dammit.. i thought the hose barb fittings were 1/4!! i guess i have to go back to ACE!

 

I don't think anyone suggested the turbo coolant line for the sender. We were talking about the throttle body coolant line

 

I had to go back too!!

 

What drives the flow when running is pressure drop between the 2 points, and the pressure drop is very low at idle, t-stat wide open. Highest flow will be when t-stat is near closed and revs are high, with high drop across the restrictive bypass path. If turbo line was started at the wp discharge, that would not be the "hottest" source, but would result in highest flow as it is the highest pressure point.

But your right in that flow should always be into the turbo, from a hotter point than the TB input, be it slow at idle. The gage will read very high temps after shutdown, likely higher than at other possible sensor locations, due to thermally induced reverse flow from the turbo. Hope someone tries it ... could be scarey for some :o

 

Dale...it worked like a charm. Thanks for the write up and bump for others looking.

 

I know this thread is old but I had a question, if I have made TB coolant line removal mod, what other coolant line I can use and tap my "T" ?

Thank you !

 

If you did the TB mod, you wouldnt need to "T" into the line, you can just use a straight coupling.

 

I'm personally not sure but according to maxcooper a temp sensor needs to be in the flow of the fluid. Makes sense to me after thinking about it.

http://maxcooper.com/rx7/how-to/spa_gauges/index.html
"Note that temp senders must be in the oil flow, rather than at a dead end to read correctly, unlike pressure senders. "

 

If you are using a Power FC and replace the stock sensor with an aftermarket one, I would assume that the PFC no longer gets a coolant temp reading. Is that correct?

 

True.

Well then he can "T" off where the 2 coolant hoses used to meet at the TB. Thats what i did for my TB mod. I didnt cap off either hose, i simply joined them together.

Im assuming he can "T" off there for the gauge no?

 

You can just loop a section of hose from the T-stat housing to the rear iron, by-passing the TB. Then just insert the 'T' fitting, which I covered with an old section of hose.

 

I didnt tap anything at all. I just purchased a buddy club WATER SENDER ADAPTOR that attches between my coolant hose & where it attaches to the rest of the coolant housing/stock sensor I'll take pics tomorrow morning. Greddy also sells one. I didnt have to drill anything...just 2 clamps & a cut radiator house. Literally 5 minutes & my Water Temp gauge works perfect. looks like this...
then in the center on the other side there is a 1/8 hole drilled for the water sender adaptor

 

That is easier, but doesn't tell you anything until your t-stat opens up. Check the OP's very first post for the downsides. One reason he was motivated to try the TB line in the first place.

 

I see. Well that was my easy solution hahaha

 

^That is also what adam_c had referred to at the beginning of the thread before switching to the throttle body coolant hose as Dale and others recommended.

 

I may have skimmed over it, but did anyone give any pros/cons to putting the sensor here?


Additionally I remember seeing a post not long ago that installed the sensor in the plug on the TOP of the filler neck, are there any pros/cons to that location as well?


Personally I would prefer to install the sensor into the already tapped hole on the top of the filler neck, right next to the cap. I already have a fitting that adapts the sensor to the correct size for that hole, and it fits fine, I just want to make sure it's going to work correctly before I get everything else I'm doing wrapped up and go to use it.

 

JHew84, the photo in your post shows the thermostat housing. When the thermostat is closed, there will be very little coolant flow through this area and the temperature will be much colder than the coolant that is being recirculated inside the engine. This is exactly the place that DaleClark (and others) suggested NOT to put a temperature sensor in the first few posts of this thread.

The filler neck is also on the wrong side of the thermostat and will not see much coolant flow when the thermostat is closed. In the worst case scenario, the thermostat could stick closed and the coolant inside the engine could be boiling but a temperature sensor installed in either of those locations would not know the difference.

 

Ah, thank you, I actually tore apart my old motor last night and realized the same thing. I was under the impression that the two plugs went to different areas and one might be behind the thermostat, but it's not. I also thought they were discussing something different because they kept talking about "tapping" the thermostat housing and both of those places were already tapped, semantics :P.

Guess I'll be hitting up the hardware store tomorrow to get that T setup and install it on the TB line, I agree with dale completely about it being pointless to only see the temp when the thermostat opens.

 

Perfect I'll try that, thanks !

 

^ - regarding the pic above, I understand that the hose goes to the nipple on top of the rear of the engine. But which nipple does it connect to at the front?

My engine came with a single turbo, so the nipple at the rear of the engine (top of pic) is just plugged, but at the front of the engine (bottom of pic) I have two nipples about 3 inches apart, facing the rear of the car, and they are linked by a short piece of hose. My question is which one are you using, and is it safe to just block one off?

It looks like I have 3 options, what would you do?

1. cut the short hose between the two front nipples and splice in a t for the sensor.

2. join the two front nipples with a Y connector, and then run a hose from the connector to the rear of the engine.

3. block one of the front nipples off, and run a line from the rear to the front like in the pic above (if this is the best option, which front nipple is best, upper or lower).

Also, what am I missing that required the front nipples to be looped together? Im sure it was part of the single turbo conversion.

 

The nipple that the hose is connected to is just barely out of frame in my earlier picture. It's high on the back of the waterpump housing. Your just by-passing the TB and going straight to the nipple on the rear iron. (See circled areas in diagram)
They may have looped the TB outlet to one of the turbo coolant line nipples for the twins.

 

I was looking at this area as well to mount a thermo sensor. Has it been ultimately determined that this location is a good / bad spot to place a sensor? To me it seems simple enough to get a 3/8 to 1/8 brass reducer and mount the sensor.

 

Can you explain

 

^^ you should PM him, he posted that over 5 years ago

 

I don't think KevinK2 visits these forums anymore, his account hasn't been logged in for a long time. Search for 'temp gauge linearization,' it may be in the 3rd Gen FAQ /useful links thread: https://www.rx7club.com/3rd-generation-specific-1993-2002-16/faq-3rd-gen-other-useful-links-68640/