage until you open the drain plug (now replaced with a sensor). So this water in that eight inch long dead end is slow to get up to temperature.

Fortunatly my stock series four gauge works fine. I reckon I'll buy a new sensor and do the drill job on the back of the water pump. CAn't use the one in the drain because I used a die to make threads on it of the drain size for that installation. Or maybe just put it back in the home made pipe in the upper radiator hose where it was before last weekend.

The plug in the front housing that was mentioned above sounds promising but I have A/C and it would be harder than drilling the back of the water pump housing where there is a boss already waiting to be drilled. hope nzconvertible does not read this and say *told you so*

 

That is the oposit flow chart diagram I looked at for my RAD S4 FC but allrighty I trust you and the FSM thx HAILERS.

 

This is what I was trying to explain to ICEBLUE.. Water goes FROM THE RADIATOR, to the BLOCK, then OUT the block at the TOP of the motor, and BACK TO THE RADIATOR.

How about you apoloze for calling me out?

 

I didn’t call you out I asked you to explain. The remark on bad rat was humor that was the point of the smile face "sorry". I argued my explanation of how my diagram I was going off of worked. It was wrong HAILERS explained why since no one else did and cleared it up that’s it. The proper temps on the outlet line can be found on fc3spro.com as I thought was the lower it apparently is the upper.

 

I know, I have the threaded adapters too. so this plug goes into the water? or do you have to drill it

 

no tapping required, just thread it in. make sure to use some teflon paste, not tape